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smithsonian contributions to zoology • number 639

The Maned Wolves of 

Noel Kempff Mercado 

National Park

Edited by

Louise H. Emmons
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smithsonian contributions to zoology • number 639

The Maned Wolves of

Noel Kempff Mercado

National Park

Edited by

Louise H. Emmons

washington d.c.

2012
ABSTRACT

Emmons, Louise H., editor. The Maned Wolves of Noel Kempff Mercado National Park. Smithsonian Contributions to Zoology, number 639, xii + 135 pages, 60 figures, 37 tables, 2012.—We studied the behavioral ecology of maned wolves (Canidae: 

Chrysocyon brachyurus) for 10 years in Cerrado habitat of Noel Kempff National Park, Bolivia. Most data were collected by 

GPS-collar technology, which yielded over 37,000 locations in 27 collar deployments on 10 individuals. The eight chapters 

introduce the study area and methods (1) and describe daily and seasonal activity (2); movements and ranges (3); diet and energetics (4); social interactions and reproduction (5); disease exposure, morbidity and mortality (6); maned wolf conservation 

(7); and finally, we synthesize the results in an overview of maned wolf behavioral ecology, with hypotheses about the unique 

form and function of this atypical canid (8). Activity was temperature related and sharply nocturnal in the dry season but partly 

diurnal in the rainy season. Adult home ranges were 40–123 km2, with strong seasonal variations in land use. Maned wolves 

averaged 14 km/night travel in dry months and 7 km/night during wet months. Breeding pairs shared territories with contiguous borders, which did not overlap with neighboring pairs. Young females twice stayed until adulthood on natal territories, 

as presumed helpers, and acquired the territory upon disappearance/death of the adult females. Females were the holders of 

territories into which males moved to form pairs. Young males all emigrated. By 8 years old, maned wolves showed extreme 

tooth wear, and dental disease was a major cause of morbidity. Habitat loss is the chief conservation issue for the species, but 

drought-related resource loss appears to be reducing the study area population.

RESUMEN

Emmons, Louise H., editor. Los Lobos de Crin de Parque Nacional Noel Kempff Mercado. Smithsonian Contributions to Zoology, 

número 639, xii + 135 páginas, 60 figuras, 37 tablas, 2012.—Estudiamos la ecología de los lobos de crin (Canidae: Chrysocyon) 

durante 10 años en el Parque Nacional Noel Kempff, Bolivia. La mayoría de los datos fueron colectados por la tecnología GPS-decollar, que generó más de 37.000 ubicaciones en 10 individuos. Los ocho capítulos dan a conocer el área de estudio y métodos (1), y 

describen la actividad diaria y estacional (2), movimientos y rangos (3), dieta y energética (4), interacciones sociales y reproducción (5), 

exposición a enfermedades, morbilidad y mortalidad (6), conservación del lobo de crin (7) y, finalmente, sintetizamos los resultados 

con información general de la ecología y comportamiento del lobo de crin, con hipótesis acerca de la singular forma y función de este 

atípico cánido. La actividad estuvo relacionada con la temperatura y fue claramente nocturna en la estación seca, aunque en parte 

diurna en la temporada de lluvias. El área del territorio de adultos fue de 40–123 km2

, con marcadas variaciones estacionales en el 

uso del hábitat. El desplazamiento promedio fue de 14 km/noche en los meses secos y 7 km durante los meses húmedos. Las parejas 

reproductoras compartieron territorios con límites contiguos, los cuales no se superpusieron con el de las parejas vecinas. Una hembra 

joven permaneció en dos ocasiones hasta la edad adulta en su territorio natal, se supone como “helper” y adquirió el territorio, a la 

desaparición/muerte de las hembras adultas. Las hembras fueron las dueñas de los territorios, en los que los machos se trasladaron para 

formar parejas. Los machos jóvenes emigraron. A los 8 años de edad, los lobos de crin mostraron desgastes extremos de los dientes, y 

las enfermedades dentales fueron una importante causa de morbilidad. La pérdida de hábitat es la amenaza principal para la conservación de la especie, pero la sequía relacionada con la pérdida de recursos parece estar reduciendo las poblaciones del área de estudio.

Cover images from L to R: Maned wolf male M3 sitting in long grass; view during the wet season of the great Huanchaca 

tableland, a major feature of Noel Kempff Mercado National Park; and maned wolf youngster F9 with mane ruffled. All 

photos: L. H. Emmons.

Published by Smithsonian Institution Scholarly Press

P.O. Box 37012, MRC 957

Washington, D.C. 20013-7012

www.scholarlypress.si.edu

Compilation copyright © 2012 Smithsonian Institution

“Introduction: Study Site and Methods” and “Synthesis,” both by Louise H. Emmons, as well as the Preface and Acknowledgments are in the public domain. The rights to all other text and images in this publication, including cover and interior designs, 

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Library of Congress Cataloging-in-Publication Data

The maned wolves of Noel Kempff Mercado National Park / edited by Louise H. Emmons.

 p. cm. -- (Smithsonian contributions to zoology ; NUMBER 639)

Includes bibliographical references.

1. Maned wolf—Bolivia—Parque Nacional Noel Kempff Mercado. I. Emmons, Louise.

QL737.C22.M3525 2012

599.77—dc23

2011045004

ISSN: 0081-0282 (print); 1943-6696 (online)

The paper used in this publication meets the minimum requirements of the American National Standard for Permanence 

of Paper for Printed Library Materials Z39.48–1992.
Contents

LIST OF FIGURES v

LIST OF TABLES vii

PREFACE ix

ACKNOWLEDGMENTS xi

1 Introduction: Study Site and Methods 1

Louise H. Emmons

2 Activity Patterns 15

Louise H. Emmons, Verónica Chávez, Luis Fernando 

Del Aguila, and Sixto Angulo

3 Ranging Patterns 25

Louise H. Emmons, Verónica Chávez, Luis Fernando 

Del Aguila, Sixto Angulo, and Matthew J. Muir

4 Variation in Diet and Resources 37

José Miguel Castro and Louise H. Emmons

5 Social Interactions and Reproduction 57

Louise H. Emmons, Verónica Chávez, Luis Fernando 

Del Aguila, Sixto Angulo, and Matthew J. Muir

6 Morbidity and Mortality 77

Sharon L. Deem, Ellen Bronson, Sixto Angulo, Veronica 

Acosta, Suzan Murray, Richard G. Robbins, Urs Giger, 

Bruce Rothschild, and Louise H. Emmons

7 Conservation 91

Matthew J. Muir and Louise H. Emmons

8 Synthesis 117

Louise H. Emmons

REFERENCES 125

INDEX 133

Figures

Frontispiece. Maned wolf male M8 on release with a new collar xii

1.1 Simplified diagram of major biomes of South America 2

1.2 Location of the study area in Bolivia 6

1.3 Campo Cerrado, Los Fierros savanna 7

1.4 Termite savanna (pampa) of Los Fierros savanna from the air 8

1.5 Maned wolf F3 in termite pampa 9

1.6 False color image of flooding levels, Los Fierros savanna 10

1.7 Bajío savanna at the beginning of February flooding 10

1.8 Mean monthly rainfall and total annual rainfall 11

1.9 Rainfall trends by season during the study years 11

1.10 Fires of 2009 12

2.1 Average proportion of “active” intervals between hourly fixes 17

2.2 Activity and collar temperature for F3 17

2.3 Hourly ambient temperature and average hourly collar 

temperature 18

2.4 Hourly activity by season 19

2.5 Average daily total travel distance 20

2.6 Circadian pattern of visiting water 21

2.7 F3 rest sites during 90 consecutive days 22

2.8 Daytime bed of M5 22

3.1 Pathways of single, three-night samples 28

3.2 Area accumulation by number of hourly locations 29

3.3 Average distances and areas per weekly sample 30

3.4 Proximity to water sources by month 31

3.5 Positions of maned wolf ranges on the Los Fierros savanna 32

3.6 Synchronous locations of neighboring males 32

3.7 Home range shifts of M5 33

3.8 Fine-scale temporal boundary adjustments of adjacent pair 

territories 33

3.9 Movements of M6 34

4.1 Rodent captures over 7 years and changes in prey eaten 44

4.2 Percent of total scats in which the dominant six fruits occurred 45
v i • smithsonian contributions to zoology

4.3 Rodent biomass and maned wolf weights and range sizes 48

4.4 Skeleton of maned wolf F9 50

4.5 A termite hummock with Alibertia edulis 52

4.6 Fruits in maned wolf scat 53

5.1 Schematic outline of maned wolf pairs on study area 60

5.2 Range expansion of F3 and range shifts of M5 60

5.3 Switch of M8 from South Range to North Range 61

5.4 Percentage of total fixes during which F3 and M5 were 

<100 m apart 63

5.5 Distribution of minimum lengths of time that pair F3 and 

M5 were together 64

5.6 Hourly distribution of 326 synchronous locations of F3-M5 65

5.7 Distance traveled between hourly fixes of F3 near parturition 69

5.8 Entire recorded location record during lactation for F3 70

5.9 Movements of males M5 and M8 and female F3 during 

lactation 71

6.1 Upper left teeth P4 and M1 of maned wolf F9 81

6.2 Teeth of geriatric male M6 with multiple dental lesions 81

6.3 Vertebrae of M6 showing severe bridging 

spondyloarthropathy 86

7.1 Publications on maned wolves by decade 93

7.2 Maned wolf distribution map and protected areas 94–95

7.3 Methods to document maned wolf presence 96

7.4 Satellite image of Noel Kempff Mercado National Park 98

7.5 One of two maned wolf skins found on an estancia 99

7.6 Projected influence of +4°C temperature change on activity 101

7.7 Number of savanna species that share IUCN 102

categories 102

7.8 Conceptual model of the threats to maned wolf conservation 104

7.9 Public awareness poster about the ineffectiveness of animal 

parts as medicine 105

7.10 Veterinarian Ellen Bronson monitoring domestic dog health 106

7.11 Twenty-two identified landscapes for maned wolves 108

8.1 Height contrast between a maned wolf and a crab-eating 

zorro 120

8.2 Height of maned wolf M8 and J. M. Castro inspects a tree 

of Solanum gomphodes 122

8.3 Relative heights of maned wolf F3 and a mother tapir 

with young 123
Tables

1.1 Average measurements of females of the seven largest Canidae 3

1.2 Relative tooth morphology of canid species 4

1.3 Individuals captured, estimated ages, and telemetry collar 

deployments 13

2.1 Resting behavior of maned wolf F3 20

2.2 Mean total daily hours active 21

3.1 Data sets from which movements and range sizes were

calculated 27

3.2 Daily linear distances traveled 28

3.3 Estimation of the straightness of travel trajectories 29

3.4 Area and distance covered in three night samples 30

4.1 Occurrence of food items in scats 40

4.2 Summary of overall occurrence and frequency of 520 items 

in 108 scats 40

4.3 Taxon list of items from 108 maned wolf scats 41

4.4 Seasonal occurrences of general categories in diets of MW 43

4.5 Percentages of total field-inspected scats in which fruit species 

occurred 46

4.6 Estimated caloric contents of maned wolf food items 47

5.1 Adult resident pairs for which synchronous GPS data sets 

were acquired 59

5.2 Numbers of fixes at different proximities of adult M-F pairs 62

5.3 Frequency and duration of encounters of pair F3-M5 62

5.4 Percent of nights that maned wolves were recorded meeting 66

5.5 Summary of roar-bark calls heard during on-foot VHF radio 

tracking 66

5.6 Roar-barks ascribed to individuals 66

5.7 Outline of known and presumed events of reproduction 67

5.8 Reproductive life of F3 68

6.1 Clinical and pathological dental findings for free-living 

maned wolves 80

6.2 Hematology for free-living maned wolves 82
viii • smithsonian contributions to zoology

6.3 Chemistry profiles for free-living maned wolves 83

6.4 Test results for selected parasitic and pathogenic agents 

of free-living maned wolves 84

6.5 Comparison of seroprevalence of selected parasitic and 

pathogenic agents of free-living maned wolves and 

domestic dogs 85

6.6 Ecto- and endoparasites of free-living maned wolves 85

6.7 Results from urinary testing in free-living maned wolves 85

6.8 Findings from five maned wolves that died 86

7.1 Densities reported for maned wolves 97

7.2 Infectious and parasitic agents of domestic dogs 99

7.3 Projected changes in temperature and precipitation in 

Amazonia, 2020–2080 100

7.4 Twenty-two identified subpopulations of maned wolves 109

8.1 Characteristics of all large Canidae 118
Preface

Our investigations into the lives of maned wolves (“borochi” in 

Bolivia) began as infatuation at first sight, which engendered an 

unanticipated side branch to a research project on mammal communities in Noel Kempff Mercado National Park. This branch 

grew until it became a main trunk of the project. We began with an intentionally 

arduous method. We used hand-held antennas and receivers to follow maned 

wolves that carried old-fashioned VHF radio collars. We followed the wolves 

on foot (or tried to) from when they stirred from their daytime rest in the late 

afternoon to when they settled back to sleep through the day. We did not see 

them, nor try to, for fear of altering their behavior. As we triangulated the signals through the night, we tracked along beside them on a maze of narrow paths 

in the grass. We mirrored their movements, sensed their pace, rested during their 

rests, smelled their passage, and heard their deep barks and the faint answering 

calls of their companions. When later in the study we turned to GPS telemetry, 

we often missed the moonlit grasslands, cold starlit nights, and dawns emerging 

through the ground fog, but mostly we missed feeling the presence of the wolves 

and the exhilaration when suddenly they materialized from the tall grass beside 

us. We continued to follow so few animals year after year, always under trying 

and occasionally nearly impossible logistical difficulties, because we acquired a 

nonscientific connection to the animals and passionately wanted to know their 

individual stories. 

Louise Emmons, August 2010

Acknowledgments

This project was a collaboration with the Museo de Historia Natural 

Noel Kempff Mercado (MNK), Santa Cruz, Bolivia. We are most grateful to the Dirección General de Biodiversidad (DGB) and the Servicio 

Nacional de Áreas Protegidas (SERNAP) of Bolivia for granting us 

permits to conduct our research in Noel Kempff Mercado National Park (NKP) 

and for otherwise facilitating our studies. The directors of MNK, M. Suárez and 

P. Herrera, encouraged and aided our collaboration. Kathia R. Rivero provided 

essential help with logistics and obtaining permits and was throughout an invaluable friend, as was Damian Rúmiz of Wildlife Conservation Society. Able 

field assistance was given by S. Angulo, A. Céspedes, J. M. Castro, S. Copetto, 

S. Cabrera, V. Chávez, P. Cuellar S., F. Del Aguila, F. Huaquipa, R. Peña F., N. 

Rocha, and L. Sainz; some field associates are coauthors. Essential logistical help 

and good company in the field were volunteered by the late B. Phillips, I. Phillips, 

R. Choré, and M. Choré of El Refugio Huanchaca. Fundación Amigos de la Naturaleza supported and encouraged our work in NKP. Gelguer Añez and the park 

guards of NKP and people of the community of Florida helped us in many ways. 

Steffen Reichle, Yuvinka Gareca, Alan Hesse, and Erika Cuellar gave us bed and 

board and logistical support in Santa Cruz. Melissa Rodden generously provided 

unpublished data and information from the Smithsonian Conservation Biology 

Institute (formerly, the Conservation Research Center) maned wolf breeding program and from her own encyclopedic knowledge. Matias Tobler kindly wrote 

scripts for R-Ade and gave us advice on geographic information system (GIS) 

analysis. For their generous financial support we thank The Douroucouli Foundation, The National Geographic Society, The Wildlife Conservation Society, The 

Amazon Conservation Association and W. Alton Jones Foundation, The Friends 

of the National Zoo, The Conservation Endowment Fund of the Association of 

Zoos and Aquariums, SeaWorld Busch Gardens Conservation Fund, the Maned 

Wolf Species Survival Plan, The Department of Animal Health of the National 

Zoological Park (Smithsonian), The Maryland Zoo, and Alan Weedon. Louise 

Emmons is indebted to the Smithsonian Institution, Division of Mammals, for 

their many years of support: they provided both the spatial home from which all 

research was launched and the intangible benefits of collegiality. Two anonymous 

reviewers made helpful comments that improved the manuscript. Acknowledgments specific to individual chapters are given therein.
Frontispiece. Maned wolf male M8 on release with a new collar. Photograph by Louise Emmons.
1 Introduction: Study Site 

and Methods

Louise H. Emmons

RESEARCH OVERVIEW

Although few outsiders know of its existence, a remarkable carnivore lives 

in the tropical and subtropical grasslands of southern South America. Maned 

wolves (MW) (Canidae: Chrysocyon brachyurus Illiger, 1815) combine distinctive physical and ecological features that place them in a unique category among 

living species (Moehlman and Hofer, 1997). This misfit among the large Canidae chiefly inhabits the Cerrado, a critically threatened South American Biome 

(Figure 1.1). We studied MW for 10 years in Noel Kempff Mercado National 

Park (NKP), Bolivia.

Our overall initial research goal in NKP was to describe the spatial assortment of mammal species among the diversity of habitats where Amazonian forest meets the tropical savanna complexes of the Cerrado (a and b diversity and 

habitat associations). By recording how species respond to increasing forest dryness and the transition to grassland, we set out to discover which species are the 

most robust to environmental stress (including climate change) and which are 

the most susceptible. We focused on the small mammal communities and on the 

maned wolf, a predator linked closely to small mammals by diet. MW are the 

largest endemic Carnivora of the southern grasslands, and as such, they may be 

indicators of the ecological integrity of such systems, as they are both primary 

and secondary consumers. In the end, temporal variation that we recorded during our research proved to be equally or more informative than spatial distribution (Emmons, 2009; Chapter 4). What we did not expect to observe during our 

study were severe climate phenomena that already exerted profound effects on 

all of our focal taxa (Emmons, 2009; Xu et al., 2011; Chapters 3–5).

A species is understood in the framework of its physical and social environment, and we aimed to discover how the unique suite of maned wolf physical 

adaptations might be fitted to the ecological conditions in the Cerrado. More 

Louise H. Emmons, Department of Vertebrate 

Zoology, National Museum of Natural History, 

P.O. Box 37012, MRC 108, Smithsonian Institution, Washington, D.C. 20013-7012, USA; Correspondence: emmonsl@si.edu. Manuscript received 

25 August 2010; accepted 26 August 2011
2 • smithsonian contributions to zoology

specific objectives of the research were to reduce multiple 

gaps in our knowledge of the behavior of individual MW. 

Among these objectives were basic questions: how far and 

fast, and when and where, do MW travel each day; when 

and how do they interact with other MW; what is their 

reproductive biology; how do floods and fires affect them; 

what are their diseases and causes of death; and might 

management improve their conservation prospects? In this 

monograph we group together what we have learned. Although each of the following chapters might stand alone, 

each is tied to the information in the others: movements 

cannot be understood without knowing the activity and 

diet, diet and ranging influence health and reproduction, 

and knowledge of diet and movements are required for understanding the social behavior and reproductive parameters. Together the information in these chapters aggregate 

into the holistic view of the species needed to understand 

its place among Mammalia.

This introduction gives a brief overview of our research. We describe the MW that were the object of our 

studies, the habitats they occupy, and the location and climate of the study area. We outline our methods for field 

research and analysis of data.

In Chapter 2 we describe how the circadian pattern 

of activity varies temporally, how many hours individuals 

spend traveling and resting in different seasons, and where 

they go when inactive. Our data suggest that temperature 

and water supply are critical issues for MW in the dry 

season. This routine knowledge is basic to understanding 

both habitat requirements and the energy balance of MW.

In Chapter 3 we extend the analysis of movements to 

describe the spatial patterns of landscape use, the size of 

FIGURE 1.1. Simplified diagram of major biomes of South America. The black area between the 

Chaco and Cerrado represents the Pantanal wetlands.
number 639 • 3

ranges, and how individuals divide the landscape among 

themselves. The amount of space used by each animal, and 

how it shares space with others, is a fundamental property 

of its energetics, ecology, and conservation needs.

In Chapter 4 we analyze the diet qualitatively and 

quantitatively, and we estimate the calories represented by 

individual food items and the number of each item that a 

maned wolf needs to acquire each day based on the travel 

times and distances estimated in Chapters 2 and 3. We 

assess the changes in species in the diet after fires and following the decline to extinction of the dominant rodent 

prey from the study area after 2004 (Emmons, 2009), and 

we show some probable consequences of a prey decline on 

maned wolf ecology and behavior.

In Chapter 5 we summarize our limited data on social behavior and reproduction based on interactions surmised from proximity patterns of maned wolf telemetry 

locations. We also document long-distance calling behavior noted as we followed MW on foot with old-fashioned 

very high frequency (VHF) telemetry. We describe pair formation, estrus, parental behavior, and the fates of a few 

young born in the study area. Their social organization 

is the most fascinating aspect of canid biology, as it can 

rival in complexity that of primates and cetaceans. Our 

results hint that MW have more complex family lives than 

sometimes supposed.

In Chapter 6 we describe maned wolf health and 

mortality based on serology, ecto- and endoparasites, and 

tooth and skeletal lesions. Our study population is one 

of the few that is isolated from human-caused mortality 

(road kill, shooting, toxins), so our health survey exemplifies an “isolated” population in a pristine national park. 

Maned wolves that have never been in direct contact with 

domestic dogs and cats evidence frequent exposure to their 

pathogens. Infectious diseases are a wildcard that must be 

considered in conservation planning.

In Chapter 7 we give an overview of both range-wide 

and local conservation issues, and we list the known and 

likely threats to maned wolf survival. A summary of the 

existing published knowledge base uncovers little data on 

maned wolf population biology, probably because of the 

great difficulty of detecting and counting individuals. We 

map the distribution of the species in relation to protected 

areas and identified population subunits. From our findings in Chapter 7 and the preceding chapters we outline 

some recommendations for conservation and research.

In Chapter 8 we give an overview of our conclusions 

and develop some hypotheses about maned wolf functional morphology. We conclude with a list of unanswered 

questions about MW biology that we propose as fruitful 

subjects for future research. 

The Maned Wolves

Measuring 90 cm in standard shoulder height (SH), 

MW are the tallest of wild Canidae (Table 1.1). For their 

TABLE 1.1. Average measurements of females of the seven largest Canidae. No measurements of female Dhole (Cuon alpinus) seem 

available (nd, no data found). Maned wolves (MW) (indicated in bold) are the second heaviest species when females are considered, but 

because red wolves and African wild dogs have relatively heavier males, MW males are outweighed by three species. Maned wolves are 

the tallest, with the longest hind foot, but the head and body length ranks fourth, much shorter than that of similar-weight African wild 

dogs. Measurements in millimeters: shoulder height (SH); head and body length (HB); and hind foot length (HF). Data from current 

study (SH) and Jácomo et al. (2009; MW), Sillero-Zubiri et al. (2004; other species), Mech (1970; gray wolf, part), and Creel and Creel 

(2002; SH of Lycaon). Coyotes and gray wolves show great geographic size variation, and some populations are larger or smaller than 

tabulated. We measure SH as tip of the scapula to tip of the toes, leg of prone animal stretched. Jácomo et al. (2009) give much shorter 

measurements of “Height” (M:F 86:83 cm) than ours of SH (M:F 93:90 cm), so their measurement was taken differently. Jácomo et al. 

(2009) had a sample size tenfold greater than ours.

Species Mass, kg SH HB HF HF/HB

Maned wolf, C. brachyurus 24.6 900 1068 292 0.27

Gray wolf, Canis lupus 39 700 1150 279 0.24

African wild dog, Lycaon pictus 24 700 1265 241 0.19

Red wolf, Canis rufus 24.3 662 1073 222 0.21

Ethiopian wolf, Canis simensis 12.8 nd 919 187 0.20

Dhole, Cuon alpinus 11.5 nd nd nd nd

Coyote, Canis latrans 10.1 570 824 180 0.22
4 • smithsonian contributions to zoology

height they are lightweight (25 kg), with little muscle mass. 

Adult females are slightly lighter than males (females, 

24.6 kg, standard deviation (SD) 3.2; males, 26.6 kg, SD 

3.6) but overlap with males in size range, and males and 

females average the same body length (Dietz, 1984; Jácomo et al. 2009). This handsome canid has thick, rustred body fur highlighted by a pure white throat and ear 

linings, and a pale to white tail tip and eyebrows. These 

contrast with pitch-black legs, muzzle, lower throat, and 

mane (see Frontispiece). The dorsal pelage and its mane 

of long black hairs on the neck and shoulders are raised 

in excitement or alarm, and the tail is fluffed, exaggerating the apparent body size (Kleiman, 1972). The fox-like 

head has a narrow pointed muzzle and exceptionally large 

ears. The mouth is framed by black lips, but the upper lip 

has a narrow white band under the nose (“Got Milk?”); 

perhaps this is a target for pups to solicit regurgitation. 

The two center toe pads of the feet are joined at the base 

to form a single unit that along with shape, distinguishes 

the tracks of pups from those of foxes (Pocock, 1927; a 

character shared with the bush dog, Speothos venaticus). 

Long legs and a short back mandate a pacing gait (ipsilateral legs move together), and normal maned wolf travel is 

at a walk, with head held lower than the salient shoulder 

blades, and outsized ears pointed forward (Frontispiece). 

Maned wolves are calm and even timid, but to their peril, 

when free, they are generally unafraid of humans. The species occupies tropical and subtropical mesic savannas of 

Argentina, Brazil, Bolivia, Paraguay, and Peru, with most 

of the current range in the Cerrado ecoregion, but including drier parts of the Beni and Pantanal flooded grasslands, 

and humid grasslands of subtropical Argentina (Quierolo 

et al., 2011). They are considered Threatened or Endangered in all of their range countries, but Near Threatened 

by International Union for Conservation of Nature Red 

List (IUCN, 2009).

The behavioral ecology of MW was first studied with 

radio telemetry by Dietz (1984), in the Brazilian Cerrado. 

Free-living MW are rarely visible, and Dietz complemented 

his field studies with behavioral observations of captive individuals at the Smithsonian Conservation Biology Institute (formerly Conservation Research Center), which has 

maintained the Association of Zoos and Aquariums (AZA) 

Studbook and a breeding program for nearly 40 years. 

Dietz described MW as socially monogamous, solitaryliving canids that share exclusive pair territories (we follow 

Reichard and Boesch [2003] for definitions of monogamy). 

Dietz’ (1984) basic findings have been confirmed (Jácomo 

et al., 2009), but surprisingly little new has been added to 

his outline of their socioecology. Maned wolves are omnivores, with a diet of about half each of fruit and small vertebrate prey (Dietz, 1984; Rodden et al., 2004; Rodrigues 

et al., 2007). Their home range size varies from about 25 to 

100 km2

 (Dietz, 1984; Jácomo et al., 2009). Diet and home 

range sizes have been well documented in multiple populations (Jácomo et al. 2009; Rodden et al., 2004; Rodrigues 

et al., 2007), but only a few details are recorded of the 

interactions or life histories of free-ranging individuals in 

any part of their range (Melo et al., 2007, 2009). Current 

knowledge of the species was summarized in Rodden et al. 

(2004), and recent important additions include Melo et al. 

(2007, 2009), Coelho et al. (2007, 2008) Rodrigues et al. 

(2007), and Jácomo et al. (2009). 

Seven species of living Canidae can weigh over 15 kg 

(Table 1.1), and MW are the only omnivore among these. 

All but the coyote normally live in packs, and the heaviest 

all cooperatively hunt prey larger than themselves, making 

MW an ecological outlier. Their dentition shows MW to 

be morphologically adapted to their diet of relatively little 

meat and relatively more plant matter (which requires 

molar crushing to release cell contents; Table 1.2; Van 

Valkenburgh, 1989). 

TABLE 1.2. Relative tooth morphology of canid species (from Van Valkenburgh, 1989). The first two species are omnivores; the last four 

are the most carnivorous of living Canidae. Canine shape is the ratio of cross sectional width/cross sectional length.

Species Canine shape m1 relative blade length Relative molar grinding area

Maned wolf, Chrysocyon brachyurus 63.7 0.57 1.08

Crab-eating zorro, Cerdocyon thous 59.4 0.59 0.99

Gray wolf, Canis lupus 53.6 0.72 0.66

Dhole, Cuon alpinus 58.8 0.74 0.66

African hunting dog, Lycaon pictus 64.2 0.72 0.57

Bush dog, Speothos venaticus 72.4 0.72 0.55
number 639 • 5

Of 12 Canidae examined, MW have the largest relative molar grinding area, and of 31 total Carnivora, only 

omnivores and invertebrate feeders, such as bears, badgers, 

and procyonids, have greater molar grinding surfaces than 

MW (Van Valkenburgh, 1989). Similarly, the relative blade 

length of the lower first molar, used for slicing meat, is 

shorter in MW than in any other of the 12 Canidae. Even 

the sympatric crab-eating zorro (Cerdocyon thous) (following Macdonald and Courtenay [1996], we use the term 

“zorro” for South American foxes to distinguish them from 

other fox lineages) has teeth with slightly more meat-eating 

architecture than those of MW (Table 1.2). These features 

show MW to have an ancient evolution as omnivores, and 

it is unlikely that their current habits are a switch from 

greater carnivory in the recent past. We thus view their current ecology as reflecting an ancient adaptive suite. 

Their distinctive teeth were the basis for classification 

of a 5–4 Ma old jaw fragment from North America as 

the earliest known Chrysocyon, C. nearcticus (Tedford et 

al., 2009; Wang et al., 2008). The earliest known South 

American C. brachyurus fossils are much younger, from 

the Early Pleistocene of Bolivia (Ensenadan, 1.2–0.8 Ma; 

Berta, 1987). Slater et al. (2009) recently clarified the evolutionary relationships of South American Canidae by 

DNA analysis. Their hypothesis shows the nearest recent 

relative of MW to be the mysterious Falkland Island wolf 

(Dusicyon australis), which was found by Europeans in 

1690 and extinct by 1876, extirpated by shepherds. The 

closest living species to MW is the bush dog (Slater et al., 

2009; Wayne et al., 1997), with an estimated divergence 

time from MW of 10 Ma (compared with 6.7 Ma for D. 

australis; Slater et al., 2009). If confirmed, these early dates 

imply that the diversification of South American genera 

occurred in North America, prior to the arrival of Canidae 

on the South American continent (Slater et al., 2009), as 

is also suggested by the fossil record (Berta, 1987; Wang 

et al., 2008).

The Cerrado Habitat

The Cerrado ecoregion crosses South America in a diagonal belt south of the Amazon rain forests, in a band 

of about 1.9 million km2 of tropical dry forests interdigitated with a complex mosaic of wet and dry savannas and 

shrublands (Figure 1.1). A quarter of the area of Amazonian rain forests, Cerrado is the second largest biome in 

South America. Annual rainfall is moderate but strongly 

seasonal, with 4–6 months of little rain. El Niño Southern Oscillations (ENSO) cause rapid interannual shifts 

in severity of drought and flooding. Monthly and annual 

average temperature excursions are much higher than in 

the evergreen rain forests, and daily temperatures can 

rise 20°C between dawn and afternoon. Cerrado soils are 

often acidic, with low cation exchange capacity and high 

aluminum saturation (>40%), which makes them toxic 

to many plants (Gottsberger and Silberbauer-Gottsberger, 

2006). Moreover, Cerrado grasslands are fire-adapted ecosystems and frequently burn. The biota is thus challenged 

by environmental extremes, although to a lesser degree 

than those of the southern deserts or Chaco. Half or more 

of the area has been deforested for agroindustry.

The Cerrado flora is well known. With high  diversity and local endemism it is the richest tropical savanna 

region in the world for vascular plants, with estimates of 

6,700 to 10,000 species (Bridgewater et al., 2004; Klink 

and Machado, 2005). The fauna, in contrast, is poorly 

studied. For mammals, the region has been supposed to 

be depauperate (Klink and Machado, 2005). In 1986, 100 

nonvolant mammal species were listed, 11 of them endemic (Redford and Fonseca, 1986). By 2002, the list had 

grown to about 200 species of Cerrado mammals (143 

nonvolant), 18 of them endemic (one a bat; MarhinoFilho et al., 2002). However, by 2011, this still seems 

significantly underestimated, with about 34 mammalian 

species now recognized as endemic to the Cerrado and 

related habitats (Emmons, unpublished list) from a total 

of at least 230 species (IUCN, 2009). At 46% of the richness of Amazonian rain forests on 25% of its landmass, 

the fauna now appears species rich in all orders except 

Primates. Our incomplete inventories record 91 species of 

nonvolant mammals and 72 species of bats in NKP (some 

of them Amazonian; Emmons et al., 2006a, 2006b). Most 

of these are small-bodied taxa.

The modern Cerrado fauna includes only the survivors/

successors of an extinction event that eliminated at least 

72 taxa of Pleistocene/early Holocene megafauna (>44 kg; 

de Vivo and Carmignotto, 2004; Martin and Klein. 1984), 

leaving it nearly empty of large mammals (>20 kg). There 

are but three endemic, large-bodied species restricted to 

open habitats of the humid southern tropical grasslands: 

the maned wolf and two large deer (marsh deer, Blastocerus dichotomus Illiger; 100 kg; pampas deer Ozotoceros 

bezoarticus L.; 35 kg). All three are declining and listed as 

Near Threatened or Vulnerable (IUCN Red List). Other 

large taxa found in open Cerrado habitats are ubiquitous 

throughout all tropical lowlands of the continent (jaguar, 

puma, tapir, capybara, peccaries, giant armadillo, and giant 

anteater). The causes of Pleistocene extinctions are beyond 

the reach of our research, but in Chapter 8 we speculate on 

reasons for the persistence of MW.
6 • smithsonian contributions to zoology

The Study Area in Noel Kempff Mercado National Park

Parque Nacional Noel Kempff Mercado, Santa Cruz 

Department, Bolivia, is a 1.523 million ha IUCN World 

Heritage site. A third of NKP is open savannas, in fragments separated by forests (Figure 1.2). The park was 

established to protect the massive Huanchaca tableland 

(“Meseta”), which rises 500 m above the plain of the adjacent lowlands (120 km × 30 km, 900 m maximum elevation). We studied MW in the 21,883 ha Los Fierros 

savanna near Los Fierros camp (14°33.24′ S; 60°55.40′

W; elevation 220 m). The southern half of the savanna is 

in El Refugio Huanchaca Biological Station (ERH; Figure 

1.2), a privately managed property partly within the park. 

Noel Kempff Park is on nutrient-poor soils of the Brazilian Shield geological formation and spans a transition 

zone between tall Amazonian humid forests, semideciduous and deciduous forests, dry upland Cerrado savannas, 

and seasonally flooded savannas (Killeen and Schulenberg, 

1998). Habitat nomenclature has been developed in Brazil for the major Cerrado plant formations, as defined by 

Gottsberger and Silberbauer-Gottsberger (2006).

Dry Ground Habitat Types

Cerradaõ. Dense woodland with >60% tree cover and 

canopy >7 m tall and a shaded woody and herbaceous understory. This mainly occurs on forest “islands” in Los Fierros savanna and on the slopes of the Huanchaca Meseta.

Cerrado sensu stricto. A low canopy (<7 m) woodland 

and scrub with >40% canopy cover. This habitat is widespread on the northern part of the Meseta.

Campo Cerrado. Savanna woodland with 10–40% 

canopy cover over a continuous layer of grasses (Figure 1.3). This is the principal maned wolf habitat type 

on never-flooded areas of Los Fierros savanna. Its local 

FIGURE 1.2. Location of the study area. The pale areas in the satellite image are grasslands; the darker matrix is forest. The park boundary is 

along the river that dissects the image diagonally from upper left to lower right. The finger of grassland from the river in the center of the image 

and up to the right is Los Fierros savanna, where we studied the maned wolf population. The southern half of the savanna within the park is 

part of the El Refugio Huanchaca (ERH) Biological Station. The sharp-edged, dark areas in grasslands south of the park are fire-scars on cattle 

estancias. Bolivia map after Navarro and Maldonado (2002).
number 639 • 7

name is “pampa arbolada.” The Spanish term “pampa” is 

equivalent to the Portuguese and Spanish “campo” (field), 

both terms are used for natural and anthropic savannas.

Campo Sujo. Open grasslands with scattered shrubs 

and few low trees. This covers many open areas on top of 

the Meseta, along with Campo Rupestre, which is similar, 

but on a rocky substrate.

Wet Ground Habitat Types

Hummock Campo. Also “Campo de murunduns,” 

an open grassland matrix studded with small humps of 

high-ground formed around termite mounds topped with 

trees and woody shrubs. When the grassland is shallowly 

flooded from about February to April, the hummocks become dry ground islets surrounded by water. From August 

to late December or early January, there is no standing 

water in the grassland. This is the major maned wolf habitat of the northern half of Los Fierros savanna and locally 

called “pampa termitero” or “termite” savanna, a term 

we use herein (Figures 1.4 and 1.5). Its fringing forests are 

Cerradaõ on the north and Amazonian humid forests on 

the east and west.

Pampas de bajíos (Navarro and Maldonado, 2002). 

Open grasslands more deeply flooded seasonally than 

termite pampas (above), with water 0.5–1 m deep. These 

FIGURE 1.3. Campo Cerrado, Los Fierros savanna, under a pall of late dry season smoke. This habitat never floods and is the home 

the endemic rodent Juscelinomys huanchacae. The blackened trunks are evidence of the frequent fires in this zone, which is part of the 

PA rodent trapping plot (Chapter 4) (photograph by L. H. Emmons). 
8 • smithsonian contributions to zoology

open grasslands include larger islands of tall forest. The 

Los Fierros savanna slopes downward, with increased 

depth of flooding, from north to south (Figures 1.6 and 

1.7). The southern half is Bajío pampa, and most of its 

fringing forests and forest islands are likewise flood prone. 

Along the river, there are some permanently wet open 

marshes.

The geology, habitats, flora, and fauna of NKP are 

described in Killeen and Schulenberg (1998) and the mammals in Emmons et al. (2006a, 2006b). All savannas in 

NKP support maned wolf populations (Rumiz and Sainz, 

2002). The Los Fierros study savanna is separated on 

the southeast by a river, open marshes, and gallery forest 

from larger, flood-prone Bajío grasslands (Figure 1.6) and 

Campo Cerrrado on cattle estancias, and on the northeast by 9 km of forest from a large pristine Campo Sujo 

savanna on top of the Huanchaca tableland (Figure 1.2). 

The adjacent grasslands have maned wolf populations 

that can interchange with the study groups. One all-season 

road crosses 10 km of the Los Fierros pampa, and a 25 km 

dry season-accessible track penetrates its length. To follow 

MW with VHF telemetry, we made a network of footpaths marked for radio-tracking at GPS-mapped 100 m 

intervals. 

FIGURE 1.4. Termite savanna (pampa) or Hummock Campo of Los Fierros savanna from the air, showing regular spacing of termite 

mounds topped by woody vegetation. The Huanchaca Meseta, major feature of Noel Kempff Mercado National Park (NKP), fills the 

background. Pozo Matt (PM) waterhole is in the clump of tall trees, 2/3 down the image, in a pale streak directly below the point of the 

wing. This grassland matrix is lightly flooded in the wet season (photograph by L. H. Emmons).
number 639 • 9

Climate and Seasonality

Rainfall was measured at ERH with a garden gauge 

(1995 onward) and temperature with a max-min thermometer or digital home weather station (2003 onward). 

In July–August 2009, hourly climate variables were taken 

with a Kestrel® weather logger placed under a shade 

roof in the grassland of Los Fierros savanna. Rainfall and 

water availability in the NKP savannas are highly variable 

(Figure 1.8). Annual rainfall averages 1.4 m (range, 2000–

2010 1.2 to 1.8 m), with a strong dry season from May 

to October and a rainy season from November to March 

(Figure 1.8A). Standing water normally covers parts of 

the landscape from January or February to May, but in 

2009, water remained until July. Ground flooding is temporally displaced about three months after the beginning 

and end of the rains (Figure 1.8A). By mid-August, there 

is little to no surface water on the Los Fierros grasslands 

and most streams and waterholes are dry. The savannas 

are both fire and flood maintained: without these events, 

woody plants overgrow and shade out the grasses. Over 

the years of the study, annual rainfall did not show any 

overall trend (Figure 1.8B), but dry season rainfall (July–

September) showed a gradual and striking decline, from a 

maximum of 172 mm in 2002 to 20 mm in 2010 (Figure 

1.9). There was exceptionally high late wet season rainfall 

in 2008 and 2009, which caused deeper and later flooding 

of the savanna, followed immediately by a catastrophic 

FIGURE 1.5. Maned wolf F3 (with piloerection) in termite savanna or hummock campo, showing structure of grass and shrubs relative 

to the size of a maned wolf (photograph by L. H. Emmons).
1 0 • smithsonian contributions to zoology

FIGURE 1.6. False color image of flooding in Los Fierros savanna 25 April 2008, during exceptionally high water 

levels. Darker blue indicates deepest flooding of Bajío savanna; palest blue more open, lightly flooded grasslands; olive 

tinge, shrubs and trees; intermediate blues, lightly flooded termite savanna; uniform olive, Campo Cerrado; green, 

closed canopy woodland and forest; yellow, marshland and swamp. Note progressive deepening of flooding from 

north to south, with drop in land elevation. The Río Paraguá-Tarvo runs along the lower edge.

FIGURE 1.7. Bajío savanna, ERH, at the beginning of February flooding. This savanna has tallgrass marshes in the wet season, with large islands 

of Campo Sujo, but no water at all in the late dry 

season. R. Choré and E. Bronson riding in to trap 

maned wolves (MW) from a tent camp (photograph 

by L. H. Emmons).
number 639 • 1 1

FIGURE 1.8. (A) Mean monthly rainfall (bars) and mean monthly temperature maxima and minima at El Refugio Huanchaca (lines, 2003–

2010) and months when there is usually standing water on parts of the area (light shading) and (B) total annual rainfall (1995–2010).

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

0

100

200

300

400

500

600

700

800

900

1000

0

50

100

150

200

250

October–March Rainfall, mmApril–September Rainfall, mm

Year

OND

JFM

AMJ

JAS

FIGURE 1.9. Rainfall trends by season during the study years, with drier seasons on the right axis. Linear 

regressions for the wettest (January–March) and driest (July–September) months are shown as dotted lines. 

Data from records kept at ERH.
1 2 • smithsonian contributions to zoology

drought (Figure 1.9, JFM; Xu et al., 2011). The northern 

half of the Los Fierros savanna burned in 1999, half of 

that burned again in 2003, and about a quarter in 2007. 

Lightning strikes sporadically burned a few hectares between 2003 and September–October 2009, when nearly 

the entire savanna burned during six weeks (Figure 1.10).

General Methods

Trapping and Radio-Tracking

The following methods apply to all chapters, but those 

specific to individual chapters are included therein. Field 

studies took place over several months yearly from 2001 

to 2011, and the study is ongoing. We captured MW in 

wooden drop-door box traps (Dietz, 1984; less successful) 

or metal and hardware-cloth drop-door cage traps (more 

effective) baited initially with live chicks, but after 2007 

with sardines and dried fatty beef (“charqui”). Lures of 

maned wolf urine dried on gauze and hung in the back of 

traps improved success. Three trap-shy individuals were 

free darted with a DanInject® rifle. Captured MW were 

immobilized with 100 mg of Telazol® delivered by a Telinject® or DanInject dart. If needed, anesthesia was supplemented by ketamine HCl. A veterinarian performed a 

physical examination and collected blood, urine, and fecal 

samples for analysis of pathogen exposure, health metrics, 

and genetic analysis. Deem and Emmons (2005) detail 

procedures. Captured MW were measured, weighed, photographed, marked with Rototag® ear tags, and fitted with 

VHF radio collars (ATS®) or archival GPS collars with 

scheduled drop-off (2003–10; Lotek®, ATS®, and Telemetry Systems®). We estimated age from tooth wear, compared with that of a known-age individual on the same 

study area and the wear trajectories of other individuals 

followed for multiple years. We captured 14 individuals a 

total of 55 times, but we immobilized captured individuals only once per field session. Procedures of capture and 

handling were approved by the Institutional Animal Care 

and Use Committees, National Zoological Park, and Department of Vertebrate Zoology (Smithsonian Institution).

MW were not generally wary, but they were rarely 

visible in the dense vegetation. Presence of individuals was 

photo documented with camera traps placed at points of 

maned wolf activity, especially at dry season water holes. 

We maintained several of these by digging them out as 

the water table dropped, and at one (Pozo Matt, PM) we 

observed visitors from a blind as well as with cameras 

(Emmons et al., 2005). We color coded radio collars with 

reflective tape for field and photo recognition (Frontispiece). MW are nearly size monomorphic, with inconspicuous external genitalia, and few unmarked MW can be 

identified on sight to either individual or sex, or in photos 

to sex (Frontispiece).

We tracked VHF-collared MW on foot and triangulated locations from GPS fixes or mapped markers on 

trails and roads. We tried to follow single MW for entire 

activity periods, with about three, three-point triangulations per hour for samples of three sequential nights, but 

sometimes MW traveled out of receiver range. Other collared individuals within range were located ad hoc. Archival GPS collars (require retrieval to download data) were 

programmed with several schedules: (1) all days with halfhourly locations (fixes) from 1800 to 0800 hours; hourly 

fixes at 0900, 1000, 1600, and 1700 hours, and no fixes 

from 1100 to 1500 hours (2003–2004 only); (2) hourly 

fixes daily from 1600 to 1000 hours the following date 

FIGURE 1.10. Fires of 2009. October 12 composite image from 

NASA Goddard Space Flight Center (GSFC), MODIS Rapid Response and Google Earth®. All darker areas are fire scars, except the 

isolated round spot on the left, which is a lake, and cloud shadows. 

The entire Los Fierros savanna appears carbonized (fingerlike black 

area on left lower quadrant). The adjacent edge of the Huanchaca 

Meseta (top to bottom diagonal on the right of the image) shows 

numerous fire scars of different ages, as does the savanna southwest 

of Los Fierros (darkest areas are the most recent fires, paler scars 

are from earlier ones; parallel lines of cirrus clouds and their shadows form diagonal structures). Fires in NKP can be monitored daily 

through NASA/GSFC, MODIS Rapid Response. Following this fire, 

two resident adult MW were not seen again (pair F3–M8).
number 639 • 1 3

(because we thought MW to be nocturnal), for weekly 

three-night samples; (3) hourly fixes each hour for threenight (and day, 72 hours) samples (Wednesday–Saturday) 

of each week (all collars after 2005). Three collar deployments collected usable collar temperature data and “activity” at each fix. Data archived within GPS collars were 

recovered at recapture or after collar drop-off. The failure 

rate of GPS collars was high: almost 40% of 22 deployments resulted in truncated data, two of these because the 

collar housing was pierced by a maned wolf tooth mark, 

others because batteries failed and/or humidity entered 

the housings. About 90% of collar release mechanisms 

also failed to function. These problems caused data loss, 

so from 2009 we attached supplementary, 20 g ear tag 

transmitters to each collar to aid recovery when inbuilt 

VHF transmitters failed. We obtained 35,051 telemetry 

locations from 10 MW on Los Fierros pampa (Table 1.3). 

Analysis of Field Data

Triangulation data from VHF radio-collared MW 

were hand-plotted onto maps (2001–2004: 1,411 locations), scanned, and rectified on a Landsat image with ArcGis (ESRI) or plotted with LOAS software (2005 onward). 

Maps were analyzed primarily with ArcView and ArcInfo 

GIS software (ESRI) and The Home Range Extension for 

ArcView (Rogers and Carr, 1998), Hawth’s Tools (Beyer, 

2004), or R-ade (Calenge, 2006). For hand-plotted data, 

Table 1.3. Individuals captured, estimated ages, and telemetry collar deployments. Animal (M, male; F, female), data collection interval, number of fixes, number of complete nights of activity recorded, and number of weekly three-night samples where relevant. In 

“all days” data sets, fixes were taken every day at half hourly or hourly intervals. After 2005, GPS collars recorded locations on three 

sequential nights of each week. In cases with no GPS data, the capture date is given under Data start. A dash (–) indicates not applicable 

to data set.

Maned Estimated Home Data Data Total Total Three-night

wolves age, years range zone start end fixes nights samples

M2* >8 N1 20 Oct 01 1 Jan 04 800 34 –

M4* 0.6 N1 23 Oct 02 24 Feb 03 243 8 –

F3* 1.2 N1 26 Sep 02 13 Oct 03 262 12 –

F3 2 N1 13 Oct 03 16 Jan 04 1847 95 All days

F3 3 N 9 Oct 04 1 Jan 05 3403 91 All days

F3 4 N 6 Oct 05 13 Jul 06 2900 121 45

F3 5 N 6 Jan 07 30 Jan 07 130† 24 –

F3 6 N 21 Sep 07 22 Nov 07 607† 36 9

F3 7 N 16 Jul 08 18 Oct 08 1008 41 14

M5 4 N2 4 Oct 04 7 Mar 05 4631 155 All days

M5 5 N 29 Sep 05 16 Dec 06 4606 192 64

M5 5.5 N 6 Feb 07 29 Mar 07 349† 19 6

M5 6 N 4 Oct 07 12 Jul 08 1112† 61 16

M6 >7 S 27 Sep 05 23 Feb 06 1514 – 21

F7 0.6 S 21 Oct 05 Lost – – –

M8* 2 S 25 Oct 05 5 Sep 06 140 6 –

M8 3 S 5 Sep 06 7 Oct 06 428† 20 5

M8 4 S 25 Jul 07 26 Sep 07 635† 36 10

M8 5 N 9 Jul 08 18 Oct 08 1080 44 15

M8 5 N1 22 Oct 08 22 May 09 2249 – 31

F9* 1.5 S 18 Jul 07 7 Jul 08 – – –

F9 2.5 S 7 Jul 08 28 Aug 08 536† 23 8

F9 2.8 S 12 Oct 08 16 Apr 09 2131 69 25

M10* 0.8 S 16 Sep 06 Collar lost – – –

F11 6 S 4 Feb 07 26 Mar 08 3784 201 59

F12 0.5 N1 16 Oct 07 NA No collar – –

F13 3 All 16 Sep 10 14 Sep 11 2787† 88 22

*VHF transmitter. 

†GPS collar failures.
1 4 • smithsonian contributions to zoology

we mapped only one location point (fix) if an animal was 

stationary, and we used all available points to calculate 

home range size. Activity periods (nights) are calculated 

from the first VHF or GPS fix after noon on a given date 

to the last fix before noon on the following date. Mean 

GPS PDOP (positional dilution of precision, a measure of 

probable fix accuracy) was 4.3 ± 1.2 (median 3.6, mode 

2.7, range 0.5–25) for 4,612 fixes of a Lotek collar on M5 

and 2.9 ± 1.2 (median 2.8, mode 2.5, range 0–6) for 3,402 

fixes of an ATS collar on F3; other data sets were similar. 

To estimate the distance traveled by MW between successive GPS collar fixes, we considered all distances of <50 m 

from the previous fix to represent inactivity. For analysis, 

all such distances were converted to 0 m, so as to exclude 

random GPS errors around a stationary maned wolf from 

inflating travel. A collar stationary on the ground after a 

maned wolf death collected 869 fixes. Of these, 97% were 

≤50 m from the geometric centroid of the cloud of fixes, 

despite the GPS antenna lying sidewise on the ground surface and partially covered with dirt (mean PDOP 5.0), 

which are adverse conditions for GPS location. For analysis of travel distances and rates, as well as rest and activity 

cycles, we use only GPS collar data. There was complete, 

hourly GPS data of weekly three-night samples of 9–14 

months duration for three females and two males (F3, F9, 

F11, M5, M8; Table 1.3). These large data sets are used 

as exemplars for many analyses of temporal activities. 

To compare seasonal behaviors, the year is divided into 

quarters: January–March (JFM, ground flooded and much 

rainfall); April–June (AMJ, much surface water but little 

rainfall); July–September (JAS, almost no rain, surface 

water scarce to absent); and October–December (OND, 

some rain and ephemeral surface pools, no flooding).
2 Activity Patterns

Louise H. Emmons, Verónica Chávez, 

Luis Fernando Del Aguila, and 

Sixto Angulo

Abstract. We studied the activity patterns of maned wolves (MW), Chrysocyon 

brachyurus, by VHF and GPS telemetry in Noel Kempff Mercado National Park (NKP), 

Bolivia, in upland and seasonally flooded savannas. Eight of 13 individuals captured on 

three home ranges were followed for up to six years. MW were sharply nocturnal in the 

dry season, but in some months of the wet season they were cathemeral. They traveled 

for 10 to 15 hours of each day. Total hours of activity and travel distances were longer 

in dry season than in wet season months. Temperature sensors on collars showed that 

MW became inactive as the collar temperature rose above 27°–28°C and travel rate decreased somewhat at below 21°C. The circadian activity pattern in months of drought 

and heat may be driven by exigencies of water balance and thermoregulation. During 

daytime inactivity, MW rested within hollows under tall, dense clumps of bunchgrasses. 

All individuals apart from females with newborns changed rest sites daily. Daytime beds 

were distributed over the entire home range, but there were favored zones where tall 

bunchgrasses were plentiful.

Introduction

In this chapter we explore the daily and seasonal activity patterns of maned 

wolves (MW) and discuss the environmental factors that might influence these 

behaviors. Activity patterns may be humdrum descriptors in behavioral ecology, but they underlie much of an organism’s fundamental energetics. The time 

needed to acquire nutrients, with its associated energy expenditure, can determine how large an area can be traveled in daily or monthly ranging and whether 

females can sustain pregnancy and lactation in particular months or years. The 

hourly activity pattern can determine which prey species a predator is most 

likely to encounter. Constraints on activity may limit litter and home range sizes. 

Similarly, an excessive search time for particular food items could preclude their 

use and determine diet options.

GPS telemetry has brought an incremental leap in the depth and accuracy of movement data recordable from large species in open habitats. By 

Louise H. Emmons, Department of Vertebrate 

Zoology, National Museum of Natural History, 

P.O. Box 37012, MRC 108, Smithsonian Institution, Washington, D.C. 20013-7012, USA; 

Verónica Chávez, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Luis 

Fernando Del Aguila, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Sixto 

Angulo, Fundación para la Conservación del 

Bosque Chiquitano, Calle René Moreno, Santa 

Cruz, Bolivia. Correspondence: emmonsl@si.edu. 

Manuscript received 25 August 2010; accepted 26 

August 2011.
1 6 • smithsonian contributions to zoology

custom-programming GPS collars to take long series of 

consecutive locations (fixes) at regular intervals, the movements of individuals can be plotted on landscape spatial 

scales and on temporal scales from minutes to years. With 

synchronous samples of hundreds of fixes, the behavior of 

different individuals can be directly compared. There is no 

observer bias from differences between human trackers, 

reflection from objects, or access to remote terrain, nor 

any need to use models to extrapolate ranges from small 

samples. We owe the data presented below to GPS technology developed in the last decade.

Materials and Methods

Methods of capture and telemetry are detailed in 

Chapter 1, with descriptions of the study area, habitat, 

and climate. We tracked the activity of MW in Los Fierros 

savanna with archival GPS telemetry collars. We initially 

programmed collars to acquire fixes each 30 min, which 

limited the battery life to from three to five months. We 

later scheduled collars to acquire hourly fixes for three 

nights of each week, which yielded data sets of from 10 to 

14 months. For a male (M5) and two females (F3, F11), we 

acquired one or more data sets for all 12 calendar months, 

for another male (M8) for 11 months, and for a female 

(F9) for 9 months. We use these long data series to examine temporal changes in activity. Three collar deployments 

(ATS®) returned good temperature data, recorded hourly 

at the time of each GPS fix. The temperature sensor was 

ventral to the neck and away from the body, so that it was 

shaded from sun and insulated from body heat by thick 

neck hair. We have no simultaneous hourly ambient temperature data from the study area for months when collars recorded temperature, but in July and August 2009, 

we took hourly savanna temperatures and other variables 

with a Kestrel® weather logger.

Because stationary GPS receivers record small spurious differences in location that are generated by instrument errors (registering as nonexistent “movement”), all 

distances of <50 m between successive fixes were treated 

as representing stationary, “inactive” MW and were converted to 0 m for analysis. Similarly, all interfix intervals were classed as 0 (“inactive” <50 m) or 1 (“active” 

≥50 m), so as to calculate hours of activity apart from 

travel distance. Because the average travel rate for MW 

in our study was 600 to 1000 m/h, converting distances 

of <50 m/h to 0 has little effect on estimated daily total 

movement distances.

Hourly GPS telemetry fix periods are too short 

(55 s average) to adequately record brief events, such as 

drinking. Water is scarce in the study area in the late dry 

season, and we maintained several water holes by digging 

them down to the water table. To monitor the presence of 

MW and other taxa, we set 24 hour digital camera traps 

to record visits to water holes (Emmons et al., 2005), and 

watched behaviors from a blind. If a maned wolf was captured in several images within the same hour, only the first 

image is considered as a visit or event. 

RESULTS

Circadian Activity

MW were largely nocturnal/crepuscular in the dry 

season, when they became inactive at their daytime resting sites (for brevity, “beds”) by 0800–1000 hours, and 

resumed activity at 1600–1800 hours (Figure 2.1A). In 

the wet season, activity in some months showed no clear 

nocturnal-diurnal pattern (Figure 2.1B) except perhaps a 

trend for crepuscular activity. Some individuals were more 

likely to be active at midday in January than at 1800–2100 

hours, the most active dry season hours (Figure 2.1B). The 

general pattern of increased diurnal activity and reduced 

nocturnal activity from January to March was recorded 

in all individuals sampled during those months. However, 

the degree of diurnality, and the month where diurnality 

was maximal, varied between years and individuals. Averaging all data sets thus dampens the truly striking behavioral differences between the most divergent months 

within single data sets for one individual (Figure 2.1B). 

Circadian Activity and Temperature

Three MW had collar temperature sensors operational for three to ten months. In all of the data, maned 

wolf activity dropped abruptly from about 90% at 27°C, 

to about 20% at 29°C and to nearly zero at above 30°C 

(Figure 2.2A). Average travel rate decreased steadily from 

about 600 m/h at 24°C, to about 100 m/h at 29°C (Figure 2.2A). Whereas MW were active during 100% of fixes 

when it was below 23°C, travel distance seemed to decline 

at coolest temperatures, especially below 20°C (Figure 

2.2A). The circadian curve for hourly travel distance is the 

inverse of the curve for collar temperature (Figure 2.2B).

Hourly instrument readings within the grassland in 

July and August 2009 (Figure 2.3A) show daily curves 

with an abrupt temperature increase from the Tmin at dawn 

to Tmax at 1200–1400 hours, with a slower pm decline 

from Tmax when the ground is warm. These are cool winter 
number 639 • 1 7

Figure 2.1. Average proportion of “active” intervals between hourly fixes (movement >50 m, see Materials and Methods), based on hourly 

GPS fixes recorded during three days of each week, with all fixes classed as either active (1) or inactive (0). (A) Monthly dry season averages for 

male M8, July–October 2008, from 1,080 fixes. (B) October 2005 (dry season, solid lines) and January 2006 (wet season broken lines) average 

hourly activity of female F3 (thin lines) and male M5 (thick lines), a pair on the same area (N = 269 to 304 fixes per month per maned wolf).

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20

Proportion Active

Hour

F3 Oct-05

F3 Jan-06

M5 Oct-05

M5 Jan-06

B

0 1 23456 789 10 11 12 13 14 15 16 17 18 19 20 21 22 23

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Proportion Active

Hour

Jul-2008

Aug-2008

Sep-2008

Oct-2008

A

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20

Proportion Active

Hour

F3 Oct-05

F3 Jan-06

M5 Oct-05

M5 Jan-06

B

0 1 23456 789 10 11 12 13 14 15 16 17 18 19 20 21 22 23

0

0.1

0.2

0.3

0.4

Propo

Hour

Jul-2008

Aug-2008

Sep-2008

Oct-2008

Figure 2.2. Activity and collar temperature for F3 October 2004–January 2005; T (°C) measured at each GPS fix by collar sensor (distance 

traveled is for the hour preceding the T reading; N = 1,847). (A) Raw data sets for distance traveled from the previous fix and temperature at 

that fix time (solid symbols) and proportion of fixes active at given temperatures (open triangles). (B) Average hourly travel from the same 91 

day data set (solid line and symbols) and average hourly collar temperature (broken line and open symbols); 0800 to 1700 hours averaged from 

84–95 fixes per hourly interval, other hours from 173–180 half-hourly fixes per interval.
1 8 • smithsonian contributions to zoology

months, with frequent, overcast, cold fronts (Figures 1.8, 

2.3A). We have no maned wolf collar temperatures for the 

same 2009 months, but a set for M8 during August 2007 

(Figure 2.3B), shows a close coincidence between the diel 

patterns of ambient and collar temperatures. This suggests 

that at least in this cool month, M8 did not greatly modify 

his temperature exposure, compared to an instrument in 

the shade. The morning grass is soaked with dew in winter months; perhaps the sharp drop in collar temperature 

before dawn is due to evaporative cooling on a wet collar during rapid predawn travel (Figure 2.2B). The shaded 

weather instrument does not collect dew. However, August 2007 (mean Tmax = 32.0°C, Tmin = 16.2°C) was colder 

than August 2009 (mean Tmax = 33.6°C, Tmin = 20.2°C), so 

Figure 2.3. (A) Hourly ambient temperature 15–27 August 2009, with passage of a cold 

front 21–22 August (Kestrel® weather logger in open Los Fierros savanna) and (B) average 

hourly instrument temperature reading in savanna August 2009 during 13.5 days (N = 322 

readings) (dashed line); and mean hourly collar temperature for M8 August 2007 (N = 340 

fixes) (solid line). August 2007 was exceptionally cold, with mean minimum temperature of 

16.2°C, compared to the 6 year mean of 18.1 for August. Collar temperatures for that month 

include a minimum of 10°C and maximum of 36°C. There were several strong cold fronts.
number 639 • 1 9

the predawn collar temperature drop may reflect cooler 

nights.

Daily temperature excursions did not seem to influence the total distance a maned wolf traveled on a given 

night. For a continuous 90-day data set (F3 04–05, 3,400 

fixes), there is no significant correlation between the total 

distance traveled on a given date and the ambient Tmax for 

that date as measured nearby at El Refugio Huanchaca 

(Spearman rank correlation, r = –0.098, p level 0.36; Tmax

range 22°–37°C) nor for the Tmin (r = 0.032, p level 0.76; 

Tmin range 15°–25°C). In contrast, for the same data set, 

hourly travel distance was strongly correlated with temperature for that hour as registered in the GPS collar 

(Spearman rank correlation r = –0.92, p level 0.0000). In 

other words, on hot days, MW traveled just as far during 

the cooler night hours as they did on cool days, but they 

hardly moved during the hottest hours. 

Seasonal Activity

Activity as categorized nominally, from whether an animal was active or inactive in a given hourly interval, gives 

the clearest index of presence or absence of movement, 

hence the circadian pattern of rest (Figure 2.4A). The ordinal measurement of distance moved between hourly fixes 

shows a similar pattern, but the rate of travel varies with 

the hour (Figure 2.4B), so the patterns are not identical. In 

the wettest season (January–March), MW traveled more 

in daylight; they were more often active at midday and 

would become inactive later in the morning and begin activity earlier in the afternoon (Figure 2.4). Although there 

was variation both between individuals in the same year 

and between the same individual in different years (Figure 

2.5), all individuals showed the same general pattern of 

shortest daily movements in February–May, and longest 

daily movements in August–October (Figure 2.5B).

For the seasonal daily travel averages of the three longest data sets (F3, Oct 05–Jun 06; M5, Oct 05–Dec 06; 

F11, Feb 07–Feb 08), dry season (July–September, October–December) daily travel distances were significantly 

different from wet season travel (January–March, April–

June) in all pairwise cases (Kolmogorov-Smirnov test, P < 

0.02), whereas within-season trimesters were not significantly different. 

Resting Behavior

To explore resting behavior, we use data sets from the 

first GPS collars, which were programmed to acquire fixes 

at half-hourly intervals during the 15 hours of greatest 

daily activity. Later data sets record rests of no shorter 

than one hour, so are more likely to underestimate the 

true duration of daily resting. The average time F3 spent 

in daytime rest was 9.3 hours, but she usually rested for 

0 2 4 6 8 10 12 14 16 18 20 22

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Average Proportion Activ

e

Hour

JFM

AMJ

OND

A

02468 10 12 14 16 18 20 22

0

200

400

600

800

1000

1200

Average Hourly Travel, 

m

Hour

B

Figure 2.4. Hourly activity by season. (A) The average proportion of fixes for a given hour during which F3 was active (movement >50 m 

between fixes, nominal data active/inactive) and (B) the average distance traveled between hourly fixes from the same data set. On the basis 

of three-night weekly samples averaged seasonally, data continuous from October 2005 to June 2006. Dotted line, October–December (drier 

months); broken line, January–March (wettest months); solid line, April–June (transition months).
2 0 • smithsonian contributions to zoology

another hour twice during the night (Table 2.1). Although 

January was sampled for only 7 days, these clearly show 

the increased daytime activity and reduced nighttime activity seen in the other wet season data sets (Figures 2.4, 

2.5). In January, the time spent resting at midday was two 

hours shorter than it was in October–December. This was 

more than compensated for by increased rest periods at 

night, with about a doubling of nocturnal resting time 

(Table 2.1). Consequently, F3 rested for a total of about 

an hour longer per 24 hours in January, the only month 

of this sample where she was inactive for more than half 

of the 24 hours.

On a coarser, hourly scale for the longest data sets, the 

mean total daily hours active (resting is the inverse), over 

the year and seasons, shows that the MW spent on average 

one or two hours more in travel and fewer in resting in the 

dry season than in the wet season (Table 2.2). The seasonal 

differences in hours active between wet season quarters 

(January–June) and dry season quarters (July–December) 

were significant for all MW (Kolmogorov-Smirnov test, p

level 0.05), but within-season differences were not significant. The difference between highest and lowest monthly 

activity of individuals was approximately five hours 

daily, and in some months, all MW were traveling 15 to 

Figure 2.5. Average daily total travel distance (sums of average hourly travel) by month. (A) Six data sets from three individuals show the 

variation between individuals and months and (B) average daily travel of five adult MW combined from 40 monthly data sets 2003–2008 (solid 

line) and average monthly rainfall during those years (broken line).

Table 2.1. Resting behavior of maned wolf F3, from continuous GPS collar data for 90 sequential days 13 October 2003 to 16 January 2004, 3,403 fixes. Fixes were programmed hourly from 0800 to 1700 hours and half-hourly for all other hours. Movement during 

midday rest is movement >50 m between fixes, with at least one hour of rest before and after the movement.

Mean hours Mean night Mean total rest per Days moved during Mean rests

Month No. days in midday rest rests, hours 24 hours, hours mid day rests in nighttime

Oct. 2004 22 9.0 2.5 11.48 3 2.4

Nov. 2004 30 9.6 2.1 11.60 6 1.7

Dec. 2004 31 9.7 1.9 11.51 10 1.8

Jan. 2005 7 7.1 5.3 12.42 1 3.2

Grand total 90 9.3 2.3 11.6 22 2
number 639 • 2 1

16 hours of a 24 hour period (Table 2.2). Because rests 

shorter than one hour are not detectable in these data sets, 

the true hours of inactivity are likely to be underestimated 

and activity similarly overestimated.

Travel to Water

Maned wolves apparently need to drink liquid water 

at least daily. They were not registered by camera traps at 

water holes when other water sources were widespread, 

such as after heavy rains or before the savanna dried out 

in about mid-August (Chapter 3). Camera trap data from 

158 visits shows that MW came to water holes at any hour 

of the night, with peak visits from 1900–2200 hours and 

at 0400 hours (Figure 2.6). Cameras did not trigger well 

during daytime heat, but as telemetry showed MW to be 

generally immobile at midday in late dry season (Figure 

2.1A), it is unlikely that many visits were unrecorded. We 

watched MW drinking from an arboreal blind. They generally drank long and intensely and could return to drink 

several times within a few minutes. Unlike zorros (Cerdocyon thous), which foraged intently around the water hole 

and ate items found on or dug from the boggy ground 

during multiple extended visits in an evening, MW usually came, drank, and departed, as also inferred from telemetry. MW tracked on foot with VHF telemetry would 

abruptly change pace to travel quickly, without stopping, 

directly to a water hole up to 4 km away. 

Resting Sites

Each maned wolf used many daytime rest sites (beds) 

that were scattered widely on its range (Figure 2.7). Adults 

without pups rarely used the same place on sequential 

days, but subadults sometimes did so. We visited 14 sites 

of five MW where telemetry showed them to have spent 

the day or where we encountered them by chance. Twelve 

of these beds were in dark, denlike hollows pushed deep 

under long, dense, fine grass clumps in open areas (Figure 2.8). All but two were in seasonally flooded habitats, 

including three that were used for litters of pups, one of 

which was surrounded by water when occupied. Most 

beds in flood-prone areas were used when the ground was 

dry, and many geographic information system (GIS) located beds were in uplands. There were clusters of contiguous rest sites in zones of tall dense bunchgrasses, and 

range mates could share these zones. A nongrass bed 

was in a narrow, cool, damp, dark tunnel under a dense 

thicket of low Mauritiella palms, and another was a nest 

in grass exposed to the sky in the shade of shrubs. Grass 

bed entrances were low and inconspicuous, and MW had 

to crawl into them through a fringe of stems. We saw M7 

drop to creep on his belly into a grass bed. None had space 

for more than one individual. Beds were not marked by 

beaten pathways, but areas with many beds had networks 

Table 2.2. Mean total daily hours active, with one fix per hour, 

based on whether an animal moved ≥50 m since the previous 

GPS fix. Rests of <1 hour are not detectable, so table represents 

minimum resting time. Multiple data sets for a given month 

are averaged for a given maned wolf, N = 99 total maned wolf 

months of GPS data. Here n/a, not available

Month F3 F9 F11 M5 M6 M8 Average

Jan. 13.99 12.66 11.93 12.59 10.74 10.62 12.09

Feb. 12.31 13.87 12.73 12.49 n/a 9.91 12.26

March 11.93 12.01 12.83 10.86 n/a 10.61 11.65

April 10.09 13.91 13.20 12.39 n/a 11.19 12.16

May 12.60 n/a 13.41 11.97 n/a 11.93 12.48

June 12.01 n/a 12.75 13.81 n/a n/a 12.85

July n/a 14.73 16.74 14.24 n/a 13.12 14.70

Aug. n/a 14.21 14.75 15.59 n/a 13.48 14.51

Sept. n/a n/a 16.64 15.00 n/a 11.90 14.51

Oct. 13.67 15.26 15.16 14.96 13.76 12.54 14.22

Nov. 15.34 14.18 16.02 13.05 13.37 12.63 14.10

Dec. 13.70 13.68 15.50 13.34 12.20 11.68 13.35

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20 22

Nearest hour

Photo Events

Figure 2.6. Circadian pattern of visiting water. Time to the nearest 

hour of photos of MW at water holes, including only the first photo 

(event) of a given individual in a given hour (N = 158 events).
2 2 • smithsonian contributions to zoology

of multiple trails. To us, beds had no detectable maned 

wolf odor, suggesting that MW may avoid urinating near 

their refuges (we can smell maned wolf urine marks for 

many weeks). MW were totally hidden in beds and either 

slept heavily or were reluctant to move. Three times we 

approached to within 5 m of resting individuals before 

they abruptly emerged. 

DISCUSSION

Activity Pattern and Temperature

In our study area, MW are not obligately crepuscular/

nocturnal but can vary their circadian activity to become 

nearly cathemeral in some months, with the flexible behavior typical of many Canidae. Quantitative records of 

maned wolf circadian activity from telemetry are scarce 

and difficult to compare to ours: Dietz (1984) divided the 

day into 6 hour blocks for analysis of records for seven 

MW in Brazil (0600–1200; 1200–1800, etc.). He found 

MW to be constantly active in 96% of nocturnal fixes and 

intermittently active in 35% of diurnal ones, but midday 

and early morning/evening are not distinguishable. Melo 

et al. (2007), with GPS collars on three MW, collected twohourly fixes for 6 months in Minas Gerais and reported 

data like that in Figure 2.1A, with virtually no activity 

from 0700 to 1600 hours. On the basis of direct observations, Silveira (1999) described MW as bimodally active, 

with peaks from 0600 to 1000 and 1800–2400 hours. 

Seasonal differences such as we found have not been elsewhere reported. Activity patterns may differ in different 

habitats or latitudes, as suggested by the entirely nocturnal 

behavior of MW reported by Melo et al. (2007). Likewise, 

crab-eating zorros (Cerdocyon thous), the most numerous 

canids syntopic with MW in our study area, are noted to 

be strictly nocturnal in both Pará, Brazil (Macdonald and 

Courtenay, 1996) and in Venezuela (Brady, 1979), where 

Brady attributed nocturnality to thermoregulation. However, in our study area, zorros are regularly seen traveling about until 0900–1000 and after 1500–1700 hours, 

as also documented by Juarez and Marinho-Filho (2002). 

The hourly activity of MW in relation to temperature 

has not been previously documented. There are two plausible explanations of the patterns in Figure 2.2: either (1) 

temperature itself drives maned wolf activity or (2) the 

observed pattern of maned wolf activity is an incidental 

result of a temperature-independent circadian cycle that 

coincides with the daily light/dark/temperature cycle. MW 

have a dense dorsal pelage, and when lying in the daytime 

Figure 2.8. Daytime bed of M5 in a hole under long grass. The 

entrance was enlarged and cleared to make it visible. Photograph by 

L. Emmons.

Figure 2.7. F3 rest site locations during 90 consecutive days (rest 

sites are at noon fixes: of 89 noon fixes, 88 were inactive from previous fix); rest sites, black dots; broken double line, outline of grassland; single black line, polygon of F3 home range during that time 

(60 km2

). Many locations are superimposed or apparently so owing 

to scale.
number 639 • 2 3

shade, they pant like other canids, tongue hanging out and 

dripping. Thermal panting is costly in water loss: up to 50 

mL/h in 25 kg dogs at 40°C (Blatt et al., 1972); but paradoxically, it is an energy-neutral behavior (Robertshaw, 

2006). Dogs (25 kg) began to secrete water from the nasal 

glands for panting at 30°C (Blatt et al., 1972), which is 

exactly the temperature at which MW cease activity (Figure 2.2). MW thus seek shelter and become inactive at 

the threshold where panting is required for thermoregulation in dogs of the same weight. Moreover, parturition is 

concentrated in the cooler winter months (Rodden et al., 

2004), when more diurnal foraging time below 30°C is 

available (Figure 1.8; Chapter 5). Under the tropical sun 

in the grassland, it is, of course, much hotter than shade 

temperatures used in meteorology.

In the late dry season our study MW could travel several kilometers to reach water, an energetically expensive 

activity. In captivity, MW had a water turnover rate of 2.3 

L/day (Boniface, 1998; based on doubly labeled water in 

three MW). This is one fifth as much per kilogram as that 

of domestic dogs, which under intense exercise can further quintuple their water requirements (Boniface, 1998). 

MW thus may have some physiological adaptation for 

arid habitats. Nonetheless, they must drink considerable 

amounts, especially when panting, as supported by our 

observations and photos at water holes. The months with 

least diurnal activity (August–December) are those with 

both drought and highest maximum temperatures (Figures 

2.4, 1.8), while those with most diurnal activity are the 

coolest and wettest (in terms of drinking water, January–

July). The need to visit water sources (Figure 2.6) likely 

also contributes to longer travel distances in dry season, 

than in wet season, months (Chapter 3). To prevent water 

loss and/or hyperthermia, temperatures above 27°C may 

drive restriction of daytime dry season activity (Figure 

2.2), but there are alternative explanations.

Diurnality of rodent prey has been invoked as the 

driver of diurnality in grassland Ethiopian wolves (Canis 

simensis; 96% of dietary prey occurrences; Sillero-Zubiri 

and Gottelli, 1995). During the early years of our study, 

cavies (Cavia aperea) were the main prey of MW, with 

about 80% occurrence in scats (Emmons, 2009; Chapter 

4). Cavies are active in early morning and late afternoon, 

as are the numerically dominant mice of the savanna, 

Necromys lenguarum (Francisco et al., 1995). Cavies vanished from the study area between 2004 and 2007, with 

0% occurrence in scats after 2006 and none trapped on a 

trapping grid after 2003 (Emmons, 2009; Chapter 4). Our 

observations from VHF-tracking and GPS collar results do 

not show that MW were more diurnal when cavies were 

abundant. However, because cavies do not burrow, MW 

perhaps could hunt them at any hour. The reverse hypothesis, that the activity of rodent prey species shifts diurnally to avoid predator activity peaks, is likewise plausible 

(Fenn and Macdonald, 1995).

Resting Behavior

The daily energy balance of an individual includes 

trade-offs between travel, resting, and thermoregulation. 

Daily, monthly, and seasonal resting patterns have not previously been quantified for free-living MW. Our most noteworthy result is how little MW rested, and consequently, 

how long they were active (Tables 2.1, 2.2). In comparison, 

hypercarnivorous African wild dogs rested for 20.5 hours 

per day and hunted for only 3.5 hours, generally in the 

morning and late afternoon (Gorman et al., 1998). These 

two species represent the opposite extremes of resting/activity ratios among large Canidae. Coyotes (Canis latrans) 

in Yellowstone Park rested on average 66% of the day (16 

hours) from December to July, when they fed on ungulate 

carcasses, but when they hunted rodents in October and 

November, resting decreased to about 27% of the day (Gese, 

2004). The latter is even less rest than we documented in 

MW and clearly illustrates the costs of solo hunting of individual small prey. Interestingly, ocelots (Leopardus pardalis) in forest, which also solo-hunt rodents, traveled for 

daily averages of 9.4 to 11.9 hours, close to the number of 

hours per day used by MW, but ocelots walked slowly and 

traveled only about 3.2 km/night, with an estimated prey 

capture rate of 0.9/km; to maintain body masses one third 

of that of MW (Emmons, 1988). This perhaps points to a 

similar return per kilometer of hunting.

Resting Sites

Few rest sites or dens of MW have been reported: 

Dietz (1984) described a grass den and three that were 

within crevices. Melo et al. (2007:34) described a den with 

pups as in “a maze of grass tunnels . . . [in] an open area 

of cerrado covered with tall grass species” similar to those 

that we document. The wide dispersal of daytime of beds 

on the home range (Figure 2.7), not previously mapped, 

may establish individual presence across the range, as a 

possible territorial reinforcement (Chapters 3, 5).

Most MW we examined lacked fleas, as also reported 

by Dietz (1984), while four syntopic zorros (Cerdocyon 

thous) were heavily infested. Fleas have a terrestrial larval 

phase, and beds and dens are the most usual foci of infestation. Daily rest-site shifts by MW should reduce flea and 
2 4 • smithsonian contributions to zoology

perhaps tick loads and any associated disease exposure 

(Chapter 6).

Finally, insect pests could influence maned wolf resting 

and activity. Los Fierros savanna is plagued with irritating 

insects: by day in the dry season, swarms of feral africanized honeybees (Apis melifera) climb over the faces of stationary MW, humans, and horses and enter their mouths, 

ears, and noses. Diurnal sweat bees (Halictidae) and biting 

flies (Tabanidae) likewise torment stationary mammals in 

the dry season. Before sundown, swarms of blood-sucking 

gnats (Simuliidae) emerge, and at night in the wet season, 

there are clouds of biting mosquitoes (Cuculicidae). As 

well as cover from the elements, the thick blanket of dense, 

fine, stems of grass beds (Figure 2.8) offer protection from 

bees and flies. Daytime wet season activity would decrease 

exposure to mosquitoes, and nighttime dry season activity would decrease exposure to bees and tabanids. When 

following VHF-tagged MW on foot, we repeatedly noted 

that MW moved off from their beds just as biting simuliid 

flies became intolerable to us in late afternoon (walking 

dispels gnats). Similarly, most daytime dry season moves 

of MW were directly from one bed to another, possibly to 

escape bees (or hot sun patches). Aggravating insects seem 

unlikely to be major drivers of maned wolf circadian patterns, but pest avoidance could push activity an hour or 

two in one direction or another.

In summary, MW in NKP spend 10–16 hours a day in 

travel that is nocturnal/crepuscular during most months 

of the year, but their travel shifts to increased diurnality in the months of wet season flooding. Maned wolves 

show an abrupt decline in activity at temperatures above 

27°–30°C, coincident with rising daytime temperatures, 

implicating but not proving physiological issues of thermoregulation and water balance as likely drivers of circadian activity during the hottest months of drought. Long 

daily activity and short total resting times are probably 

correlates of long search times needed for hunting sufficient small prey and widely scattered fruit to nourish large 

body size (Chapters 4, 8). Low maned wolf reproductive 

rates and small litter sizes (Rodden et al., 2004; Chapters 

5, 8) may be consequences of an ecology that leaves little 

temporal cushion to acquire extra resources.
3 Ranging Patterns

Louise H. Emmons, Verónica Chávez, 

Luis Fernando Del Aguila, Sixto Angulo, 

and Matthew J. Muir

ABSTRACT. The ranging patterns of maned wolves (MW), Chrysocyon brachyurus, 

were studied in Noel Kempff Mercado National Park (NKP), Bolivia. Adults traveled 

mean distances of 11 km/night based on hourly locations. When location fixes were 

half-hourly, nightly distance for the same data sets were 5–16% longer, or an estimated 

12 km/night over all data. Nightly travel distances averaged longer during dry season 

(14 km/night maximum average monthly travel), than during wet season months (7 km/

night, minimum average monthly travel). Ninety-nine percent kernel home ranges of 

adults were 40–123 km2

. MW varied their sequential nightly trajectories such that an 

average of 34 km2

 (minimum convex polygon) was covered during each weekly threenight data sample. Area accumulation was rapid, with a seasonal asymptote reached at 

200–300 locations, or about three, three-night samples. The need to visit water holes in 

the late dry season may increase dry season travel distances. Reproductive MW live in 

monogamous pairs on territories (Dietz, 1984). Because of habitat restriction by forest, 

maned wolf pairs on our study area shared only one or two boundaries of their ranges 

with other pairs. When location data sets coincided in month, there was no range overlap 

between neighboring adult resident pairs, but range boundaries shifted temporally, so 

that out-of-phase data can show spurious overlap. Nonreproductive MW could be found 

temporarily within pair ranges.

INTRODUCTION

Maned wolf home range sizes have been determined by telemetry for several regions of Brazil (Coelho et al., 2008; Dietz, 1984; Jácomo et al., 2009; 

Melo et al., 2007; reviewed in Rodden et al., 2004; Rodrigues, 2002; Trolle et 

al., 2007), but little has been recorded of the nightly movements of free-ranging 

individuals in relation to their overall ranges, habitats, or seasons. We used GPS 

collars to record hourly movements of individuals, in weekly samples over many 

sequential months. In this chapter we report our results on ranging behavior, 

which comprise the first telemetry study of maned wolves (MW) in either Bolivia or seasonally flooded grasslands. Our goals for this arm of the study were 

to understand the land use patterns of MW in terms of their home range sizes, 

Louise H. Emmons, Department of Vertebrate 

Zoology, National Museum of Natural History, 

P.O. Box 37012, MRC 108, Smithsonian Institution, Washington, D.C. 20013-7012, USA; 

Verónica Chávez, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Luis 

Fernando Del Aguila, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Sixto 

Angulo, Fundación para la Conservación del 

Bosque Chiquitano, Calle René Moreno, Santa 

Cruz, Bolivia; Matthew J. Muir, Division of International Conservation, U.S. Fish and Wildlife 

Service, 4401 N. Fairfax Drive, ARLSQ 100c, 

Arlington, Virginia 22203-1622, USA Correspondence: emmonsl@si.edu. Manuscript received 25 

August 2010; accepted 26 August 2011.
2 6 • smithsonian contributions to zoology

conservation needs, and general energy budget. The key 

topics we address include the following: (1) the relation between nightly foraging trajectories and total range size, (2) 

how home ranges are defined temporally, (3) how nightly 

trajectories vary between individuals and seasons, and 

(4) how individuals are spatially distributed in relation to 

others. Conditions for MW changed over the study years, 

so that year-to-year variation in use of the same area by 

the same or different individuals became an important ecological variable. All of these topics form a continuum with 

those addressed in Chapter 2 on activity patterns and in 

Chapter 5 on social interactions. Our study area is the only 

savanna in Parque Nacional Noel Kempff Mercado (NKP) 

with partial vehicle access. It is small, inhabited by only a 

few maned wolf individuals, so we focused on acquiring 

detailed longitudinal data on these accessible groups.

A species’ daily path mirrors the distribution of all its 

resources and social interactions. With GPS telemetry we 

could follow with high accuracy the landscape-scale travels of this wide-ranging species. GPS telemetry is restricted 

to a finite number of locations (fixes) by the weight of the 

batteries that power the internal processor (about 4,000 to 

8,000 fixes, depending on temporal and temperature parameters). Thus there is a trade-off between interfix interval and the total data collection time in months. We chose 

to program data collection in weekly, three-night samples 

of hourly fixes, so that entire nightly movement sequences, 

social interactions, and habitat use could be acquired regularly over many months. However, as each GPS fix took 

only about 55 seconds, the location of a maned wolf is 

known for at most 22 minutes of each 24 hour day. By 

connecting sequential locations into a route, a greater area 

traversed can be inferred than can be seen from individual 

fixes, but nightly routes neither reliably include quick visits to point resources nor generate time budgets such as 

can be developed with continuous observation (Coelho et 

al., 2007). The information acquired from GPS telemetry 

obviously depends on the scheduling of the GPS fixes: the 

closer they are in time, the more accurately the fixes map 

the path and the more exact spots visited are recorded 

(Mills et al., 2006). GPS telemetry technology has rapidly 

improved since we began our work, and soon, battery life 

may no longer be an issue (Tobler, 2009).

Materials and methods

Study Area

Field studies on ranging were done in the Los Fierros savanna (or pampa) in NKP from October 2001 to 

July 2009 (Figure 1.2). Habitats and climate are described 

in Chapter 1. The forest encircled, J-shaped, Los Fierros 

grassland is 4–10 km wide and about 26 km long and includes 219 km2

 of maned wolf habitat. It is separated by a 

river and gallery forest from larger savannas on cattle estancias and by 9 km of forest from a large pristine savanna 

on top of the Huanchaca tableland massif in NKP (Figure 1.2). Maned wolves can move between populations in 

adjacent grasslands. The study savanna is nearly flat and 

includes no permanently flowing watercourses other than 

at one corner that abuts the Río Tarvo/Paragua (Figure 

1.2). As the ground dries from wet season flooding in June 

to mid-August, scattered low points retain seasonal ponds 

that eventually dry until there is no open water source 

in the savanna from late August to late October or early 

November. The middle and most northerly parts of the 

savanna include larger patches of upland Campo Cerrado 

habitat that never floods, and the southern end is seasonally deeply flooded “Bajío.” Wet season flooding forces 

MW into drier areas and restricts the habitable landscape 

(L. Emmons and P. Cuellar, unpublished data). 

Analysis of Field Data

Capture, handling, and telemetry methods are described in Chapter 1 and by Deem and Emmons (2005). In 

2001–2002, MW were followed first with VHF telemetry, 

and after mid-2003 with GPS collar telemetry. Most GPS 

collars were programmed to take hourly fixes for three sequential nights of each week (samples), but some collars 

took few or no fixes at midday, when MW were generally 

inactive. The first three GPS collars deployed took continuous half-hourly fixes during maximal activity, from 1700 

or 1800 to 0800 hours, and hourly fixes during the day 

(see Chapter 1 for collar schedules). The VHF data may 

be autocorrelated and biased toward maned wolf locations close to roads or trails, so we use them to generate 

home range boundaries and travel rates but not to analyze 

habitat use. Activity periods (nights) are calculated from 

the first radio location or GPS fix after noon on a given 

date to the last location before noon on the following date. 

Travel distances and rates are calculated only from sequential fixes within continuous data series (distances between 

the last fix of a three-night sample and the first fix of the 

next sample are excluded from all analyses). The Los Fierros savanna is small relative to maned wolf home ranges, 

and its irregular outline precludes use of the standard measurement of minimum convex polygon (MCP) home range 

areas, which would force inclusion of adjacent forest where 

MW never ventured, thereby overestimating range size. To 

estimate home range boundaries, we connected the outer 

points to the next nearest points (excluding forests), so that 
number 639 • 2 7

polygons may have concavities (not “convex”). Other telemetry studies show that mammalian home range edges 

are often concave and spiky, such that forcing convexity 

upon them (MCP) can create spurious home range inflation 

and overlaps with neighbors (Emmons, 1988, 2000), as we 

will see below for MW. Nonetheless, for standardized comparisons between areas estimated from subsamples of fixes 

(seasonal, monthly, or three-night samples), we generated 

MCP areas with Hawth’s Tools (spatialecology.com) and 

R-Ade (Calenge, 2006). Each successive deployment of a 

new GPS collar on a given animal (generally in sequential 

years) is treated as a different data set if data series have 

gaps of longer than a month (Table 3.1). 

All fixes less than 50 m from the previous fix are 

treated as “inactive” (or “resting”) MW, and are set to 0 

m apart for analysis. We assume that the animal moved 

if fixes were over 50 m apart, (“active”; Chapter 1). 

Maned wolf mean travel rates were 600 to 1,000 m/h, 

and we treat sequential locations as independent. None 

was discarded for computation of range areas (in contrast 

to Jácomo et al., 2009). Moreover, the large numbers of 

unbiased GPS locations, sampled at equal intervals, obviates the need for models to extrapolate range areas from 

small samples (Kenward, 1987). Relative to the kilometer 

scale of maned wolf movements, the random, meter-scale 

intrinsic GPS location errors are inconsequential to the 

calculation of maned wolf travel distances or rates. As the 

habitat is open, the success rate of GPS fix attempts was 

generally high (90–97% for whole data sets), with a mean 

time to fix of about 55 seconds. Later collars improved 

much in performance over the first one deployed in 2003, 

which had 57% fix success, perhaps from poor satellite 

coverage in Bolivia coupled with early technology.

Hourly fixes inadequately documented the use of 

water points, as MW did not linger while drinking. To 

explore the influence of water sources on movements, we 

tabulated all active locations within 150 m of all known 

water points. Only the first fix was tabulated for each 

water-proximity location event.

RESULTS

Home Range Size

The Los Fierros savanna was divided by maned wolf 

home ranges into northern and southern halves (North 

Range, South Range). Initially (2001–2003) the northern 

half was itself subdivided into two areas (North Ranges 1 

and 2) that subsequently merged. Home range areas from 

TABLE 3.1. Data sets from which movements and range sizes were calculated. Kernel home range areas (KHR) were calculated with 

R-ade (Calenge, 2006), without regard to habitat edges. Long data series used for seasonal analyses shown in bold. M4 and F3 were

subadults in 2002; M6 was not resident on a single range. M, males; F, females; NR, North Range; SR, South Range; n/a, not available.

hree-night KHR, km2

Animal (Site) Collar Data start Data end Fixes samples 99% 95% 75% 50%

M2 (NR 1) VHF 20 Oct 01 1 Jan 04 800 n/a 40.42 30.58 15.29 7.79

M4 (NR 1) VHF 23 Oct 02 24 Feb 03 243 n/a 15.68 10.82 5.66 3.03

F3 (NR 1) VHF 26 Sep 02 24 Feb 03 240 n/a 20.43 14.84 7.22 1.35

F3 (NR 1) GPS 13 Oct 03 16 Jan 04 1847 n/a 52.86 39.57 19.42 8.99

F3 (NR 1) GPS 9 Oct 04 7 Jan 05 3403 n/a 75.21 57.1 31.69 17.22

F3 (NR all) GPS 6 Oct 05 13 Jul 06 2900 45 73.88 56.47 32.63 16.6

F3 (NR all) GPS 21 Sep 07 21 Nov 07 607 9 86.07 63.51 28.54 11.72

F3 (NR all) GPS 16 Jul 08 18 Oct 08 1008 14 77.49 60.83 29.96 12.32

M5 (NR 2) GPS 4 Oct 04 7 Mar 05 4631 n/a 73.88 56.47 32.63 16.6

M5 (NR all) GPS 29 Sep 05 16 Dec 06 4606 64 85.29 67.5 38.61 21.14

M5 (NR all) GPS 6 Feb 07 29 Mar 07 349 6 61.44 45.99 21.47 9.42

M5 (NR all) GPS 4 Oct 07 30 May 08 1112 16 98.2 78.08 41.87 19.63

M6 (unfixed?) GPS 27 Sep 05 23 Feb 06 1340 21 n/a n/a n/a n/a

M8 (SR) GPS 25 Jul 07 26 Sep 07 635 10 75.5 56.11 25.85 10.14

M8 (NR) GPS 9 Jul 08 22 May 09 3329 46 108.67 89.29 48.09 22.55

F9 (SR) GPS 7 Jul 08 16 Apr 09 2667 33 110.89 87.51 49.28 25.08

F11 (SR) GPS 4 Feb 07 26 Mar 08 3784 59 123.19 92.71 43.86 18.37
2 8 • smithsonian contributions to zoology

seven data sets of three resident adult males and three females (635 to 4,406 fixes per data set, including two data 

sets for M8 on different home ranges) averaged 89.3 km2

99% kernel home range (KHR), 69.4 km2 95% KHR, 

and 17.6 km2 50% KHR (Table 3.1). If the VHF data set 

for M2 is excluded (possibly underestimated), the areas 

are, respectively, 96.2, 74.9, and 19.0 km2. Females had 

slightly larger average 95% KHR ranges than did males 

(79 km2 versus 71 km2); but sample sizes are too small for 

meaningful inference. Because the home ranges are superimposed over the same 220 km2

 fragment of savanna and 

include pairs on the same territories, they are not independent. However, they do represent the area use and needs 

of different maned wolf individuals on this particular savanna. These area uses changed both interseasonally and 

interannually (see also Chapters 4, 5). 

General Movement Patterns and Distance Traveled

Straight-line measurements between telemetry locations of resident adult MW averaged 11.1 km per 24 hours 

over all months of the year (Table 3.2). On-foot VHS telemetry data had gaps when signals were lost, so the data 

underestimate both travel distance and range area. Nonetheless, an estimate of kilometers traveled per night, from 

on-foot VHF telemetry, was similar to those obtained with 

GPS collars: mean travel of M5 for 27 October nights 

(850 GPS fixes) was 13.7 km/night, while that of M2 for 

15 on-foot VHF-tracking nights (306 fixes) was 11.19 km/

night, or within the variation seen between individual GPS 

telemetry data sets (Table 3.2). Subadults traveled shorter 

paths within smaller areas than did adults (F3 and M4 in 

2002; Table 3.1).

At the scale of hourly fixes, adults typically walked in 

fairly straight paths that rarely zigzagged or doubled back 

but made large loops that extended to near an edge of the 

home range (Figure 3.1). On sequential nights they took 

different paths, so that a large part of the home range was 

crossed in a few nights (Figure 3.1). Adults tended not to 

TABLE 3.2. Daily linear distances (km) between hourly GPS locations, averaged by month, from 92 monthly data sets of three 

female and two male maned wolves (MW). Standard deviations 

(SD), monthly means of all MW; N, number of monthly threenight samples.

Month M5 M8 F3 F11 F9 Average

(N) (28) (16) (25) (14) (9) (92) SD

1 (9) 8.80 10.35 12.74 11.28 11.09 10.85 1.29

2 (8) 9.00 9.85 9.43 8.85 5.74 8.57 1.46

3 (8) 7.92 10.73 8.82 6.79 6.65 8.18 1.50

4 (4) 7.68 10.06 5.87 7.81 4.99 7.28 1.76

5 (4) 9.54 10.47 8.48 9.73 n/a 9.56 0.71

6 (3) 9.65 n/a 7.24 13.26 n/a 10.05 2.47

7 (6) 11.54 15.55 11.67 13.39 14.71 13.37 1.60

8 (6) 13.07 13.13 15.89 14.38 13.03 13.90 1.12

9 (8) 10.94 11.40 8.57 10.95 n/a 10.47 1.11

10 (13) 13.74 11.44 14.47 11.61 13.70 12.99 1.23

11 (12) 12.90 14.51 15.52 13.74 13.26 13.99 0.94

12 (11) 12.41 14.61 14.90 11.69 13.87 13.50 1.25

Average 10.95 11.97 12.54 10.65 10.78 11.06

FIGURE 3.1. Pathways of single, three-night samples: (A) M2, 

17–19 November 2001, each day with different symbols, double 

line is savanna edge, stipple, and circular outline represents the range 

polygon (49.1 km2

, 800 fixes), W is Pozo Matt water hole; (B) M5, 

dry season 6–8 October 2005 (three-night range 47.3 km2

, 59.3 km 

traveled); and (C) M5, wet season, 9–11 February 2006 (three-night 

range 24.4 km2

, 21.2 km traveled). Outline in B and C is the home 

range polygon from the total M5 data set October 2005–December 

2006 (86 km2). Note the travel pattern of long, straight trajectories 

with extensive coverage of home range. Star in B indicates Pozo Matt 

water hole.
number 639 • 2 9

repeat their pathways. If they had a frequently visited goal 

such as water or pups, a different route was taken to and 

from it on sequential nights of a sample (Figure 3.1A, B).

To estimate how much nightly travel might have been 

missed between fix times, we extracted route length from 

both half-hourly and hourly locations for the three data 

sets with fixes half-hourly, including only hours with both 

intervals of fixes (Table 3.3). The total daily distances 

between hourly fixes were on average 91% of the path 

length generated with half-hourly fixes. The largest trajectory differences, up to 17%, are seen in data from F3 when 

her home range was small (2003–2004) and likewise for 

M5 in January–February 2005 when his monthly ranging 

was shortest (Table 3.3). This likely results from simple 

geometry, because for a given walking rate, more turns 

are executed to travel in a smaller space, and it reflects 

a slightly more intensive use per km2

 of the landscape. 

Minimum actual average daily travel distance for all MW, 

incorporating the average difference between hourly and 

half-hourly data, thus should be at least 12.2 km daily, or 

1.1 km longer than found by connecting hourly fixes. We 

note that only half of the year was sampled in this way, 

and possibly, some of the seasonal differences in nightly 

ranging might in reality be smaller if MW zigzag more in 

January–March than in July–September. 

A result of nightly route variation is a rapid increase 

in range area with fix number (Figure 3.2). The area accumulation curves start to flatten at 100 to 200 fixes, and 

in 2005–2009 data, reach asymptote for a given data set 

at about 300 locations and 60 km2

. One hundred to 300 

TABLE 3.3. Estimation of the straightness of travel trajectories 

by comparison of distances traveled nightly in the same data sets 

when fixes were half-hourly or hourly, and the percentage of hourly to half-hourly distance. Daytime periods when all scheduled 

fixes were hourly are removed, so total 24 hour travel is not represented. Average nightly travel (m) for given months. Maned wolf 

individual and its 99% KHR home range size for the data sets (F3, 

52 km2

). These MW were a pair, and from October 2004 to January 2005 the fixes were synchronous and on the same territory.

Month Fixes half-hourly Fixes hourly Percent

F3 (52 km2

)

Oct. 2003 21,677 17,944 83.6

Nov. 2003 20,570 19,502 95.8

Dec. 2003 17,899 15,458 87.2

Jan. 2004 16,149 13,545 84.7

F3 (75.2 km2)

Oct. 2004 14,481 13,528 93.4

Nov. 2004 13,765 12,762 92.7

Dec. 2004 13,967 12,781 91.5

Jan. 2005 10,868 10,836 99.7

M5 (73.8 km2)

Oct. 2004 12,453 11,599 93.1

Nov. 2004 11,675 10,772 92.3

Dec. 2004 11,625 10,800 92.9

Jan. 2005 7,242 6,529 90.2

Feb. 2005 7,906 7,022 88.8

March 2005 7,518 6,884 91.6

FIGURE 3.2. Area accumulation by number of hourly locations from GPS collar single data sets of adult residents, all fixes <50 m from 

the previous fix excluded; and one VHF data set (A, M2 lowest curve). Data are accumulated in increments of 12 fixes, to 99% KHR. 

(A) One female and three males on the North Range, longer sets cut off at 1000 fixes. (B) Two females and one male on South Range, 

the longest set cut off at 2,088 fixes.
3 0 • smithsonian contributions to zoology

fixes represents two to four, three-night weekly samples. 

The curves flatten completely at about four to six samples. 

Six adult residents, male and female, behaved alike. Steps 

in the curves represent seasonal shifts in habitat use, which 

were most pronounced in the more flood-prone South 

Range, where the slow rise above some steps represents 

a slow expansion into drying seasonally flooded habitat 

(F11, Figure 3.2B). The position of steps is a chance consequence of the collar deployment month (F11 was tagged in 

February and expanded her range over many months; F9 

was tagged in September when her whole range was used).

Travel distances and areas encompassed during threenight samples were quite similar for all individuals, although the standard deviations are high (Table 3.4). These 

measures varied in parallel over wet and dry-season samples (Figure 3.3). It is curious that the areas of three-night 

sample polygons, in km2

, approximate the sum of kilometers traveled during given samples (Table 3.4, Figure 3.3). 

This results from a uniform rate of travel, similar for all 

MW. The geometry of travels was therefore quite constant 

throughout the year.

Despite the large spatial areas visited during short 

times, temporal use of home ranges was highly nonuniform, with about half of all locations (that is, hours when 

a maned wolf was at a place) in a data set falling within 

about 20% of the total range area (50% KHR; Table 3.1; 

Figure 3.5B). 

Water

In the late dry season, MW seemed to travel daily to 

points of water (Chapter 2). There is a large dry season 

peak in North Range GPS events with 150 m proximity 

to water (Figure 3.4A). On this range, only a few natural 

TABLE 3.4. Area and distance covered in three night samples. 

The mean minimum convex polygon area covered (calculated in 

R-Ade), and mean total distance and SD of distance traveled per 

three night sample, for individual MW with large data sets. Data 

are for M8 total and segregated into samples taken in different 

home range areas (SR, South Range; NR, North Range). Samples 

for F3 with newborn pups omitted.

Maned N Mean Mean SD

wolf samples area, km2 travel, km travel

F3 59 30.84 28.66 9.02

F9 30 33.51 39.79 19.70

F11 59 32.65 34.80 12.09

M5 86 33.65 33.89 9.13

M8 all 60 37.47 32.58 8.73

M8 SR 14 48.44 34.89 9.93

M8 NR 46 34.13 31.74 8.36

FIGURE 3.3. Average distances (broken lines) and areas (solid lines) of three-night weekly samples for the male and female of a pair, by month, 

in 2005–2006. (A) Female F3, 10 months of continuous data (she had new pups in July); (B) Male M5, 14 months of continuous data.
number 639 • 3 1

or artificial (dug by us) savanna water holes existed in 

the late dry season. Streams in nearby forest retained 

isolated pools, but we do not know if MW used these. 

On the South Range, MW in two data sets preferentially 

used savanna water holes and shifted to riverside marshes 

when water holes dried in September (Figure 3.4B). North 

Range water holes were in flood-prone terrain not generally visited when water was widespread, but South Range 

water holes were near often used parts of the range, where 

MW might go for reasons unrelated to drinking, as shown 

by January–May proximity when water covered much of 

their range. 

Territoriality

We define territoriality as the exclusive use of an area 

by members of a class of individuals, regardless of how it 

is achieved. We began our study with VHF telemetry of 

an old adult male, M2, and two subadults/yearlings (M4, 

F3) that co-occupied the same home range (the presumed 

adult female/mother was seen and photographed, but not 

captured). The 2001–2004 data sets showed superposition of M2 and F3 ranges, with a sharp, common southern boundary across the savanna (Figure 3.5A). Because of 

difficult access, the M2 data set (from on-foot VHF tracking) likely underrecorded the SE corner of his range (Figure 3.5A). Nine months later, the first M5 data set shows 

a range largely south of, and abutting that of M2 and F3, 

and with a sharp line at its opposite, southern, border 

across the pampa. M5 was by then consorting with F3 on 

her range, so a few fixes overlap (Figure 3.5A; see Chapter 

5). When we followed south-traveling M2 or F3 on foot 

with VHF in 2002–2003, we noted them to turn abruptly 

when they reached the midsavanna range boundary and 

then to travel along its general edge. Kernel analysis for 

the F3, 2003–2004 data set, shows 50% of locations concentrated in a 9 km2

 strip near the SW boundary of her 52 

km2, 99% KHR (Figure 3.5B). No obvious topographic or 

vegetation features coincided with any midsavanna range 

boundaries. 

Neighboring territories met along sharp lines of locations on across-pampa range boundaries (Figures 3.5–3.8). 

Locations of neighbors for the same month show virtually 

no overlap (Figures 3.6–3.8). However, range boundaries shifted from season to season or from one year to the 

next (Figures 3.6, 3.8). Data that were not simultaneous, 

or that were summed over many months, might therefore 

show spurious home range overlap that did not exist in 

real time (Figure 3.8). The male and female of pairs tightly 

shared boundaries that abutted other pairs (M5 and F3 in 

Figure 3.8A), although they did not otherwise necessarily 

coincide exactly in their monthly ranges. Offspring shared 

the parental territories. We conclude that resident adult 

pairs were strictly territorial. 

On the basis of range boundaries from telemetry fixes, 

there were three maned wolf territories on the Los Fierros 

savanna from 2001 to early 2004. From late 2004 through 

2009, there were only two territories, the North and South 

Events at Waterholes

0

5

10

15

20

25

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Event

s

A

Events Water S Range

0

2

4

6

8

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Waterholes River Marsh

Month

N Range

B

FIGURE 3.4. Proximity to water sources by month. (A) North Range, three, 11–12 month continuous data sets (35 months) from two males 

and a female (N = 64 events). (B) South Range, two, 11–12 month continuous data sets from two females (N = 61 events); river marsh, shaded 

bars. Only the first fix (event) within 150 m of a known water source was included if series were larger.
3 2 • smithsonian contributions to zoology

722000 726000 730000

8378000 838400

0

X

Y

95 

95

75

75 

50

A B

FIGURE 3.5. Positions of maned wolf ranges on the Los Fierros savanna from October 2001 to March 2005. (A) Los Fierros savanna 

outline with all October 2003 to January 2004 GPS locations of F3 (open circles), overlaid by M2 range polygon outline (dark pointed 

oval, 2001–2003 VHF locations); and M5 GPS locations from October 2004 to March 2005 (black triangles). Note sharp boundaries 

of southernmost range edges of F3 and M5. M2–F3 and M5 data are from different years. (B) The 50%, 75%, 90%, 95%, and 99% 

KHR contours for the F3 data set in A; axes are Universal Transverse Mercator (UTM) coordinates. Fixes during inactivity excluded.

FIGURE 3.6. Synchronous locations of neighboring males M5 (North) and M8 (South) during September and October 

2006, home range polygons shown as thin lines. (Left) Whole ranges; (right) mutual boundary, enlarged. The cluster of 

locations at bottom center at left are along the river; cluster above the W on the NW side of the North Range is at Pozo 

Matt water hole.
number 639 • 3 3

Ranges (boundaries figured in Figures 3.5 to 3.8); and by 

September 2010, there was only a single territory, which 

included all of the savanna. Range shifts are discussed further in Chapters 4 and 5.

Exceptions to Territoriality

Even though adult pairs were territorial with respect 

to neighboring pairs, other individuals could be temporarily present on a territory. Most were grown young 

of the pairs, and some were transients recorded once in 

camera trap images; but there were several exceptions. In 

2002–2003, other MW, likely of the neighboring group 

(on North Range 2), came to Pozo Matt water hole on 

the territory of M2 and family, then close to the territorial 

boundary (Figure 3.5). After 2004, when the North Range 

boundary was 7 km farther south, only territorial family 

members were photographed at this site (Chapter 5).

In September 2005 on the South Range, we caught old 

male M6, when M8 was present, as well as females and 

young pups (Chapter 5). Until December, M6 traveled in 

and out of the South and North Ranges, spending weeks 

on the territory fringes and in distant river marshes (Figure 3.9A). He crossed the river several times and traveled 

FIGURE 3.7. Home range shifts of M5, moving gradually northwestward over three years, and February 07 locations of F11 (black 

circles). Note that data sets are of unequal length (2 to14 months), 

the February–March 2007 range (heavy line) shows avoidance of a 

recently burned area on its NE side.

FIGURE 3.8. Fine-scale temporal boundary adjustments of adjacent pair territories. (A) February 2007 boundary (broken line) of F11 (black 

circles) with M5 (open squares), and F3 January 2007 locations (black stars, no F3 February 2007 locations available). The single fix of M5 that 

is beyond the line is 100 m from it. (B) February 2007 (broken line) and March 2007 (solid line) boundaries of F11–M5 and March 2007 locations of F11 (black circles) and M5 (open squares). Note that both maned wolf ranges shifted NE together, without incurring range overlaps, 

and that neighbors share locations exactly on boundaries. The savanna at the territorial boundary is 4 km wide (grassland border outlined by 

thin lines that bracket location points).
3 4 • smithsonian contributions to zoology

in October and November to a neighboring estancia in 

three-night samples of 51, 52, and 59 km, but otherwise 

he moved little (average of 18 three-night samples excluding these three longest, was 14.8 km; entire range polygon, 174.2 km2

). When rising waters flooded the marshes 

and savannas in December, he returned to near his capture point in the nonflooded border zone of the North 

and South Ranges, mostly in the North Range territory 

of M5, where he spent January and February with everdecreasing movements in an area of 10 km2

 (Figure 3.9B). 

During synchronous samples from December to February, 

M5 twice briefly approached M6 to within 150 m (149 m 

apart 17 December 2005; 87 m apart 2 February 2006); 

and they certainly met for a single fix on 16 February (6 m 

apart at 0300 hours), after which M5 left the area and did 

not soon return. M6 died two days later (ceased motion).

In a case with some similarities, young male M5 made 

incursions into the territory of geriatric male M2 to consort with young F3 after the adult female had disappeared 

(see Chapter 5) and during the last 5–7 months of M2’s 

life. With no GPS collar, the final movements of M2 were 

unrecorded.

DISCUSSION

Home Range Size

Telemetry-generated maned wolf home range areas 

reported in the recent literature are in the same size range 

that we found for Los Fierros (Coelho et al., 2008; Jácomo 

et al., 2009; Melo et al., 2007; Rodrigues, 2002), suggesting similar ecological conditions. The largest such study, of 

37 resident adult MW studied by Jácomo et al. (2009) in 

Emas National Park, Goiás, Brazil, had mean 95% KHR 

areas of 80.2 km2 and mean 50% KHR areas of 13.8 km2: 

close to our mean values of 74.9 and 19.0 km2 for ranges 

from 2005–2009 (Table 3.1). In contrast, at the beginning 

FIGURE 3.9. Movements of M6 through the territories of three or more pairs, before his death. (A) All locations September 2005 to 

February 2006 (concave polygon connecting points, 174.2 km2

). (B) Locations in January 2006 (open circles, area = 9.2 km2), and 

1–22 February 2006 (black circles, 4.8 km2

), when he died. Outline is the Los Fierros savanna, with river marshes and gallery forest 

border its southern edge; the southernmost fixes are on Caparú estancia 20 km south of the river (area image in Figure 1.2).
number 639 • 3 5

of our study, two MW co-occupying the same range used 

areas of 40 km2 (VHF, perhaps an underestimate) and 52 

km2: more like the smaller ranges of 20–40 km2 reported 

by Dietz (1984) and 40–50 km2 reported by Trolle et al. 

(2007) and Melo et al. (2009). In our study, increases in 

range sizes after 2005 corresponded to a decline in prey 

numbers (Emmons, 2009), which suggests an influence of 

resource density on range size, as we report in more detail 

in Chapters 4 and 5.

General Movement Patterns and Travel Distance

Maned wolf sequential nightly movements can be 

characterized as (1) long in path length; (2) nonrepeating 

in routes; (3) paths quite straight, often traveling to an 

edge of the range before turning; (4) likely to take divergent directions on sequential nights; (5) longer in the dry 

season than in the wet season (Chapter 2); and (6) generally uniform in travel rate regardless of month.

The true area seen by a body traveling 12 km, scanning a fixed-width band on each side, is the same whether 

it moves in a straight line or a circle, which subtend maximally different area polygons. The MCP per sample data 

(Table 3.4) illustrate the home range coverage patterns of 

MW, but they do not imply that the real area scanned for 

foraging is different under different configurations of the 

same path length. Only total path length and degree of 

path overlap influence the dimensions of the nightly foraging area an animal visits (Emmons, 2000b).

GPS telemetry underestimates the true path length of 

an animal by an amount related to the intrinsic straightness 

of the path and the interval between locations (Mills et al., 

2006). Actual maned wolf travel distances, from the difference between hourly and half-hourly data, were on average 

at least 1.2 km per night longer than those estimated from 

hourly fixes, or 12.2 km global nightly average. For thin 

data sets, energy use calculated from movement distance 

will therefore be underestimated by telemetry (Goszczyski, 

1986). May to October maned wolf travel distances reported in Minas Gerais by Melo et al. (2007) from 12 daily 

fixes (2-hourly) for a pair and subadult female, were much 

shorter than those we recorded, 9 km/day for a female and 

only 7 km/day for a male (not significantly different). These 

shorter trajectories may result from half as many locations 

per day, coupled with small home range sizes that produce 

more turns (40–50 km2

; Melo et al., 2009), additive factors 

that will underestimate travel distances. We note, however, 

that our male M2, also with a 40 km2 range size, moved 

11 km/night (N = 15 nights of VHF tracking), while F3 on 

a 52 km2 range, moved a mean of 21.7 km each night in 

October (Table 3.2), so ranges of this size do not alone account for short trajectories.

MW at Los Fierros chose sequential nightly paths so 

as to rapidly visit much of the home range, as shown by 

steep area accumulation curves (Figure 3.2). GPS collar 

data from three individuals in Minas Gerais (Melo et al., 

2007), showed similar rapid area accumulation, but because fixes were taken at half the rate (every two hours), 

asymptotes were reached at half as many fixes (i.e., within 

an equivalent time span). Melo et al. (2007) found no seasonal differences in daily ranging like those we document 

in our study animals (Figure 3.3; Tables 3.2, 3.3; Chapter 2), but their study did not include the critical months 

of November to March. Seasonal flooding, which is not 

present in Melo et al’s. study area, caused seasonal ranging differences at Los Fierros. Because our study MW also 

shifted activity toward more diurnality and resting during 

the wettest months (Chapter 2), the seasonal variation in 

ranging was thus driven not only by the presence/absence 

of water but also by an undefined seasonal circadian factor such as prey type.

The nightly movement rates of MW were similar for 

different sexes, seasons, and territories (Tables 3.2, 3.4; 

Figure 3.3). The travel distances summed over three-night 

samples (Table 3.4) are a simple function of average rates 

of travel. Maned wolves of both sexes thus moved at similar average speeds, as is expected from their near monomorphy (Dietz, 1984; Jácomo et al., 2009). Similar leg 

and stride lengths produce similar average kilometers per 

hour for the same gaits. The seasonal differences in ranging (Figure 3.3) are due to changes in the number of hours 

that MW are active in each season, rather than to changes 

in travel speed. This reinforces the data in Chapter 2 that 

show more hours of resting in wet season than in dry season months (Table 2.2, Figure 2.5).

The parallel variation in area and distance traveled 

in samples from months of greater or lesser travel (Figure 3.3) shows that the shapes of travel routes remained 

similar when movements were compressed into to smaller 

areas during the wet season. Nonetheless, when the home 

range size of F3 was smaller, there was an increase in the 

relative length of trajectories of half-hourly, compared to 

hourly, locations: from an average of 12% difference in 

a home range of 52 km2

, to a 6% difference in one of 75 

km2 the following year (Table 3.3). Thus our failure to observe increased relative path lengths on smaller wet season 

ranges may be because hourly fixes are too widely spaced 

to detect increased zigzagging.

Nonrepeating and wide-ranging trajectories can establish territorial presence, uncover isolated fruit sources, 
3 6 • smithsonian contributions to zoology

and maximally spread prey encounters over time and 

space, so that prey have less expectation of predator encounters (wariness). However, the more frequently used 

50% KHR “core” areas (Table 3.1, Figure 3.5; Jácomo et 

al., 2009) were often in bands adjacent to the boundaries 

between neighboring pairs. The influence on home range 

use of neighboring pairs per se is not clear, as these areas 

also included favored long-grass resting sites, high-ground 

refuges, and dense populations of a favored fruit tree, Alibertia edulis.

Territoriality

Among our few study animals there was sharp territoriality between neighboring adult pairs or family groups 

(see also Chapter 5). We did not attempt to calculate percentages of overlap between neighboring pairs, because the 

sole boundary that existed for most of the study (Figures 

3.5–3.7) was nonoverlapping when simultaneous data 

sets were available. Because MW in Los Fierros savanna 

shared only short borders with other pairs, perhaps they 

devoted more effort to maintaining tight boundaries than 

they could have if surrounded on all sides by neighbors.

Dietz’ first telemetry study of MW (1984) likewise 

showed strong exclusivity and stability of pair ranges, 

and he considered MW to be territorial, as did Rodrigues 

(2002). Jácomo et al. (2009), with a much larger sample 

of 28 MW followed in the same year, found about 20% 

overlap between male-male or nonpair neighbors and 8% 

between female-female neighbors, while presumed pairs 

had, by definition, >75% intrapair overlap. Their study 

was based on small numbers of manual VHF fixes (mean 

of 60 locations per animal, but as few as 10), and to prevent autocorrelation, they discarded fixes <12 hours apart 

(Jácomo et al., 2009). They concluded that territoriality 

was likely, but not definitively shown by their data. The 

looser-knit range structure found by Jácomo et al. (2009) 

might have been due to the combination of few location 

points coupled with data summed across a number of 

months. With few locations, the bordering lines of range 

polygons cross long stretches of terrain without points, enclosing areas that may not actually be used by the animals. 

All studies to date are at least consistent with the territoriality postulated by Dietz (1984), but possibly the tightness 

of boundaries varies. 

The use of a water hole near the range boundary 

by adults of more than one pair, in the drought years of 

2002–2003 (Figure 1.8), suggests that the need for water 

outweighed territorial imperatives. However, we know 

nothing of the family relationships or ranges of the interlopers, as we could not trap near the water hole until 

late 2004, when we opened a 4 km access road. All MW 

subsequently detected there were members of the North 

Range family (Chapter 5).

The movements of old male M6 in his final months 

show no territory, and he appears to have been seeking 

a place of refuge. He moved between the territories of at 

least three pairs. He would stay some days in a small area 

then move to another for up to two weeks. He returned 

repeatedly to his zone of capture then left quickly again 

for fringe areas unused by other tagged MW. A reproductive pair or two occupied the savanna across the river into 

which he briefly made long excursions. His final return to 

the territory of male M5 coincided with rising waters that 

flooded all of his recent haunts. Gray wolves (Canis lupus) 

commonly kill interlopers on their territories, and intergroup conflict is a major source of mortality (Vucetich and 

Peterson, 2004). M6 died two days after meeting M5, but 

he had moved little in the previous two weeks (penultimate sample, 3.4 km2

; final sample, 2.3 km2). We cannot 

know whether they fought, and M5 killed him, but M6’s 

skeleton showed severe dental and bone disease (Chapter 

6) and no obvious bite marks. In the other case of overlapping adult males, M5 was on M2’s territory from time to 

time a few months before the latter died, and both males 

used the water hole. As neither had GPS collars, their interactions are unknown.

This pair of events implies that adult males do not 

kill other males for territorial acquisition, because in 

both cases, younger males on the territories had months 

in which to kill the old males, yet they did not do so, or 

vice versa. Mateless old males may be able to defend small 

personal spaces and/or do not represent a threat worth 

the risk of injury to younger territorial males. Both old 

males died before the normal reproductive season, when 

extra-pair mating could become an issue (Chapter 6). We 

recorded no case of a reproductive female tolerating an 

older, unpaired female on her territory. Despite cases of 

range infringement by outsiders, the reproductive pair is 

certainly the territorial unit, as further discussed in Chapter 5. Because it is rare to observe the fates of secretive 

mammals at the ends of their lives, these examples give a 

small glimpse into what are surely complex relationships 

that develop over the lifetimes of the MW.
4 Variation in Diet 

and Resources

José Miguel Castro and 

Louise H. Emmons

ABSTRACT. The diet of maned wolves (MW) was investigated during a general study 

of the ecology of the species in Noel Kempff Mercado National Park, Bolivia. Qualitative 

field records of scat contents were recorded from 2001–2007, and a quantitative analysis 

comparing wet and dry seasons was based on scat collections from 2008–2009. Like 

other studies, we found the diet to be composed of about half each of fruit and animal 

prey, with ratios that changed slightly with seasons. Prey included all small mammal species found on the savanna, and fruit eaten included a wide array of seasonally changing 

species, but frugivory was dominated by Alibertia edulis, present in 47% of all scats, 

and by Solanum gomphodes, in 18% of scats. Rodents declined by >90%, and a major 

prey species, Cavia aperea (cavies; over 60% occurrence), went to extinction in the study 

savanna from 2003–2006. No other species replaced cavies in importance, and their loss 

coincided with changes in maned wolf territory size and body condition. Savanna fires 

influenced the fruiting of major dietary taxa, which peaked in the diet 2–3 years following burns, but were almost absent in the first year postfire. We estimate daily energy 

consumption and foraging return based on the biomass of items enumerated in scats and 

the nightly distances MW traveled.

INTRODUCTION

Diet is the paramount characteristic of animals, as it is associated with 

nearly every aspect of ecology, from morphology to geographic range. The diets 

of MW (Chrysocyon brachyurus) in many localities have been studied by analysis of scats. Maned wolves are dietary opportunists that feed on fruit, small 

vertebrates, and invertebrates, according to local availability. All studies show a 

diet that varies closely around half of fruits and half of small animal prey (Aragona and Setz, 2001; Bueno and Motta-Junior, 2004, 2006, 2009; Dietz, 1984; 

Jácomo et al., 2004; Juarez and Marinho-Filho, 2002; Queirolo and MottaJunior, 2007; Rodrigues et al., 2007; Santos et al., 2003; Silva and Talamoni, 

2003). The frugivorous part of the diet is usually dominated by a single species: 

José Miguel Castro, Museo de Historia Natural 

Noel Kempff Mercado, Avenida Irala 565, Santa 

Cruz de la Sierra, Bolivia; Louise H. Emmons, 

Department of Vertebrate Zoology, National Museum of Natural History, P.O. Box 37012, MRC 

108, Smithsonian Institution, Washington, D.C. 

20013-7012, USA. Correspondence: emmonsl@

si.edu. Manuscript received 25 August 2010; accepted 26 August 2011.
3 8 • smithsonian contributions to zoology

the giant fruits of Solanum lycocarpum (Solanaceae; “lobeira” or wolf’s fruit); and the carnivorous part is usually 

dominated by either rodents and other small mammals or 

armadillos (summarized in Rodden et al., 2004; Rodrigues 

et al., 2007). Nonetheless, Bestelmeyer and Westbrook 

(1998) and Rodrigues et al. (2007) reported MW chasing 

and killing large prey in Emas National Park, Brazil (pampas deer, Ozotoceros bezoarticus).

We studied the behavioral ecology of a small population of MW on Los Fierros savanna, Noel Kempff Mercado National Park (NKP), Bolivia. For seven years we 

concurrently documented the relative numbers of rodents 

on trapping plots in maned wolf habitat (Emmons, 2009; 

Emmons et al., 2006a). Lilienfeld (2000) studied maned 

wolf food habits in NKP prior to our project, and because 

he found a diet like that recorded by others, we did not at 

first repeat a quantitative analysis of scats. Nonetheless, 

we recorded the grossly visible contents of scats encountered in the field, photographed many, and tried to identify dietary species. In 2004, our long-term small mammal 

trapping studies showed a large decline in rodent abundance (Emmons, 2009). Low rodent numbers persisted 

until yearly trapping ceased in 2007, and a key maned 

wolf prey species had disappeared. This plunge in prey 

density was an opportunity to observe the consequences 

for MW of a resource decline. Thus Castro (2010) undertook a quantitative analysis of maned wolf diet, with 

the double goals of describing the seasonality of diets and 

to discover how the diet had changed in the decade since 

Lilienfeld’s research.

Maned wolves are the only omnivores among the 

largest Canidae. Their tooth morphology is strongly indicative of this dietary omnivory and provides evidence of 

a millennial adaptation to this lifestyle (Van Valkenburgh, 

1989; Chapter 1). Our ultimate aim in studying diet was 

to reach beyond the enumeration of dietary taxa to understand the costs and consequences of individual food 

choices for MW in a varying environment.

We first describe the taxonomic contents of the diet 

and evaluate its seasonal and interannual changes. We 

then estimate the daily consumption of individual food 

items and calculate their return per kilometer of daily 

travel, based on the ranging patterns reported in Chapters 2 and 3. We discovered much interannual variation 

in consumed taxa of both fruits and animal prey, which 

seemed to result from changes in the available resource 

base. We end by presenting some apparent consequences 

of resource changes on the spatial behavior of our study 

animals.

Materials and Methods

Qualitative Analysis of Diet

We studied the diet from scats of a population of MW 

on the small savanna of Los Fierros in NKP. The scats were 

derived from few individuals and home ranges and so represent temporal samples from the same piece of habitat. 

The MW, study area, climate, and habitat are described in 

Chapter 1. From 2001–2007, 161 scats encountered in the 

field were picked apart in situ, examined qualitatively by 

eye, and their contents recorded and often photographed. 

We identified some ingested seeds and fruits, and a few 

were collected for reference. Tiny items, such as teeth of 

tiny mammals, were likely to have been missed, but not 

mammal hair. Although other species were identified, for 

this set of data we distinguish only cavies (Caviidae, Cavia 

aperea) from other rodents by their unique tooth morphology, relatively large bones, and distinctive, long, banded 

hair, often excreted in intact tufts. These qualitative data 

are scored only for presence/absence of an item or category 

in a scat and percentage of all scats examined in a given 

time that included that item. Researchers were usually in 

the field from September–November (late dry season) and 

sometimes in February–March (flooded season) or June–

August; other months were not sampled for diet.

Quantitative Analysis of Diet

One hundred and thirty-five maned wolf scats were 

collected for quantitative analysis during 94 days of 

searches on the Los Fierros savanna in July 2008, October 

2008, January 2009, and July and August 2009 (114 scats 

in the dry season; 21 in the wet season). Most were found 

by walking along tracks and transects across the savanna. 

A few were collected from trapped MW. Concurrent radio 

telemetry studies allowed us to be confident of the home 

ranges used by resident MW at any place on the savanna 

and the likely movement ranges of MW that were the 

sources of scats. Each collection had time, date, and GPS 

coordinates. Scats were field dried in the sun to prevent 

mold growth, washed carefully over fine mesh screens, and 

separated into identifiable components (fruits and seeds, 

bones, hair, feathers, feet, etc.). In the laboratory, scat components were identified by comparison with vertebrate, 

invertebrate, and herbarium specimens in the Museo de 

Historia Natural Noel Kempff Mercado, Santa Cruz, Bolivia (MNK); from the literature; and by consultation with 

specialists. We generally follow the mammal taxonomy of 
number 639 • 3 9

Wilson and Reeder (2005) and for Caviidae, of Dunnum 

and Salazar-Bravo (2010a, 2010b). Lilienfeld (2000) reported maned wolf scats with Solanum lycocarpum (Solanaceae) from NKP, but M. Nee (pers. comm.) identified the 

species at Los Fierros as S. gomphodes, and noted that the 

“lobeira” is not known from Bolivia. Another giant-fruited 

species, S. crinitum (determined by Nee, pers. comm.), 

grew on the roadside at Los Fierros to at least 2007, but 

subsequently vanished. The two species grew together 

where MW often defecated, so some Solanum sp. identified in 2001–2007 scats could have been S. crinitum. Likewise, fruits identified as Bromelia balansae by Lilienfeld 

(2000) are now recognized as a new species, B. ignaciana

R.Vásquez and Ibisch. During 2008–2009, fruiting plants 

were collected from the Los Fierros savanna and preserved 

for reference as herbarium specimens in MNK. 

The biomass and numbers of prey individuals eaten 

were estimated by counting the minimum number in scats 

from hard parts such as incisor teeth, feet, tails, beaks, etc. 

Hair only was counted as one individual. For most mammal species, we used weights from voucher specimens from 

Los Fierros. To account for young in the population, we 

used 75% of adult weight to estimate prey biomass. Fruit 

numbers eaten were estimated by counting seeds in scats 

and dividing by the average seed numbers of intact fruits, 

following the methodology of Bueno and Motta-Junior 

(2004, 2009) and Rodrigues et al. (2007). Other details of 

the quantitative diet analysis are described in Castro (2010).

Relative numbers of rodents in the study area were 

monitored by annual captures on two, 17 ha trapping 

plots on the northern part of Los Fierros savanna (North 

Range maned wolf territory; Chapter 3). Each yearly sample was 10 days (1000 trap/nights) in September–October 

(Emmons et al., 2006a; 2006b; Emmons, 2009). Plot PA 

was in nonflooded Campo Cerrado (savanna woodland) 

that burned totally in 2003 and partially in 2007 (Figure 

1.3). Plot PT was in seasonally shallowly flooded termite 

savanna that did not burn from 2000–2008. In 1999 the 

entire northern half of the Los Fierros savanna burned 

rapidly in a hot fire that carbonized nearly all woody vegetation (maned wolf North Range), but in the southern 

savanna (South Range) only small patches burned in the 

15 yr before 2009, when nearly the entire savanna burned 

again (Figure 1.10).

Data Analysis

For quantitative analysis, fresh scats of <50 g mass, 

collected within the same territory, on the same day, and 

containing the same items, were grouped into single feeding events to avoid pseudoreplication, as the same MW 

could have produced them from the same meals. This reduced the effective number of scats analyzed from 135 to 

108. For comparability with other studies, we used (1) the 

crude percent of scats in the sample that included an item; 

(2) the number of items as a function of the number of 

total occurrences of all items in the sample, or frequency 

of occurrence; and (3) the minimum total number and biomass of items eaten, derived from countable hard parts 

(Dietz, 1984; Emmons, 1987; Motta-Junior et al., 1996). 

Biomass eaten was calculated with and without assigning 

an arbitrary mass representation for two fecal samples 

that included hair of marsh deer (Blastocerus dichotomus, 

115 kg). Assigning to each scat with deer hair a large meal 

of 3 kg, assuming a canid capacity to gorge on meat when 

available, greatly inflates the percent of biomass eaten represented by prey, from 33% to 45%, based on the contents of only 1.5% of individual scats. Eleven occurrences 

of maned wolf hair, likely derived from grooming, are 

omitted from calculations.

Kelly and Garton (1997) reported that whereas all 

hair was passed undigested when mice and rats were fed 

to coyotes (Canis latrans), a maximum of only 24% of 

teeth of mice and 52% of teeth of rats were recoverable 

from scats, and the rest were digested. Tallying the numbers eaten from hard parts in scats may thus underestimate prey numbers. Digestion of mouse bones and teeth 

by coyotes was enhanced by cofeeding of pure meat (Kelly 

and Garton, 1997), which is not an issue with MW. In 

contrast, feeding sporadically (as do MW in situ), decreased tooth digestion. Maximal recovery of teeth thus 

might be expected from maned wolf samples. Tiny teeth 

that we recovered from scats did not show much erosion, 

and all but two of our scat samples that included micromammal hair also included bones and/or teeth. We assume 

that there was little underestimation of prey from digestion of hard parts, but only feeding experiments can test 

whether maned wolf scat contents correctly estimate the 

number of micromammals eaten.

Energetics

The average total daily energy requirements of captive 

MW (in 12 × 45 m enclosures) are 525 kJ × kg0.75 (range: 

501–674 kJ × kg0.75; Barboza et al., 1994), that is, 5693 

kJ/d for a 24 kg maned wolf or 1,360 kcal (range 1,297–

1,745 kcal). The resting energy requirement (RER) would 

be the best baseline from which to estimate requirements, 
4 0 • smithsonian contributions to zoology

but it is not available for MW. For dogs, Burger and Johnson (1991), report that resting energy expenditure (REE) 

is 678 × M0.64 kJ/d, which for MW would be 1,205 kcal/d, 

or near the low end given by Barboza et al. (1994), of 

501 kJ × kg0.75 or 1,297 kcal. The nutrient requirements 

of dogs are similar to those of MW (Barboza et al., 1994). 

We therefore chose the low end of the maintenance estimate as the “resting” value from which to calculate the 

costs of maned wolf travel and the benefits of items in the 

diet. Pregnancy generally costs canids and other mammals 

about 1.3–1.5 times as much as maintenance, while lactation about doubles energy requirements.

“The net cost of transport for a running animal is the 

same at any speed. . . . It means that the amount of energy that an animal uses to run 1 km is almost the same 

whether it runs very fast or at a leisurely pace.” (Biewener, 

2003:208). This curiosity makes it fairly easy to calculate 

the energy expenditure of mammals when their basal expenditure is known. There is an exception if an oxygen 

debt is incurred that is repaid after travel ceases (Biewener, 

2003) but because MW travel many hours at fairly standard rates (Chapters 2, 3), they are unlikely to be generating oxygen debt, especially because animals generally 

choose to travel at the intermediate speeds of a given gait, 

where travel costs are minimal (Biewener, 2003). The generalized incremental cost of locomotion (ICL) for mammals is estimated at

ICL (kJ/km) = 10.678 × M0.70

or 99 kJ/km for a 24 kg maned wolf (23.6 kcal) (Goszczynski, 1986).

RESULTS

Food Classes and Seasonality

Maned wolves at Los Fierros had a diet nearly equally 

divided between animal prey and fruit. It varied about 

10% either way in terms of percent of scats with items, 

percent frequencies of items, and in estimated biomass 

represented in a scat, depending on the years, seasons and 

sampling (Tables 4.1, 4.2, 4.3). The species-rich list of 

items eaten included at least 30 plant and 51 animal taxa 

(Table 4.3; and other observations). The estimated overall 

TABLE 4.2. Summary of overall occurrence and frequency among 520 items in 108 scats analyzed quantitatively in 2008–2009 (Castro, 

2010) and numbers of species identified. Data exclude 11 occurrences of maned wolf hair presumed from grooming.

Fruit Mammals Rodents Birds Reptiles Fish Invertebrates

Occurrences 205 137 95 37 23 2 116

Frequency 0.394 0.263 0.183 0.071 0.044 0.004 0.223

Minimum taxa 26 15 12 5 6 2 20

TABLE 4.1. Occurrence of food items in scats. The percentages of total maned wolf scats found on Los Fierros savanna that contained 

fruit or prey types, by grouped years (N scats). Years 2001–2007 are from qualitative field inspection of scats, when small or rare items 

may have been overlooked; other data are from quantitative analysis (Castro, 2010; Lilienfeld, 2000). Both species of cavies that Lilienfeld (2000) identified are combined (see text). As methods differed, quantitative and qualitative samples are not strictly comparable. 

However, the differences are significant between qualitative data from 2001–2004 and 2005–2007, in numbers both of scats with cavies, 

or those with all mammals (X2

, p < 0.05); and likewise, there is a significant difference between the quantitative sets from 1997–1999 

and 2008–2009 (X2

, p < 0.01). Years 1997–1998 from Lilienfeld (2000), 2001–2007 from Emmons (unpublished), and 2008–2009 

from Castro (2010).

Years (N) Fruit All mammals Cavies Armadillo Birds Reptiles Fish Invertebrates

1997–1998 (51) 100.0 86.3 74.5 10.1 13.7 17.6 0 37.3

2001–2004 (106) 97.0 69.8 45.3 5.6 0.0 0.9 0 0

2005–2007 (58) 97.0 29.3 8.6 3.9 8.6 3.5 3.5 5.7

2008–2009 (108) 99.0 73.0 0 0 31.0 21.0 2.0 60.0
number 639 • 4 1

TABLE 4.3. Taxon list of items from 108 maned wolf scats collected in 2008–2009, with number of scats in which found (N), frequency 

of occurrence (FO) among all items eaten by season, the raw percentage of scats in which item was found, by season, and the percent of 

total estimated biomass consumed (modified from Castro, 2010) Dashes indicate none identified.

Wet season (15) Dry season (93) Percent of

 Percent Percent total biomass

Food Item N FO of scats N FO of scats consumed

Fruit

Rubiaceae 

Alibertia edulis 4 0.062 26.7 79 0.17 84.95 21.69

Genipa americana − − − 2 0.004 2.151 1.43

Solanaceae 

Solanum gomphodes 2 0.031 13.3 22 0.047 23.66 10.83

Bromeliaceae 

Bromelia ignaciana 5 0.077 33.3 2 0.004 2.151 1.96

Annonaceae 

Duguetia furfuracea − − − 5 0.011 5.376 2.21

Annona coriacea 1 0.015 6.7 1 0.002 1.075 2.10

Annona nutans 1 0.015 6.7 4 0.009 4.301 1.22

Icacinaceae 

Emmotum nitens − − − 6 0.013 6.452 0.97

Polygalaceae 

Moutabea longifolia 4 0.062 26.7 − − − 0.55

Menispermaceae 

Abuta grandifolia − − − 1 0.002 1.075 0.18

Hippocrateaceae 

Salacia elliptica 2 0.031 13.3 2 0.004 2.151 0.70

Malpighiaceae 

Byrsonima sp. − − − 1 0.002 1.075 0.02

Moraceae 

Brosimum gaudichaudii 1 0.015 6.7 1 0.002 1.075 0.19

Brosimum acutifolium − − − 17 0.036 18.28

Melastomataceae 

Miconia albicans − − − 1 0.002 1.075 0.04

Clidemia capitella 1 0.015 6.7 0 − − 0.00

Sapotaceae 

Chrysophyllum gonocarpum 1 0.015 6.7 0 − − 0.01

Indet. 1 − − − 9 0.019 9.677 5.51

Indet. 2 − − − 4 0.009 4.301 0.12

Indet. 3 2 0.031 13.3 2 0.004 2.151 0.01

Indet. 4 1 0.015 6.7 1 0.002 1.075 0.06

Fabaceae 1 0.002 1.075 0.04

Arecaceae 

Mauritiella armata 6 0.092 40 4 0.009 4.301 −

Euterpe precatoria − − − 1 0.002 1.075 1.41

Arecaceae 2 1 0.015 6.7 0 0 0 0.12

Poaceae spp. − − 7 0.015 7.527 0.01

Subtotal fruit 32 0.492 173 0.371 − 51.38

Mammals

Echimyidae 

Proechimys longicaudatus 4 0.062 26.7 9 0.019 9.677 6.97

Mesomys hispidus − − − 1 0.002 1.075 0.30

Cricetidae 

Holochilus brasiliensis 1 0.015 6.7 7 0.015 7.527 4.26

Pseudoryzomys simplex 1 0.015 6.7 7 0.015 7.527 1.44

Juscelinomys huanchacae − − − 2 0.004 2.151 0.48

Necromys lenguarum 3 0.046 20 13 0.028 13.98 1.91

Oecomys sydandersoni − − − 10 0.021 10.75 0.98

Oligoryzomys microtis 2 0.031 13.3 5 0.011 5.376 0.40

(continued)
4 2 • smithsonian contributions to zoology

TABLE 4.3. Continued

Wet season (15) Dry season (93) Percent of

 Percent Percent total biomass

Food Item N FO of scats N FO of scats consumed

Mammals

Euryoryzomys nitidus 2 0.031 13.3 10 0.021 10.75 1.93

Cerradomys maracajuensis − − − 6 0.013 6.452 0.90

Cerradomys scotti 1 0.015 6.7 7 0.015 7.527 1.62

Akodon sp. 1 0.015 6.7 3 0.006 3.226 0.44

Didelphidae 

Gracilinanus agilis 1 0.015 6.7 4 0.009 4.301 0.27

Marmosa murina − − − 1 0.002 1.075 0.09

Indet. 3 0.046 20 31 0.067 33.33 5.29

Cervidae 

Blastocerus dichotomus − − − 2 0.004 2.151 17.19

Canidae 

Chrysocyon brachyurus − − − 11 0.024 11.83 −

Subtotal mammals 19 0.292 − 129 0.277 − 44.47

Birds

Caprimulgidae 5 0.011 5.376 0.44

Emberizidae 3 0.046 20 19 0.041 20.43 0.81

Psittacidae 1 0.002 1.075 0.12

Columbidae 1 0.002 1.075 0.35

Indet. 1 0.015 6.7 7 0.015 7.527 0.84

Subtotal birds 4 0.062 − 33 0.071 − 2.56

Reptiles

Typhlops sp. − − − 7 0.015 7.527 0.21

Teidae − − − 8 0.017 8.602 0.39

Colubridae − − − 4 0.009 4.301 0.56

Mabuya sp. − − − 2 0.004 2.151 0.05

Boa constrictor − − − 1 0.002 1.075 −

Indet. (1) − − − 1 0.002 1.075 −

Subtotal reptiles − − − 23 0.049 − 1.21

Fish

Callichthyidae − − − 1 0.002 1.075 0.01

Doradidae − − − 1 0.002 1.075 0.01

Subtotal fish − − − 2 − − − 

Invertebrates

Orthoptera − − − 8 0.017 8.602 0.04

Isoptera 1 0.015 6.7 6 0.013 6.452 0.02

Diptera − − − 4 0.009 4.301 0.00

Hymenoptera − − − 3 0.006 3.226 0.01

Vespidae − − − 5 0.011 5.376 0.00

Apidae − − − 21 0.045 22.58 0.14

Formicidae 2 0.031 13.3 16 0.034 17.2 0.05

Gryllotalpidae − − − 2 0.004 2.151 0.00

Blattidae − − − 1 0.002 1.075 0.00

Cimicidae − − − 1 0.002 1.075 0.00

Scarabaeidae 4 0.062 26.7 25 0.054 26.88 0.07

Passalidae 1 0.015 6.7 2 0.004 2.151 0.00

Histeridae − − − 1 0.002 1.075 0.00

Cucurlionidae − − − 1 0.002 1.075 0.00

Brentidae − − − 1 0.002 1.075 0.00

Elateridae − − − 3 0.006 3.226 0.01

(continued)
number 639 • 4 3

average biomass represented in each scat in 2008–2009 

was 312.3 g.

Maned wolf diets varied little by season in major 

groups consumed (Tables 4.3, 4.4). Occurrence in the dry 

season was 37% fruit and 63% prey, with biomass 63% 

fruit and 36.7% prey; while in the wet season, occurrence 

was 51% fruit and 49% prey, with biomass 54.5% fruit 

and 45.5% animal prey (Tables 4.3, 4.4; Castro, 2010). 

In the dry season, fruit thus had fewer occurrences relative to prey but more relative biomass, than in the wet 

season, and vice versa. In all sampling efforts, fewer fruit 

species were eaten in the wet season than in the dry season: 14:21 in 2008–2009 quantitative sampling (Castro, 

2010), 7:21 in 2001–2007 qualitative sampling, and 6:10 

in 1996–2007 quantitative sampling (Lilienfeld, 2000). 

Too few wet season scats were quantitatively analyzed 

for much inference about specific prey taxa or seasonal 

patterns, but qualitative field examination provided additional taxon data. 

Animal Prey

All 12 small mammal species that we captured trapping on the Los Fierros savannas were found in maned 

wolf scats if we include two casually noted scats with Kunsia tomentosus remains (Muridae; L. Emmons and F. Del 

Aguila, pers. obs.; Emmons et al., 2006a; Emmons, 2009). 

They ate three scansorial taxa and some from forest, 

which can be found on ecotones. No species was too small 

for pursuit, including 20 g Oligoryzomys microtis. Only 

4 of 272 scats (1.5%) included large mammals: two of 

marsh deer (Blastocerus dichotomus; 2008) and one each 

of collared peccary (Pecari tajacu; 2001) and capybara 

(Hydrochoerus hydrochaeris; 2005). Fish were notably 

TABLE 4.3. Continued

Wet season (15) Dry season (93) Percent of

 Percent Percent total biomass

Food Item N FO of scats N FO of scats consumed

Invertebrates

Carabidae 1 0.015 6.7 2 0.004 2.151 0.01

Cicadidae 1 0.015 6.7 1 0.002 1.075 0.00

Araneae − − − 1 0.002 1.075 0.00

Ixodidae − − − 2 0.004 2.151 0.00

Subtotal invertebrates 10 0.154 − 106 0.227 − 0.35

Subtotal animal prey 33 0.508 − 293 0.629 − 48.61

Total 531 items 65 1 433.3 466 1 501.1 99.99

TABLE 4.4. Seasonal occurrences of general categories in diets of MW at Los Fierros, excluding MW hair; numbers of occurrences (N) 

of items by season and seasonal frequencies of occurrences, from Castro (2010). The frequency of occurrences of general groups in the 

diets were independent of sampling season (G = 7.19; df = 5; p > 0.05).

Fruit Mammals Birds Reptiles Fish Invertebrates

Wet season, N (65) 32 19 4 0 0 10

Percent frequency 49 29 6 0 0 15

Dry season, N (455) 173 118 33 23 2 106

Percent frequency 37 26 7 5 0.4 23
4 4 • smithsonian contributions to zoology

scarce. Yearly, when grasslands dry, fish are crowded into 

shrinking pools and make easy prey for foxes, ocelots, 

raccoons, and water birds. Our samples underrepresent 

months of fish die-off (June–July) but do include them. All 

listed invertebrates had been ingested, most notably the 

wasps and nest carton in five scats (Table 4.3). 

When we began our study, one species dominated 

the prey of MW, Cavia aperea (white-toothed cavy; Table 

4.1). Lilienfeld (2000) studied maned wolf diets at two 

sites in NKP, including our study area. His data for Los 

Fierros (1997–1988, both seasons combined), shows a 

higher percentage of scats with cavies than we found in 

2001–2004 (Table 4.1). Six years earlier, in 1991, Emmons (pers. obs.) inspected about 20 maned wolf scats on 

the road across Los Fierros savanna. Although not quantified, nearly all included the remains of cavies, and most 

also included dermal bones of armadillos (Dasypus spp.). 

She saw many cavies and collected a voucher specimen 

(Emmons, 2000a). Cavies were thus a mainstay of MW 

for at least the decade prior to our study. Both cavies and 

armadillos were absent from the 2008–2009 quantitative 

analysis of scats (Tables 4.1, 4.3).

Captures on trapping plots recorded a steep decline in 

rodents on Los Fierros savanna from 2001 to 2004, with 

little recovery by 2007 (Figure 4.1; Emmons, 2009). Most 

notably, cavies were not trapped after 2003. Contents of 

scats showed that cavies increased from 40% to 64% occurrence in 2001–2002, mirroring the rise in captures on 

trapping plot PA; followed by a steady decrease to zero 

after 2006 (Table 4.1, Figure 4.1B). Field observations 

confirmed the progressive disappearance of cavies from 

2004 to 2006, when we saw the last feces and tracks in 

the southern part of the North Range maned wolf territory (Chapter 3). As cavies decreased in scats, there was an 

increase both in birds and in other rodents/small mammals 

in scats (Table 4.1, Figure 4.1B). There may be a trend for 

more scats without visible prey when fewer cavies were 

recorded, in both 2001 and 2007 (Figure 4.1B); however, 

the rank correlations are not significant for these series.

In the absence of cavies, no species dominated animal 

prey. In 2008–2009, the most numerous mouse in the savanna, Necromys lenguarum (Emmons, 2009), was eaten 

the most often (14.8% of all scats, 2% of biomass), but 

heavier rodents predominated in consumed biomass, including Proechimys longicaudatus (12% of scats, 7% of 

biomass) and Holochilus brasiliensis (7% of scats; 4.3% 

of biomass; Table 4.3). The raw percentages of food categories in scats show an apparent overall decline in mammalian prey that parallels the decline in rodents on Los 

Fierros savanna from 2001–2007 (Table 4.1). In 2010, 

FIGURE 4.1. (A) Rodent captures over 7 years on trapping plot PA in nonflooded habitat in Los Fierros savanna, per 1000 trap nights in yearly 

samples. Total individuals (thin line), total species (broken line), and individuals of Cavia aperea (heavy line). Arrows indicate years when the 

plot burned. The same pattern of decline occurred on a seasonally flooded plot that did not burn after 1999 (Emmons, 2009). (B) Changes in 

percentages of scats that included the most common prey types, from qualitative field inspection, 2001–2007. None, scats without prey.
number 639 • 4 5

we again trapped plot PA and two new plots in Pampa 

Termitero. Numbers of N. lenguarum had everywhere increased considerably, but it was the only species captured 

on the new plots. Plot PA remained species poor, with but 

three species, unchanged since 2004 (Figure 4.1A). 

Frugivory

Almost all scats included seeds or other fruit parts 

(Tables 4.1–4.3). Frugivory was highly skewed in favor of 

a few species: in 2008–2009, 77% of all scats included Alibertia edulis (Rubiaceae), or 16% of 520 occurrences of 

all dietary items; while 5% were of S. gomphodes, and 3% 

of Brosimum acutifolium. Over all years and seasons, A. 

edulis was present in 47% of scats, and S. gomphodes in 

18%. The fruit taxa identified in scats from 2001 to 2007 

varied both intra- and interannually (Figure 4.2; Tables 

4.3–4.5). The most commonly eaten fruit overall was A. 

edulis; except in March, when Bromelia ignaciana (Bromeliaceae) predominated. The percentages of scats that 

included particular fruit species varied between years for 

every taxon (Table 4.5). 

Most fruits eaten by MW are from small trees and 

woody shrubs that grow on dry ground: in Campo 

Cerrado, on hummocks around termite mounds in lightly 

flooded savanna, or on roadside banks. The ground bromeliad, B. ignaciana, especially favors termite hummocks. 

One of the only fruit sources that grows directly on flooded 

ground is the small palm Mauritiella armata. In termite 

savanna, all the grassland matrix is flood prone, while the 

woody plants that supply fruit are on high points without 

grass, so there is a two-phase habitat matrix, with rodents 

in the grassland and fruits on hummocks. Two fruit species eaten by MW grow in forest surrounding the savanna. 

Fallen fruits of Cecropia spp. were eaten along a 3 km 

road through forest between the savanna and Los Fierros 

camp, where MW may also have traveled to feed on fruits 

of planted guava and cashew nut. Brosimum acutifolium

is a forest tree with fruits much used by spider monkeys 

in NKP (Wallace, 2005). We never found a B. acutifolium

tree that MW used, and it appeared in the diet only after 

2004.

The major dietary fruits (A. edulis, S. gomphodes, and 

Annonaceae) are characterized by few fruits per plant that 

ripen one by one over many weeks or months. Most fruits 

of A. edulis are parasitized by insects and do not ripen 

or are above the reach of MW where they are eaten by 

bats and birds. Frugivory is thus characterized by a daily 

Feb Mar Sep Oct Nov

0

10

20

30

40

50

60

70

80

Month

Alibertia edulis

Solanum

 Miconia albicans

Bromelia balansae

% Occurrenc

e

N 17 8 60 44 25

Brosimum acutifolium

FIGURE 4.2. Percent of total scats in which the dominant six fruits occurred from 

2001–2007, by month. Number below month is number of scats examined. Only seven 

months are represented.
4 6 • smithsonian contributions to zoology

search of hundreds of plants. We watched a maned wolf at 

dawn zigzag directly from hummock to hummock across 

grassland, lifting its muzzle to sniff A. edulis treelets in an 

apparent olfactory search for fruits, but eating none. 

Energetics

We assume that the taxon-rich, omnivorous diet 

provides MW with all required nutrient classes, such as 

proteins, lipids, minerals, and vitamins, and that consequently, meeting energy demands is the limiting dietary 

factor. Below we consider only caloric content in estimating dietary costs and benefits.

As the baseline for maintenance without travel, we 

use the minimum energy requirements of captive MW, or 

1,297 kcal per day (Barboza et al., 1994). The average 

nightly wet season travel distance of 9.0 km theoretically 

costs 212 kcal (January–June; 37 data sets of 5 MW, based 

on hourly fixes; Chapter 3); while the dry season average 

travel of 13.13 km should cost 310 kcal above resting requirements (July–December, 5 MW, 55 data sets; Goszczynski, 1986). On this basis, the overall average calculated 

costs are 1,580 kcal per day: wet season costs are about 

1,509 kcal per day, and dry season costs are about 1,607 

kcal. The travel cost difference between the month of 

minimum average nightly travel (April, 7.9 km; Table 3.2) 

and the month of maximum travel distance (November, 

14 km per night; Table 3.2) is about 144 kcal. However, 

as animals not traveling might be sleeping (with lowered 

metabolic rate), shorter trajectories could be associated 

with additional energy savings.

On artificial diets in captivity, MW produce 3–4 

scats per day (Childs-Sandford, 2005; M. Rodden, pers. 

comm.). We find no data on transit times for fruits or rodents through maned wolf digestive tracts, but for beads 

ingested with artificial diets in early morning, the median excretion time of 92% of ingested beads was 14.1 

hours, (eight individuals tested once each; M. Rodden 

TABLE 4.5. Percentages of total field-inspected scats in which fruit species occurred, by year, in the months from September to November. In descending order of percent occurrence in total sample of scats. N, number of scats in yearly sample. Years marked with asterisks 

are two years after large fires that burned half (2003) to all (1999) of the northern savanna where most scats were collected.

Percent of scats

Species 2001* 2002 2003 2004 2005* 2006 2007

Alibertia edulis 45 4 30 17 74 58 24

Solanum gomphodes 7 4 0 22 0 42 76

Brosimum acutifolium 0 0 0 11 32 0 24

Annonaceae all species 0 19 0 0 0 42 35

Miconia albicans 17 19 0 0 5 0 0

Cecropia sp. 0 0 20 11 0 0 0

Bromelia ignaciana 0 12 0 0 0 0 0

Discoid seed indet. 0 0 0 17 0 0 0

Emmotum nitens 0 0 0 0 0 8 6

Hancornia speciosa 0 4 0 0 5 0 0

Chrysophyllum sp. 0 0 0 0 0 8 0

Anacardium sp. 0 4 0 0 0 0 0

Astrocaryum sp 0 4 0 0 0 0 0

Dipteryx alata 0 0 0 0 0 8 0

Fabaceae 0 0 0 0 0 0 6

Ficus sp. 0 0 0 0 0 0 6

Vismia 3 0 0 0 0 0 0

Indet. 4 0 0 0 0 0 8 0

Indet. 7 8 10 11 0 8 24

None 3 4 0 0 11 17 0

N 29 26 10 18 19 12 17
number 639 • 4 7

pers. comm.). The beads were excreted in a median number of three scats collected within 24 hours of feeding. If 

passage times in situ for small, indigestible items (seeds, 

rodent teeth) are similar to those for beads ex situ, and a 

similar number of 4 scats is produced per day, then the 

estimated caloric values of items in the diet, and the estimated caloric return of feeding on specific items, can be 

combined with the analyzed contents of scats to estimate 

daily energy consumption (Table 4.6). Scats examined 

in 2008–2009 included an overall average of 4.8 items 

eaten per scat: 1.9 items of fruits, 1.8 items of vertebrate 

prey, and 1.1 invertebrates (Table 4.3) for an estimated 

biomass of 312.3 g eaten per scat. Dry season scats included 4.9 items versus 4.3 items in the wet season. Of 

these, fruits included 2.1 items (wet season) and 1.9 items 

(dry season); while for vertebrate prey, scats included 1.5 

items (wet season) and 1.9 items (dry season; Castro, 

2010). A daily production of four scats of our sample 

should thus represent on average 1,249 g of ingested 

foods and include 19 items, of which 7.6 are fruit and 7.2 

are vertebrate prey. In the dry season, this sums to an estimated 1.48 items eaten per kilometer traveled, excluding 

TABLE 4.6. Estimated caloric contents of various maned wolf food items; kcal per unit of an individual fruit or prey, number of units 

needed for the energy to travel 1 km (= 23.6 kcal, see Materials and Methods), and number of units needed for half of the average 

daily energy expenditure based on 12 km of travel (1,580 kcal, see text); and double that amount during lactation (fruit data from 

Gottsberger and Silberbauer-Gottsberger [2006], Motta-Junior and Martins [2002], Leung [1968], and Martins [2006]; animal data 

from Dierenfeld et al. [2002], Hill et al. [1984], Leung [1968], and Vitt [1978]). Solanum lycocarpum, Annona crassiflora, and Psidium 

guajava (guava) are items reported in the diet elsewhere (e.g., Lilienfeld, 2000; Rodrigues et al., 2007), which we use to estimate energy 

values for congeners or similar items for which we lack data. Here n/a, not available.

 Units per Units per

Weight, kcal/ kcal Units per 50% daily 50% daily

Item g 100 g per unit km travel kcal lactating

Fruit

Alibertia edulis* 30 60 18 1.31 43.89 87.78

Genipa americana 130 81.7 106.2 0.22 7.44 14.88

Solanum gomphodes† 300 41.1 124.2 0.19 6.36 12.72

Bromelia ignaciana 18.3 51 9.2 2.57 85.87 171.74

Annona coriacea 218 n/a n/a n/a n/a n/a

Hancornia speciosa 30 60 18 1.31 43.89 87.78

Annona crassiflora 650 52 532 0.04 1.48 2.97

Psidium guajava 45 64 29 0.81 27.24 54.48

Animal Prey

Dasypus septemcinctus‡ 1500 201 3015 0.008 0.26 0.52

Cavia aperea§ 300 216.7 651 0.04 1.21 2.43

Proechimys longicaudatus§ 250 200 500 0.05 1.58 3.16

Necromys lenguarum¶ 42 171 72 0.33 11.10 22.19

Snakes n/a 140 n/a n/a n/a n/a

Bee and wasp larvae n/a 254 n/a n/a n/a n/a

Grasshoppers n/a 170 n/a n/a n/a n/a

Termites n/a 356 n/a n/a n/a n/a

*Estimated based on values for Psidium guajava (guava).

†Based on value for S. lycocarpum (Martins, 2006): in many publications, that value has been given as 345, or 10 times the true value.

‡Based on D. novemcinctus, parts eaten by humans (Hill et al., 1984)

§Based on value for domestic cavies.

¶Based on value for Microtis spp.
4 8 • smithsonian contributions to zoology

invertebrates (0.35 vertebrate prey and 0.57 fruits); while 

in the wet season, the number is 1.9 items per kilometer 

(0.68 vertebrate prey and 0.95 fruits), based on 4 scats/d 

and distances taken from hourly fixes (an underestimation of actual travel, see Chapter 3). 

Lean small mammal prey are nearly alike in caloric 

value per gram (about 1.8 kcal per gram wet weight; Hill 

et al., 1984; Dierenfeld et al., 2002). If whole prey is consumed, the return per unit is a simple product of prey 

mass: a single cavy would provide 40% of all daily caloric 

needs, but 10 Necromys would be needed to achieve this 

amount (Table 4.6). A biomass of 625 g of prey (half the 

mass in 4 scats × 1.8 kcal/g) would yield about 1,124 kcal, 

or 71% of estimated daily requirements. Caloric values of 

fruit pulps are lower (Table 4.6), and they vary greatly in 

water content. Most fruits seem to yield 0.5–0.6 kcal/g, so 

646 g × 0.5 would yield 312 kcal, or only 20% of daily 

requirements. The average value represented by four daily 

scats is thus estimated at 1,436 kcal, from the estimated 

1,492 g of consumed biomass.

Consequences of a Rodent Decline

Expressed as biomass, the decline of rodents on our 

trapping plots was catastrophic, to 2% of maximal values 

in Termite Pampa (plot PT, 2001) and to 6.5% in Campo 

Cerrado (plot PA, 2003; Figure 4.3). The three MW that 

were captured in years both during and after the rodent 

crash, gradually lost body weight (Figure 4.3), which for 

two males stabilized at 2–3 kg lighter after the decline of 

rodents in 2006. Female F3, with the longest record, was 

nonparous when she was heaviest in 2003–2004, but she 

was reproductive in subsequent years and continued to lose 

weight. The mean weight for these three MW stabilized at 

26 kg in 2006–2008. Concurrent with the rodent declines, 

the number of maned wolf territories on the northern part 

of the savanna decreased from two to one, reducing the 

number of breeding pairs on Los Fierros savanna by a third 

(Chapters 3, 5). Associated with loss of a territory was an 

increase in territory size of pairs on the North Range from 

about 50 to 80 km2 (Figure 4.3C; 10 data sets from four 

MW, 2001–2008). Although the territorial boundary with 

the neighboring pair on the South Range changed little 

after 2004, the northern territory continued to increase 

through 2009, largely by expansion into formerly littleused parts of the savanna (Figure 4.3C). Linear regression 

on average 95% kernel home range (KHR) size of adults 

on the North Range, by year, gives: N = 6 , R2

 = 0.947; p < 

0.001). There is a significant negative correlation between 

the percent of scats that included Cavia and the average 

95% KHR size of the MW on the North Range (Pearson correlation coefficient, –0.86; Kendall tau –0.79, p ≤

0.03). Coincident with the decline in rodent biomass was a 

fire that burned half of the northern savanna in 2003. This 

Rodent biomass on plots

0

2000

4000

6000

8000

10000

12000

14000

2001 2002 2003 2004 2005 2006 2007

PA

PT

PA Cavia

PT Cavia

Biomass/1000 TN

15

17

19

21

23

25

27

29

2002 2003 2004 2005 2006 2007 2008 2009

Year

F3

M5

M8

F9

Mass, kg

subadult

subadult

lactating

A B Maned wolf body mass C Home range size KHR, Km 2 95

% 20

30

40

50

60

70

80

90

100

2001 2002 2003 2004 2005 2006 2007 2008

F3

M2

M5

M8

AVERAGE

FIGURE 4.3. Rodent biomass and maned wolf weights and range sizes. (A) Biomass of rodents captured in 1000 trap nights on two trapping 

plots on the North Range (solid lines) and biomass of cavies (broken lines) on each plot. Plot PT (square symbols) was not trapped in 2002 or 

2006. Biomass estimated at 0.75 of adult mass of a species. (B) Mass at yearly captures of four MW caught more than twice as adults. Subadults, 

open symbols; adults, solid symbols; males, broken lines; females, solid lines. Shaded area includes years following the total disappearance of 

cavies. (C) 95% kernel home range sizes and average (thin dotted line) of five territorial adults on the same territory (North) in successive years 

(10 data sets, > 600 fixes each, plotted by year when GPS data set was initiated).
number 639 • 4 9

would have reduced 2004 fruit production (Table 4.3) and 

perhaps directly killed rodents. 

DISCUSSION

Animal Prey

Our work confirms the results of most other studies, 

which show rodents as the chief prey taxa of MW (Table 

4.3 Aragona and Setz, 2001; Belentani et al., 2005; Bueno 

and Motta-Junior, 2004, 2006, 2009; Dietz, 1984; Jácomo 

et. al., 2004; Juarez and Marinho-Filho, 2002; MottaJunior et al., 1996; Silva and Talamoni, 2003; Queirolo 

and Motta-Junior, 2007). At some sites, cavies were important components of the diet (Bueno and Motta-Junior, 

2004; Motta-Junior et al., 1996), but in others they were 

not (Dietz, 1984; Rodrigues et al., 2007). Lilienfeld (2000) 

reported both Cavia aperea and Galea sp. (yellow-toothed 

cavies) in maned wolf diets, both from our study area and 

from Mangabalito on the far side of the park. We captured 

Galea c.f. leucoblephara at Mangabalito in 2000, but we 

did not identify it at Los Fierros (Emmons et al., 2006a). 

Because C. aperea vanished from Los Fierros between 2004 

and 2006 (Emmons, 2009), possibly Galea also went extinct there, but earlier, between 1998 and 2001. However, 

there are no specimens to voucher any Galea presence at Los 

Fierros. Galea spp. live in burrows that could shelter them 

from fires (J. Dunnum, pers. comm.); but burrows would 

exclude them from flood-prone areas of the Los Fierros savanna. Cavia aperea do not burrow (Asher et al., 2004), 

and they never occupied the deeply flooded southern parts 

of the savanna, although they lived in shallowly flooded 

zones, where we saw them sheltering on brushy hummocks 

surrounded by a few centimeters of standing water.

MW hunted prey in all savanna habitats, and all but 

one micromammal species known from Los Fierros savannas were identified in their scats. The prey species live 

in drier grasslands (C. aperea, Juscelinomys huanchacae, 

Cerradomys scotti, K. tomentosus); wet grasslands (H. 

brasiliensis, Pseudoryzomys simplex, Cerradomys maracajuensis, O. microtis); all grasslands (N. lenguarum); 

woody parts of dry grasslands (P. longicaudatus); forest 

islands in wet grasslands (Oecomys sydandersoni); or 

roadside brush, forests, and forest edges (marsupials Marmosa murina, Gracilinanus agilis, and rodents Mesomys 

hispidus, O. microtis). Euryoryzomys nitidus is a forest 

species, but we trapped rare individuals in all five sampled 

grasslands (Emmons et al., 2006a). We captured no marsupials and no wet grassland species in 15,312 trap nights 

on the two trapping plots on the northern savanna (Emmons, 2009), and no species of dry grasslands in 1,030 

trap nights in a Bajío savanna, where we caught all rodents of wet grassland and some marsupials eaten by MW. 

Maned wolves thus have wider habitat latitude than do 

their rodent prey.

Armadillos are reported as maned wolf prey in nearly 

all studies (Rodden et al., 2004), but in parts of central 

Brazil, they are the primary prey taxon in biomass, especially Dasypus septemcinctus (seven-banded armadillo; 

Rodrigues et al., 2007; Santos et al., 2003). The high energetic value of even the smallest Los Fierros armadillo (D. 

septemcinctus), enough for two days of nutrition, makes 

them the most valuable of all common maned wolf prey. 

We found them in 10% (2003) and 9% (2005) of scats 

(Figure 4.1), while Lilienfeld (2000) reported them in 15% 

of dry season scats, when they likely dominated prey biomass, as each armadillo is equivalent to about five cavies. 

Armadillos were sporadic in maned wolf diets at Los Fierros; they were absent after the destructive fire of 1999 and 

again after 2005 (Figure 4.1). Perhaps they were affected 

by whatever caused the rodent declines (Table 4.1; Emmons, 2009). As burrowers, small armadillos are susceptible to high levels of flooding, as occurred in 2008–2009 

(Emmons, pers. obs.). Maned wolves prey on at least three 

other armadillo species (Rodrigues et al., 2007), and we 

found a carapace of Euphractus sexcinctus (5 kg) with 

tooth marks consistent with maned wolf predation.

A few records of large mammal prey (>10 kg) are 

found in nearly all studies of maned wolf diet (Rodden et 

al., 2004). Our 266 samples (2001–2009) included two 

scats with marsh deer hair, one with capybara and one 

with collared peccary. Rodrigues et al. (2007) state that 

MW “commonly” pursued pampas deer at night (Ozotoceros bezoarticus, 30–40 kg adult), but in their study, one 

of 328 scats included brocket deer hair (Mazama sp.), and 

none included pampas deer. Bestelmeyer and Westbrook 

(1998) saw a female maned wolf pursue, kill with a throat 

bite, and feed on a yearling pampas deer in Emas Park. The 

maned wolf then regurgitated meat to her pup. Nevertheless, in the same park a year earlier, Jácomo (1999) found 

pampas deer remains in only 0.2% of 1,673 maned wolf 

scats, compared with a 65% presence of rodents in the 

same sample. Motta-Junior et al. (1996) found remains 

of juvenile red brocket deer in two of 304 scats (Mazama 

americana). There are now no pampas deer on Los Fierros 

savanna, but the larger marsh deer (Blastocerus dichotomus, about 100 kg) is numerous, and there are a few grey 

brockets (Mazama gouazoubira, 15 kg). The deer we found 

in two scats may have been scavenged, as in one case, there 
5 0 • smithsonian contributions to zoology

was an old carcass nearby. Jaguar and puma are common 

at Los Fierros, and we found the scat with capybara hair a 

day after campesinos reported one killed by jaguar about a 

kilometer away (they likely scared it off the kill). In Emas 

Park, where MW have been seen to scavenge on road kill 

(Rodrigues et al., 2007), surveys censused 540 vertebrate 

road kills in one year (Fischer et al., 2003). Carcasses or 

mutilated survivors could give MW a taste for deer, which 

might subsequently entrain predation. A curious feature of 

the NKP ecology is that only vultures seem to visit most 

carrion, and there are no bone scavengers.

The MW watched by Bestelmeyer and Westbrook 

(1998) chewed apart its deer kill and cached it in 10 

separate pieces. Similarly, MW stole a series of our HB 

Sherman rodent live traps several times and cached them 

out of sight shoved under vegetation, dispersed in all directions many meters from our trap line. Inveterate cachers, they also took and hid objects such as a metal water 

dish and steel water bottle. Deer bones in the Los Fierros 

savanna were little scattered, sometimes with parts missing, but bones showed few or no marks of gnawing by rodents or other mammals, or evidence of caching. Skeletons 

we found of five MW and a few zorros were complete and 

scattered within a short radius, as if by vultures (Figure 

4.4). The bones had no tooth marks, even on ribs, and a 

skeleton 82 days postmortem had all spine articulations 

FIGURE 4.4. Skeleton of maned wolf F9, dead 84 days. The head is at left of big grass tuft, and the completely articulated spine is in grass at 

top left, to the right of a dark leaf. No bones had tooth marks. Note narrow spread of only 4–5 m, as if dispersed by vultures.
number 639 • 5 1

intact. Zorros and raccoons are ubiquitous and common 

and would certainly discover any large cadaver, but there 

was no evidence of mammalian scavenging. If MW at Los 

Fierros scavenged, they did so rarely and avoided conspecific cadavers. 

Rodrigues et al. (2007:48) remark that pampas deer 

alarm at MW and “perceives the wolf as potential predator.” Marsh deer grazed the evergreen sward around the 

PM water hole (Chapter 3), where Emmons watched a 

deer and maned wolf meet. Only 10 m apart, ears cocked, 

they stretched out their muzzles toward each other, without signs of fear; and with no predatory movements by 

the maned wolf. The deer took several steps toward the 

maned wolf but then went back to grazing, and the maned 

wolf drank. If predation were commonplace, the maned 

wolf would have spooked deer from the water hole, but 

neither marsh deer nor giant anteaters avoided MW or 

alarmed noticeably at their odor. In contrast, zorros (Cerdocyon thous) made themselves scarce or hovered in the 

distance when MW were present.

We found wasps with their nests in 5 of 93 dry season 

scats, and bees in 21 (Table 4.3), items likewise reported 

in multiple scats by Dietz (1984) and Bueno and MottaJunior (2004). The high caloric content of wasp larvae may 

be worth a few stings (Table 4.6), but other arthropods in 

the diet are unlikely to contribute significant nutrition.

Frugivory

MW eat the same general fruit taxa throughout their 

geographic range (reviewed by Rodden et al., 2004; Rodrigues et al., 2007). The exceptional feature of frugivory 

at Los Fierros was the preponderance of A. edulis in the 

diet. Other maned wolf studies have been in dry grasslands, where Solanum lycocarpum strongly dominated 

diets and A. edulis was absent or nearly so (Rodrigues et 

al., 2007). The local importance of A. edulis may be due 

to flood-prone Los Fierros habitat, as the species was common on hummocks in seasonally flooded savannas, where 

Solanum gomphodes was rare. Solanum lycocarpum

is favored by anthropic disturbance (Courtenay, 1994; 

Motta-Junior et al., 1996) and S. gomphodes may have 

similar ecology, as it seems more common on roadsides 

than in undisturbed NKP savanna. The predominance of 

the genus in maned wolf diets may indicate altered habitat 

(Motta-Junior et al., 1996).

Other studies of maned wolf diets report the dry season as the time of fruit scarcity and lowest dietary diversity 

of fruits (Motta-Junior et al., 1996; reviewed by Rodrigues 

et al., 2007). In our study area the wet season period of 

deepest flooding (February–April) was the time of fewest 

dietary fruit species (Castro, 2010; Lilienfeld, 2000), as 

well as the least travel and smallest range area (Chapters 

2, 3). It was also the period of all known-date adult maned 

wolf deaths at Los Fierros (Chapter 6), perhaps reflecting 

seasonal dietary and/or social stress.

Fires can influence the production of savanna fruits 

(Sanaiotti and Magnusson, 1995). Hot fires, as in 1999 

(whole northern savanna), 2003 (half of northern savanna), 2007 (part of northern savanna), and 2009 (whole 

savanna) at Los Fierros, entirely remove the above-ground 

stems of many woody plants, which stump-sprout after 

burns (A. edulis, M. albicans). Other species have fireresistant bark and lose only leaves and thinner branches 

(S. gomphodes, Brosimum gaudichaudii, various Annona

spp.) but can also lose aboveground trunks if the fire is 

extremely hot. In the year after a burn, plants recover their 

woody vegetative parts and leaves, but with some exceptions (Duguetia furfuracea, Bromelia ignaciana), flower 

little (Figure 4.5). The second year after burns, fruiting 

may be especially abundant. Alibertia edulis peaked in 

scats two years after burns, in 2001 and 2005, with fewer 

eaten in the third and fourth years following burns (Table 

4.5; Figure 4.2). We observed that after burns, A. edulis fruits were larger and had less insect damage (study 

in progress). Fire may benefit adapted plants by reducing insect predators as well as liberating nutrients as ash. 

Lilienfeld (2000) identified A. edulis in only 4% of 51 

scats collected at Los Fierros in 1996–1997 (as “indet. D, 

marmelada”). He perhaps failed to identify the species, 

but a 1996 satellite image shows the entire northern half 

of the savanna carbonized; so it is more likely that few 

A. edulis fruited in those years. Annonaceae spp. peaked 

in scats only in the third year following burns (Table 4.6), 

but records are few. A fire-influenced pattern for S. gomphodes is unclear.

Miconia albicans is abundant on hummocks in termite savanna and its fruits ripen in October–November. It 

was important in the diet only in 2001–2002 (Table 4.5). 

In later years, its fruits did not ripen and dried up on the 

plants. Sanaiotti and Magnusson (1995) found that fire 

nearly eliminated next-year fruiting M. albicans and other 

savanna shrubs with bird-dispersed fruits, which masted 

maximally two years after burning. There is a hint of this 

in its presence in maned wolf scats (Table 4.5), but another factor, such as the decrease of dry season rainfall 

(Figure 1.9), seems to have affected fruiting after 2002.

The highest biomass fruits in the maned wolf diet, 

including S. gomphodes, A. edulis, Annona spp., and 

G. americana (Table 4.6), are soft pulped, too large to 
5 2 • smithsonian contributions to zoology

swallow whole, and dull yellow or brown when ripe, with 

scores or hundreds of small flat seeds. These fruits were 

broken by mastication before ingestion, as were the yellow, coriaceous B. ignaciana (Figure 4.6A). In contrast, 

the melostome M. albicans has clusters of small, juicy, 

blue-green, berries, which MW bit off and swallowed with 

little chewing, so that many berries were excreted nearly 

whole (Figure 4.6B). Too-large-to-swallow fruits may thus 

be better triturated and yield more of their nutrients than 

are berries that pass nearly intact through the gut (Figure 

4.6). Seeds were passed whole, unbroken by mastication. 

As elsewhere (Motta-Junior and Martins, 2002) MW disperse these fruits on the Los Fierros savanna, but tapirs 

also eat and disperse all of them. 

Dental Issues

The large molar surface area of MW should help to 

crush fruits for better assimilation than is usual for other 

Canidae (Table 1.2; Van Valkenberg, 1989), but by the age 

of about five years, our study animals had worn down the 

cusps of the second and third molars or premolars, and at 

about six years, these teeth were worn down to gum level 

(Figure 6.2). Ten-year-old zoo MW show almost no tooth 

wear (based on U.S. National Museum specimens). Likewise, free-living, wholly carnivorous gray wolves reach 

this stage of tooth wear only at 10–12 years (Gipson et al., 

2000). The rapid tooth wear of in situ MW is almost certainly associated with frugivory. Acids and sugar in fruits, 

FIGURE 4.5. A termite hummock with Alibertia edulis in Los Fierros pampa in October 2000, one 

year after the 1999 burn. The lush rounded foreground clump is new regrowth from the roots. The 

gray stems above the clump and in the background are woody stems killed by the fire, showing 

their former height. Another large-leaved species is in front of the A. edulis clump. The forest edge 

is in the background.
number 639 • 5 3

and phytoliths of B. ignaciana, probably contribute both 

to decay and to erosion of tooth enamel, but we cannot 

exclude a genetic legacy of weak teeth or thin enamel.

Free-living MW have many slab fractures of the teeth 

(Furtado et al., 2007; Chapter 6). We have no evidence 

that MW crush large bones in our study area, but MottaJunior et al. (1996) noted that armadillos, deer fawns, 

and Tupinambis lizards were eaten whole, and crushed 

fragments of crania and mandibles were found in scats. 

Fractured cheek teeth could also result from chewing 

fruits with large, hard pits (M. armata, B. gaudichaudii, 

Emmotum nitens, Dipteryx alata; Table 4.3) and/or tough 

fibrous fruits such as bromeliads. The canine teeth also 

had slab fractures, which are unlikely to be broken by frugivory. Armadillos seem the only commonly reported prey 

likely to fracture canine teeth, especially if MW bite the 

heavy braincase. Lilienfeld (2000) reported one scat with 

a tortoise (Chelonoidis sp.), but other studies with large 

samples report no chelonians in the diet (Bueno and MottaJunior, 2009; Dietz, 1984; Jácomo, 1999; Rodrigues et al., 

2007; Silva and Talamoni, 2003). Rapid tooth wear and 

molar damage may be major costs of frugivory that effect 

both morbidity and mortality (Chapter 6).

Energetics

The estimation of daily food consumption from scats 

requires data on the related variables of both food item 

passage times through the gut and the number of scats produced daily. Neither of these is recorded for in situ MW. Of 

beads added to food, 20% to 90% were passed by MW in 

the first scat after morning feeding (following a night’s fasting), and almost all passed by the third scat, generally within 

the same 12 hours (M. Rodden, unpublished data). But the 

time between feeding to the first scat varied from less than 

3 hours to over 10 hours, perhaps because defecation was 

delayed in sleeping individuals because experiments were 

done by day. Childs-Sanford and Angel (2006) measured 

the passage times of artificial maned wolf diets tagged with 

titanium dioxide dye and found transit times of 12 to 14 

hours for 50%, and 48–47 hours for 97% excretion of 

ingested dye (again, fed in the morning). Titanium dioxide 

is a hyperfine powder, and peristalsis may move it more 

slowly than beads, which better mimic indigestible seeds 

or rodent bones. The passage times of native seeds through 

crab-eating zorros averaged 7.7 hours to 80%–91% recovery, with larger seeds passing more rapidly than smaller 

seeds (Varela and Bucher, 2006). In wolves (C. lupus), the 

passage time of prey was 8–56 hours, but no very small 

prey were fed. Hares of 1.4 kg produced only 1.2 collectible scats (Floyd et al., 1978). From these reports, it seems 

likely that undigested parts of fruit and small prey of MW 

are nearly or entirely excreted in scats within 24 hours of 

feeding, or at most, within 48 hours.

If four scats represent one day of foraging, as ex situ

(Rodden, pers. comm.), our estimate of daily consumed 

FIGURE 4.6. Fruits in maned wolf scats on road. (A) Bromelia ignaciana, crushed fruits, and rodent foot in old, rain-washed scat; two 

bromeliad seeds are circled. (B) Miconia albicans (nearly whole berries) and Duguetia sp. (leaf-shaped sheaths and isolated seed on right 

below mass).
5 4 • smithsonian contributions to zoology

biomass sums to 1,249 g total, or 1,436 kcal if the diet is 

50/50 prey/fruit. This is close to the theoretical calculated 

value of 1,580 kcal. If, instead, the biomass eaten is 60/40 

prey/fruit, the total comes to 1,598 kcal: precisely the 

same as the 1,607 kcal per day theoretical value that includes the dry season travel average of 13.1 km per night. 

The wet season ratio of 45/55 prey/fruit yields 1,378 kcal, 

but the calculated requirements for maintenance plus 

9 km average nightly travel are 1,509 kcal. Thus, in the 

wet season, there seems to be a caloric deficit in the estimated contents of scats. We reported that MW are active 

for averages of over 14 of the 24 hours during dry season 

months, but for only about 12 hours during wet season 

months (Chapter 2; Table 2.2). Two hours of extra rest 

would reduce wet season maintenance energy needs and 

account for some of the estimated deficit. We also expect 

some underestimation in our calculations of the biomass 

represented in scats: from guesswork in calculations of 

item weights, scat numbers per day, and energy values, 

or from failure to identify all items in scats. Nevertheless, 

the close correspondence between our estimates from scats 

and those from theoretical calculations of energy expenditure confer some confidence to both the methods of analysis and the completeness of identification of scat contents. 

During the months in 2008–2009 when we collected scats 

for quantitative analysis, one of the females was pregnant, 

but none was lactating. Because diets include many fruits 

and small prey, gleaned one by one over hours of foraging, we would expect the greater energy consumption of 

lactating females to be reflected in a greater number of 

scats produced per day rather than in a greater biomass 

representation per scat (in the absence of larger prey, such 

as armadillos). One more scat per day would balance the 

accounts. It would be informative to experiment ex situ on 

passage times of fruit, rodents, and armadillos fed at night 

to better calibrate diet analysis from field-collected scats.

Santos et al. (2003) estimated a consumed biomass per 

scat of 469 g, while Rodrigues et al. (2007) calculated 900 

g/scat. In the former study, armadillos comprised 44% of 

consumed biomass, and in the latter, 37% of consumed 

biomass, while C. aperea was only 0.5%. Calculating consumed biomass from scats is problematic if (1) a prey item 

is too large to be eaten in one meal and is eaten in several (Ackerman et al., 1984; Marucco et al., 2008), (2) if 

only parts are eaten, (3) if scats are highly variable in the 

amount of a day’s food they represent, or (4) if parts used 

to count ingested individuals are digested variably (Kelly 

and Garton, 1997). We cannot directly compare our findings of 312 g per scat with those of the above studies, 

where the consumed biomass was dominated by Dasypus 

septemcinctus (1.5 kg each, 27% of biomass eaten; 16% 

of scats; Rodrigues et al., 2007). Nonetheless, 900 g/scat 

exceeds the daily energy requirements, even of lactating 

females. If daily scat production was equivalent to one 

or two feeding events, the discrepancy is reconciled (i.e., 

analyzed scats are not independent; one armadillo in 2–3 

scats). We grouped scats into events to avoid counting the 

same food item more than once. If consumed prey was 

partly regurgitated to young, assimilated biomass would 

be also overestimated.

The energetic consequences to MW of the rodent decline are clear (Table 4.6). It is reasonable to assume that 

the chance of a maned wolf encountering a savanna rodent decreased by 95%, in parallel with the number of 

individuals trapped. It is hard to imagine that this did not 

greatly affect all carnivores on the savanna, but the loss in 

body mass, increase in territory size, and reduction in territory number that simultaneously occurred among MW 

(Figure 4.3) are nevertheless correlations without proof of 

causation. A future reversal of these trends would help to 

support a causal hypothesis.

Maned wolves should obviously prefer to eat armadillos and larger rodents, such as cavies and Proechimys, and 

large fruits, such as S. gomphodes and Genipa, just three 

or four of which can satisfy their daily energy needs (Table 

4.6). Instead, scats show that they apparently eat everything encountered, no matter how small, such as insects, 

tiny mice, and tiny berries. This implies a high unpredictability in meeting the daily requirements. The long, nonrepeating, nightly trajectories of MW and movements with 

few pauses (Chapters 2, 3) match the diet of small, highly 

dispersed, and unpredictable items, a score of which were 

required to meet the needs of each day at Los Fierros (four 

scats). The low reproductive rate may reflect the difficulty 

for MW of increasing their daily food intake (Chapter 5).

Conclusions

Ours is the first multiyear study to record the interannual variation of fruit and prey species eaten by MW, with 

a concurrent independent study by trapping of the rodent 

resource base. Our samples were small, but they point to 

unexpected levels of interannual variation in dietary fruit 

and prey that were coincident with changes in maned wolf 

home range size and body mass. Shorter projects would not 

have detected these changes. Mammalian prey declined in 

the study area, without reversal through 2007. Likewise, 

all fruit resources of MW were variable seasonally and unpredictable interannually, with production dependent on 
number 639 • 5 5

chance fires and probably rainfall. The opportunistic omnivorous diet allows MW to survive extreme resource unpredictability on the temporal scale of their lifetimes, but 

only to a point: the combination of extreme events from 

2003–2009 resulted in a population reduction of Los Fierros MW of as yet unknown duration (2011). Conservation of the heterogeneous matrix of woody fruiting plants 

and grassland rodent habitat is critical to maned wolf viability. The grasslands require fire maintenance to prevent 

the overgrowth of trees (Chapter 7), but woody fruiting 

plants cannot be burned more often than every three years 

without loss of fruit diversity and productivity. Our results 

suggest that maned wolf breeding populations might be 

doubled in optimal, compared to depleted, resource conditions. To maintain sustained resource levels, on the 100 

km2

 scale of maned wolf home ranges, a patchwork rotation of a quarter of the habitat burned yearly, such that the 

other three quarters are in one, two, and three year stages 

of regeneration, would seem to be the best initial plan for 

maximal resource production. Much can be gleaned from 

longitudinal analysis of scats, but experimental studies are 

needed to better define the variables used in calculations 

of energetics

Acknowledgments

The large list of maned wolf dietary taxa was identified with the help of many specialists in the Museo de 

Historia Natural Noel Kempff Mercado. We are indebted 

to all who generously volunteered time to help us. In Zoology: Norka Rocha, Lucindo Gonzáles, Ronald Sossa, 

Edsón Cortes, Miguel A. Aponte, Karina Osinaga, María 

I. Farell, Julieta Ledezma, Alejandra Valdivia, Mirtha Saldias, and Pamela Sandoval. Botanists from the Herbario 

Regional del Oriente Boliviano: Mario Saldias, Fabiana 

Mamani, Luzmila Arroyo, Alejandro Araujo, Daniel Villarroel, Ivan Linneo, Daniel Soto, Alexander Parada, Aquilino Molina, and Eliana Calzadilla. Michael Nee kindly 

identified Solanum spp., and John Wood helped with logistics and identification of NKP flora.

5 Social Interactions 

and Reproduction

Louise H. Emmons, Verónica Chávez, 

Luis Fernando Del Aguila, Sixto Angulo, 

and Matthew J. Muir

Abstract. Social interactions of a small population of maned wolves in Parque Nacional Noel Kempff Mercado, Bolivia, were studied by radio telemetry for over eight 

years. Reproductive pairs co-occupied exclusive territories. Outside of reproductive periods, members of adult pairs on a territory rarely traveled together or met for long enough 

to be recorded by hourly GPS fixes. An exception was a young pair that met on 55% of 

all days during three months, traveling together for an average of 7.6 hours when they 

met. Members of family groups with young often met or interacted vocally. Two young 

females remained on the natal territory with the parents as presumed “helpers” and inherited the territory upon the death of their mothers. Another female helper was replaced 

by a younger one, and we recorded only single female helpers. Young males and other 

females seemed to emigrate when over a year old. Females were the holders of territories 

into which males moved to form pairs and possibly females are the dominant sex.

INTRODUCTION

The first important account of maned wolf social behavior was by Dietz 

(1984), who combined radio telemetry of free-living animals in Brazil with observations of captive animals in large enclosures at the National Zoological Park 

(Smithsonian). He described maned wolves (MW) as monogamous canids in 

which reproductive pairs share territories but seldom meet during their activities (Dietz, 1984). In the next two decades, Dietz’ conclusions were generally 

confirmed by VHF telemetry studies, but without additional insights on maned 

wolf social organization (Jácomo et al., 2009; Juarez and Marinho-Filho, 2002; 

Rodrigues, 2002). More recently, a GPS telemetry study contributed the first 

data on in situ interindividual interactions (Melo et al., 2007). For six months, 

Melo et al. followed a single pair and a young female that shared the same home 

range while the pair raised a litter (Melo et al., 2007). Subsequently, they observed care of young in situ (Melo et al., 2009).

We studied the behavioral ecology of MW for nine years on a small savanna 

in undisturbed, flood-prone habitat in Noel Kempff Mercado National Park 

Louise H. Emmons, Department of Vertebrate 

Zoology, National Museum of Natural History, 

P.O. Box 37012, MRC 108, Smithsonian Institution, Washington, D.C. 20013-7012, USA; 

Verónica Chávez, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Luis 

Fernando Del Aguila, Museo de Historia Natural 

Noel Kempff Mercado, Santa Cruz, Bolivia; Sixto 

Angulo, Fundación para la Conservación del 

Bosque Chiquitano, Calle René Moreno, Santa 

Cruz, Bolivia; Matthew J. Muir, Division of International Conservation, U.S. Fish and Wildlife 

Service, 4401 N. Fairfax Drive, ARLSQ 100c, Arlington, Virginia 22203-1622, USA. Correspondence: emmonsl@si.edu. Manuscript received 25 

August 2010; accepted 26 August 2011.
5 8 • smithsonian contributions to zoology

(NKP), Bolivia. Our goals were to learn how free-living 

MW interact with each other at different stages of their 

lives and to fit their social organization into the vista of 

their ecology and conservation. We began by following 

MW on foot with VHS telemetry but later switched to 

GPS telemetry, which allowed us to follow pairs simultaneously throughout nearly all months of the year, and to 

follow a few individuals for most of their lives.

GPS telemetry produces accurate and objective arrays 

of location points (fixes) on a geographic information system (GIS) map. When we followed a focal maned wolf 

on foot, triangulating with VHF telemetry, our location 

data were imprecise, but we took coordinates all night and 

knew from their signals the proximities of other collared 

individuals. By physically following them across the landscape in real time, hearing their calls, and once in a while 

glimpsing them, we gained different insights into their behaviors and interactions than those that can be extrapolated from GPS locations mapped months after the events.

Materials and Methods

Study Site and Field Methods

We followed MW by radio telemetry from October 

2001 to October 2011, in the small Los Fierros savanna 

of NKP. The climate and habitats of the study area, and 

trapping and handling methods for MW, are described 

in Chapter 1. The key feature of the habitat is that much 

of the savanna is flood prone from late January to May. 

The northern part (“termite” savanna) floods with shallow water, and the southern part (“bajío”) fills with water 

too deep for MW to occupy at that season (Chapter 1) and 

takes longer to dry. In a seasonal reverse, no surface water 

may be available on the northern savanna from mid-August 

to October, when water becomes a strong attractor for MW 

(Chapters 2, 3). The vegetation is dense, and we rarely saw 

the animals. To monitor marked and unmarked individuals, we set camera traps at water holes and along roads. For 

field and photo recognition, telemetry collars and ear tags 

were marked with colored reflective tape (Frontispiece).

All adults and subadults over 20 kg in mass were fitted with radio collars, for a total of 28 collar deployments 

on 10 individuals (Chapter 1, Table 1.3). In 2001–2002, 

three MW carried VHF collars, but from 2003–2009, all 

but two subadults and one adult carried archival GPS collars. From 2001 to 2004 we trapped MW on the northern 

part of the pampa, and from 2005–2010 we trapped in all 

territories. Our on-foot VHF following was limited to October 2001 through September 2003, when we followed 

adult resident M2 and subadults M4 and F3, and to six 

nights in October–November 2005, when we followed 

M8 (Mx, males; Fx, females). We used VHF signals to 

locate MW throughout the study: on foot, from vehicle 

roof, or by climbing trees; and we chartered light aircraft 

to search for missing signals. When we followed MW on 

foot, we kept silent, well out of sight, and behind them, 

so as to avoid influencing their behavior. If one was near, 

we turned off our light and sat still until it moved away. 

We attempted to follow VHF-tagged animals for complete 

nights, with three bearings taken for a fix each 20 min, 

as close in time as we were able to (sit for 10 min, take 

bearings 10 min, etc.), but when they traveled, we walked 

continuously to keep up, taking bearings each 100 or 200 

m. Meetings between VHF-collared animals were defined 

as distances of <100 m between locations (as with GPS 

data), but we could also identify them in real time, when 

we noted bearings of collar frequencies converge until the 

bearings coincided, with equal signal amplitude.

We quantified calling behavior as we followed MW on 

foot, by noting the numbers of calls, the bearings of calls 

and answering calls; and the identities of callers from VHF 

collar frequencies. Calls of young were recognizable by their 

higher pitch, and to us, several MW had clearly distinguishable voices, although we did not use this for identification 

without confirmation from associated radio frequencies.

The GPS collars were programmed to take synchronous locations for all collared individuals. To explore 

movements in detail, the first three GPS deployments took 

fixes half-hourly, except around midday (2003–2004). 

After 2005, all collars were scheduled to take hourly fixes, 

in three-night weekly samples. Early collars were shut off 

around midday to save battery life, but recent improved 

technology has permitted complete, 72 hour (72 fix) 

weekly samples. Functioning collars with the latter schedules took from 10 to 14 months of data. Repeated GPS 

collar failures prevented the success of many attempts to 

get complete reproductive behavior of pairs. Study animals were recaptured approximately yearly and the collars 

exchanged, and each discontinuous collar deployment is 

treated as one data set. Collar deployments and schedules 

are listed in Chapter 1 (Table 1.3).

We captured six immature animals, all in September 

and October. It was difficult to estimate the exact ages 

of these “subadults,” which were characterized by lack 

of tooth wear, small size, and nonreproductive state, as 

well as by subjective traits (high pitch of barks, lack of 

odor, slender build, and timid behavior). With a growth 

curve generated from captive bred animals (Smithsonian 

Conservation Biology Institute; M. Rodden, pers. comm.), 
number 639 • 5 9

we interpolated the weights of the six youngsters, and 

backdated them to estimated birth months. At 17–24 kg, 

with full dentition (achieved at 7–8 months; Maned Wolf 

Species Survival Plan, 2007), these young corresponded in 

weight to 7–10 months-old ex situ youngsters. Other evidence, including dates of sightings of pups (3–4 months 

old), condition of the presumed mother, and slightly more 

tooth wear, suggested that the two heaviest youngsters 

were older than predicted by body weight alone (thinner 

than same-age captives), likely 14–18 months.

Data Analysis

With simultaneous GPS locations, we measured the 

proximity between pairs of animals at each fix time. We 

classify an interanimal distance of <100 m as an encounter 

(meeting), so as to capture a time window when animals 

were moving together or apart. From the average maned 

wolf movement rate between hourly fixes (Chapter 2), 100 

m represents only 6.3 min (Table 5.1) or 3.2 min from 

a contact between two MW to a separation of 100 m if 

they go in opposite directions. Only encounters of longer 

than the interfix interval (30 or 60 min) were certain to 

be recorded. Because the duration of an encounter could 

be measured only in increments longer than an interfix interval, averages of time spent together were by definition 

averages of the minimum time animals were in proximity 

(if animals were together 1.8 hours, hourly fixes would 

show them as together for one hour).

To compare the proximity of maned wolf pairs to 

that expected from a random distribution of points for 

each data set of a male-female pair tracked synchronously, 

the temporal order of the actual locations of each animal 

was randomized, by randomizing the sequence number of 

each fix (fix ids), pasting it into the data set, and resorting it into numerical order. The distances between the two 

location sets were measured in the order that they were 

in after randomization (distance from fix 1 to fix 1, 2 to 

2, . . . , N in each set). Using the same locations inserts a 

possible bias into the data, because animals might preferentially use particular areas of the home range because the 

other animal was likely to be present. For comparison, we 

also generated two shapefiles of random points within the 

home range polygon of each data set, each with the same 

number of points as there were synchronous acquired fixes 

for the pair. We then measured the distances between the 

two sets of random points. Because use of the home range 

is highly nonuniform (50% of fixes are in 20% of the area; 

Table 3.1, Chapter 3), the degree of “random” proximity 

is much less by this method (because the fixes are distributed on the whole home range, rather than concentrated 

as the animals actually used it). The first method is the 

most likely to overestimate random encounters and therefore is a more stringent comparison, and we use it below.

RESULTS

Pair Formation and Territory Acquisition

We followed one or both members of five resident 

adult pair combinations by GPS telemetry, but we acquired 

TABLE 5.1. Adult resident pairs for which synchronous GPS data sets were acquired, with dates, number of acquired synchronous fixes 

for the pair, schedules of collars, the average distance that females moved between successive fixes while active in those data sets, and 

the size of the home range during those data sets. Collars of F11 and M8 were not well synchronized, that of F11 took fixes only from 

1600 to 1000 hours on the following date for part of the set. Here n/a, not applicable.

 Distance between Home

Data Data successive range,

Pair start end Fixes Days GPS schedule fixes, m km2

F3/M5 9 Oct 04 7 Jan 05 2712 91 Half hourly Continuous 620 74.1 

F3/M5* Same Same 1596 91 Hourly Same 985 Same

F3/M5 6 Oct 05 13 Jul 06 2707 274 Hourly 3 days/week 797 75.2 

F3/M5 4 Oct 07 22 Nov 07 472 27 Hourly 3 days/week 908 76.6 

F11/M8 25 Jul 07 26 Sep 07 456 64 Hourly 3 days/week 977 65.5

F3/M8 16 Jul 08 18 Oct 08 728 94 Hourly 3 days/week 1022 66.5

*The same as the previous data set but including only hourly fixes for comparability with other data. The short distance between successive fixes in the 

first data set is because there were twice as many fixes per hour.
6 0 • smithsonian contributions to zoology

synchronous fixes for only two males (M5, M8) and three 

females (F3, F9, F11), in five data sets. Three male-female 

combinations were followed for a total of 95 weeks (Table 

5.1). Other pair members were not captured the same year 

or yielded no useful telemetry data. A male of a reproductive pair, M2, was followed only by VHF, along with two 

youngsters of his family (F3, M4). From 2001 to 2004, there 

were three territories on the Los Fierros savanna, which became reduced to two after 2004 (Chapters 3, 4) and then to 

one in 2010–2011. Adult pairs on our study area occupied 

exclusive territories with sharp interpair boundaries (Chapter 3). The individuals and spatial arrangements of resident 

adults changed several times (Figure 5.1).

We recorded three cases of new pair formation. Female F3 was a nulliparous subadult–young adult on North 

Range 1 in 2002, when it was occupied by adult pair M2–

FT (FT was not captured, but we saw and photographed 

this grizzled maned wolf for over a year). F3 had many 

interactions with M2, her presumed father. She was of full 

body length and had almost no tooth wear. She at first 

used a small area (13 km2

) within North Range1 that over 

a year expanded to 50 km2 (Figure 5.2A). A litter born 

2001–2004 2005–2007 2008–2009

North

Range

1

2

South

Range

M2

FT

MBL

F?

m5?

m4 mx f3

M5

F3

M8

F3

M8

F11

f9

M5

F9

M6

F11??

FIGURE 5.1. Schematic outline of maned wolf pairs followed and 

their locations in the study area. The two territories on the North 

Range merged in late 2004/early 2005 (Chapters 3, 4). Lowercase 

letters (f3) indicate subadults. FT was seen, but not captured.

FIGURE 5.2. (A) Range expansion of F3 from subadult in 2002 (20.4 km2 99% kernel home range [KHR]) to 

“helper” using full parental range (North Range 1) in October 2003 (52.3 km2

 99% KHR) and to breeding territorial adult using combined North Ranges in October 2004 (75.2 km2

). Double broken line is the LF savanna 

outline, W is PM water hole. (B) Range shifts of M5 to coincide with F3; 2004–2005, diagonal lines; 2005–2006, 

stipple; 2007–2008, no shading.
number 639 • 6 1

on North Range 1 in about March 2003 was seen in May 

(three pups) and July (two pups), but mother and young 

had disappeared by October and were presumed dead. 

Adult male M2 was geriatric and also died in about January 2004. F3 was nulliparous in October 2003, when M5 

was seen and photographed with her in North Range 1 

(when M2 was alive there), although he chiefly occupied 

North Range 2 (Figure 3.5A). By October 2004, F3 and 

M5 had established as the adult resident pair on a single, 

larger, combined North Range territory (Figure 5.2B).

Subadult female F9 occupied the South Range territory with adult pair F11–M8. At first capture in September 2006, F9 was below adult size and too small for 

a telemetry collar (17 kg). In 2007 she was fitted with a 

VHF collar, followed in 2008 by a GPS collar. Females 

F9 and F11 were closely associated in 2007: they shared 

the same home range, rested near each other by day, and 

once were trapped side by side on the same night. The 

adult pair F11–M8 remained together with nulliparous F9 

on the South Range until the death of F11 on 26 March 

2008, but there was no evidence that any litter was born 

after 2006. By June 2008, M5, from the neighboring territory (with F3), had moved into the South Range with 

F9. Owing to GPS collar failures, the movements of M8 

and F9 were not recorded until July 2008. By then males 

M5 and M8 had entirely switched territories, while the 

females remained where they had been, so that the North 

Range was now occupied by F3–M8 and the South Range 

by F9–M5 (Figures 5.1, 5.3). The new range boundaries of 

M8 were similar to the previous ones of M5 (Figures 5.1, 

5.3). Thus, in one case on each range, one female young 

stayed on the natal territory until adulthood, as a nonbreeder, and when the adult female on that range died, she 

became the territorial resident, paired with a male from 

outside the range. Males moved into the territories where 

females were established on three occasions, but in the 

first case, the female also eventually expanded her own 

territory to encompass his former range as well as her own 

(Figure 5.2A; Chapter 4).

Interactions between Adult Pairs: GPS Telemetry

In 2004–2005, the number of encounters between 

newly formed pair F3–M5 vastly exceeded that recorded 

in later years, both between this pair, and between all other 

male-female pairs (Tables 5.2, 5.3). In this 91 day data set, 

FIGURE 5.3. Switch of M8 from South Range (with F11) to North Range (with F3), note that 

boundary remained nearly the same.
6 2 • smithsonian contributions to zoology

F3 and M5 met on 55% of all nights, when they traveled 

together for long distances, for an average minimum of 

7.6 hours spent together when they met (Table 5.2A, Figures 5.4, 5.5). The nights when they met were distributed 

across the three month sample. Their relative movement 

patterns showed that either F3 or M5 could deviate from 

a previous course to join that of the other. Before meeting, one would occasionally follow the other’s exact path 

with a 30 min delay (the time between fixes), consistent 

with tracking by scent trail. The most common pattern 

of encounters (23 nights) was for the pair to meet late in 

the night and travel tightly together for some hours until 

after dawn, when they separated each to its own rest site 

(bed) at 0700–0800 hours (Figure 5.6). Thrice they spent 

22–24 hours together, and on 9 days they bedded together 

≤25 m apart (within the error of the GPS fixes). On seven 

other days they rested <100 m apart, but on most days 

(80 others), beds were far apart (2.46 km overall average).

After 2005, F3–M5 rarely were recorded meeting 

or traveling together outside of the period of estrus and 

pregnancy (Figure 5.4B). Likewise, pairs F3–M8 and F11–

M8 scarcely met and never traveled together during the 

months when they were followed (Table 5.2D,E). Of the 

six meetings of F3–M5 in 2007, three were for single fixes 

and three for two fixes, or over an hour, and the two encounters (at <300 m) of F11–M8 were for single fixes of 

probability no greater than random (Table 5.2). In a different pattern, F3–M8 registered no fixes <100 m apart 

during late pregnancy and lactation (16 July 2008 to 18 

September 2008), although they were often <300 m apart 

(Table 5.2D,E). After loss of their litter, they met on 5 

days: on two of these, they bedded <100 m apart, and on 

one, they traveled near each other for about 3 hours.

We watched, from a blind at a water hole, F3 meet M5 

for 10 minutes, and we saw F3 there three times that night. 

However, GPS fixes registered the closest pair proximity as 

321 m, and no fix was at the water hole. The 100 m, proximity/time window that we define as encounters (see methods), strongly biases our recognition of proximity in favor 

of long meetings, but longer distances between maned wolf 

locations, of 100–300 m and 300–1000 m, occur at the 

TABLE 5.3. Frequency and duration of encounters of pair F3-

M5, and the mean minimum time they were together if they met. 

In 2007, no fixes were <100 m apart, so <300 m is used as the 

criterion for meeting (weak/no evidence of association). For data 

set B we use calendar days instead of nights, because samples 

started and ended at 0000 hours because of a factory programming error (two whole and two half nights).

Percent Percent Mean time 

fixes nights together, 

Data set meet meet hours

A. 2004–2005 (N < 100 m = 486) 17 55 7.6

B. 2005–2006 (N <100 m = 50) 6.2 16.5 13.9

C. 2007 (N < 300 m = 8 ) 1.7 18.5 0.6

TABLE 5.2. Numbers of fixes at different proximities of adult 

M-F pairs for complete data sets of synchronous fixes. The 

numbers of actual fixes within different distance categories, 

compared to those of the same set of points assorted randomly 

in time. Table 5.1 lists home range sizes during the data series. 

Number of synchronous fixes (N) is given in the column head.

F/M Percent Same fixes Percent

Proximity Actual actual random random

A. F3/M5 Oct 2004–Jan 2005 (2712)

0–50 326 12.02 2 0.1

50–100 160 5.90 7 0.3

100–300 129 4.76 21 0.8

300–1,000 162 5.97 169 6.2

B. F3/M5 Oct 2005–Jul 2006 (2707)

0–50 158 5.8 0 0.0

50–100 9 0.3 3 0.1

100–300 40 1.5 14 0.5

300–1,000 163 6.0 83 3.1

C. F3/M5 Oct–Nov 2007 (472)

0–50 0 0.0 0 0.0

50–100 0 0.0 1 0.2

100–300 8 1.7 6 1.3

300–1,000 37 7.8 23 4.9

D. F11/M8 July–Sept 2007 (456)

0–50 0 0.0 1 0.2

50–100 1 0.2 0 0.0

100–300 1 0.2 4 0.9

300–1,000 22 4.8 20 4.4

E. F3/M8 July–Sept 2008 (728)

0–50 1 0.1 0 0.0

50–100 14 1.9 1 0.1

100–300 25 3.4 7 1.0

300–1,000 90 12.4 27 3.7
number 639 • 6 3

20

40

60

80

5 25 45 65 85

 Day

% of Fixes <100 

m

20

40

60

80

100

1 4 7 10 13 16 19 22 25 28 31 34 37 40 Nov Jan

Estrus Birth

2005–6

% of Fixes <100 

m

Sample Week

May

A 2004–5

B

FIGURE 5.4. Percentage of total fixes during which F3 and M5 were <100 m apart. (A) During 91 days of continuous, half-hourly locations, 9 October 2004 to 7 January 2005 (2947 fixes). (B) During 3 day weekly samples of 

hourly fixes, over 10 months in 2005–2006. Note that the scales are different.
6 4 • smithsonian contributions to zoology

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

0

2

4

6

8

10

12

14

16

Occurrenc

e

Sequential Fixes Together

A 2004–5

1 6 11 16 21 26 31 36 41 46 51 56 61

0

1

2

3

4

5

6

Occurrenc

e

Sequential Fixes Together

B 2005–6

FIGURE 5.5. Distribution of minimum lengths of time (number of sequential fixes <100 m apart) that pair 

F3 and M5 were together. (A) Nights of a continuous 91 day series of half-hourly fixes, 9 October 2004 to 7 

January 2005 (2947 fixes). (B) During the 15 meetings in the 2005–2006 data set. From the same meetings 

shown in Figure 5.4.
number 639 • 6 5

same frequencies in both actual and some random data sets 

(Table 5.2C, D), so we cannot justify expanding our definition to classify larger separations as “meetings.”

Family-Group Social Interactions

Because we followed VHF-tagged animals nearly continuously, we were able to identify short meetings between 

MW with greater success than with hourly GPS fixes. 

Most of our on-foot VHF following was of members of 

a single family group, adult male M2 and subadults F3 

and M4 of the North Range. At that time this group also 

included an unmarked adult female and a male littermate 

of M4. These MW met often, and each encountered all 

others (Table 5.4). We were never aware of agonistic interactions, heard no growling, nor noted MW chasing each 

other. There were more encounters between subadults F3 

(N = 13) and M4 (N = 12) and others than between adult 

M2 and others (N = 9), but as F3 and M4 shared a smaller 

home range, they were more likely to meet. As the subadults aged, recorded meetings decreased (Table 5.4).

We saw a meeting of adults F3–M5 (from a blind), 

then paired for two years. Male M5 approached to 15 m 

behind F3 when she was at the water hole. She turned 

and walked toward M5, and as she approached, he lay 

down flat to the ground on his sternum, head down. As 

she reached him, M5 rolled onto his back, belly-up, while 

F3 stood straddling him, with her tail up, for several minutes. In this position, the pair played briefly by sparring 

with their mouths, calling with high-pitched whines. The 

posture of M5 was the classic canid “passive submission” 

display, linked with the classic “dominance” stance of F3 

(Ewer, 1973). 

Roar-­Bark Vocalizations

MW communicate with explosive, deep-throated 

“roar-barks” (Kleiman, 1972) audible to us for hundreds 

FIGURE 5.6. Hourly distribution of 326 synchronous locations of F3–M5 <50 m apart, during 91 

days in 2004–2005, as a percentage of all locations at that distance. There were no data from 1100 

to 1600 hours, but in this data set the animals usually were stationary during those hours (same 

location at 1000 and 1600 hours).

0246 8 10 12 14 16 18 20 22

0

5

10

15

20

25

30

Percent of Fixes Together

Hour
6 6 • smithsonian contributions to zoology

of meters but to MW perhaps across a home range. Most 

roar-barks occurred at night, when MW are most active 

(Chapter 2) and sound travels best in humid air, but once 

in a while, we heard barks by day (not quantified). Barks 

are given singly or in irregularly spaced series of up to 30, 

spaced 2–8 s or more apart (Dietz, 1984; Kleiman, 1972). 

Wide spacing of calls permits listening for replies, and our 

subjective impression was that callers often waited for a 

reply before calling again, thus alternating calls (Table 

5.5). From October 2001 to February 2003, when two or 

three adults and two or three young were present, other 

MW answered in 31% of 110 calling bouts. Often, more 

than one answered, such that roar-barking was a group 

activity. Countercalling MW sometimes approached each 

other.

When three of at least five MW on North Range 1 

were identifiable by telemetry (M2, M4, F3), 21% of 82 

calling bouts were answered (Table 5.6). Subadult F3 both 

initiated and answered more calling bouts than did other 

known individuals. If M4 and his unmarked littermate 

brother initiated/answered equal numbers of calling bouts 

(13/2), then the unmarked reproductive female may have 

initiated the remaining 20 bouts, equivalent to F3. This 

hypothesis is supported by the scarcity of replies from 

unknown MW, if an unknown maned wolf initiated calling (we knew of only one unmarked male juvenile who 

could have answered). In September–October 2003, when 

there were no young on North Range 1, and the former 

reproductive female had disappeared, we noted no roarbarks during 6 nights of on-foot telemetry of F3 and M2. 

When we observed most of the tabulated calling behavior, 

the family group was far from a territorial boundary with 

other MW (3.5 km), and answering calls did not come 

from outside the territory. We never heard with certainty 

any countercalling between neighboring territories, but we 

cannot exclude it, as we could not localize far-distant calls.

There was a calling-fest of 37 roar-bark bouts on 4 

November 2005, as we followed M8 all night on foot 

(South Range). A minimum of 6 MW were known to be 

on South Range at that time (M8, subadult F7, geriatric M6, at least two young pups, and presumably, their 

mother). Sixteen bouts were answered with countercalls 

from within the South Range: at least six were initiated 

by M8, three of these answered by a (high-voiced) pup; at 

least three were initiated by a pup, two of which were answered by M8; four bouts included at least three MW. M8 

once approached a caller, another caller once approached 

M8 (countercalling until they were at the same bearing), 

and after hearing many roar-barks from a maned wolf that 

TABLE 5.4. Percent of nights (N) that maned wolves (MW) were 

recorded meeting during all-night on-foot VHF tracking of the 

North Range 1 family group, including adult male M2 and subadults M4 and F3. Monitoring was not always continuous, so records represent minimum numbers of encounters between MW.

Percent of nights met

M4 M4 F3

 Nights and and and

Field dates followed F3 M2 M2

Oct.–Dec. 2002 9 67 (6) 33 (3) 33 (3)

Jan.–Feb. 2003 24 8.3 (2) 4.2 (1) 8.3 (2)

TABLE 5.5. Summary of roar-bark calls heard during on-foot 

VHF radio tracking of the MW group on North Range 1. Some 

roar-barks were at our hearing limits, so answering calls are 

likely to be underestimated.

 Total Total Percent Answered

Dates bouts answered answered by 2–3 MW

Oct. 2001–March 2002 28 19 68 5

Sept. 2002–Feb. 2003 82 16 19 11

Total 110 35 31 16

TABLE 5.6. Roar-barks ascribed to individuals, September 2002–

February 2003, when three of at least five MW present on North 

Range 1 were radio tagged. Number of bouts, and mean number 

of barks in each bout are provided. Initiators and answerers were 

identified by radio signals of appropriate frequency and strength 

from the azimuth of calls. One unmarked adult female, and one 

unmarked littermate of M4 were part of the family group. Here 

n/a, not applicable.

Initiator Answerer

Mean No. 

no. barks bouts M2 F3 M4 Unknown

M2 8.1 13 – 2 0 0

F3 8.5 23 1 – 1 7

M4 11.4 13 0 3 – 2

Unknown n/a 33 1 3 1 –
number 639 • 6 7

was following M8, we saw a three- to four-months-old 

pup trailing 100 m behind him. Barking was so frequent 

that it was hard to define discrete bouts or to decide which 

MW had initiated them. Barking was almost as frequent 

on the following two nights.

Reproductive Behavior and Seasonality

We followed female F3 throughout her reproductive life (Tables 5.7, 5.8). She was presumed born in July 

or August 2001 on the North Range 1, the daughter of 

M2–FT. After the death/disappearance of both FT (about 

August 2003) and M2 (January–February 2004), when 

she was about three years old, she became the resident 

adult, paired with male M5. She was still nulliparous in 

October 2004 and may have given birth to her first litter in 

February 2005 (no GPS record), for by October 2005, her 

mammae showed use (pigmented and elongated), but she 

was past lactation. M10 was a likely offspring of this litter, 

as his birth date, backdated from tooth wear and weight 

at capture, both suggested that birth month. Her first welldocumented litter was born on 1 July 2006, when she was 

five years old (Table 5.8), and she had two to three more 

litters by 2008.

GPS telemetry recorded an estrous period. In three 

weekly samples from 7 to 23 April 2006, F3 and M5 registered no proximity <300 m. In the next sample, on 27–29 

April, 65 of 66 sequential fixes of the pair were so tightly 

together that most were superimposed, with 63 locations 

<50 m apart while they traveled together for 16.4 km. In 

the following weekly sample (5–7 May) the pair did not 

meet (Figure 5.4). Calculated back from her 1 July parturition, 27–29 April corresponds to a 65 day gestation 

(Rodden et al., 2004). During this estrus, F3–M5 had slow 

and reduced movements, averaging only 145 m/h for the 

72 hour sample, compared to an average of 432 m/h for 

F3 over all 41 weekly samples of the same data set. During 

estrus, the pair stayed near the South Range border, where 

there was another adult male.

On days 12–28 of pregnancy (11–27 May), F3–M5 

traveled together continuously during large parts of three 

samples (Figure 5.4), logging bouts of 12, 4, 15, 2, 19, 5, 

and 33 sequential hours together; for 42% of the total 

sampling time (including three samples truncated by GPS 

shutoff). This chummy behavior abruptly ceased in June, 

when the pair was recorded together only thrice, but interestingly, two of these were in the 48 hours prior to parturition, when they met for bouts of three and two hours. 

They registered no other proximity through 13 July, at 

GPS failure for F3.

The prior year, 2004–2005, when the pair often traveled 

together during three months (Figure 5.4A), F3 was initially 

nulliparous. On the basis of the behavior in 2006, she may 

have been in estrus from 19 to 22 November (Figure 5.4; 

nights 42–44), when the pair were <100 m apart for 75% 

of 85 fixes and <300 m apart for 100% of simultaneous 

locations. Shortly after this, there was a gap of a week when 

they did not meet, but four weeks later, there was another 

period of extended meetings (Figure 5.4A). This partially 

mirrors the pattern during estrus and pregnancy in the following year, when there was a week of extended proximity 

two to four weeks after estrus (Figure 5.4B).

TABLE 5.7. Outline of known and presumed events of reproduction and presence of immature MW on the study area by year 

and territory. Nonparous females were first captured at 7–18 

months old, as subadults, M10 was a young adult recorded in 

two territories. MX, unidentified male; FX, unidentified female; 

UX, unknown sex. Here n/a, not applicable or unknown. In 

2010–2011 both ranges were occupied by a single pair.

Adult Adult Nonparous Immature

Territory male female female male Births

North Range

2001 M2 FT “White tail”? n/a July

2002 M2 FT F3 M4, MX Feb.–March

2003 M2 n/a F3 n/a Feb.–March

2004 (Sept.) M5 F3 none none none

2005 M5 F3 none none Feb.–March

2006 M5 F3 none M10? 1 July

2007 M5 F3 F12, FX MX March?

2008 M8 F3 none? none 30 July 

2009 M8 F3 none none n/a?

South Range

2004 n/a n/a n/a n/a Feb.–March?

2005 M6, M8 F11 F7 none July

2006 M8 F11 F9 M10 none?

2007 M8 F11 F9 none June?*

2008 M5 F9 none none none

2009 none F13 none none none

2010 UX F13 none none October?†

2011 M14 F13 none none n/a

*F11 appeared to be postlactation (mammae with thin watery milk, 18 

July), but continuous, February–July GPS trajectories indicate no pointfocused behavior consistent with lactation, so she either lost a litter near 

birth or lactation resulted from pseudopregnancy.

†F13 was pregnant at capture 16 September, but GPS records do not 

indicate lactation, so she lost her litter or was pseudopregnant.
6 8 • smithsonian contributions to zoology

Maternal Behavior

Two parturitions of F3 were recorded by GPS telemetry, in July 2006 and July 2008. The first was signaled by 

a striking change to a den-centered behavior on the last 

day of a weekly 72 hour sample. On 1 July, F3 traveled 

2.87 km to the pup den between 0500 and 0700 hours, 

after a normal night of travel (9.9 km) that included a rest 

at 0200–0300 hours (Figure 5.7). She then was present at 

the den at all hourly fixes for 15 hours, until GPS sampling 

ended at 2300 hours (Figure 5.7A). For 2 days prior to 

parturition she had no locations near that den site. During 

the following sample (6–8 July, pups 5–7 days old), her 

movements were characterized by 11 to 12 hour absences 

from the den, followed by abrupt return after long movements; then uninterrupted 10 to 14 hour stays at the den 

(Figure 5.7B). Only once, at 2200 hours on 7 July, did she 

return for a short visit to the den during her night’s activity. The second parturition was quite similar: there was 

no evidence of a birth 23–26 July, but birth had evidently 

occurred by 1300 hours on 30 July, when the next GPS 

sample began. She may have given birth on that day, as 

she stayed in the den until after 2100 hours. As before, F3 

spent the day at the den and left it at night, but in contrast 

to 2006, she returned to the pups once or twice during the 

night on six nights (Figure 5.8).

We have no data on litter sizes at birth, and none 

on maternal behavior beyond 16 days postpartum, but 

F3 was still abundantly lactating on 4 September 2006, 

two months after parturition. We saw pups of only three 

months old or older, with a maximum number of three.

Paternal Behavior

The male M5 registered no approach to either the 

pup den or to F3 during the three samples from birth of 

the young, to 15 days postpartum, when the GPS collar 

on F3 failed and we could no longer be certain of their 

location (Figure 5.9). However, at 4–6 weeks postpartum 

(August–September), M5 showed repeated, daily returns 

to a focal point near to the pupping den. If, as we think, 

M5 was then visiting the pups daily, they had moved 

about 150 m.

In contrast to the behavior of M5 after parturition, 

M8, newly resident with F3 in 2008, often visited the area 

of the pups in the days following birth (about 30 July). 

On each of 30 and 31 July, he came to the pup den at 

2200 hours and on the next night at 0500 hours. F3 was 

absent at the first visit and present at the following two. 

In the next sample (6–9 August), he spent the whole day 

of 8 August 360 m from the pup den, and at 1700 hours 

approached to 160 m, where he stayed two hours. During 

TABLE 5.8. Reproductive life of F3. Litter dates are backestimated from size of young (see Materials and Methods) and from records of 

their presence, reproductive state of F3 at capture, and preliminary genetic evidence of kinship. Two litters were born on known dates, 

and two were estimated from estimated ages of young captured as subadults. “Successful” indicates that at least one young lived to 

weaning. F3 ceased behavior consistent with lactation of the fourth litter about 18 days after parturition. Her fate was not known after 

2008 as her collar was not recovered. NR, North Range; SR, South Range; n/a, not applicable or unknown.

Birth Fate of

F3 reproductive life Date Age interval litter

Born on NR1 to M2-FT July 2001* 0 n/a n/a

First capture Sept. 2002 1.2 n/a n/a

First seen with M5 Sept. 2003 2.2 n/a n/a

Territory with M5, NR March–Sept. 2004 3 n/a n/a

Birth first litter (young M10?) Feb. 2005* 3.6 n/a Successful?

Birth second litter with M5 1 July 2006 5 17 mo Successful

Birth third litter (3 young weaned) March 2007* 5.6 7 mo Successful

Change male to M8 May 2008? 6.6 n/a n/a

Birth of fourth litter with M8 30 July 2008 7 17 mo Failed at 18 days

Last record, photos only 20 July 2009 8 n/a n/a

*Date estimated. Possibly born in February 02. See discussion.
number 639 • 6 9

F3 Perinatal movements

0

500

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Hour

Parturition

Day

At Den

F3 6-8 July 06

0

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At Den At Den At Den

Distance, 

m Distance, 

m

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7:00

FIGURE 5.7. (A) Distance traveled between hourly fixes of F3 on the 2 days prior to and on the day of parturition (1 July 2006). (B) Movement 

pattern in the following sample (6–8 July) when she is at the pup den whenever inactive, including at 2200 hours on the second night.
7 0 • smithsonian contributions to zoology

the final sample (13–16 August), M8 rested 1 day at 760 

m from the pups but was recorded no closer.

When we followed M2 by on-foot VHF tracking in 

March 2002, he showed strongly point-centered activity, 

a radical change of movement pattern that we ascribed to 

attendance on pups. He made long, direct travels to return 

repeatedly to the same site and spent the day there. He had 

frequent vocal interactions with an unmarked maned wolf 

in his territory. When one of us (LHE) went in to find M2 by 

day, she heard a low growl before the signal moved away. 

Nothing was visible in the dense, chest-high grass, and LHE 

left so as not to disturb pups. This was the only time a free 

maned wolf growled at our approach. The same month, 

tracks of small pups were seen with those of an adult.

Dispersal of Young

Of the six young captured in the study area, we know 

the lifetime fates of just two: females F3 and F9, who remained on their parental territories and inherited them at 

the deaths of their mothers. They stayed on those territories for their whole lives. In September 05, subadult female 

F7 occupied South Range along with adults and a litter 

of 3–4 month old pups. She disappeared by March–April 

2006, at 12–18 months old. By September 2006, a new 

subadult, F9, now occupied the South Range, along with 

adults F11 and M8. Female F12 (North Range, too small 

to collar at capture October 2007), was not recorded the 

following year. Male M4 (VHF collar October 2002) and 

FIGURE 5.8. Entire recorded location record during lactation for F3 in July–August 2008. Gray bars are times in the pup den; 

black bars indicate the distance moved from the previous location. Broken lines indicate breaks between weekly samples: 30 July–2 

August, 6–9 August, and 13–16 August. By the following sample on 20 August, all behavior indicating lactation had ceased.
number 639 • 7 1

his littermate brother disappeared from the natal territory 

between February and May 2003, at 12–18 months old. 

Another litter was born on that territory in about March, 

and the brothers had gone by June, presumably emigrating. 

Male M10, presumed from the first litter of F3–M5 (VHF 

collar, October 2006), was captured 2.5 km outside the 

parental territory at about 18 months old. He returned to 

the North Range, where he was located in December 2006 

near the PM water hole. Aircraft search failed to locate 

him in February 2007, so he had apparently emigrated at 

20–22 months old. No young males were recorded again 

after they had left the area, but one 2.5-year-old female 

(F13) may have returned from a neighboring estancia after 

death of a resident female (see Postscript).

DISCUSSION

Social Organization

As reported by other authors, MW at Los Fierros are 

socially monogamous, with pairs co-occupying territories 

in long-term relationships (Dietz, 1984; Rodden et al., 

2004). However, pairs were not always lifelong, as we 

recorded males switching to pair with other females, in 

one case after the pair had been together for four years 

and produced multiple litters. We found variable amounts 

of association between maned wolf pairs and group members. Some appeared “solitary” as earlier reported (Dietz, 

1984; Melo et al., 2007; Rodden et al., 2004): “The 

maned wolves of the Serra da Canastra led predominantly 

solitary existences. Wolves were never observed resting 

together, and they rarely traveled or hunted together” 

(Dietz, 1984:16). In contrast, we sometimes recorded 

more cohesive behavior, as reported by Melo et al. (2006) 

with a GPS-collared pair and subadult female: “During 

the night . . . the three individuals avoided contact with 

each other. However, during the day, the adult pair usually slept together and their juvenile slept within a few 

hundred meters of their location.” (Melo et al., 2007:1). 

Unlike either Dietz (1984) or Melo et al. (2007), we recorded frequent nocturnal meetings between maned wolf 

family members when juveniles were present and when 

we followed them on foot with VHF. One GPS-collared 

FIGURE 5.9. Movements of males M5 and M8, and female F3, following parturition. (A) Parturition 1 July 2006, movements 1 July to13 

July. M5 did not approach the pups. Although the trajectories interdigitate, no simultaneous locations of F3–M5 were less than 300 m apart, 

and only four were within 1000 m, all distant from the den, and 8 days after birth; (B) Parturition about 30 July 2008, movements 30 July to 

16 August. In this case, M8 visited the pups. Broken lines, trajectories of males; solid lines, trajectories of F3 radiating from pup den. Note that 

adults take different routes each night and that none are exactly repeated. Birth of young can immediately be identified by point-focused movements of the mother. Such focus never occurred otherwise (e.g., Chapter 3, Figure 3.1). Note the difference in scale.
7 2 • smithsonian contributions to zoology

pair without young also initially showed strongly cohesive behavior (F3–M5), but they greatly decreased their 

encounter rates between their first year together and the 

following years. We believe that many brief meetings are 

unrecorded when GPS locations are at hourly or greater 

intervals, thus leading to underestimation of intrapair sociality. The two-hourly interfix intervals used by Melo et 

al. (2007) may have failed to capture some nocturnal encounters between active MW.

During pregnancy, F3–M5 had episodes of prolonged 

proximity (Figure 5.4B). These may correspond to the 

large progesterone peaks recorded at about 5–7 days and 

35–40 days postestrus, or to the sharp peak of estrogen at 

20–30 days (Velloso et al., 1998). High female hormone 

levels perhaps trigger attraction between the pair. Unlike 

the pair followed by Melo et al. (2007), it was exceedingly 

rare for F3–M5, or any other pairs, to rest together by day 

(except during estrus), but exceptionally, during midpregnancy, the pair rested together on a third of days. Melo et 

al. (2007) began their study during a female’s pregnancy, 

which perhaps contributed to their finding that a pair 

“slept together.”

If the close association of F3–M5 when first paired 

(Figure 5.4A) was partly due to proestrus, estrus, and 

pregnancy, three months seems, nonetheless, far too long 

for reproduction to explain the whole duration of cohesiveness (Figure 5.4). As a new pair with a nulliparous 

female, perhaps close proximity was a male strategy to advance estrus though hormonal stimulation (DeMatteo et 

al., 2006). However, between 2004 and subsequent years, 

there was also a dramatic change in the prey resources and 

diet of MW in the study area (Chapter 4).

Another hypothesis for the unusual level of close 

cohesiveness in 2003–2004 is that this pair hunted cavies (Cavia aperea) cooperatively. White-toothed cavies 

do not burrow but shelter in tunnels under dense bunch 

grasses. Maned wolves could flush them or drive them 

toward each other, a tactic also perhaps possible with armadillos, which are large enough prey to share. Cavies 

sharply declined after 2004, then disappeared to zero in 

the diet after 2006, while armadillos did not appear after 

2005 (Chapter 4; Emmons, 2009). Any cooperative hunting for these prey thus would have ceased. That either 

male or female could initiate contact (change its trajectory to join the other) may support this hypothesis, but 

unfortunately, we never saw the pair when they traveled 

together. The hypotheses are not mutually exclusive. Pair 

cohesiveness thus varied between pairs, years, and reproductive condition.

Parental Behavior

Maned wolf pairs cooperate to provision young 

(Bestelmeyer et al., 1996; Melo et al., 2009; Rasmussen 

and Tilson, 1984). Our brief data sets indicated that in 

one case the male did not interact at all with the newborn 

litter or their mother, but when the young were about a 

month old, he showed repeated, regular return to a focal 

area near the birth den, consistent with provisioning. In 

captivity, provisioning by regurgitation begins as nursing 

bouts decline at four weeks of age (Rodden et al., 2004), 

which matches our interpretation that M5 began to visit 

pups several weeks postpartum. In contrast, M8 (who had 

previously raised young successfully) started short visits in 

the week of parturition, and the second week twice rested 

by day near the pup den. After both births, the female 

spent most of each night away from the pups and all day 

with them. Melo et al. (2009) directly observed a pair attending a den with one pup. The male attended the mother 

and pup and provisioned the female, but he rarely visited 

when she was absent (Melo et al., 2009). Their observations (1700–0600 hours) showed both the female and 

male to spend a great many more nighttime hours at the 

den than we recorded (71% and 31%, respectively). These 

MW were fed daily with meat at a hotel, and the authors 

note that this might have both reduced the need to forage 

and accounted for the pattern of visits (return to pups immediately following feeding; Melo et al., 2009).

On the basis of the mother’s behavior, the 2008 litter died at about 18 days of age. The male M8 had been 

with F3 on the territory for less than three months (M5 

was there earlier). The possibility that the young were not 

fathered by M8 and that he killed them seems unlikely. He 

visited the pup den when the female was absent on the first 

day we recorded lactation, and he did not kill them then 

but continued to visit. Moreover, his visits declined the 

week before they died.

Vocal Communication

The only quantitative report of maned wolf calling 

behavior in situ is that of Dietz (1984), who heard maned 

wolf roar-barking 46 times during his two year study, 

with maximal calls (eight bouts) in August and zero to 

one bouts in March–May. Dietz’ study wolves did not successfully raise young, but one litter was lost. We noted 

much higher levels of vocal interaction between group 

members than did Dietz (1984). Our data on roar-barking 

highlights calling as an intragroup activity that is most 
number 639 • 7 3

frequent when young are present and probably serves for 

within-group communication across the great distances of 

the home range. Countercallers sometimes converged, as 

if calls were used for finding group members. The rarity of 

calling when no young were on the territory, as noted both 

by ourselves and by Dietz (1984), suggests that calling is 

not primarily a between-group spacing signal associated 

with territorial behavior (Brady, 1981), although we do 

not rule out a territorial function. The most intense calling that we noted, involving three- to four-month-old pups 

and two or three adults may have been triggered by anxious, newly weaned pups beginning to forage alone, countercalling with their parents, sibs, and the female helper.

Dispersal of Young

We recorded only females to be philopatric, and we 

documented three cases of a single female young present 

beyond the birth of the next litter. In one, the young female 

(F7) was replaced the following year by another young 

female (F9); and in the other two (F3, F9), she acquired 

the maternal territory on the death/disappearance of her 

mother over a year later. There was a probable fourth case 

(2001), when an “extra” unmarked animal was seen and 

photographed several times near pups, but was gone and 

“replaced” by F3 the following year. Melo et al. (2007) 

likewise documented with GPS telemetry the presence of a 

young female with an adult pair and their litter. Their data 

suggest that the young female was a “helper” that guarded 

and/or provisioned the pups (Melo et al., 2007). It now 

seems certain that, as in all other large Canidae and many 

small ones (Macdonald et al., 2004a), young of MW can 

stay in the parental group beyond the birth of the next litter and likely assist in the care of younger siblings. Three 

male young dispersed from the study area at the estimated 

ages of 15–22 months old, but there is much ambiguity 

in birth dates. Another, present at 6 months, was likewise 

gone by 18 months.

The rare data so far point to helpers being female, 

being restricted to one, being common, but not obligatory, and sometimes remaining for only about two years. 

With small litter sizes (one to three), yearling female helpers may not always be available, and perhaps females stay 

on the natal range only until replaced by another yearling 

female. If so, it would be interesting to know the mechanism by which this occurs (does a mother drive out her 

older daughter when she has another? Does a daughter 

evaluate the chances of her mother’s survival, and stay, or 

leave?). A helper may directly benefit a reproductive pair 

and her own inclusive fitness by increasing pup survivorship, and a mother could favor the survival of her matriline by allowing one daughter to remain, who if she dies, 

immediately acquires a full territory and optimal potential 

for reproduction.

The little available data suggest that MW are not longlived, with a mean survival rate for all age groups of about 

0.64 per year (Sollmann et al., 2009), but highly variable 

by year from 0.97 to 0.28 (Sollmann et al., 2010). In our 

study area, tooth wear, tooth loss, and tooth infections 

start to affect most individuals by the time they are about 

five (Chapter 6). All known mortality on our study area 

was “natural,” and most occurred in the late wet season 

(January–April). Because the yearly probability of death is 

quite high, it could benefit a youngster to remain on the 

natal territory at least past the season of most likely liberation of territories by deaths of parents or neighbors.

The inheritance of territories by females, with males 

switching territories while females remained, and females 

apparently the helper sex, suggest that female MW are the 

socially dominant sex and the primary “owners” of territories. This was supported by our observation of F3 displaying dominance over a prone, belly-up, M5. Likewise, 

as a yearling, F3 was strong smelling and aggressive when 

trapped and initiated many calling bouts. As a youngster 

with a small home range, she marched prominently up and 

down the road depositing scats, as if participating in territorial behaviors. In contrast, young male M4 was odorless 

(to us) and whined like a pup when trapped, initiated half 

as many calling bouts, and kept more hidden from sight in 

the grass. Maned wolf males are only slightly larger than 

females (Dietz, 1984; Jácomo et al., 2009), with inconspicuous genitalia. The sexes were to us generally indistinguishable by sight or in lateral photographs (Frontispiece, 

Figure 8.1). The visual similarity between male and female 

MW may be a correlate of female dominance (or absence 

of male dominance), as it is in some other mammals (e.g., 

hyenas: Mills, 1989).

We lack a telemetry record of the intriguing switch 

of males after the death of F11, when neighboring M5 

moved into the South Range territory to pair with F9, and 

M8 joined F3 on North Range (Figure 5.1). This double 

move obviously prevented incest between F9 and M8, 

but there are unanswered questions: Did nulliparous F9 

drive out M8 and seduce M5 into her territory? Or did 

M8 leave voluntarily and displace M5? Or did M5 seek 

a younger female, abandon F3, and force out M8? The 

missing details are key to understanding the social dynamics of the species. When F9 in turn died, M5 disappeared, 
7 4 • smithsonian contributions to zoology

but we do not know if he died or emigrated or (his collar 

had expired).

Dietz (1984:15) observed a parallel case: two months 

after death of the female of a pair, a new young female 

moved into her territory, and a month later, the male of 

the previous pair, who had not associated with the new 

female, moved outside of it and disappeared, just as a new 

young male took over the territory with the new female. 

This sequence closely matches behaviors we observed: (1) 

after the death of a female, the male left the territory and 

did not pair with the replacement female; (2) a new male 

joined the replacement female after she had established 

as resident on a territory. As we recorded three (possibly 

four) times, a male moved in to join a female on her territory, not the reverse.

Reproductive Season

The two known birth dates of litters on our study area 

were in July, as were two others based on estimated ages 

of observed pups (Table 5.7). Our data present an enigma 

regarding other birth dates. In September and October we 

caught immature females of 17–18 kg, with body measurements below adult size. At least one of these youngsters 

had grown in length by the following year. Captive bred 

MW reach full weight (26 kg) at 10.5 months (M. Rodden, pers. comm.). Backdating their birth dates from their 

weights at capture (see Materials and Methods) yields 

births in about February, as it does for some other youngsters of 21 kg. This presents two possibilities: (1) young 

really were born in January–March or (2) they were born 

the previous year and were not fully grown at 12–14 

months old. In one case (young F12), the mother (F3) was 

known to have given birth the previous 1 July, and she was 

still lactating in September. If F12 was of that July litter, 

she would have weighed only 18 kg at 15.5 months old 

and been incomplete in body measurements. Otherwise, 

the mother gave birth twice in the same year, once on 1 

July, and again in the following February–March. There 

is some evidence that F3 also gave birth to her first litter 

in around January–February 2005 (estrus in November, 

presence of M10 of the right age; see above) and that the 

final litter of M2 was born February–March, as tracks 

were seen in March and pups were seen in May. In Emas 

Park in Brazil, gestation is reported from April to August, 

and births from June to August (Vynne, 2010), consistent 

with some of our results. Dietz (1984) reported the birth 

months of 21 litters, from local interviews in Serra da Canastra. Maximum births also occurred from July to September (three to five litters each), but two were reported in 

February, one each in March and May, and two in April. 

Vynne (2010) shows a small uptick in December maned 

wolf fecal progestin levels in Emas Park, which could signal early estrus in a few females.

MW are believed to enter estrus just once per year 

(Asa, 1997, Rodden et al., 2004; Velloso et al., 1998), but 

two South American Canidae, including bush dogs (Speothos venaticus; the nearest living relative of MW) and 

crab-eating foxes (Cerdocyon thous), are polyestrous or 

can even have two litters a year (C. thous; DeMatteo et 

al., 2006). We lack data to prove that a February–March 

birth can follow a July birth by less than 8 months, but 

some evidence implies it to be so, and long-term in situ

data are needed.

After inheriting a territory and acquiring a mate, F9 

died at three years old, (12.5 months after her mother), 

without indication of ever giving birth. The riskiness of 

maned wolf life could foster seasonally early breeding to 

result in February–March litters in nulliparous females or 

if an earlier litter is lost. Velloso et al. (1998) suggested 

that estrus in MW is triggered by photoperiod, because 

Northern Hemisphere ex situ MW breed in autumn, six 

months displaced from the autumn reproduction of Southern Hemisphere females. This idea merits another look as 

young were born at Los Fierros over at least half the year.

Does July parturition benefit MW? Both forest and savanna rodents and marsupials in NKP have fairly synchronized reproductive peaks in the first week in September, 

before which few juveniles can be trapped. Reproduction subsequently continues for several generations, so 

that high small mammal numbers coincide with the early 

rainy season (November–December; L. Emmons, unpublished). The dominant fruit in the diet, Alibertia edulis, is 

found in scats from July to February (Chapter 4, Figure 

4.2). Pups can start to accompany parents to hunt at seven 

weeks but are provisioned by regurgitation for up to seven 

months (event timing reviewed in Rodden et al. [2004]). 

July births thus result in maximal resource availability at 

weaning (three months old) and maximal yearly abundance of prey and fruit when postweaning pups begin foraging. Pregnancy and lactation occur when food resources 

may be more limited, with possible prejudice to maternal 

body condition. Maned wolves have short lives and few 

young. With adult survivorship that can be as low as 0.28 

per year (Sollmann et al., 2010), a female should favor 

survival of her current young over that of her possible future young: that is, the birth month favors survivorship of 

the young somewhat more than that of the mother. An influential factor might be that as February–July are months 

of lowest yearly maximum temperatures (Figure 1.8), in 
number 639 • 7 5

these months increased hours below 30°C (the temperature limit of maned wolf activity, Chapter 2) are available 

for foraging to compensate for low resource levels, but we 

do not know if this occurs. Likewise, water is abundant 

throughout the Cerrado during these months (Chapters 2 

and 3), so little energy is expended to acquire it.

To conclude, we have raised more questions than were 

answered in this chapter. Every aspect of maned wolf social interaction and reproductive biology that we describe 

needs confirmation with a great many more in situ studies, 

especially the kind of longitudinal research that has provided understanding of the socioecology of gray wolves, 

African wild dogs, Ethiopian wolves, coyotes, and jackals 

(MacDonald and Sillero-Zubiri, 2004). Even when Canidae can be directly observed and followed throughout their 

activities, it has taken decades to chronicle sufficient life 

histories to understand the sociobiology of a species. It will 

be a daunting task to acquire such knowledge for MW.

Postscript

After writing this chapter we continued our work Los 

Fierros. F9 had died in April 2009, and her mate M5 had 

disappeared by July, when F3 and M8 were still the pair 

of the North Range territory. On 19 August 2009 we photographed a new young female (F13) in F9’s old territory, 

but we could not trap her. The largest fire in over 25 years 

burned nearly all of the savanna in October 2009. When 

J. M. Castro returned briefly in November 2009, he could 

find no tracks or signs of MW nor any signal from M8 

who had carried the only functioning collar. We recorded 

no further trace of F3, M8, or M5. We captured F13, now 

primaparous (pregnant) in September 2010 during the 

most severe drought of recent memory. She then occupied 

both North and South Ranges, and there was evidence of 

but one other maned wolf on the savanna. In September 

2011, an even more severe drought year, we captured F13 

and recovered 52 weeks of GPS data, and we captured and 

collared her mate, M14. These were the only individuals 

in the study area, and they used the whole savanna. At 

least eight MW, including pups, had been present in 2008. 

Because nulliparous F13 had replaced F9 by August 2009 

(with no evidence of a mate), and she became primaparous 

only in September 2010, this represents a fourth case on 

our study area of a female first acquiring a territory, subsequently to be joined by a male. Photographs suggest that 

F13 was sibling to F12 and one of a litter of three weaned 

by F3-M5 in 2007. If so, three generations of a matriline 

have sequentially inherited the Los Fierros savanna, but 

no males of the family persist there. Genetic support for 

these relationships is pending.

6 Morbidity and Mortality

Sharon L. Deem, Ellen Bronson, Sixto 

Angulo, Veronica Acosta, Suzan Murray, 

Richard G. Robbins, Urs Giger, Bruce 

Rothschild, and Louise H. Emmons

ABSTRACT. The health status of a population of maned wolves (MW), Chrysocyon 

brachyurus, in Noel Kempff Mercado National Park (NKP), Bolivia, was studied from 

2000 to 2009 by direct observations, GPS and VHF telemetry, and biomaterial collection. A total of 12 MW were anesthetized for 33 events. Causes of morbidity included 

severe dental disease, skin lesions, lameness, endoparasites (among them, Dioctophyme 

renale and Dirofilaria immitis), ectoparasites, urinary cystine calculi, traumatic injuries, 

and exposure to infectious disease agents. During this decade, five of the 12 (42%) MW 

died. Age at time of death varied from 1.5 to >10 years. Pathologic findings identified 

postmortem included vertebral pathology (n = 2) and severe dental disease (n = 2). The 

remaining seven MW either emigrated with fate unknown or were alive in 2009 and 

ranged in age from 8 months to 7 years. Maned wolves in NKP are geriatric by age 8 or 

9. We estimated that a total of seven litters were born to three resident adults. Of these 

seven litters, five included at least one pup raised to 6–8 months subadults and two litters 

were lost, one at 16 days and the other at 5 months (Chapter 5). Our data support the 

observation that dental and skeletal diseases are limiting factors for the longevity of both 

captive and free-living MW.

INTRODUCTION

One of the main goals of conservation is to evaluate and, if possible, optimize the factors that are most important for maintaining population fitness 

of a species. Knowing the causes of mortality and morbidity of a free-ranging 

species is essential to knowing how best to protect it from hazards that pose 

present or future threats to species survival. During our studies of the ecology 

of the maned wolves (MW) (Chrysocyon brachyurus) in Noel Kempff Mercado 

National Park (NKP), we took advantage of the trapping and immobilization 

required to deploy telemetry collars for collecting as much health information as 

we could under primitive field conditions. This part of our research was a major 

collaborative effort that over the years involved not only our field crew and 

four veterinarians but also the specialist knowledge of diagnostic laboratories, 

Sharon L. Deem, Institute for Conservation 

Medicine, Saint Louis Zoo, Saint Louis, Missouri 

63110, USA; Ellen Bronson, Maryland Zoo in 

Baltimore, Druid Hill Park, Baltimore, Maryland 

21217, USA; Sixto Angulo, Fundación para la 

Conservación del Bosque Chiquitano, Calle René 

Moreno, Santa Cruz, Bolivia; Veronica Acosta,

Smithsonian Conservation Biology Institute, National Zoo, 1500 Remount Road, Front Royal, 

Virginia 22630, USA; Suzan Murray, Smithsonian National Zoological Park, 3001 Connecticut 

Avenue, Washington, D.C. 20008, USA; Richard 

G. Robbins, ISD/AFPMB, Walter Reed Army 

Medical Center, Washington, D.C. 20307-5001, 

USA; Urs Giger, School of Veterinary Medicine, 

University of Pennsylvania, 3900 Delancey 

Street, Philadelphia, Pennsylvania 19104-6010, 

USA; Bruce Rothschild, Department of Medicine, Northeastern Ohio Universities College of 

Medicine, Rootstown, Ohio 44272, USA and 

Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA; Louise H. Emmons, 

Department of Vertebrate Zoology, National 

Museum of Natural History, P.O. Box 37012, 

MRC 108, Smithsonian Institution, Washington, 

D.C. 20013-7012, USA. Correspondence: deem@

stlzoo.org. Manuscript received 25 August 2010; 

accepted 26 August 2011.
7 8 • smithsonian contributions to zoology

parasitologists, medical entomologists, laboratory technicians, and a dentist.

Few studies have been conducted on the health of freeliving MW, however, available reports include baseline hematology and chemistry profiles (Dietz, 1984; May-Júnior 

et al., 2009) cystinuria and cysteine calculi (Carvalho and 

Vasconcellos, 1995; Deem and Emmons, 2005; Dietz, 

1984), descriptions of endo- and ectoparasites (Beldomenico et al., 2002; Bevilaqua et al., 1993; Carvalho and 

Vasconcellos, 1995; Deem and Emmons, 2005; Robbins 

and Deem, 2002), dental trauma (Furtado et al., 2007), 

and evidence of exposure to a number of infectious agents 

(Deem and Emmons, 2005; Deem et al., 2008). All diseases reported in free-living MW (except gunshot wounds 

and trauma caused by vehicle contact) are also commonly 

reported in captive MW, including some not yet identified 

in free-living individuals, such as dermatitis, proliferative 

gingivitis, neoplasia, and spondyloarthropathy (Fletcher 

et al., 1979; Hammond, 2012; Maia and Gouveia, 2002; 

Norton, 1990; Reid et al., 2005; Maned Wolf Husbandry 

Manual, 2007; Rothschild et al., 2001). 

Causes of mortality of MW in captivity are similar to 

those reported above for morbidity. However, euthanasia 

(commonly elected due to pain and immobility resulting 

from skeletal problems) and perinatal losses account for 

many ex situ deaths (National Zoological Park, unpublished data). The majority of captive MW die by 15 years 

with the longest lived captive-born MW in the North 

American population recorded at 16 years 7 months for 

males and 17 years 10 months for females (M. Rodden, 

pers. comm.). Causes of mortality in the wild, except by 

vehicle road kill and shooting, are largely unknown, as is 

age at death. A recent study by Sollmann et al. (2009) in 

Emas National Park, Brazil, found survival rates of approximately 64% annually for both genders and for subadults and adults alike.

We describe what we learned of the causes of morbidity and mortality in a population of free-living MW in 

NKP, as an integral part of a study of their ecology. We 

compare our findings to causes of morbidity and mortality 

in captive MW at the Smithsonian Conservation Biology 

Institute.

Materials and Methods

Field Site

Noel Kempff Mercado National Park lies between 

13°31′–15°05′S and 60°14′–61°49′W at the interface of 

Amazonian forest with diverse savanna ecosystems, and it 

includes broadleaf semi-evergreen forest, dry forest, inundated forest, dry savannas, and flood-prone savannas. The 

habitats and climate are described and illustrated in Chapter 1. The complex habitat mosaic of NKP results in a rich 

fauna of 604 bird species (B. Hennessy, Armonia, pers. 

comm.) and 172 mammal species, including 20 Carnivora 

(Emmons et al., 2006a, 2006b); all with potential to interact with MW: as prey, predators, and vectors or hosts of 

pathogens and parasites. The territories of the MW in our 

study population in Los Fierros savanna are isolated from 

direct contact with human settlements, pets, or livestock, 

except horses that travel briefly on one road a few times 

a year (without staying overnight or grazing). However, 

at least one GPS-collared maned wolf (M6) traveled 30 

km to a neighboring estancia that has dogs, cats, poultry, 

and hoofstock and then returned into Los Fierros savanna 

(Chapter 3), so isolation is incomplete. There is little vehicle traffic on the single, potholed, dirt road that crosses 

the savanna, and we found only one maned wolf road kill, 

in about 1995, when there were logging trucks still speeding on that road.

Sample and Data Collection in the Field

Maned wolves were captured within NKP in wooden 

box traps or hardware-cloth cage-traps baited at first with 

live chicks, but later with sardines and fatty dried beef (see 

Chapter 1 for more detail). From February 2000 to July 

2009, 12 MW were captured for a total of 33 anesthetic 

events. Immobilization was with tiletamine plus zolazepam (Telazol®, Fort Dodge Laboratories, Fort Dodge, 

Iowa 50501, USA; 3.5–4.5 mg/kg, intramuscular [i.m.]) 

or a ketamine (Ketaset®, Fort Dodge; 6–8 mg/kg, i.m.)/ 

xylazine (Xylazine: TranquiVed, Vedco, Inc., St. Joseph, 

Missouri 64507; 1.1 mg/kg, i.m.) combination delivered 

through Telinject® plastic darts (Telinject USA Inc., Agua 

Dulce, California 91390, USA) using a Telinject® pistol 

(Bronson et al., in preparation). If needed, anesthesia 

was supplemented with ketamine (Ketaset®, Fort Dodge; 

25–50 mg increments, intravenous or i.m.). For the ketamine/xylazine combination, the xylazine was reversed 

with yohimbine (Wildlife Pharmaceuticals, Inc., Fort Collins, Colorado 80522, USA; 0.125 mg/kg, i.m.). 

A physical examination was performed on each maned 

wolf at the time of anesthesia and included temperature, 

pulse, respiration, detailed oral examination, detection 

of skin lesions, and abdominal palpation. Ages were estimated by physical characteristics (e.g., dentition, coat appearance, mammae appearance, and body measurements) 

according to the criteria of Dietz (1984) and in comparison 
number 639 • 7 9

to known-aged individuals of our study. We documented 

with photographs the whole body, dentition, and lesions, 

and various samples were collected from each maned wolf. 

Blood was collected by venipuncture of the jugular, cephalic, or the lateral saphenous vein and was immediately 

placed in ethylenediaminetetraacetic acid (EDTA) anticoagulant tubes (Becton Dickinson, Franklin Lakes, New 

Jersey 07417, USA) and serum separator tubes (Corvac 

Sherwood Medical, St. Louis, Missouri 63103, USA). The 

sample tubes were placed in the shade until clot formation, at which point sera were separated by centrifugation 

(Mobilespin, Vulcan Technologies, Grandview, Missouri 

64040, USA) at 3,000 g for 15 min and stored in a freezer. 

Alternatively, blood was allowed to clot at ambient temperature, and the serum was then decanted and kept in a 

cool place for 48 hours before storage in a freezer. 

Blood in EDTA was used to prepare thin blood smears 

fixed with 99% methanol. Packed cell volumes (PCV) were 

determined using a portable 12 V centrifuge, and plasma 

total solids (TS) were measured with a handheld refractometer (Schulco, Toledo, Ohio 43608, USA) calibrated at 

the site. White blood cell (WBC) counts were determined 

manually with a prepackaged dilution system (Unopette 

Test 5877, Becton-Dickinson Vacutainer Systems, Rutherford, New Jersey 07070, USA). Samples were transported 

on dry or wet ice to the Department of Animal Health, 

Smithsonian National Zoological Park, USA, for storage 

at –70°C and laboratory testing.

Fecal samples were collected manually from the rectum and preserved in 10% formalin. Ectoparasites were 

collected, stored, and shipped in 70% isopropanol or ethanol. Urine was collected by cystocentesis using a 0.7mm × 

25.4 mm needle, and 12 mL syringe, but not all individuals could be sampled. Urine samples were divided into aliquots and frozen in cryotubes as well as fixed in formalin. 

The remaining urine was evaluated using a refractometer 

calibrated at the site, and with Multistix-Reagent Strips 

for Urinalysis (Bayer Corporation, Elkhart, Indiana 46515 

USA), followed by immediate centrifugation at 3,000 g for 

5 min. Urine sedimentation was examined directly by microscope in the field. Preservative solutions were removed 

before air travel and supplemented upon arrival in the 

USA. All appropriate export and import permits accompanied the samples during transport and the studies were 

approved by the IACUC of Smithsonian National Zoological Park and Smithsonian National Museum of Natural 

History.

With the exception of subadults weighing <20 kg, GPS 

or VHF telemetry collars were placed on each maned wolf 

at the initial anesthetic event (see Chapter 1). On the basis 

of signal immobility, MW assumed dead were retrieved 

and any teeth or bones were collected for later evaluation. 

Salvaged skeletons were deposited in the Museo de Historia Natural Noel Kempff Mercado, Santa Cruz, Bolivia.

Laboratory Diagnostics

Thin blood smears were stained with a modified 

Wright-Giemsa stain (Hematology Three-Step Stain, 

Accra Lab, Bridgeport, New Jersey 08014, USA) or a DiffQuick stain (DipQuick Stain, JorVet, Jorgensen Laboratories, Loveland, Colorado 80538, USA) and examined for 

blood parasites, blood cell morphology and WBC differentials. Serum biochemistries were processed on a COBAS 

MIRA Plus chemistry system (Roche Diagnostic Systems, 

Inc., Branchburg, New Jersey, 08876). 

Serologic testing for antibodies was conducted at the 

New York State Veterinary Diagnostic Laboratory (Cornell University, Ithaca, New York) using serum neutralization for canine adenovirus (CAV-II), canine coronavirus 

(CCV), canine distemper virus (CDV), and canine herpesvirus (CHV); using hemagglutination inhibition for canine parvovirus (CPV); using slide agglutination/agar gel 

immunodiffusion for Brucella canis; using indirect hemagglutination assay for Toxoplasma gondii; and by microagglutination for Leptospira interrogans serovars. The 

same laboratory was used for detecting Dirofilaria immitis

antigens using an occult antigen test. The five L. interrogans serovars tested included L. pomona, L. hardjo, L. 

icterohaemorrhagicae, L. grippophytosa, and L. canicula. 

Serologic testing for rabies virus was performed at Kansas 

State Veterinary Diagnostic Laboratory (Kansas State University, Manhattan, Kansas) using the rapid fluorescent 

focus inhibition test. Antibodies to Ehrlichia canis, Borrelia burgdorferi, and Rickettsia rickettsii were tested at 

the Texas Veterinary Medical Diagnostic Laboratory using 

an immunofluorescence assay. These serologic diagnostic 

tests are targeted at canine pathogens known from North 

America, leaving unexplored the world of native sylvatic 

pathogens. 

Fecal samples were examined by direct microscopic 

examination, sodium nitrate flotation, and sedimentation 

methods at the New York State Veterinary Diagnostic 

Laboratory. One adult worm was collected perirectal and 

submitted to Dr. Michael Kinsella for identification. Adult 

ticks were identified on the basis of external morphology, 

using the keys of Kohls (1956) and Jones et al. (1972). 

Urine was assayed semiquantitatively for increased cystine 

concentrations using the cyanide-nitroprusside method 

(Shih, 1973). 
8 0 • smithsonian contributions to zoology

Data Analyses

Results were analyzed using a commercial statistical 

software package (NCSS, Kaysville, Utah; SPSS, version 

13.0, Chicago, Illinois). Numerical data were inspected 

for normality and t-tests were performed on normal data 

and Mann-Whitney U-tests were used where normality 

was rejected (Petrie and Watson, 2006). Statistical significance was determined as p < 0.05.

RESULTS

Among the 12 MW, seven were immobilized once, 

three were anesthetized two, four, and eight times, respectively, and two others were each immobilized six times. 

Maned wolves were generally immobilized and sampled 

once yearly, but a few were immobilized twice within a 

year at intervals of over three months. Six were male and 

six were female. 

Physical Findings

Body weights were recorded for six females (16 measures) with a mean of 23.2 kg ± 3.6, range 17–29 kg and 

for six males (13 measures) as 26.2 kg ± 2.4, range 21–29 

kg. Males were significantly heavier than females (t-test; P 

= 0.0076) when both age groups (i.e., subadult and adult) 

were combined. Body weight of adult females, based on 

10 measures from three animals, was 25 kg ± 2.9, range 

22.9–27.1 kg. Body weight of adult males, based on 11 

measures from four animals, was 26.96 kg ± 1.64; range 

23–29 kg. Adult female body weights were significantly 

lower than adult male body weights (t-test; P= 0.03). 

The most striking lesions on physical examination 

were the dental lesions, such as abnormal conformation, 

wear and attrition, fractures, missing teeth, gingivitis, and 

caries (Table 6.1 and Figures 6.1, 6.2). Male M5 had class 

II brachygnathia (underbite) and several other oral lesions 

(Table 6.1). Other specific findings included the following: 

M2 was blind in the left eye due to a shrunken globe at 

time of anesthesia, female F3 had signs of old ear pinna 

trauma (probably from myiasis around an ear tag), M6 

was thin with mild crepitus in multiple metatarsal joints 

on palpation, M8 had moderate conjunctivitis and a grade 

IV/VI heart murmur and was limping on release following 

anesthesia, F12 had a laceration on the caudal footpad, 

and two animals (F3, M4) had bald areas on the lateral 

thigh regions. Uncaptured individuals photographed by 

camera traps had similar ear lesions (one) and large bald 

areas on the thigh (one).

Hematology

Males had higher packed blood cell volumes (PCV) 

(37% ± 3.8) than did females (32% ± 5.3) and lower total 

Table 6.1. Clinical and pathological dental findings for free-living maned wolves (MW) (C. brachyurus) in Noel Kempff Mercado 

National Park (NKP). Ages are estimates. Here n/a, not present; X, present.

Age, Abnormal Missing Gingival

ID Years conformation Wear Fractures teeth Gingivitis hyperplasia Caries Osteomyelitis

F1* 0.7 n/a X n/a n/a n/a n/a n/a n/a

M2* 10+ n/a X X X X n/a n/a X

F3 1.5–8 n/a X n/a X X X X n/a

M4 0.8 n/a n/a n/a n/a n/a n/a n/a n/a

M5 3–7 X X X X n/a X X n/a

M6* 10 n/a X X X n/a n/a X X

F7 1 X X n/a n/a n/a n/a n/a n/a

M8 3–7 n/a X n/a X n/a n/a X n/a

F9* 0.6–3 n/a X n/a X n/a n/a X X

M10 1 n/a X n/a n/a n/a n/a n/a n/a

F11* 8–10 X X X X n/a n/a X n/a

F12 0.6 n/a n/a n/a n/a n/a n/a n/a n/a

*Animal died during course of study. Skull was recovered for evaluation.
number 639 • 8 1

solids (7.1 mg/dL ± 0.5) than females (7.9 mg/dL ± 0.6) 

(t-test; p < 0.05). One female (F3) had a PCV of 22% in 

2007 and 2008 but had values in the normal range in other 

years (38% in 2005, 35% in 2006, and 31% in 2008). 

When we removed the two lowest PCV values (22% and 

both from F3), there was still a significant difference between males and females (34% ± 3.3) (t-test; p < 0.05). All 

other hematological values were not significantly different 

between the sexes (Table 6.2). 

Serum Chemistry

Among all the parameters we measured, only the 

serum creatinine kinase (CK) activities differed (MannWhitney U-test; p < 0.05) between genders, with a median 

of 353 U/L (n = 10) for males and of 147 U/L (n = 12) for 

females. This may be due to the high value in one male 

(M5 1,310 U/L), and that both of the highest CK values 

were males (Table 6.3).

Serologic Testing

All 11 of the MW had antibodies to CAV-II at every 

sampling date (n = 30) with titers ranging from 512 to 

4096 (Table 6.4); 85% of samples were heartworm (D. 

immitis) antigen positive and 56% tested positive for 

toxoplasma (T. gondii) antibodies. A low prevalence of 

antibodies to CDV, CPV, Ehrlichia canis, and the five serovars of Leptospira (L. interrogens) was found (Tables

6.4, 6.5). 

Endoparasites and Ectoparasites

Eggs of endoparasites were found in all of the 14 

fecal samples from the 7 MW evaluated. One adult worm, 

found perianally on F9, was identified as a dog roundworm (Toxocara canis). Eggs of pinworms, mites, and 

mite eggs from the family Listrophoridae were detected in 

4 samples from 3 MWs (F3, M8, and F9). All ticks identified were from the pantropical genus Amblyomma. Few 

Figure 6.1. Upper left teeth P4 and M1 of maned wolf F9, 3 years 

old at death. Note that M2 was lost before death and the alveolus 

healed (closed), that the labial cusps of M1 are already worn flat, 

and that P4 shows almost no wear. P2 and P3 were lost postmortem. 

Osteomyelitis has eroded the bone at the root of M2. The right M2 

was likewise missing. Photograph, L.H. Emmons.

FIGURE 6.2. Teeth of geriatric male M6 with multiple dental lesions. (A) Teeth at capture including slab fracture of upper canine, 

other canines and premolars worn to root canals or broken off to 

roots, missing first lower premolars and outer upper incisors, and 

the broken, worn, and infected lower molars and third premolars. 

(B) Recovered mandible of M6, who died about 5 months after the 

photo in A, showing the severe bone infection underlying the cheek 

teeth shown in A. Photograph, L.H. Emmons.
8 2 • smithsonian contributions to zoology

individuals had fleas and they were rare on those that did 

carry them (Table 6.6).

Urinary Findings

Nitroprusside test results were strongly positive for 

urine from two of four males and for both females tested, 

indicating that these MW carried the inherited disease 

cystinuria. Three of five urine sediments that we evaluated microscopically revealed cystine crystals. Curiously, 

cystine crystals were found in the urine sediment of M6, 

who tested negative by cyanide-nitroprusside testing. 

Perhaps dissolved cystine had precipitated, and only the 

supernatant was examined by nitroprusside testing. In 

contrast, urine from F3 was negative for cystine crystals by microscopy but positive by nitroprusside testing. 

Furthermore, ova of the giant kidney worm, Dioctophyme renale, were detected in three of five maned wolf 

samples examined by microscopic evaluation in the field 

(Table 6.7).

Mortality

Up to September 2009, five of the 12 MW studied 

died, with four deaths occurring between February and 

April, and three of these five were over 7 years of age 

(Table 6.8). Following a major fire that swept the entire 

area in October 2009 (Figure 1.10), two other adults disappeared (F3, M8) and were presumed dead (Chapter 5, 

Postscript). Examination of five retrieved skeletons revealed severe vertebral pathologies (Figure 6.3), and tooth 

loss and osteomyelitis of the skull in two geriatric individuals (Figures 6.1, 6.3). An exception was for elderly 

F11, who had molar teeth worn down to the gums, but 

no skeletal and only minor dental lesions: a lost premolar 

and a small slab fracture of a canine tooth. One female 

(F9), 3 years old at time of death, had an infected tooth 

and was positive for D. renale and D. immitis antemortem 

and died when the study area was experiencing unusually 

strong flooding. The other young female that died (F1) 

was believed to have succumbed to an infectious agent as 

the fox (Cerdocyon thous) population in the same section 

of NKP was decimated at this time. 

We estimated that at least seven litters were born to 

three females (Chapter 5; Table 5.7). Of these, five included at least one pup raised to >6–8 month subadults, 

and two litters were lost, at 16 days (F3 in 2008) and at 

5 months (unmarked mate of M2 in 2003), respectively. 

Table 6.2. Hematology for free-living MW (C. brachyurus) in 

NKP. Here n/a, not applicable.

Male

 Range or

 Mean (SD) 10%–90%

Measure N or median quartiles

PCV (%)* 11 37 (3.8) 31–42

TS (mg/dL)* 11 7.1 (0.5) 6.4–8.2

WBC 9 13,036 4,840–21,780

(X103/μL) (6,130)

Neutrophils (% ) 12 79.5 51.4–91

Bands (%) 12 0 0–2.4

Lymphocytes (%) 12 10 5–33.9

Monocytes (%) 12 2.5 0.3–12.8

Eosinophils (%) 12 1 0–8.7

Basophils (%) 12 0 0–0

Female

 Range or

 Mean (SD) 10%–90%

Measure N or median quartiles

PCV (%)* 13 32 (5.3) 22–41

TS (mg/dL)* 12 7.9 (0.6) 6.9–8.8

WBC 9 10,872 5,500–23,015

(X103/μL) (5,937)

Neutrophils (% ) 11 87 53.2–91

Bands (%) 11 0 0–2.6

Lymphocytes (%) 11 8 0–28

Monocytes (%) 11 3 0.2–10.8

Eosinophils (%) 11 1 0–22.6

Basophils (%) 11 0 0–0.8

Both sexes

 Range or

 Mean (SD) 10%–90%

Measure P value N or median quartiles

PCV (%)* 0.01* n/a n/a n/a

TS (mg/dL)* 0.04* n/a n/a n/a

WBC 0.46 18 11,954 4,840–23,015

(X103

/μL) (5,959)

Neutrophils (% ) 0.54 23 81 56.4–91

Bands (%) 0.93 23 0 0–2.2

Lymphocytes (%) 0.19 23 10 2–26.4

Monocytes (%) 0.58 23 3 0.4–10.6

Eosinophils (%) 0.25 23 1 0–12.4

Basophils (%) 0.3 23 0 0–0

*t-test; statistical significance.
number 639 • 8 3

DISCUSSION

Physical Condition

The 12 MW we evaluated in NKP over a 10-year 

study period included equal numbers of males and females and ranged in age from 0.6 to over 10 years. The 

sex and age structure suggest juvenile recruitment into the 

population, although three of seven observed litters had 

no successful pups reared. Body weights for the MW in 

our study were less than those for MW in a recent study 

in Brazil (May-Júnior et al., 2009). The difference in body 

weight could be related to food availability as individuals 

lost weight coincident with a decline in rodents (Emmons, 

2009; Chapter 4; Figure 4.3).

The most significant physical findings in live-captured 

MW were associated with dental disease (Figures 6.1, 

6.2). Many individuals had lesions consistent with caries, 

which could be caused by the high quantities of sugars 

and acids from fruits in the diet (Chapter 4; Bestelmeyer, 

2000; Dietz, 1984; Motta-Junior et al., 1996). Many MW 

had evidence of traumatic injuries to their teeth (slab 

fractures). This is consistent with findings from free-living 

MW in Brazil (Furtado et al., 2007) and captive MW 

(Hammond, 2012). Although we did not see the degree of 

gingival hyperplasia commonly seen in captive MW in the 

1980s and 1990s in North America (Norton, 1990), three 

MW had some evidence of gingival hyperplasia.

Other clinical findings included probable traumatic 

injuries (e.g., blind left eye and split lower lip and eyelid in 

M2 and paw lesion in F12) and possibly infectious agents 

(e.g., conjunctivitis in M8). Additionally, the IV/VI heart 

murmur in this individual (M8) may have been associated 

with heartworm infestation as he consistently tested high 

positive to D. immitis antigen. M8 also demonstrated persistent weight-bearing lameness over 3 years and a slow 

recovery after one anesthetic event. A diagnosis for the 

cause of the alopecia in the hindquarters of three youngsters, seen only in 2002–2003, was not determined but 

most likely was due to parasitic or traumatic events. 

One blood sample was removed from the data set for 

hematology and chemistry analyses as values from this 

sample were not consistent with life, and thus improper 

sample handling was suspected. Only PCV and TS differed 

Table 6.3. Chemistry profiles for free-living MW (C. brachyurus) in NKP. Here n/a, not applicable.

Male Female Both sexes

Measure N

Mean (SD) 

or median

Range or 

10%–90% 

quartiles N

Mean (SD) 

or median, 

Range or 

10%–90% 

quartiles P value N

Mean (SD) 

or median

Range or 

10%–90% 

quartiles

Glucose (mg/dL) 10 70.1 (12.8) 51–88 11 67.1 (16,7) 44–88 0.65 21 68.5 (14.7) 44–98

AST (U/L) 10 57.5 22.7–125.3 12 33.5 18.3–135.3 0.08 22 39.5 19.9–123.9

ALT(U/L) 10 85.5 25.3–350.4 12 58.5 17.9–191 0.21 22 67 24.9–214.4

ALP(U/L) 10 6 1.92–41.7 11 9 1.84 0.20 21 8 1.84–22

TP (g/dL) 10 7.26 (0.8) 5.7–8.2 12 7.66 (0.7) 6.7–8.7 0.21 22 7.5 (0.74) 5.7–8.7

Albumin (g/dL) 10 2.5 (0.5) 1.5–3.5 12 2.3 (0.4) 1.9–2.9 0.32 22 2.4 (0.5) 1.5–3.5

Globulin (g/dL) 10 4.74 (0.5) 3.9–5.5 12 5.35 (1.0) 4.2–7.0 0.96 22 5.07 (0.8) 3.9–7

BUN (mg/dL) 10 29 (14.4) 15–55 12 30.8 (10.2) 16–46 0.84 22 29.6 (12.0) 15–55

Creatinine (mg/dL) 10 1.25 (0.2) 1–1.7 11 1.2 (0.3) 0.9–1.7 0.83 21 1.2 (0.2) 0.9–1.7

Phosphorus (mg/dL) 10 4.2 3.6–6.6 11 4.3 3.3–7.6 0.92 22 4.25 3.53–6.67

Calcium (mg/dL) 10 8.51 (0.97) 6.7–10.2 11 8.54 (0.45) 7.9–9.3 0.94 22 8.5(0.7) 6.7–10.2

Sodium (mmol/L) 10 147.5 127.9–156.8 12 146 140.3–154.4 0.43 22 146.5 140.3–155

Potassium (mmol/L) 11 4.4 4.12–7.12 11 4.3 3.94–4.76 0.13 21 4.4 4.1–4.88

Chloride (mmol/L) 10 121.5 101.4–124.9 12 117 106.9–125.2 0.16 22 118 106.9–124.7

Bilirubin (mg/dL) 10 0.3 0.2–0.49 12 0.3 0.2–0.4 0.68 22 0.3 0.2–0.4

CK (U/L)* 10 352.5 136.6–1310.2 12 146.5 50.9–520.3 0.01* n/a n/a n/a

*Mann-Whitney U-test; statistical significance.
8 4 

• smithsonian contributions to zoology Table 6.4. Test results for selected parasitic and pathogenic agents of free-living MW (C. brachyurus) in NKP. CAV-II, canine adenovirus; CCV, canine coronavirus; CDV, canine distemper virus; CHV, canine herpesvirus; CPV, canine parvovirus; ND, no data. Leptospira L. Dirofilaria Toxoplasma Ehrlichia Rickettsia Borrelia ID Date ictero grippophytosa CAV-­II CCV CDV CHV CPV immitis gondii Rabies canis rickettsii burgdorferi F1 15 Feb 00 0 0 512 0 0 0 10 Positive 0 0 ND ND ND M2 20 Oct 01 0 0 512 0 12 0 10 0 0 0 ND ND ND F3 7 Oct 03 0 0 512 0 12 0 10 0 0 0 ND ND ND F3 9 Oct 04 0 0 1536 0 12 0 40 0 256 16 ND ND ND F3 2 Oct 05 0 100 1024 8 16 0 0 0 512 0 80 Positive 0 F3 4 Sep 06 0 0 256 0 0 0 0 Positive 256 0 0 64 0 F3 21 Sep 07 0 0 2048 8 0 0 0 0 ND 0 0 256 ND F3 15 Jul 08 0 0 4096 0 0 0 0 Suspicious ND 0 320 0 ND F3 19 Oct 08 0 0 768 0 0 0 0 Low 180 0 80 64 0 M5 4 Oct 04 0 0 1024 0 24 0 20 High 128 13 ND ND ND M5 28 Sep 05 0 0 512 0 0 8 0 High 128 0 80 Positive 0 M5 29 Jan 07 0 0 384 0 0 0 0 High 256 0 0 0 0 M5 26 Jul 07 200 0 4096 0 0 0 0 High ND 0 80 0 ND

M5 16 Jul 08 200 0 768 0 0 0 80 0 ND 0 0 0 ND

M6 27 Sep 05 0 0 1024 0 8 0 0 Positive 512 0 80 Positive 0

F7 21 Oct 05 0 0 1024 0 8 0 0 0 128 0 80 Positive 0

M8 25 Oct 05 0 0 512 0 0 0 0 High 128 0 80 Positive 0

M8 5 Sep 06 0 0 512 0 0 0 0 High 128 0 0 64 184

M8 25 Jul 07 0 0 1024 0 0 0 0 High ND 0 80 0 ND

M8 8 Jul 08 0 0 2048 0 0 0 0 High ND 0 0 0 ND

M8 22 Oct 08 0 0 768 0 0 0 0 High 180 0 320 64 0

M8 7 Jul 09 0 0 3072 0 0 0 0 High 180 ND 80 64 0

F9 4 Sep 06 ND ND 512 0 0 0 0 Low 128 ND 0 256 242

F9 18 Jul 07 0 0 4096 0 0 0 0 Positive ND 0 0 256 ND

F9 7 Jul 08 0 0 768 0 0 0 0 0 ND 0 80 256 ND

F9 12 Oct 08 0 0 2048 0 0 0 0 High 60 ND 80 ND 120

M10 16 Sep 06 ND ND 512 0 0 0 0 0 64 ND 0 256 25

F11 4 Feb 07 ND ND 192 0 0 0 0 High 256 ND 80 0 161

F11 18 Jul 07 0 0 1024 0 0 0 0 High ND 0 0 0 ND

F12 16 Oct 07 0 0 2048 0 0 0 0 0 ND 0 0 256 ND

Total 1/11 1/11 11/11 1/11 5/11 1/11 4/11 7/11 8/10 2/10 7/9 8/9 4/8

Animals (9%) (9%) (100%) (9%) (45%) (9%) (36%) (64%) (80%) (20%) (78%) (89%) (50%)

Total 2/27 1/27 30/30 2/30 7/30 1/30 6/30 20/30 17/20 2/25 14/25 16/24 5/15

Samples (7%) (4%) (100%) (7%) (23%) (3%) (2%) (67%) (85%) (8%) (67%) (67%) (33%)
number 639 • 8 5

between our male and female MW. Females had significantly lower PCV and higher TS values than males. One 

possible explanation for this difference was a chronic underlying infectious process in the females, which may have 

been responsible for the two low (22%) values for F3. 

Packed cell volume values in both male and female MW in 

our study were lower than both those for captive MW in 

North America, with values of 40.9 % ± 6.5 (sample size 

of 132 animals and 579 points) (International Species Information System [ISIS], 2002), and for free-ranging MW 

tested in Brazil (about 40%; May-Júnior et al., 2009).

On chemistry profile, only CK differed between males 

and females in our study, with males having a higher median value. This may be due to the high value in one male 

Table 6.5. Comparison of seroprevalence of selected parasitic and pathogenic agents of free-living MW (C. brachyurus) in the NKP 

and domestic dogs on the perimeter.

Dirofilaria T. E. R. B.

Animal immitis gondii Rabies CAV-­II CHV CDV CPV CCV Leptospira canis rickettsii burgdorferi

MW 7/11 8/10 2/10 11/11 1/11 5/11 4/11 1/11 2/11 8/9 8/9 4/8

(n = 11) (64%) (80%) (20%) (100%) (9%) (45%) (36%) (9%) (18%) (89%) (89%) (50%)

Dog* 13/40 32/40 22/39 7/40 28/40 37/40 34/40 3/40 8/40 19/22 19/22 0/22

(n = 40) (33%) (80%) (56%) (18%) (70%) (93%) (85%) (8%) (20%) (86%) (86%) (0%)

P value NS NS 0.04 <0.001 <0.001 <0.001 0.003 NS NS NS NS 0.003

*Data from Bronson et al. (2008). Here NS, not significant.

Table 6.6. Ecto- and endoparasites of free-living MW 

(C. brachyurus) in the NKP. 

Parasites Males Females

Endoparasites (eggs)

Ancylostoma caninum 1 1

Ancylostoma sp. 3 2

Ascarid-like egg (avian) 0 1

Capillaria aerophilia 3 3

Capillaria sp. 4 2

Coccidia 0 1

Diphyllobothrium sp. 2 1

Fluke-like eggs 1 0

Gnathostoma sp. 0 1

Isospora sp. 1 0

Mite and mite eggs (Family Listrophoridae) 3 2

Physaloptera sp. 2 0

Pinworm eggs 3 2

Strongyle-like egg (avian) 0 2

Trichuris sp. 3 1

Toxocara canis 0 1 adult

Ectoparasites

Amblyomma sp. 14 6

Amblyomma ovale 4 0

Amblyomma cajennense 6 2

Amblyomma pecarium 0 1

Amblyomma tigrinum 6 5

Amblyomma triste 4 3

Mallophaga (chewing lice) 1 0

Rhopalopsyllus australis spp. (flea) 0 1

Table 6.7. Results from urinary testing in free-living MW 

(C. brachyurus) in NKP. Here n/a, not available.

Identification

(no. of 

samples) Laboratory Microscope

F1 (1) n/a No crystals; Dioctophyme renale ova

F3 (1) Positive No crystals; D. renale ova

M5 (3) Positive Crystals (3/3); D. renale ova (2/3)

M6 (1) Negative Crystals; no ova

M8 (1) Positive n/a

M10 (1) Negative n/a

F11 (1) Positive Crystals; no ova
8 6 • smithsonian contributions to zoology

(M5) (1,310 U/L) and the fact that both of the highest 

CK values were from males. Interestingly, in the Brazil 

study, there was also a difference in CK between males 

and females, with females having higher values than males 

(May-Júnior et al., 2009).

A number of differences were evident between chemistry profile results of our NKP MW and those in captivity and free-living MW in Brazil. The glucose mean value 

(68.5 mg/dL) in Bolivian MW was significantly lower than 

the ISIS value (114 mg/dL ± 25) and the value for MW in 

Brazil (106.4 mg/dL ± 5.0) (ISIS, 2002; May-Júnior et al., 

2009). The glucose value in the MW of this study was low 

for a carnivore and warrants further investigation. 

Serology and Endoparasites

Maned wolves in NKP were seropositive for parasitic 

and infectious diseases of concern in carnivore conservation, and known to cause high morbidity and mortality in 

captive MW. Our original hypothesis was that domestic 

dogs living at the perimeter of the park were the likely 

route of exposure for these MW. However, we did not find 

Figure 6.3. Vertebrae of M6 showing severe bridging spondyloarthropathy. Photograph, L.H. Emmons.

TABLE 6.8. Findings from five MW (C. brachyurus) that died in the NKP during our study period of February 2000–July 2009.

Wolf Date Age Cause(findings)

F1 March–Oct. 2000 Young (8 mo) Disease epidemic?

M2 Feb. 2004 Old Date of death during flooding in study area. Changes consistent with geriatric status. 

Most severe vertebral pathology lesions of all MW we have examined. Maxillary 

osteomyelitis. Multiple tooth loss.

M6 Jan. or Feb. 2006 Old Date of death during flooding. Changes consistent with geriatric status. Many teeth 

missing with lytic bone surrounding, mandibular osteomyelitis, osteoporosis, vertebral pathology.

F9 16 April 2009 3 years Date of death during flooding. Osteomyelitis of maxillae, zygomatic arch.

F11 22 March 2008 10 years Date of death during flooding. There were no obvious bony lesions. Molars worn to 

gums. This female was small in stature.
number 639 • 8 7

support for this, because high seroprevalence was found 

in MW for a number of pathogens that were at low prevalence in domestic dogs near the park (Table 6.5; Bronson 

et al., 2008). In 40 domestic dogs around NKP, seroprevalences were high for CDV (93%), CHV (70%), CPV

(85%), T. gondii (80%), and E. canis (86%) (Bronson et 

al., 2008). In these dogs, CAV-II prevalence was low at 

18% as compared to the 100% prevalence in the MW. Because the dogs were short lived and all young, their disease 

profiles may reflect short exposure times and be highly 

variable from one year to the next. We recommend further 

studies that include longer-term sampling and molecular 

testing for virus typing to determine the relationship between the viruses within the maned wolf and domestic dog 

populations.

All MW were seropositive for CAV-II with titers waxing and waning during the 10 year study period. Canine 

adenovirus is a known cause of pup mortality in captive 

MW (Barbiers and Bush, 1995) and is suspected to have 

caused hepatitis in one individual (Hammond, 2012). Although we cannot confirm an association based on these 

data, it is interesting to note that in the years when F3 

(2008) and F11 (2007) had high adenovirus titers (4096 

and 1024, respectively), neither had successful litters. The 

mate of F3 (M8) also had a CAV-II titer change from 768 

(in 2008) to 3072 (in 2009). This litter died at about 16 

days postpartum (August 2008), based on F3’s abrupt cessation of movement behavior associated with lactation 

(Chapter 5). 

Seven of the 11 MW tested were positive for the antigen of D. immitis, the causative agent of canine heartworm. This is a potentially fatal, mosquito-borne disease 

of domestic and wild carnivores. In captivity, MW are 

often maintained on a heartworm prophylactic because of 

the devastating effect of this parasite. The role of D. immitis in morbidity and mortality of free-ranging MW is not 

known, although one of the MW (M8) had high positive 

antigen to D. immitis and an IV/VI heart murmur during 

anesthetic events. At the beginning of our study in Los 

Fierros pampa, geriatric M2 was negative for D. immitis

(2001), while F3 on the same territory, who was sampled 

yearly from 2003, was seronegative until she was four. 

At 5 years she had converted to antigen positive status, 2 

years after acquiring a highly-positive mate (M5). Of six 

animals tested less than 1 year of age, four were antigen 

negative and two were already positive, one less than 6 

months old, born of positive parents. All four adults captured for the first time after 2004 were antigen positive. 

This suggests an increase during our study to 100% adult 

prevalence. Thirty-three percent of the domestic dogs 

tested were also positive to D. immitis (Bronson et al., 

2008). It is possible that a dog-mosquito-wild carnivore 

endemic cycle operates in the NKP region of Bolivia, but 

our data also suggest that currently heartworm may circulate between the MW and mosquitoes.

Many of the MW were positive for T. gondii, as in a 

study of captive MW in Brazil (Vitaliano et al., 2004). This 

is not surprising for a species that eats positive prey (rodents 

and other small mammals; Deem et al., 2009) and is sympatric with seven native felid species (the definitive host).

Free-ranging Canidae usually harbor enteric parasites 

(Kennedy-Stoskopf, 2003), including those found in the 

MW in this study. These parasites are not often present 

in high numbers and do not cause a clinical problem in 

healthy adult free-living canids. However, in animals immunocompromised because of factors such as concurrent 

disease or physiologic stress related to habitat or population modifications, enteric parasites may result in disease. 

The lungworm Capillaria aerophila, detected in the feces 

of six MW in this study, can cause clinical signs associated 

with bronchitis and pneumonia, but these animals had no 

overt respiratory signs. Eggs of pinworms, mites, and mite 

eggs from the rodent-specific family Listrophoridae were 

detected in three MW, probably ingested with their rodent 

prey (Chapter 4). Likewise, ascarid-like and strongyle-like 

eggs from bird parasites were found in three MW, indicating ingestion of avian prey. A tapeworm, likely Spirometra spp., also associated with rodents, was recovered from 

maned wolf feces in the savanna (Mike Kinsella, pers. 

comm.). One adult worm, Toxocara canis, was identified in a female maned wolf (F9) approximately 6 months 

prior to her death around 3.5 years of age. On postmortem evaluation, there was evidence of severe osteomyelitis 

of the skull, believed to be from a tooth infection (Figure 

6.1). Thus F9 possibly succumbed to sepsis, confounded 

by heartworm and gastrointestinal parasite infestation.

Ectoparasites

Of the five definitively identified tick species collected 

during this study, only Amblyomma cajennense, which 

we earlier reported from the maned wolf (Robbins and 

Deem, 2002), is known to be of veterinary importance. 

This tick has been found infected with Encephalitozoonlike microsporidia (Barbosa Ribeiro and Guimarães, 

1998) and, together with its congeners, may be a vector 

of filarial worms, such as Yatesia hydrochaerus, which is 

specific to capybaras (Yates and Lowrie, 1984). Amblyomma cajennense also causes paralysis in bovine, ovine, 

and caprine hosts in Brazil (Serra-Freire, 1983). In the 
8 8 • smithsonian contributions to zoology

medical literature, A. cajennense is recognized as the principal vector of so-called Rocky Mountain spotted fever in 

the Neotropics, and, given its vast range and propensity 

for attacking humans, is a known or suspected vector of 

arboviruses, Chagas disease, and even leprosy (Guglielmone et al., 2003). We note that eight of nine tested MW 

were positive for Rickettsia rickettsii (Rocky Mountain 

spotted fever; but the antisera may cross-react with a local 

variant).

Amblyomma spp. ticks were previously reported from 

free-living MW (Dietz, 1984); but the first documented 

A. ovale was from our study population (Robbins and 

Deem, 2002). In Brazil, A. ovale has been implicated as 

a vector of Rickettsia parkeri, strain Atlantic rainforest, a 

novel spotted fever agent pathogenic to humans (Sabatini 

et al., 2010). Amblyomma pecarium is an uncommonly 

collected parasite of Artiodactyla known from Mexico, 

Panama, and Bolivia (Fairchild et al., 1966; Robbins et 

al., 1998). It might occasionally transfer to carnivores that 

prey on these herbivores or their carrion. Amblyomma 

tigrinum adults are highly specific to wild and domestic 

carnivores, so its occurrence on a maned wolf is expected. 

Adult stage Amblyomma triste likewise parasitize carnivores. Our records (4♂, 3♀; Table 6.6) from NKP are the 

first for Bolivia.

Urinary Health

Morbidity from the genetic disease cystinuria, and resulting cystine calculi with urinary blockage, has been a 

common problem estimated to affect up to 80% of both 

wild and captive MW and led to nutritional modifications 

to minimize the occurrence of these calculi among captive 

MW in the United States (Bovee et al., 1981; Fernandes 

and Marcolino, 2007; Norton, 1990). Similarly, 71% of 

MW we tested (n = 7) were cystinuric, but we found no 

evidence of cystine calculi or urinary blockage. This agrees 

with another study in a free-living maned wolf population 

(Dietz, 1984). An ancient mutation and founder effect 

has been proposed (Bovee et al., 1981; Dietz, 1984; Fernandes and Marcolino, 2007; Norton, 1990), and mutations in the renal basic amino acid transporter have been 

identified in Newfoundland and Labrador retriever dogs 

with type I cystinuria and an autosomal recessive trait. 

However, there are many other breeds with type I and 

non–type I cystinuria (only males are cystinuric) where 

the molecular defect has not yet been defined. Initial studies of MW did not identify a mutation in the renal basic 

amino acid transporter (Kehler et al., 2002). With the recent completion of the full canine and low-density wolf 

genome sequences, progress can be made in MW. Samples 

have been preserved for future DNA studies.

Our finding of D. renale ova in three MW was not surprising, as this parasite is a common pathogen of recently 

captive MW (Kumar et al., 1972). Dioctophyme renale is 

often associated with a hypoplastic right kidney in infected 

MW and could contribute to mortality, especially with 

concurrent disease (Kumar et al., 1972; Norton, 1990).

Mortality

Forty-two percent (5/12) of the MW in our study died 

before September 2009, with deaths throughout the study 

years. This mortality rate is similar to that recorded in 

Emas National Park, where the survival rate was estimated 

at 64% per year for all age classes (Sollmann et al., 2009). 

All deaths at Los Fierros occurred between February and 

April, the months of flooding when foraging and movement in the study area are limited and could contribute 

to poor nutrition, debilitation, and death. The fates of the 

two individuals that vanished after the October 2009 fire 

are uncertain, as they could have escaped to die elsewhere. 

One was about 8 years old (F3) and the other 7 years old 

(M8), the latter in good health but the former geriatric, 

with severe dental problems. One yearling female survived 

the fire and was alive in 2011 (Chapter 5, Postscript).

Three of the five (60%) MW that died before September 2009 were estimated at 8 to >10 years old and considered geriatric at the time of death. Two of these three 

(67%) had severe spondyloarthropathy. This pathologic 

finding was previously considered a disease of captivity, 

with an incidence of about 80% of geriatric captive MW 

(Elizabeth Hammond, pers. comm.; Rothschild et al., 

2001). The two affected MW in our study (M2 and M6) 

had the most severe skeletal lesions among any of three 

wild-taken and seven zoo skeletons (NZP) evaluated at the 

National Museum of Natural History (evaluated by LHE). 

The one geriatric maned wolf (F11) with no vertebral lesions was unusually small (22 kg). We conjecture that the 

body structure of MW (e.g., long legs and short back) and 

hunting style, of pouncing on small prey, make MW prone 

to vertebral pathologies. Further investigation is needed 

into this pathologic condition of captive and free-living 

MW. The two animals with severe vertebral lesions had 

likely lived with the condition for years.

Three of the MW that died had indication of severe 

osteomyelitis of the maxillae (M2, F9) or mandible (M6; 

Figure 6.2B) that was most likely associated with a tooth 

root abscess. M6 was geriatric at the time of death and had 

evidence that osteomyelitis had spread into the postcranial 
number 639 • 8 9

skeleton. However, F9 was only 3 years old but had evidence of spread of infection into the adjoining zygomatic 

arch, above and below the eye (Figure 6.1). This female 

died when the study area was experiencing unusually prolonged and deep flooding, and we hypothesize that the 

oral infection and associated pain decreased appetite while 

flood waters made finding food difficult. Prior to death 

she traveled from her own flooded territory into the drier 

adjacent territory, where she may have also experienced 

social conflict and stress. These two factors, in addition to 

her positive status for D. renale and D. immitis, may have 

led to poor nutrition and possible sepsis as the proximate 

and definitive cause of death. The other young maned wolf 

that died (F1) was believed to have succumbed to an infectious agent, as the fox (Cerdocyon thous) population in 

the same section of NKP was also decimated at this time. 

Necropsy results of 47 MW housed at the Smithsonian Conservation Biology Institute, Front Royal, Virginia, 

from 1975 to 2003, list the primary cause of death as follows: 17 perinatal, two urolithiosis (cystine calculi), three 

infectious agents (e.g., CDV, CPV, and Escherichia coli), 

one trauma, three digestive, one cardiomyopathy, and 19 

euthanasias. The reasons stated for euthanasia included 

four neoplasia, two infectious (one pyometra and one rabies virus), one trauma, four kidney related (two of these 

were urolithiasis), two spondylosis, one postsurgical, one 

cull, one arthritis, two old age, and one digestive problems. Thirteen of these 19 (68%) euthanized MW were 

>10 years old at time of euthanasia, and there were 11 

males and 8 females.

Conclusions

We found a surprising number of significant clinical 

and pathologic findings in this small population of freeliving MW in Bolivia. The NKP maned wolf population 

was previously estimated at 120 pairs (Rumiz and Sainz, 

2002), but we now believe it is closer to 20–30 pairs (see 

Chapter 3). On the basis of our findings for the 12 MW 

in our study, the health of the Los Fierros population may 

be rated as only moderate. The lower body weights, PCV, 

and glucose values compared to other maned wolf populations, as well as the many dental abnormalities, may indicate a lower plane of nutrition in this population. Recent 

evidence of rodent population declines indicates that the 

prey base for this population of MW declined over 94% 

in biomass during the study (Chapter 4; Emmons, 2009).

We had not anticipated such a high number of dental 

and bony lesions. The prevalence of dental disease was 

most likely associated with the dietary intake of acidic, 

sweet fruits such as Alibertia edulis and Solanum gomphodes (Chapter 4), and tooth fractures related to chewing fruits with hard stones and perhaps armadillos. The 

high prevalence of vertebral pathologies in the older MW 

that died was similar to that found in captive populations 

and may suggest that this pathology is more a function of 

body structure and behavior than a disease of captivity as 

previously thought (Rothschild et al., 2001).

Although there is no definitive diagnosis for the cause 

of death in the one maned wolf (F1) that died at less than 

1.5 years of age; a concurrent large decline in crab-eating 

foxes implicates an infectious disease epidemic. We therefore recommend continued domestic dog health monitoring, domestic animal vaccination, and enforcement of the 

prohibition of all domestic animals within the park, especially of carnivores.

Our ability to conserve the growing number of endangered species will necessitate an understanding of the 

health of both captive and free-living populations. We anticipate that studies similar to this one will provide data 

necessary for the long-term conservation of animals in 

their natural habitats and proper captive care and propagation of endangered species in captivity.

Acknowledgments

We thank Dr. Michael Kinsella for tapeworm identification, Dr. Ira Luskin for interpretation of dental pathologies, Dr. Edward Dubovi for laboratory assistance, and 

Melissa Rodden for kindly providing data from the captive breeding program at the Smithsonian Conservation 

Biology Institute. Thanks also to Dr. Michael W. Hastriter 

and Dr. Robert M. Timm for lice identification.

7 Conservation

Matthew J. Muir and Louise H. Emmons

ABSTRACT. Maned wolves (MW) (Chrysocyon brachyurus) are classified as “Near 

Threatened” on the International Union for Conservation of Nature (IUCN) Red List. 

Twenty-two subpopulations have been identified in Brazil, Argentina, Paraguay, Bolivia, 

and Peru, with an estimated 80%–90% of all MW occurring in Brazil. Only 5%–10% 

of maned wolf range is globally protected, but to understand how unprotected wolves 

are faring, better population surveys are needed on land outside of national parks and 

reserves. Although agricultural expansion is responsible for a contraction in the species’ 

southern range, field studies consistently show that MW can survive in agricultural land 

with sufficient refugia and prey. Publicized threats include disease transmission by domestic dogs, road mortality, and hunting for folk medicine and in retaliation for livestock 

deaths. To these, we add fire and fire suppression, clear-cut pasture for livestock, and the 

emerging threat of climate change. Despite these ongoing threats, MW do not require 

intensive management to remain in a human-dominated landscape, and this resilience 

is the best hope for their successful conservation. Nonetheless, habitat management of 

grasslands could increase the population density of MW in protected areas.

Introduction

Through our research, we wanted to learn enough about maned wolves 

(MW) (Chrysocyon brachyurus) to suggest how their needs might be better 

met by conservation efforts in Bolivia. In the preceding chapters, we have presented field data and results on many aspects of the ecology of the MW on our 

study area: some findings are well known and many are new. These descriptive results pertain to individual animals in a specific place and time, and they 

can be generalized only by comparison with the results from other times and 

places. Compared to ecology, conservation is a different kind of subject, as 

we can bring to it no specific field results from regional management efforts. 

Rather, we can apply what we have observed to predict the status of future 

maned wolf populations. To include the variability and flexibility found across 

Matthew J. Muir, Division of International Conservation, U.S. Fish and Wildlife Service, 4401 

N. Fairfax Drive, ARLSQ 100c, Arlington, Virginia 22203-1622, USA; Louise H. Emmons, 

Department of Vertebrate Zoology, National Museum of Natural History, P.O. Box 37012, MRC 

108, Smithsonian Institution, Washington, D.C. 

20013-7012, USA. Correspondence: matt_muir@

fws.gov. Manuscript received 25 August 2010; accepted 26 August 2011.
9 2 • smithsonian contributions to zoology

the species’ range, we start with a range-wide overview 

of issues that can determine if a population will thrive or 

dwindle.

Within the Canidae, MW are exceptional not only 

in their ecology and evolutionary history (Chapter 1) but 

also in their conservation status. They are listed as “Near 

Threatened” by the International Union for Conservation 

of Nature (IUCN) (a threat category below “Vulnerable”; 

IUCN, 2009), but they have life history traits that predict 

high extinction risk for other carnivores, such as low reproductive capacity and occurrence at low density (Purvis 

et al., 2000; Chapter 4). Canids of similar size (>15 kg) in 

monotypic genera are classified as “Endangered” (African 

wild dog, Lycaon pictus; dhole, Cuon alpinus; IUCN Red 

List). Because MW do not kill ungulate livestock or wild 

species valued by human hunters, they have not been subjected to the campaigns of deliberate extermination that 

have brought other carnivores to extinction (Falkland Island wolf) or to its brink. Of no threat to people, they 

have stayed below the radar of both publicity and of conservation efforts. For example, in a review of maned wolf 

global status, Rodden et al. (2004) cited no conservation 

strategies for MW. This deficiency was remedied by a recent maned wolf conservation workshop in Brazil (Paula 

et al., 2008), which outlined status and threats in all range 

countries but primarily highlighted the vast information gaps to be filled. Relatively few conservation-related 

papers have been published on MW (15% of citations) 

compared to other large canids like the African wild dog 

(38%), dhole (20%), and Ethiopian wolf (46%, Canis simensis; Web of Science, keyword search, i.e., Chrysocyon 

brachyurus: subject category, Biodiversity and Conservation, June 2010).

This chapter is thus an assessment of what is known 

about maned wolf conservation and management, including where populations occur, what threatens these 

populations, and what conservation actions might mitigate those threats. Our focus is range-wide, but we will 

end with specific management recommendations for 

our study area in Noel Kempff Mercado National Park 

(NKP), drawing on findings from our 10 year field study 

(Chapters 2–6).

What Is Known and What More

Needs To Be Known?

New literature on MW has grown exponentially since 

the 1960s, increasing by 50%–75% per decade (Figure 

7.1). Starting with Reginald Pocock’s (1927) notes on 

MW held at the London Zoo, we estimate that by 2010, 

235 citations existed in English, German, Czech, Spanish, 

and Portuguese. 

Information on maned wolf biology has accumulated 

unevenly. Excluding general reviews (N = 29), over half 

of all maned wolf citations originate from observations 

of captive individuals (N = 109). In the 1960s and 1970s, 

studies on captive MW outnumbered field observations 

by a factor of 5 (Figure 7.1). Since 1997, publications on 

free-ranging MW have steadily become more prevalent 

until they have equaled or exceeded literature on ex situ

MW (excepting 2001). Of the 80 citations on free-ranging 

MW, 35% focus on diet (N = 28); 23% concern health 

and disease (N =18); 9% report ranging data (N = 7; home 

range, telemetry); and 6% deal with genetic analysis (N = 

5). Literature highlighting MW as a conservation concern 

appeared as early as the 1960s (Carvahlo, 1968) and recent overviews include Rodden et al. (2004), Paula et al. 

(2008), and Pautasso (2009).

Planning for conservation action requires taking stock 

of what is known and what more needs to be known 

(Woodroffe et al., 2005). On the basis of current work, 

MW have the following requirements:

1. Diet: MW subsist primarily on fruit and small 

mammals (Chapter 4; Dietz, 1985) and consume 

most food items according to their availability 

(Rodrigues et al., 2007). We calculated the average 

daily energy needs of MW to be 1,580 kcal (Chapter 4). On the basis of the 50-50 prey-fruit diet generally reported for MW, this daily requirement can 

be met by two or three large rodents such as cavies 

(>250 g) and six to eight large, soft-pulped fruits 

such as Solanum spp. (Table 4.6, Chapter 4). 

2. Space and habitat: maned wolf home ranges are 

from 25 to over 80 km2

 (Rodden et al., 2004; Jácomo et al., 2009; Chapter 3). Breeding pairs have 

little or no range overlap with other pairs (Dietz, 

1985; Chapter 3) but can be associated with 

young adult females (Melo et al., 2007; Chapter 

5). MW occur primarily in grassland and savanna 

and avoid areas where canopy cover exceeds 30% 

(Vynne, 2010). They can also be found in scrub 

forests, flooded habitats, livestock rangelands 

(Rodden et al., 2004), and cropland with refugia 

and prey (Vynne, 2010). 

3. Population size and structure: Simulated populations of at least 50 MW were modeled to persist in 

the absence of harvest or habitat loss, while populations of over 250 MW were thought to be relatively robust to these threats (Paula et al., 2008). 
number 639 • 9 3

The persistence of MW populations is most sensitive to female mortality (Paula et al., 2008). No 

survivorship cost of inbreeding was found in captivity (Ralls et al., 1988).

4. Climate: Most areas in which MW occur receive 

1,000–2,000 mm annual rainfall and the species’ 

lower limit is likely between 600 and 1,000 mm 

(Quierolo et al., 2011). MW cease sustained activity 

when temperatures reach 30°C, probably to prevent 

water loss from panting, and in NKP they seemed to 

decrease travel below 20°C (Chapter 2).

Behavior (Dietz, 1984; Kleiman, 1972) and health 

(Bovee et al., 1981; Lamina and Brack, 1966) are relatively long- and well-studied aspects of maned wolf biology in captivity, but they are little known in situ (Chapters 

5, 6). Information is scarce and scattered on the size and 

shape of populations, the scope and impact of threats, and 

the effectiveness of conservation strategies. Almost nothing is reported but anecdotal evidence on key life history 

parameters, such as litter size at birth, survivorship to 

weaning, or lifetime reproductive success of females.

Population and Geographic Distribution

The most definitive maned wolf distribution map is 

based on a collaborative effort that compiled all known 

point records of maned wolf occurrence (Queirolo et al., 

2011). A 2005 population viability analysis (PVA) workshop held in Brazil identified maned wolf subpopulations 

in Brazil, Argentina, and Paraguay (Paula et al., 2008) 

with Bolivia and Peru evaluated later (R. C. Paula and 

FIGURE 7.1. Publications on maned wolves (MW) by decade from 1927 to 2009. Secondary axis and point data 

show the ratio of publications on captive to field studies (Web of Science [keyword search = Chrysocyon] and personal libraries of L. H. Emmons and M. Rodden).
9 4 • smithsonian contributions to zoology

L. H. Emmons, unpublished). We here combine the two 

maps and hypothesize where discrete subpopulations still 

occur within the recent maned wolf distribution (Figure 

7.2A, B). We emphasize that Figure 7.2B is hypothetical 

and that the existence and margins of subpopulations 

represented by polygons need both refining by local experts, and regular revision of maps, to track the collective understanding of where MW occur. Surveys of MW 

presence have included spoor identification, camera traps, 

informant interviews, and detection dogs (Vynne et al., 

2011; Figure 7.3). Documenting absence is always problematic in conservation, and the maned wolf traits that increase detection probability (large-bodied, conspicuously 

colored, occasionally vocal) are countered by cryptic behavior (nocturnal, shy) and common names shared by 

other carnivore species (Queirolo et al., 2011).

Twenty-two subpopulations were identified in the 

2005 workshop (Appendix A) and 1,126 occurrence records were collected by Queirolo et al. (2011). Approximately half of occurrence points fell within identified 

subpopulations (N = 586). Points falling outside of subpopulation polygons may represent transient individuals, 

an unidentified subpopulation or a more accurate margin 

of a nearby subpopulation, historical records from extirpated areas, or erroneous records of maned wolf presence. 

For example, subpopulations were not identified in the 

FIGURE 7.2. (A) Maned wolf distribution map and occurrence records. Point records from Queirolo et al. (2010) combined with 22 identified 

populations from Paula et al. (2008): red shading. Source for habitat coverage: WWF Terrestrial Ecoregions.
number 639 • 9 5

Brazilian state of Sao Paulo or southern Brazil because 

workshop participants considered those populations “isolated and very small” (Paula et al., 2008). Thus the interstitial areas of Figure 7.2B may still contain resident MW. 

For example, there were no data available for a large area 

of potential habitat in the Beni savannas of Bolivia (Quierolo et al., 2011). See Appendix A for a description of 

each subpopulation and population estimate from Paula 

et al. (2008). 

The available data suggest that more MW are found 

outside of formal conservation areas than within them. 

Only 5%–10% of occurrence records from Queirolo et 

al. (2011) are within a protected area (N = 54–117; range: 

IUCN Protected Area Categories Ia-IV to Ia-­VI). Likewise, 

protected areas comprise only 7%–11% of the area included within identified subpopulations (Range: IUCN 

Ia-­V to Ia-­VI). Five subpopulations intersect no protected 

areas. If indigenous reserves are included, an additional 

2% of both maned wolf records (N = 18) and area within 

subpopulations (34,000 km2

) are added.

There is no credible estimate of the global maned wolf 

population. Approximately 23,000 MW were counted 

FIGURE 7.2. (B) Maned wolf distribution map and protected areas. Protected areas within populations from Paula et al. (2008): dark blue represents wetlands; red, subpopulations; paler shading, protected areas. Source for protected area coverage: World Database on Protected Areas 

(http://www.wdpa.org/ on 26 Jan 10). Source for habitat coverage: WWF Terrestrial Ecoregions.
9 6 • smithsonian contributions to zoology

in the summed efforts of the 2005 PVA workshop, with 

over 90% of them in Brazil (Paula et al., 2008: Brazil, N

= 21,746; Argentina, N = 660; Paraguay, N = 830; Paula 

and L. H. Emmons, unpublished: Bolivia, N = 380). This 

estimate combined the best guesses of four national delegations and used extrapolations from density studies 

and informed speculation by local experts. For example, 

workshop participants from Brazil used a range of densities (2–10 individuals/100 km2

) to calculate a low and 

high estimate across the subpopulations there (Paula et 

al., 2008). Density estimates at individual sites, however, 

reach a maximum of 5.2 individuals/100 km2 (Table 7.1). 

The range of published densities in Brazil (~1–5/100 km2

) 

suggests that the workshop estimates were overly optimistic. Using this published range instead, a revised population estimate for Brazilian MW is 11,820. Conversely, we 

now believe that the population in Bolivia was underestimated and that least 1,000 individuals may occur there. 

Combining these two revisions with the country estimates 

from Paula et al. (2008), we propose that approximately 

14,700 MW occur in the wild. 

Rodden et al. (2004) highlight the need for better 

population surveys. We suggest the following survey priorities: (1) censuses that distinguish breeding populations 

FIGURE 7.3. Methods to document maned wolf presence (top left, clockwise): (A) camera trap, unmarked individual with ear damage 

(NKP, photograph by M. Swarner), (B) scat-detection dog pointing at an old scat below right hind leg (Emas NP area; photograph by 

C. Vynne), (C) tracks and small (immature) Solanum gomphodes fruit with teeth marks, perhaps rejected as unripe (NKP, Bolivia; photograph by M. Swarner), (D) Scat with seeds of Duguetia furfuracea, Solanum gomphodes, Emmotum nitens, and other fruit, but no animal 

prey (NKP, photograph by L. Emmons).
number 639 • 9 7

from transient individuals; (2) a refinement of the distribution maps by re-evaluating the subpopulations identified 

in the 2005 workshop with the data from Queirolo et al. 

(2011) and other newly reported maned wolf occurrences; 

and (3) more population surveys on agricultural land under 

different crop systems to understand the impact of human 

encroachment on maned wolf habitat suitability (Vynne, 

2010).

Threats

By prioritizing identified threats, conservation action 

can be focused on the most relevant human actors. The 

IUCN Species Account for MW (Rodden et al., 2008) 

identifies four threats: habitat conversion to cropland, 

road mortality, domestic dogs, and hunting for folkloric 

medicine. Participants in the 2005 workshop identified 

habitat loss (including conversion to cropland and pasture) and harvest (including hunting, road kill, and shooting of “problem animals”) as the two greatest threats to 

maned wolf populations (Paula et al., 2008). In Argentina, 

conflict with humans is also considered a serious threat 

(Soler et al., 2005).

In the following section, we consider these threats in 

Bolivia and propose two additional threats (fire and climate change). We focus on population-level threats but 

note that wherever MW live in small isolated populations, 

any combination of threats that increase mortality may 

have population consequences.

Conversion to Cropland

Savannas in maned wolf range are threatened by 

industrial-scale monocultures of soya, sunflower, sugar 

cane, maize, sorghum, rice, and others (Ratter et al., 1997). 

More than half of the Brazilian Cerrado has been cleared 

for agriculture (Klink and Machado, 2005), and it is being 

lost at a higher rate than is the Amazon forest (1.1% per 

year, Machado in Butler, 2009). As the most significant 

threat to MW (Rodden et al., 2008), agricultural expansion is thought to destroy habitat needed for reproduction and dispersal, as well as to increase the risk of other 

anthropogenic pressures (hunting for folkloric medicine, 

road mortality, disease transmission by domestic animals). 

Habitat loss has been greatest in southern Brazil, Argentina, and Uruguay (where MW may be represented only 

by transient individuals), and populations in those regions 

are restricted to remnant pockets of habitat “hemmed in 

on all sides by fields of soy, corn, sunflower, and wheat” 

(Queirolo et al., 2011).

Several studies suggest cautious optimism for maned 

wolf survival in farmland (Courtenay, 1994; Dietz, 1984; 

Lyra-Jorge et al., 2008; Santos et al., 2003; Vynne, 2010). 

Outside Emas NP, Brazil, Vynne (2010) found that MW 

can even survive in mechanized cropland where there is 

adequate land management, including at least 20% set 

aside on each farm as a wildlife refuge, and low-growing 

crops (soya) with sufficient rodent prey. It was not shown, 

however, whether the croplands were merely a sink for 

animals emigrating from the park. Quierolo et al. (2010) 

reported some recent expansion of the maned wolf geographic range into grazing land created by deforestation 

of humid Atlantic Forest (Mata Atlantica) of Brazil. In 

Bolivia, however, there is no evidence of MW expanding 

into or surviving in agroindustrial croplands. Sugar cane 

for biofuel production is now rapidly expanding in Brazil (Rudorff et al., 2010), ballooning from 2.57 million 

ha in 2003 to 4.45 million ha in 2008, and it now accounts for almost a quarter of all agricultural crops (Klink 

and Machado, 2005; Rudorff et al., 2010). Because of 

its height and lack of foraging opportunities, sugar cane 

is likely inhospitable to MW, and its expansion rapidly 

TABLE 7.1. Densities reported for maned wolves (MW).

Density estimates

(individuals /100 km2) Habitat and country Estimate method Citation

3.6 ± 0.8 Cerrado farm, Brazil Camera traps Trolle et al., 2007

1.6 ± 0.8 Protected pantanal, Brazil Camera traps Trolle et al., 2007

5.2 Protected grassland, Brazil Mark-recapture trapped MW Silveira et al., 2009

4 Protected grassland, Bolivia Longitudinal study of marked Emmons et al., this volume, Chapter 3

MW + camera traps
9 8 • smithsonian contributions to zoology

threatens to reverse any range gains for MW from deforestation (Vynne, 2010).

In Bolivia, monoculture crops overlap current maned 

wolf range only to a moderate extent and populations 

are primarily separated by forest. The greatest threat to 

connectivity is the extensively cleared land in Brazil that 

separates Bolivian MW from maned wolf populations 

in the Brazilian state of Mato Grosso. For example, the 

border between Bolivia and Brazil (and the edge of the 

protected area where our maned wolf fieldwork was conducted) is clearly defined in satellite imagery by intensive 

agriculture on the Brazilian side (Figure 7.4). The threat 

posed by modern crop production is likely to increase 

dramatically in Bolivia, especially if the proposed dams 

and inland waterway (Hidrovía) on the Rios MadeiraGuaporé-Paraguay lead to rapid agricultural growth and 

development in the adjacent Beni grasslands and Bolivian 

Pantanal. Recent expansion of industrial rice into Beni savannas is already directly replacing maned wolf historical 

habitat.

Domestic Dogs

Domestic dogs can threaten maned wolf populations 

by food competition, aggression, and disease transmission (Rodden et al., 2008). In Bolivia, where feral domestic dogs are rare in maned wolf habitat, we consider 

only disease to be a plausible population threat. Depending on the pathogen and its local dynamics, diseases can 

be actively maintained by the domestic dog population 

(such as distemper) or persist as a legacy threat (such as 

canine heartworm) where the disease has been historically introduced by domestic dogs but can persist in their 

absence via reservoir species. In our study area in NKP, 

MW have been exposed to many disease agents spread by 

domestic dogs (Chapter 6; Table 7.2; Deem and Emmons, 

2005; Fiorello et al., 2004), via either hunting dogs entering maned wolf habitat or perhaps by crab-eating zorros 

(Cerdocyon thous) moving between human and natural 

communities (Bronson et al., 2008). Pathogens now endemic to MW (canine adenovirus, giant kidney worm: 

Dioctophyme renale) may not always be shared by domestic dogs and are not normally considered a population 

threat.

Road Traffic

Maned wolf mortality due to vehicle traffic (i.e., road 

kill) is, unsurprisingly, greatest in areas where high-speed 

roads intersect or border maned wolf habitat. Fischer et 

al. (2003) note that MW are killed “more than rarely” 

on both Pantanal and Cerrado roads. While road traffic is 

considered a significant threat to maned wolf populations 

in Brazil and Argentina, the density and quality of Bolivian roads is lower. Thus, while individual MW do die on 

Bolivian roads, we suggest that the severity of this threat 

is relatively minor. As an additional mitigating factor, protected areas in Bolivia are not subdivided by high-speed 

roadways as they are some in other countries.

Hunting for Folkloric Medicine

MW are killed for numerous uses in traditional folk 

medicine: bronchitis, epilepsy, dizziness, kidney disease, 

back pain, love potions, protection against snakebite, and 

to bring good luck (Alves et al., 2010; L. H. Emmons, 

unpublished interviews). Because trade in maned wolf 

body parts is not on a large commercial scale (Rodden et 

FIGURE 7.4. Satellite image of NKP, indicating much more intensive deforestation for agroindustry (palest polygons) in Brazil compared with Bolivia. Natural grasslands are darker pale areas, while 

the darkest zones are forest. Our Los Fierros (LF) study area, blackened by fire, is in the center of the image, and the Huanchaca Meseta 

is the curved structure to its NE–SE. The border of Brazil follows 

the edge of the agroindustrial deforestation, and new colonization in 

Bolivia can be seen approaching NKP on the lower left edge. Image 

by NASA-Terra FAS-Bolivia, October 2009.
number 639 • 9 9

al., 2008), medicinal harvest is not judged to be a major 

conservation concern for MW or indeed, any canid species (Alves et al., 2010). Our impression, however, is that 

hunting MW for folk medicine is greater in Bolivia than 

elsewhere and can be a substantial source of mortality in 

areas where maned wolf parts can bring high prices due 

to strong local beliefs in sorcery and folklore (M. Herrera, pers. comm.; Figure 7.5). For example, in San Matias, Bolivia, the meat of MW was purported to improve 

a person’s ability to withstand chemotherapy for cancer, 

the pelt and bones to cure rheumatism and prevent osteoporosis, and pieces of skin to block malicious attempts of 

witchcraft (V. Sandoval, pers. comm.).

Retaliatory Killing for Livestock Damage

Killing of “problem animals” is an important source 

of maned wolf mortality in some areas (Paula et al., 2008). 

Over about a dozen years, Dietz (1984) recorded 21 maned 

wolf deaths caused by people; 16 of which occurred while 

MW were preying on chickens. Methods varied: “seven 

were shot, five were run down and killed by dogs, [and] 

four were trapped” (Dietz, 1984:27). Because maned wolf 

predation on poultry can be prevented with nighttime 

enclosures and predation does not extend to high-value 

livestock (cattle), human–MW conflict does not seem to 

be a severe threat to the species. MW are perceived to kill 

hoofed stock in some areas, but the lack of evidence in 

studies of diet suggests that hoofed stock predation is extremely rare or folkloric legend. In Bolivia, some cattlemen believe that MW kill calves to drink their blood, and 

in the Beni Department, a few ranch owners pay a bounty 

TABLE 7.2. Infectious and parasitic agents of domestic dogs to which MW show serologic exposure or that have been identified in the 

species.

Pathogen Lethality Transmission

Canine adenovirus Can cause mortality in neonatal MW Direct contact with body fluids or urine

Canine coronavirus Not lethal; can cause mortality in conjunction Oral-fecal contact with feces

with other pathogens

Canine distemper virus Can cause mortality in MW; linked to serious Respiratory and contact with body fluids

population declines in other canid species

Canine parvovirus Can cause mortality in MW Oral-fecal; virus can survive for months in environment

Rabies virus Fatal to MW Bite of rabid animal

Sarcoptes scabiei (causative Susceptibility varies Direct and indirect contact

agent of mange)

Dirofilaria immitis (causative Can cause mortality in MW Mosquito-borne

agent of heartworm disease)

FIGURE 7.5. One of two maned wolf skins found on an estancia in 

Bolivia. The wolf was killed for medicinal use of body parts. (Photograph by Vanessa Sandoval)
100 • smithsonian contributions to zoology

for killing MW as well as for jaguar and puma (M. Herrera, pers. comm.).

Fire and Fire Suppression

Fire and fire suppression are human activities that 

threaten maned wolf habitat (Klink and Machado, 2005). 

Outside of protected areas, farmers set annual fires for 

weed control and pasture maintenance that can inhibit 

the fruiting of woody plants for several years, depriving 

MW of fruit resources (Chapter 4; Sanaiotti and Magnusson, 1995). Inside protected areas, managers prevent and 

suppress fires, leading to the total loss of the grassland 

habitat through overgrowth by woody shrubs and trees 

that shade out grasses. These grass-free shrublands are 

depauperate of the rodents on which MW feed (Chapter 

4; Emmons, unpublished) and fire suppression can lead 

to a vast accumulation of dry plant matter. The resulting 

buildup can fuel infrequent but exceptionally destructive 

fires (Silveira et al., 1999). In Emas NP, where protected 

area management resisted the controlled use of fire, catastrophic fires killed hundreds of large mammals and “a 

maned wolf Chrysocyon brachyurus was observed alight, 

running along a fire line towards a dead end” (p. 111, 

Silveira et al., 1999). A territorial maned wolf pair on our 

study area disappeared without trace after a fire burned 

the entire area in October 2009 (Chapter 6, Figure 1.10). 

We do not know when or how the pair died, but it was the 

only year that more than one collared adult resident was 

presumed to have died.

Although the balance between too much and too little 

fire is a site-specific function of the flora, climate, and soil, 

we believe that the appropriate fire frequency for maned 

wolf habitat is about every 3 to 4 years. Prior to European 

colonization, burn intervals ranged from three to 10 years 

and savanna fruit productivity requires at least three years 

to recover to pre-burn levels (Hoffman, 1998; Sanaiotti 

and Magnusson, 1995). Silveira et al. (1999) suggest that 

after three years, the accumulated fuel load creates a high 

risk of a catastrophic fire. Because recovery times vary between savanna shrub species, a spatial and temporal heterogeneity is required to maintain maximal populations of 

woody fruiting plants (such as Solanum spp., Anonnaceae 

spp., Alibertia edulis, and Miconia albicans). Our data 

also hint that fruit production may start to decrease the 

fourth year after fires (Table 4.5), which we attribute to 

increased loads of insect parasites on fruits, coupled with 

the waning of effects of ash fertilizers.

At our study site in NKP, we suspect that fire contributed directly to short-term cavy and armadillo declines 

in the NKP savanna at Los Fierros (Chapter 4), and indirectly, to long-term declines. Emmons hypothesized 

that dense atmospheric smoke from large, regional fires 

raises nocturnal temperatures and prevents dew formation, decreasing an important water source for savanna 

rodents and microbiota during months of drought (Emmons, 2009). Whether fire-related or perhaps related to 

some broader climatic shift, the volatility of the maned 

wolf food base has emerged from our studies in NKP as 

a potentially important threat to maned wolf fitness, but 

one perhaps amenable to management.

Climate Change

MW do not survive in hot and dry climates. The geographic range of MW skirts around Chaco habitat in western Paraguay and Bolivia, where annual precipitation is 

550–1000 mm annually and temperatures can reach 40°C 

in the hottest month of January. Pautasso (2009) estimated 

that more than 10% of MW die in periods of extreme 

drought in Santa Fe, Argentina (2008, 615 mm), including 

deaths due to thirst-driven MW killed at drinking points 

for cattle and poisoned by drinking from the only surface 

water available, toxic canals.

In the next 70 years, temperatures are projected to 

increase across the maned wolf geographic range (Table 

7.3; Intergovernmental Panel on Climate Change [IPCC], 

2007). Comparing seven models, Boulanger et al. (2006) 

estimate that the region will warm by as much as 4°C 

by 2075–2100. In Chapter 2, we showed that maned 

wolf activity had a clear relationship with temperature, 

abruptly decreasing above 27°C–29°C and nearly ceasing 

above 30°C (Figure 2.2A). In a +4°C scenario, MW are 

TABLE 7.3. Projected changes in temperature and precipitation 

in Amazonia, 2020–2080. Source: Intergovernmental Panel on 

Climate Change (2007).

 Projected Projected

 temperature precipitation 

Year Season change (°C) change (%)

2020 Dry season +0.7 to +1.8 –10 to +4

Wet season +0.5 to +1.5 –3 to +6

2050 Dry season +1.0 to +4.0 –20 to +10

Wet season +1.0 to +4.0 –5 to +10

2080 Dry season +1.8 to +7.5 –40 to +10

Wet season +1.6 to +6.0 –10 to +10
number 639 • 101

projected to lose 5 hours of daily activity time (Figure 7.6). 

To compensate, all maned wolf behavior—foraging, social 

interactions, travel—would need to either become more 

efficient (i.e., accomplish the same amount in less time) or 

take place under heat stress that would require permanent 

proximity to water. In our study site at Los Fierros, the 

observed loss in body weight and reproductive failure of 

MW during a rodent decline is evidence that our study 

animals are living near their energetic limits. The stress of 

adapting to the new rhythms of a warmer climate is likely 

to push more marginal populations of MW to extinction.

Our +4°C adjustment (Figure 7.6) is an oversimplified representation of the complex climatic factors that 

will interact at a finer scale than the broad projections of 

the IPCC or Boulanger (2006). It also ignores all other 

environmental responses (vegetation change, reduction in 

rodent carrying capacity, water scarcity) to a 4° change in 

temperature. We believe, however, that our example illustrates the physiological limits that conservation biologists 

soon will be forced to consider, as well as the data that 

current behavioral ecology fieldwork can contribute to 

such scenarios. Precipitation and maned wolf water regulation will be even more difficult to predict and manage. 

The IPCC suggests that rainfall in the Amazonian region 

may increase or decrease from current levels. Given the 

great distances that MW traveled to seek water at NKP, 

FIGURE 7.6. A modified Figure 2.2B (Chapter 2), illustrating a projected +4°C temperature change. Female maned wolf F3 2004–2005 average 

hourly travel (left axis, open squares) and average hourly collar temperature (right axis, closed circles); broken line is the collar T ̊C with 4°C 

added; vertical solid lines indicate the hour where the 2004–2005 collar temperature curve intersects 30°C (where travel nearly ceases); outer 

vertical dashed lines indicate where the same curve +4°C intersects 30°C. In the projected scenario, the temperature reaches at 30°C about 2.8 

hours earlier in the morning (~0715) and goes below 30°C about 1.5 hours later in the evening (~2000), removing about 5 hours of peak travel 

time from the current maned wolf activity pattern.
102 • smithsonian contributions to zoology

we expect any decreases in precipitation to have at least as 

great, if not greater, an effect on maned wolf populations 

than would temperature increases alone.

Threats to Maned Wolf Habitat Integrity

As illustrated by the discussion of fire management, 

the health of maned wolf populations depends on the 

health and functionality of the ecosystems they inhabit. 

The major threats shared by species that co-occur with 

MW and are components of intact savanna ecosystems are 

also threats to MW, and the conservation of MW could 

likewise preserve those taxa.

To identify the species that share threats with MW, 

we used the search function of the IUCN Red List (Version 2009.2) and filtered species by country, habitat, and 

threat type. Of 1,080 terrestrial vertebrate species that 

share range countries and habitat types with MW, 4% are 

classified as Vulnerable (N = 46), 3% as Endangered (N

= 29), and 1% as Critically Endangered (N = 15; IUCN 

Red List). Of the four threats identified for MW by Rodden et al. (2008), agriculture is the most widely shared 

threat, followed by hunting, roads, and nonnative species 

(Figure 7.7). While nonnative species likely refers to domestic dogs in the maned wolf species assessment, exotic 

grasses, introduced as pasture for cattle, are a major threat 

to Cerrado biodiversity and exacerbate the effects of other 

threats (fire: Klink and Machado, 2005).

Three other threats to savanna and grassland species are widespread (listed for more than 10% of IUCNassessed species), but not identified in the IUCN maned 

wolf assessment (Rodden et al., 2008): fire or fire suppression, logging or wood harvesting, and livestock ranching. 

Maned wolves share fire as a threat, and its effect should 

be considered in conservation efforts across the species’ 

range. In contrast, selective logging is unlikely to directly 

affect maned wolf populations. Wood harvest does not 

target the open vegetation or fruit species on which MW 

FIGURE 7.7. Number of savanna species that share IUCN threat categories (numbers) with MW by conservation status (IUCN Red List).
number 639 • 103

forage, so the fauna most likely to be affected are forest dwellers such as the monster rice rat (Euryoryzomys 

lamia) or tree nesters. Clear-cutting can increase available 

open habitat for MW (Quierolo et al., 2011).

Livestock ranching is likewise a mixed prospect for 

MW. Dietz (1984) found MW thriving on ranchland and 

Kawashima et al. (2007) suggested that MW may expand 

their range as forest is cut down for pasture, as has occurred in areas previously covered by Atlantic Forest 

(Queirolo et al., 2011; Santos et al., 2003). The lobeira 

fruit (Solanum lypocarpum) favored by MW can grow 

in abundance in rangelands and may even be facilitated 

by the disturbed areas associated with cattle ranching 

(Courtenay, 1994). Traditional cattle ranching on natural 

grasslands in Bolivia seems fully compatible with maned 

wolf survival, but conversely, “modern” ranching methods can destroy the plant and animal life on which MW 

depend. Pastures are bulldozed, burned, and seeded with 

invasive African grasses as forage (Klink and Machado, 

2005). These grasses outcompete native vegetation and 

increase the intensity of fires, thus altering the system’s 

succession and recovery. Vynne (2010) detected few MW 

in the surveyed cattle pastures of Goiás, Brazil. Because 

some pastures have little biomass to support rodent populations and few fruiting woody species (Santos et al., 

2003, Vynne, 2010), artificial pasture may present lower 

food availability for MW than natural areas or even some 

cropland. As planted pasture has become the most widespread land use across the maned wolf range (40% of the 

Cerrado biome: Klink and Machado, 2005), we are only 

beginning to learn how maned wolf ecology and population trends are affected by rangeland conditions and how 

land use interacts with other threats, such as increased exposure to ectoparasites, diseases, pesticides, and stressors 

(May-Júnior et al., 2009).

Our web sample does not reflect threats to Data Deficient species on the IUCN Red List, including three species 

of the rodent genus Juscelinomys. Two are endemic to the 

grasslands of NPK, where MW eat them (Chapter 4). These 

are the only known surviving populations of their genus, as 

the other species (J. candango, from a now-destroyed Brazilian Cerrado site), has no known populations (Emmons, 

1999). Juscelinomys spp. and other rare cerrado grassland 

rodents such as Kunsia tomentosus and Kerodon acrobata 

are threatened by any destruction of their habitats. The 

local extinction of Cavia aperea, the chief rodent prey of 

MW at Los Fierros, shows that even common and widespread rodents can be sensitive to apparently small environmental variations (Emmons, 2009), as Magnusson et 

al. (2010) also found for Necromys lasiurus.

Strategies To Reduce Threats to MW

Effective conservation action requires an understanding of the causal relationship between human activities 

and biodiversity threats. We constructed a conceptual 

model to diagram proximate and ultimate causes of 

maned wolf endangerment (Figure 7.8; Margoluis et al., 

2009), based on the conservation issues known to affect 

MW and their habitat (Deem and Emmons, 2005; Dietz, 

1984; Klink and Machado, 2005; Paula et al., 2008; Rodden et al., 2008).

More than describing how we understand the world to 

work, our conceptual model highlights which are the key 

threats and contributing factors where conservation efforts 

can intervene. We divide the effects of threats into those 

that directly affect MW (agriculture, domestic dogs, road 

traffic, and intentional mortality caused by people; Figure 

7.8) and those that affect maned wolf grassland habitat 

(agriculture and fire management). Some contributing factors (maned wolf dispersal behavior, international demand 

for soya or biofuels) are unlikely to be influenced by a 

maned wolf conservation project and so would be unproductive as a focus for conservation efforts. Other factors, 

such as the perception that maned wolf body parts can 

cure sickness, can be mitigated by campaigns to change 

attitudes, values, and behaviors (Figure 7.9). Likewise, 

our veterinary team has worked to improve domestic dog 

health in the communities surrounding our maned wolf 

field site (Figure 7.10; Deem and Emmons, 2005; Bronson 

et al., 2009), as has been done by other maned wolf projects. Depending on the site and local capacity, programs 

can be developed to mitigate many causes of mortality 

(speed limits, incentives to provide legal frameworks to 

mitigate agricultural conversion).

Recommendations for Noel Kempff

Mercado National Park

The conservation status of MW is tenuous within 

NKP. Because of the park’s relative isolation and protected 

status, MW are unlikely to suffer some threats (road kill), 

but the small and fragmented populations are susceptible 

to unpredictable factors such as the 2004–2007 rodent 

decline, droughts, flooding, and fires (Chapters 4, 5; Emmons, 2009). We present recommendations by scale: (1) 

local management within the park and (2), regional or 

country-wide management. Both are vital to maintaining 

the ecological resilience of the park and healthy maned 

wolf populations, but while regional leadership must 

prepare for and address an external dynamic (Hidrovía 
104 

• smithsonian contributions to zoology

FIGURE 7.8. Conceptual model of the threats to maned wolf conservation and their contributing factors.
number 639 • 105

FIGURE 7.9. Public awareness poster about the ineffectiveness of animal parts as medicine, from Bolivia. The maned wolf in the lower right-hand corner is saying, “I’m not 

a pharmacy!” Color version of the poster is available at http://www.canids.org/species/Chrysocyon_brachyurus.htm. Artist: Alan Hesse.
106 • smithsonian contributions to zoology

project and climate change), park management must 

tackle the on-the-ground direct threats to NKP MW (fire 

suppression and disease). 

Local park management recommendations:

1. Mitigate the effects of fire suppression and catastrophic fire by conducting yearly prescribed 

burns. To maintain optimal habitat for MW, NKP 

lowland savannas will require burning with sufficient frequency to preserve the habitat as grassland, but in a spatial and temporal patchwork that 

maintains populations of woody fruiting plants 

(such as Solanum spp., Anonnaceae spp., Alibertia 

edulis, and Miconia albicans) in several stages of 

annual postfire regeneration on each maned wolf 

home range. In the flood-prone lowland savannas, 

prescribed burning in patches should occur on a 

3–4 year rotation, and in months when conditions 

are not so dry that fires escape into nonprescribed 

areas. More urgently, overgrown savanna edges 

should be burned to restore the habitat’s former 

extent. Existing roads can be cleared to act as fire 

breaks, as has been done in Emas NP, Brazil (Silveira et al., 1999). Savannas on the southern part 

of the Huanchaca Meseta burn regularly, perhaps 

too often, from fires started on fazendas in Brazil 

that propagate yearly across the tableland, but the 

northern part of the Meseta seems to be losing its 

grassland to overgrowth by shrubs.

2. Suppress disease transmission between wildlife and 

domestic dogs and cats by excluding domestic animals from the park and vaccinating those on the 

periphery. Exposure to a number of pathogens was 

found at high prevalence in domestic dogs near the 

park, but not simultaneously in the NKP maned 

wolf population (canine distemper and rabies; 

Bronson et al., 2008; Chapter 6). This encouraging 

result suggests that domestic dogs are not directly 

FIGURE 7.10. Veterinarian Ellen Bronson monitoring domestic dog health in the community of Florida, outside NKP. 

Photograph by L. Emmons.
number 639 • 107

exposing MW to disease. Maintaining this separation is extremely important and to continue to do 

so, we recommend two universal rules: “1) prohibit the release of individuals of wild species from 

captivity into wild populations, unless the wild 

populations are threatened and in need of augmentation for survival, and strict health and genetic 

evaluations have been performed before release; 

and 2) exclude all pets and other domestic animals from parks” (Deem and Emmons, 2005:196). 

While perhaps not by direct transmission from 

dogs, MW in NKP have been exposed to a number 

of potentially lethal diseases that are transmitted 

by domestic dogs and cats. We recommend regular rabies vaccination of local pets and livestock 

and distemper vaccination of dogs. Both diseases 

have effective vaccines and recur in multiyear cycles when new generations of susceptible animals 

are at sufficient density. Healthier pets also mean 

healthier children.

Regional-scale recommendations: 

1. Seek partnerships with adjacent ranchers to resist 

and mitigate the effects of agroindustrial development. The proposed Hidrovía inland waterway 

and consequent traffic on the park border would 

be disastrous to maned wolf populations. Adjacent ranches, now in seminatural grassland, 

would likely be converted into agroindustry and 

isolate MW in the park. Buffers should be sought 

to maintain adjacent land in seminatural pasture 

with appropriate land management, including at 

least 20% set aside on each farm as an undeveloped refuge for wildlife (as per Brazilian land use 

laws). Partnerships should also be established with 

ranchers between the park and adjacent villages 

(e.g., Campamento) to create seminatural cerrado 

habitat for maned wolf subsistence and dispersal.

2. Prepare for climate change by increasing connectivity to other grasslands. The type of peripheral 

land connectivity described above is also thought 

to be one of the best strategies for protected areas 

to prepare for climate change (Hannah, 2008). 

Early interventions can be both more effective and 

less costly than delayed or no action (Hannah et 

al., 2008). If climate changes render some fragments of savanna unsuitable for MW (lack of dry 

season water), park managers should consider support for more intensive management interventions, 

such as maintaining water holes at several points in 

August–October.

Conclusion

Enabled by the technology of GPS telemetry, we are 

now in a golden age of maned wolf study. Insight into their 

ecology and daily lives is growing sharper and a growing cohort of researchers contributes information about 

wild maned wolf populations. We are also more acutely 

aware of the human activities that threaten them. The species as a whole is endangered by unmitigated agroindustry. 

Where populations are small and isolated, a number of 

threats and management actions have been identified for 

conservationists and park managers. The next challenge is 

to link maned wolf conservation to the emerging threats of 

climate change, invasive grasses, and biofuel production. 

Long-term field studies have never been more important, 

but funders want quick results. Only longitudinal research 

supplies the baseline for detection of emerging problems 

and helps identify environmental change early enough to 

pose research questions and eventually help mitigate them 

(rodent declines: Emmons, 2009; biofuels: Vynne, 2010; 

climate change: Chapter 2).

As understanding of maned wolf ecology grows, so, 

too, does the evidence that MW are resilient for a large 

canid. Dietz (1984) reported that although MW were 

highly sensitive to the physical presence of people, they 

were tolerant of agriculture and persisted where ranchers and farmers had earned a livelihood for generations. 

Vynne (2010) has found MW in soya fields, Lyra-Jorge 

et al. (2008) documented their presence in eucalyptus 

plantations, and Santos et al. (2003) showed them to 

thrive on dairy farms cut from Atlantic forest. If sufficient resources are available, MW do not need intensive 

management. Long-distance dispersal is crucial to the 

conservation success of species in fragmented landscapes 

(Trakhtenbrot et al., 2005) and fortunately, MW are far 

travelers. In rare events, they have been recorded crossing hundreds, even thousands, of kilometers of unsuitable habitat (Queirolo et al., 2011). Models, imperfect as 

they are, suggest that maned wolf populations have the 

potential to grow quickly (Paula et al., 2008) and that 

some populations are expected to persist for hundreds of 

years, even under worst-case scenarios (high inbreeding, 

high rates of habitat loss, and high population variability; Rodrigues and Diniz-Filho, 2007). Nonetheless, we 

should not diminish the evidence that in the past hundred 

years, MW have lost extensive habitat and geographic 
108 • smithsonian contributions to zoology

range, and the status of many subpopulations is desperate. However, it is also clear that if enough prey and fruit 

can be kept in the landscape, MW can live beside us for 

a long time to come.

Acknowledgments

We thank Adrianna Muir for writing support, Sharon Deem and Ellen Bronson for feedback on the domestic 

dog section, Dan Cole for GIS assistance, Carly Vynne for 

generously sharing photos and comments that improved 

an earlier version of this manuscript, Melissa Rodden for 

assistance in compiling a maned wolf bibliography, and 

Diego Queirolo and colleagues for kindly sharing the data 

set on maned wolf point records.

APPENDIX A: 

MANED WOLF SUBPOPULATIONS

In October 2005, a PVA workshop was held in Serra 

da Canastra National Park, Brazil (Paula et al., 2008). 

National delegations identified 19 maned wolf subpopulations in Brazil, Argentina, and Paraguay. Bolivia and Peru 

were considered later (R. C. Paula and L. H. Emmons, unpublished) with three additional subpopulations being recognized. Here, we compile workshop results into one map 

(Figure 7.11). Each identified maned wolf subpopulation, 

or landscape, is represented as a numbered polygon. We 

know the map is incomplete. For example, subpopulations 

were not identified in the Brazilian state of São Paulo or 

southern Brazil because workshop participants considered 

FIGURE 7.11. Twenty-two identified subpopulations (or landscapes) for MW. Source: Paula et al. (2008) and Quierolo 

et al. (2011).
number 639 • 109

those populations “isolated and very small” (Paula et 

al., 2008). We have also introduced a source of error by 

manually drawing the polygons in ArcGIS 9.1, based on 

the figures in Paula et al. (2008) and political and natural 

boundaries. 

We tabulate the basic details of each subpopulation, 

including protected areas and population estimates given 

by Paula et al. (2008; Table 7.4). Workshop participants 

estimated that 23,631 MW exist in the wild. On the basis 

of the published range of maned wolf densities and our 

own upwardly revised estimate of MW in Bolivia, we propose that the number is likely closer to 15,000. The total 

estimated area of the 22 landscapes is approximately 1.5 

million km2. Within that, approximately 200,000 km2 is 

included within a protected area under the most inclusive 

definition: all IUCN categories, plus uncategorized. The 

IUCN Protected Areas I–IV compose 102,000 km2

, IUCN 

Protected Areas V–VI contribute 63,000 km2, and all 

others, 34,000 km2. These are likely maximum estimates 

of protected coverage for MW because not all protected 

areas in the subpopulation margins likely support MW, 

and much of the habitat within them is not suitable (e.g., 

only a third of NKP is savanna).

We reemphasize that Figure 7.11 is hypothetical and 

that the existence and margins of subpopulations need verification by local experts. New data have already improved 

upon this map; for example, in Landscape 18, the distribution of MW has been refined into two areas of high density, 

one in Santa Fe Province, the other straddling the border 

of Córdoba and Santiago del Estero Province, and a larger, 

less dense zone of occupation that is fully joined with Landscapes 19 and 20 (Pautasso, 2009: fig. 9). Queirolo et al. 

(2010) also present more detail on connectivity and presence 

in individual states and provinces. For consistency we did 

not revise any subpopulations from the 2005 contributions. 

Revising the global distribution of MW is a continual necessity, and also a Herculean task that is best tackled by the 

community of all those interested in the status and future of 

MW. A campaign for mammals on the model of the Christmas Bird Counts in the United States, perhaps with the 

participation of schools, or a web tool like iNaturalist.org 

might yield better data on current distribution trends.

TABLE 7.4. Twenty-two identified subpopulations of MW in Brazil, Argentina, Paraguay, Bolivia, and Peru. Source: Paula et al. (2008).

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs

1 Bolivia and Peru. Includes 

populations in the grasslands 

of the Beni Department, 

Bolivia, and the tiny population in the Pampas del Heath 

National Sanctuary, Peru. 

Some exchange is expected 

with Noel Kempff Mercado 

population (2).

Estación Biológica del Beni 

(Biosphere Reserve, IUCN 

VI); Estancias San Rafael 

(Wildlife Refuge, IUCN IV); 

Estancias Elsner Espírir 

(Wildlife Refuge, IUCN IV); 

El Dorado (Wildlife Refuge, 

IUCN IV); Madidi National 

Park (IUCN II); Bahuaja 

Sonéné National Park (Peru, 

IUCN II).

130 150,343 5,259 1,440 3,130 9,829

2 Bolivia. Includes the populations in and around Noel 

Kempff Mercado National 

Park, Santa Cruz Department. Some exchange is expected with the Beni (1) and 

San Matías (3) populations.

Noel Kempff Mercado National Park (IUCN II).180 25,229 14,377 0 0 14,377

(continued)
110 • smithsonian contributions to zoology

3 Bolivia. Includes the populations in the Pantanal and in 

the two large protected areas 

(Otuquis National Park in 

the south and San Matías 

in the north) and associated 

reserves, Santa Cruz Department. Some exchange is expected with the Noel Kempff 

Mercado (2) and potentially 

with the Mato Grosso do Sul 

(12) and West Paraguay (14) 

populations.

San Matías Integrated 

Management Natural Area 

(IUCN IV); Otuquis National 

Park (IUCN II). 

70 33,886 33,886 0 0 33,886

4 Brazil. Includes the populations in the cerrado of central 

and southern Mato Grosso 

State. Some exchange is 

expected with the Emas (5) 

and eastern Mato Grosso (6) 

populations.

Cabeceiras do Rio Cuiabá 

(State Environmental Protection Area, IUCN V); Chapada dos Guimarães (State 

Environmental Protection 

Area, IUCN V); Serra das 

Araras (State park, IUCN II); 

Dom Osório Stoffel (State 

Park, IUCN II); Serra Azul 

(State Park, IUCN II); Gruta 

da Lagoa Azul (State Park, 

IUCN II); several indigenous 

reserves (the largest: Parabubure Indigenous Area).

1,764 165,450 990 6,804 8,444 16,237

5 Brazil. Includes the cerrado populations in and 

around Emas National Park, 

southern Goiás State. Some 

exchange is expected with the 

southern Mato Grosso (4) 

and Mato Grosso do Sul (12) 

populations.

Emas National Park (IUCN 

II), associated buffer PAs 

around Emas National Park.

127 3,374 1,283 1,088 2,371

6 Brazil. Includes the populations in the cerrado of 

eastern Mato Grosso, which 

includes several indigenous 

reserves. Some exchange is 

expected with southern Mato 

Grosso (4) populations and 

potentially with the western 

Tocantins (7) population.

Rio das Mortes (State 

Wildlife Refuge, IUCN III); 

Meandros do Rio Araguaia 

(Environmental Protection 

Area, IUCN V); indigenous 

reserves with MW records: 

Pimentel Barbosa Indigenous 

Area, Areões Indigenous 

Area.

1,412 51,952 3,312 2,496 5,256 11,064

(continued)

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs
number 639 • 111

7 Brazil. Includes the populations in and around the cerrado and flooded grasslands 

of Bananal Island, the largest 

fluvial island in the world, 

western Tocantins State. Potential exchange is expected 

with eastern Mato Grosso (6) 

and Piauí and Maranhão (8) 

populations.

Araguaia National Park 

(IUCN II); also indigenous 

area, large adjacent to south 

of National Park: Parque do 

Araguaia Indigenous Area.

1,625 41,927 5,402 14,954 4,302 24,658

8 Brazil. Includes populations 

in the Cerrado of Piauí, 

Bahia, Maranhão, and 

eastern Tocantins States. 

Some exchange is expected 

with the Goiás (9) and 

central Minas Gerais (10) 

populations.

Mirador (State Park, IUCN 

II); Chapada das Mesas 

National Park (IUCN II); 

Uruçui-Una Ecological Station (IUCN Ia); Nascentes do 

Rio Parnaiba National Park 

(IUCN II); Cabeceira do Rio 

das Balsas, (State Environmental Protection Area, 

IUCN V); Serra Geral do 

Tocantins (IUCN Ia); Jalapão 

(State Park, IUCN II, and 

State Environmental Protection Area, IUCN V); Serra 

da Tabatinga (Environmental 

Protection Area, IUCN V); 

Bacia do Rio Janeiro (State 

Environmental Protection 

Area, IUCN V); Serra do 

Lajeado (State Environmental Protection Area, IUCN 

V); Cristópolis National 

Forest (IUCN VI); Veredas 

do Oeste Baiano (Wildlife 

Refuge, IUCN III); Grande 

Sertão Veredas (IUCN II); 

Veredas do Acari (State 

Park, IUCN II); Cavernas 

do Peruaçu (Environmental 

Protection Area, IUCN V); 

several indigenous areas, 

including Kraolandia Indigenous Area.

10,384 327,751 30,024 9,207 6,440 45,672

(continued)

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs
112 • smithsonian contributions to zoology

9 Brazil. Includes populations 

in the cerrado of Goiás. Some 

exchange is expected with the 

Bahia (8) and central Minas 

Gerais (10) populations.

Chapada dos Veadeiros 

National Park (IUCN II); 

buffer: Pouso Alto (State Environmental Protection Area 

(IUCN V); Planalto Central 

(Environmental Protection 

Area, IUCN V); Bacia do Rio 

São Bartolomeu (Environmental Protection Area, 

IUCN V); several other EPAs 

in this Planalto complex.

2,173 55,551 1,334 14,077 0 15,412

10 Brazil. Includes populations in 

the cerrado of central Minas 

Gerais. Many MW records 

from Queirolo et al. (2011) 

were identified to the south of 

this landscape, suggesting that 

its margins may be larger or 

that distinct subpopulations 

exist in southern Minas Gerais 

and São Paulo States. Some 

exchange is expected with 

the Bahia (8), Goiás (9), and 

northeastern Minas Gerais 

(11) populations.

Serra da Canastra National 

Park (IUCN II); Córrego Feio 

e Fundo e Areia (State Area 

of Special Protection, IUCN 

V); Confusão (State Area of 

Special Protection, IUCN V); 

Sempre-Vivas National Park 

(IUCN II); Biribiri State Park 

(IUCN II); Águas Vertentes 

(State Environmental Protection Area (IUCN V).

3,091 186,264 3,501 1,165 0 4,666

11 Brazil. Includes populations 

in the Cerrado of northeastern Minas Gerais. Some 

exchange is expected with 

the central Minas Gerais (10) 

populations.

Grão-Mogol State Park 

(IUCN II); Acauã State Ecological Station (IUCN Ia).

386 13,336 409 0 0 409

12 Brazil. Includes populations 

in the Pantanal and cerrrado 

of Mato Grosso do Sul. Some 

exchange is expected with the 

Emas (5) and potentially with 

eastern (13) and western (14) 

Paraguay.

Serra da Bodoquena National Park (IUCN II); Kadiwéu 

Indigenous Area; Cachoeirinha Indigenous Area; 

Taunay/Ipegue Indigenous 

Area; Buriti Indigenous 

Area; Nioaque Indigenous 

Area; Jatayvari Indigenous 

Area; Ñande Ru Marangatu 

Indigenous Area; Pirakua 

Indigenous Area; Dourados 

Indigenous Area; Panambizinho Indigenous Area 

784 92,422 772 0 3,204 3,975

(continued)

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs
number 639 • 113

13 Paraguay. Includes populations in 12–20 cerrado and 

subtropical grassland areas 

scattered in eastern Paraguay. 

Potential exchange with 

Mato Grosso do Sul (12) 

and western Paraguay (14) 

populations.

Morombi Private Reserve 

(IUCN IV); Natural Reserve 

de Bosque Mbaracayú 

Private Reserve (IUCN V); 

Cerro Corá National Park 

(IUCN II); Arroyo Blanco 

Private Reserve (IUCN IV); 

Bella Vista National Park 

(IUCN II); San Luis National 

Park (IUCN II); Paso Bravo 

National Park (proposed).

150 50,674 653 545 993 2,191

14 Paraguay. Includes populations in the Pantanal and subtropical savanna in western 

Paraguay. Very little protected 

area coverage, but contains 

relatively low human density. 

Potential exchange with Mato 

Grosso do Sul (12), eastern 

Paraguay (13), and southern 

Paraguay (16). 

Río Pilcomayo (IUCN II). 500 65,378 9 0 74 82

15 Argentina. Includes populations in the subtropical 

grasslands of Formosa Province. Few MW records from 

Queirolo et al. (2011) were 

identified within this landscape. Exchange is expected 

with Santiago del Estero (18) 

populations. 

No protected areas identified. 100 22,671 0 0 0 0

16 Paraguay. Includes populations in the subtropical 

grasslands and wetlands of 

southern Paraguay. Exchange 

is expected with San Rafael 

(17) populations and potentially with western Paraguay 

(14), Corrientes Province 

(19), and Santa Fe Province 

(18) populations. 

Yabebyry Wilderness Area 

(IUCN IV); Ybycuí National 

Park (IUCN II); Macizo 

Acahay National Monument (IUCN III); Ypacaraí 

National Park (IUCN II).

150 35,472 554 3 1,225 1,781

(continued)

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs
114 • smithsonian contributions to zoology

17 Paraguay. Includes a small 

population in and around 

the subtropical savannas of 

San Rafael NP. Exchange is 

expected with southern Paraguay (16) populations.

San Rafael Managed Resource Reserve (IUCN VI); 

Caaguazú National Park 

(IUCN II).

30 2,990 50 624 0 674

18 Argentina. Includes populations in the subtropical 

grasslands of Santa Fe, Córdoba, and Santiago del Estero 

provinces. Some exchange 

is expected with Formasa 

Province (15) and Chaquito 

(21) populations and potentially with southern Paraguay 

(16) and Corrientes (19) and 

Entre Ríos (20) province 

populations. 

Chiquita Nature Reserve, 

(IUCN VI).

230 106,492 0 42 0 42

19 Argentina. Includes populations in the subtropical 

savannas and wetlands of 

Corrientes and Misiones 

provinces. Several MW 

records in Queirolo et al. 

(2011) were identified to 

the east of this landscape, 

suggesting that its margins 

may be larger or that distinct 

subpopulations exist in the 

Brazilian state of Rio Grande 

do Sul and possibly into 

northern Uruguay. 

Iberá Nature Reserve, IUCN 

Category VI

300 60,718 0 11,190 0 11,190

20 Argentina. Includes populations in the subtropical 

savannas of Entre Ríos 

Province. Some exchange 

is expected with Corrientes 

Province (19) populations 

and potentially with Córdoba 

Province (18) populations. 

No protected areas identified. 20 5,734 0 0 0 0

(continued)

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs
number 639 • 115

21 Argentina. Includes a small 

population, labeled Chaquito 

in Paula et al. (2008). Expected to exchange individuals 

with the Santiago del Estero 

(18) populations. 

No protected areas identified. 10 844 0 0 0 0

22 Argentina. A newly described 

population in Paula et al. 

(2008). Potential exchange 

with Santiago del Estero (18) 

populations.

No protected areas identified. 15 1,119 0 0 0 0

TABLE 7.4. Continued

Landscape 

No. Description

Representative Protected 

Areas (PAs)

Population 

estimate

Total 

Area

PA 

I–IV

PA 

V–VI

Other 

PAs

Total 

PAs

8 Synthesis

Louise H. Emmons

Behavioral Flexibility of

Maned Wolves and Its Limits

Our multiyear study uncovered features of maned wolf ecology and behavior that were unsuspected when we set out. Some may have been unique to our 

Los Fierros study site, while others might be general to the species but heretofore 

undescribed. Many patterns of behavior turned out to be quite variable, which is 

no surprise in a member of the Canidae. We studied too few individuals to assess 

which variable behaviors, if any, were the norm in the Los Fierros population, 

especially because averaging year-to-year data was precluded by unexpected and 

major environmental changes that occurred in the short decade of our research. 

These results mandate caution about generalizing to the species from patterns of 

ecology or behavior observed in either one season, one year, one place, or one 

set of individuals.

Maned wolves (MW) declined sharply at Los Fierros during our study, from 

three pairs with many helpers and young, to a solitary pair (Chapters 4, 5). By 

chance we may have witnessed the fragility of small populations faced with additive negative environmental events. Increasing dry season drought, unusually 

high and late flooding of the savanna, prey decline, and a catastrophic fire, all 

followed one another within 4 years. Lifetime residents of the zone had not witnessed equal drought or flooding, and the extinction of cavies from Los Fierros 

suggests a new change, as cavies had been present for decades, at least. These environmental events may or may not have been exacerbated by global warming, 

compounded by the El Niño–Southern Oscillation cycle and massive regional 

deforestation in Brazil, which yearly covers the sky with smoke for many weeks 

(Figure 7.4; Emmons, 2009). At the risk of “crying wolf,” it seems safest to assume that major anthropic climatic changes are now damaging the Cerrado and 

that mitigation should be advanced.

Louise H. Emmons, Department of Vertebrate 

Zoology, National Museum of Natural History, 

P.O. Box 37012, MRC 108, Smithsonian Institution, Washington, D.C. 20013-7012, USA; Correspondence: emmonsl@si.edu. Manuscript received 

25 August 2010; accepted 26 August 2011.
118 • smithsonian contributions to zoology

MW may be not flexible enough to adapt behaviorally to much environmental variation. Their historic 

habitat breadth and geographic range (Chapter 7) were 

both much smaller than those of most large, and many 

small, Canidae (e.g., bush dogs, crab-eating zorros, red 

foxes, coyotes, gray wolves, golden jackals, and formerly, 

both dholes and African wild dogs, among others; SilleroZubiri et al., 2004). Of the large Canidae, only the Critically Endangered Ethiopian wolf (IUCN Red List, 2009) 

is more habitat-restricted, and it may not be coincidental 

that it too, feeds on grassland rodents, albeit as a carnivore 

specialized on high-density diurnal alpine species (SilleroZubiri and Marino, 2004). Their geographical/ecological 

restriction to southern humid grasslands makes MW habitat specialists, compared to the latitudes achieved by many 

other Canidae.

Implications of Maned 

Wolf Omnivory

Maned wolves differ from other large Canidae in 

their omnivorous diet, small litter size, group size of a pair 

plus one, and solitary foraging (Table 8.1). The postnatal 

growth rate of a maned wolf litter, in relation to maternal 

metabolic size, is lower by a factor of nearly 3 than that of 

the lowest among five other canid species, from gray wolf 

to red fox, placing MW close to black bears (Oftedal and 

Gittleman, 1989). The one character that sets MW into a 

class by themselves is their large body size. Their diet and 

social behavior resemble those of many small species such 

as Cerdocyon thous (crab-eating zorro), Pseudalopex griseus (chilla), and Pseudalopex gymnocercus (pampas fox), 

the common small Canidae of the Southern Temperate 

Grasslands (Courtenay and Maffei, 2004; González del 

Solar and Rau, 2004; Lucherini et al., 2004). All of these 

small species have much broader habitat and latitudinal 

ranges than do MW.

Carbone et al. (1999), based on an empirical model, 

hypothesized that carnivores above about 21 kg body 

mass cannot energetically be entirely supported by a diet of 

small prey. Maned wolves seem to validate this hypothesis. 

The Ethiopian wolf (Canis simensis), a strict predator on 

rodents (Sillero-Zubiri and Gottelli, 1995), is about 5 kg 

below this limit (Table 8.1). Paradoxically, the giant maned 

wolf can probably exist in its predatory role only because 

half of its diet is fruit. Carnivora that are omnivores, such 

as bears, can be very large, but this results in extremely low 

female reproductive output (Geffen et al., 1996).

Maned wolves probably could not capture enough 

small mice, arthropods, and birds to live and reproduce 

on these alone. Perhaps they could thrive uniquely on 

abundant cavies and armadillos, but they nowhere have 

diets primarily of prey (Chapter 4). Rodent abundance can 

roller-coaster wildly from year to year, and worldwide, 

mice are unpredictable resources (Branch et al., 1999; 

TABLE 8.1. Characteristics of all large Canidae (>15 kg) and the smaller crab-eating zorro that is everywhere syntopic with maned 

wolves (MW). All listed species are said to be territorial, and all species with packs are said to include one breeding pair and helpers 

(their previous offspring or others). The disperser sex is usually the one that is not the helper sex. Data from Macdonald and SilleroZubiri, (2004,) and Sillero-Zubiri et al. (2004), except litter growth from Oftedal and Gittleman (1989) and weights of MW from 

Jácomo et al. (2009). Helpers have not been confirmed in zorros. Here n/a, not available.

 Home Litter

Male, Female, Social Litter Helper range growth per

Species kg kg group size sex Diet size, km2 MBS*(g/d)

Maned wolf 26.7 24.6 Pair, 0–1 1–3 Female Small prey, 20–110 7.2 (76)

 helpers 50% fruit

Gray wolf 20–80 16–55 pack 5–36 6 Both Large mammals 75–2,500 67.3 (886)

Red wolf 29 24 pack 1–12 1–10 Both Medium mammals 46–226 n/a

Ethiopian wolf 16 13 pack 3–13 2–10 Male Diurnal rodents 6 n/a

Dhole 18 13 pack 5–25 5–10 Male Large mammals 40–80 41.6 (298)

African wild dog 28 24 pack 2–40 7–10 Both Large mammals 400–1,300 n/a

Crab-eating zorro 4 6 pair 3.1 n/a Omnivore 1–5 n/a

*Postnatal growth rate of litter in relation to maternal metabolic size (gk g0.75d-1), and postnatal growth weight of litter (grams/day).
number 639 • 119

Emmons, 2009; Kelt et al., 2004). Armadillos were likewise present in some years in the maned wolf diet at Los 

Fierros but absent in others (Chapter 4). Some armadillos 

aestivate in dry periods, so that even if present, they can 

be unavailable (Erika Cuellar, pers. comm.). Fruit is also 

highly variable and unpredictable, especially in fire-prone 

savannas, and alone could not support a breeding maned 

wolf. Omnivory is thus a hedge against resource swings in 

both fruits and short-generation prey in a world of unpredictable climate. Frugivory may make life at its body size 

possible for MW, but in Noel Kempff Mercado National 

Park (NKP) it does not make life easy.

South America has no large-bodied, pack-hunting, 

predatory Canidae, although nearly a third of living taxa 

are found there. The only hypercarnivorous, pack-forming 

species on the continent, the bush dog, is the World’s 

smallest (5–8 kg), and it feeds chiefly on armadillos and 

giant rodents (agoutis and pacas, 4–10 kg) that a pack 

can cooperate to run down or extract from their burrows 

(Zuercher et al. 2005), which MW cannot do. Guanacos 

(Lama glama), now the only large, high biomass, lowland 

South American grassland herbivores, have no range overlap with MW. The low large herbivore abundance and 

biomass of the Anthropocene (de Vivo and Carmignotto, 

2004) thus provides no ecological place for a “South 

American Wild Dog,” and MW probably owe their historical survival to their omnivory, whereas the Late Pleistocene dire wolf (Canis dirus) was extinguished in South 

America with is megafaunal prey (Cione et al., 2003).

Social Groupings or Not?

In their excellent review of the forces shaping the 

sociobiology of Canidae, Macdonald et al. (2004a) note 

two situations that could allow selection for grouping in 

Canidae: (1) the home range contains sufficient resources 

to sustain additional individuals, without incurring prohibitive costs to the breeding female or pair; and (2) 

constraints on dispersal opportunities would favor the retention of young past maturity. We infer from the increase 

in territory size when cavies vanished from the Los Fierros 

study area that territories may not include much excess 

food supply, so condition 1 may limit grouping for MW 

in NKP. Because only MW with a territory are known to 

breed (Chapter 5), and all good habitat appears occupied, 

condition 2 certainly does apply to the MW of NKP. Possession of a suitable territory is an essential requirement 

for maned wolf reproductive success. That female helpers 

can inherit natal territories (Chapter 5) confirms condition 

2 as a likely driver of young females remaining in the social 

group, while condition 1 may restrict their number to one. 

Moreover, small litters would limit the usefulness of more 

than one helper. Female MW appeared to be the “owners” 

of territories, and this might constrain helpers to females, 

as males would have no breeding future in a family. There 

is little evidence that grouping confers any foraging advantage to MW. Although Bestelmeyer and Westbrook (1998) 

apparently observed a maned wolf pair cooperate to hunt 

a deer and we recorded a pair often traveling together, cooperative hunting seems extremely rare, if it occurs at all.

The fruit moiety of the diet returns only about a third 

as much energy per kilogram consumed as does animal 

prey (Chapter 4; Table 4.6). A low rate of energy acquisition (herbivorous diet) in Carnivora is associated with low 

postnatal growth rates of the litter as a whole (Table 8.1; 

Oftedal and Gittleman, 1989). This is doubtless a factor 

underlying the tiny maned wolf litter size (mean 1.8, Oftedal and Gittleman, 1989; mean 3, Rodden et al., 2004), 

but there is little in situ litter data. Territorial females did 

not reproduce successfully each year, as also noted by 

Dietz (1984), and in the three cases we observed, females 

were 3 year olds before acquiring territories and mates. 

The dry season average travel of MW in our study area 

was about 14 km per night and MW were active (moving) 

for an average of 11–12 hours of each night (Chapters 2, 

3; Table 2.2). At this activity level, a female may be unable to increase her energy intake to support more than 

three pups during pregnancy and lactation. Extra hours 

of foraging would force her into the hot hours of the day, 

incurring supplementary costs in thermoregulation and 

travel to water (Chapter 2). The loss in body weight of 

MW during the decline and disappearance of cavies at Los 

Fierros suggests that they are living near their energetic 

limits in NKP (Chapter 4). If so, just one helper offspring 

at a time, placed to inherit a territory, might supply important provisioning help without compromising the resource 

supply. Melo et al. (2007) reported a helper apparently 

guarding, but the quantitative roles of males and helpers 

in provisioning females and pups in free-ranging MW is 

unknown. It can be assumed to be important, if not critical, as it is in most or all Canidae with helpers (Macdonald 

and Sillero-Zubiri, 2004). 

The Value of Size?

Size is the overriding biological characteristic of organisms. All aspects of functional morphology, physiology, ecology, and reproduction are tuned by evolution in 
120 • smithsonian contributions to zoology

relation to body size and shape. Ecological fine-tuning of 

size is on a precision scale: for example, congeners can 

coexist when feeding structures are separated by the magical size ratio of 1.2 or more (Hutchinson, 1959; Emmons, 

1980). Size is the character that most rapidly responds to 

environmental selection (including interspecific interaction; Grant and Grant, 2002). To understand the nature 

of MW, we must understand their giant size and assume 

that it is particularly adapted to their current ecology. For 

this, it is instructive to compare the ecological role of MW 

to that of crab-eating zorros (Cerdocyon thous, “zorros” 

for brevity), with which they live side-by-side throughout 

their geographic range. 

Maned Wolf versus Crab-eating Zorro

Large size is costly. Although larger mammals need 

relatively less fuel per kilogram than do equivalent, smaller 

ones, the larger they get, the more they need (Carbone et al., 

1999, Geffen et al.,1996). Zorros in sympatry have about 

75% dietary overlap with MW (Juarez and Marinho-Filho, 

2002; Jácomo et al., 2004) at quarter of the body weight 

(Figure 8.1). Maned wolves are completely sympatric with 

C. thous, but not vice versa, as zorros have much wider 

habitat and geographic ranges. Zorros have slightly larger 

litters, 10- to 100-fold densities, and home ranges one sixteenth of the size of those of MW (zorros, 60–400 individuals per 100 km2

 [Courtenay and Maffei, 2004]; MW, 

5.2 per 100 km2 in Emas [Silveira et al., 2009]). The diet 

of MW includes a few more medium-sized prey (Jácomo 

et al., 2004; Juarez and Marinho-Filho, 2002), but most 

of the diet of both species is of many of the same taxa of 

small rodents and fruits acquired one by one. Zorros often 

travel and forage in pairs, when each usually gleans morsels independently; and if separated, they cry until rejoined 

(Emmons, pers. obs.). Along with their small body size, a 

higher fraction of dietary invertebrates may facilitate the 

small home range needs of zorros (Jácomo et al., 2004). 

We have a number of times seen adults and pups kilometers from any water source at the height of the dry season, 

FIGURE 8.1. Height contrast between a maned wolf and a crab-eating zorro. (A) Unmarked maned wolf eating a sardine from a bait table used 

for occasional camera monitoring at El Refugio Huanchaca. (We did not provision maned wolves, but if water was too abundant to attract 

them, from time to time we lured them with treats to camera traps.) Note the long neck and that the sex cannot be determined. (B) Adult crabeating zorro (Cerdocyon thous) at the same place (Photographs by L. Emmons).
number 639 • 121

so zorros may not require surface water (we saw one drinking morning dew from grass). Being smaller, their absolute 

water needs would be less, and unlike MW, zorros occupy 

the drier Chaco and Caatinga biomes, so perhaps they have 

physiological specialization for water conservation. Nonetheless, at Los Fierros every water hole has a resident zorro 

pair that visits many times a night. 

By any usual measure (density, habitat breadth, geographic range, and reproductive output) C. thous is a 

more “successful” species than MW. Smallness confers the 

ability to easily meet energetic demands by consumption 

of small items; hence the fact that large Canidae (Carbone 

et al., 1999) and Felidae (Emmons, 1987) both “switch” 

to large prey at about 20 kg body weight. What advantage 

does a maned wolf accrue from its size?

The Tallness of Maned Wolves

Maned wolves have absolutely longer legs, and proportionally shorter backs, than do other large Canidae 

(Table 1.1), accompanied by a long neck (Figure 8.1). In 

predatory Canidae that track and run down their prey, 

the extreme being African wild dogs, the back is relatively 

long, and the hind foot is about 20% of head and body 

length (HBL). In MW the hind foot reaches nearly 30% 

HBL (Table 1.1). At normal speeds, the ipsilateral pace 

of MW is smooth, but their limb length precludes a diagonal trot. At a gallop they seem slightly ungainly, with 

much vertical motion (bouncing up and down) that must 

waste energy. Zorros traveled an average of 10.9 km during each of two, six hour half-nights (1900–0100 hours; 

Juarez and Marinho-Filho, 2002) or at a rate of 1.8 km 

per hour. This is within the highest range of nightly travel 

distances of MW but at a faster rate. When we briefly followed a VHF-collared zorro, it, too, moved much faster 

than is usual for MW (Emmons, unpublished data). Gray 

wolves in summer moved mean distances of 21 km per 24 

hour day, at a mean rate of 830 m/h (Mills et al., 2006, 

data from GPS collars), with rests included in hourly rate 

calculations. Compared with our data, in which movement rates include only hours of active travel, Mills et al. 

(2006) would underestimate wolf travel speed. The long 

legs of MW thus are not associated with greater travel 

distances per night or per hour than those reported for 

shorter-limbed Canidae that travel with the efficient, longdistance, diagonal trot. However, we have found no data 

sets exactly comparable to ours (movements based on 

large sets of hourly locations, rests removed). 

Tallness is intuitively an advantage for seeing above 

long grass or traversing tall grass or moderately flooded 

habitat without swimming (Figure 8.2A). In the tall dense 

grass on parts of our study savanna, pushing through the 

resistant grass at a trot would be impossible, but long legs 

can step over it. Tapirs use well-worn trackways, but MW 

have no fixed routes and travel ubiquitously (Chapter 

3). We found it exhausting to drag our legs even 2–3 km 

through grass (like walking through thigh-deep water or 

worse). Maned wolves forage for the same small rodent 

prey hidden under the grass as do the syntopic zorros and 

four small felids in NKP, and height confers no evident advantage in prey capture. Small Carnivora such as zorros, 

jaguarundis, and grisons can travel below the canopy of 

tall grasses, between the grass bunches, or on the networks 

of armadillo trails, in the realm of mice and cavies. Dubost 

(1979) developed an hypothesis that the height classes of 

African forest duikers are fitted to the structural density of 

fine undergrowth stems through which they must push to 

travel. His vegetation measurements confirmed that duikers occurred in the discrete height classes where stems 

presented the least resistance. Perhaps the optimal sizes 

for travel in the tall-grass savannas are either below the 

intertwined bunch-grass canopy (jaguarundis, rails, armadillos) or stepping over it with long slender legs (maned 

wolf, marsh deer, pampas deer, rhea). To feed on mice and 

invertebrates, the smaller size would seem advantageous.

Selection for large gape size and strength to tackle armadillos or medium-size prey is not associated with hypertrophy of the legs in other canine predators (bush dogs 

have the shortest legs). The reduced agility, and greater 

predator-mass/prey-mass ratio resulting from size, puts 

MW at an energetic disadvantage, where the night may be 

too short to catch enough prey to meet their needs (Carbone et al., 1999; Macdonald et al., 2004a). Because prey 

capture does not seem to be enhanced by their size, we 

conjecture that the height of MW facilitates the frugivore 

half of their diet.

Height gives MW access to fruits of shrubs and treelets that are out of reach of competing foxes, armadillos, 

peccaries, agoutis, and tapirs (Figures 8.1, 8.2B). On its 

hind legs, a female maned wolf reached to a height of 

170 cm to grasp a treat (trial in captivity, J. McLaughlin and M. Rodden, pers. comm). The “wolf fruit” that 

dominates the maned wolf diet in Cerrado (“lobeira”:

Solanum lycocarpum, in Brazil; S. gomphodes, in NKP; 

review in Rodden et al., 2004), is 10–15 cm in diameter, 

and in NKP, many S. gomphodes fruits hang well above 

the reach of zorros (Figure 8.2B). Although the ripe fruits 

drop, MW can choose them beforehand. Tapirs also eat S. 

gomphodes, but at Los Fierros, marked fruits stay on the 

plant until ripe, so tapirs apparently do not take immature 
122 • smithsonian contributions to zoology

fruits (J. M. Castro, unpublished data). The chief dietary 

fruit in NKP, Alibertia edulis, grows to above 6 m, and if 

not picked, it is opened in situ by bats and birds, or dries 

on the plant, so few ever fall (Emmons, pers. obs.). Fruits 

grow at all levels on the plant, which puts many out of 

reach of terrestrial mammals (A. edulis are yellow-green, 

mammal-dispersed fruits, Chapter 4). The few, large, 

nutritious, fruits per plant of Annona coriacea can hang 

above the reach of tapirs, which regularly bend over or 

break down the tops of the plants to reach them (Emmons, 

pers. obs.). On their hind legs, MW can reach higher than 

tapirs (Figure 8.3). In Emas Park, lobeira was 18% of all 

items eaten by MW, but only 2% of those eaten by zorros; 

for Annonaceae, the numbers were 12% and 6% (Jácomo 

et al., 2004). Of the possible reasons for this, one is that 

MW get the fruit first, another is that few fox territories 

are large enough to include the fruit species in their areas. 

Pampa fruits are scattered in a matrix of grassland, and 

height above the grass canopy could confer MW an olfactory or visual advantage for detecting them at a distance across tall grasslands (Figure 8.2A), as well as the 

height to outreach other mammals for them, and legs long 

enough to step over grass to travel efficiently.

Evolution for tallness, to reach tree leaves, has occurred repeatedly and with extraordinary diversity of 

structure throughout the history of vertebrate herbivores. 

In contrast, mammalian frugivores either feed on the 

ground on fallen fruits or climb trees to reach them; this includes the many frugivorous/omnivorous Carnivora, such 

as gray foxes (Urocyon cinereoargenteus), Procyonidae 

(coatis, kinkajous), Viverridae (palm civets), Mustelidae 

(tayras), and even Ursidae (black bears). Campo Cerrado 

trees and shrubs with mammal-dispersed fruits are usually 

short (<10 m), slender, and often brittle-stemmed from fire 

adaptation, thus poorly suited for climbing. The fruit of 

Annona coriacea dangles from long stems, while branches 

of the large-fruited Solanum spp. are heavily armed with 

spines. Dispersers must pick the fruits from a stance on 

the ground or wait for fruits to fall, unless they break the 

plant (tapirs). If the unique tallness of MW gives them a 

competitive feeding access to large, high-return, savanna 

fruit species that are dispersed over a large home range, 

FIGURE 8.2. (A) Height of maned wolf M8 relative to long grass of Los Fierros savanna. (B) J. M. Castro inspects a tree of Solanum gomphodes on a roadside outside of Noel Kempff Mercado National Park. The many fruits are immature; note that some are higher than his head 

(Photographs by L Emmons).
number 639 • 123

without compromising predation skills, then their anomalous characters as giant canids form a consistent suite of 

associated traits that places them into a unique canid category. They may also represent a unique adaptative type 

among living mammalia.

questions for future Research

Our research on MW has sprouted many questions. 

The few animals we studied varied in characteristics such 

as male behavior after parturition, togetherness of pairs, 

and breeding season. Canidae in general respond flexibly 

to changing environmental conditions (Macdonald and 

Sillero-Zubiri, 2004), but these behaviors in MW all need 

clarification with larger sample sizes. Conditions leading 

to socioecological variations need to be teased apart. Particular areas where we think research would be most fruitful include the following: 

Studies of field metabolic rates: Does the low muscle 

mass of MW correlate with low metabolic needs? 

Studies of passage times of whole prey and fruit parts 

through the digestive tract: How exactly do scats represent 

numbers and biomass of items consumed?

Studies of resource abundances and territory sizes: 

What is the relative importance for home range size of 

prey and fruit? What is the inter- and intra-annual turnover of individual resources? How can land best be managed to maintain optimal habitat? What is the optimal fire 

regime?

Studies of the epidemiology of episodic diseases and 

their possible control: Which diseases are now established 

in situ? What is the current transmission of pathogens 

between domestic animals and MW (rabies, distemper, 

heartworm, etc.)? What is the disease ecology in relation 

to syntopic savanna mammals such as raccoons, ocelots, 

and zorros and those of forests? What is the reproductive 

cost of disease?

Studies of helpers: How often do pairs have helpers? Are helpers always female? Does the abundance of 

resources influence their numbers? Do helpers help provision pups? How long do they usually stay? Does food 

resource density influence retention of helpers? Does the 

breeding female choose to accept or reject presence of a 

helper?

Studies of reproductive cycles: Are there really February–March births? If so, can a female ever have a second 

estrous cycle within the same year? What are the triggers 

for estrus? Is there a method to accurately age youngsters 

between 8 and 18 months so birth date can be calculated? 

What is the litter size and survival to weaning in freeranging MW?

FIGURE 8.3. Relative heights of (A) maned wolf F3 and (B) a mother tapir with young (standing partly below ground level). Camera trap images taken 3 hours apart at the Pozo Matt water hole.
124 • smithsonian contributions to zoology

Studies of populations: Where do maned wolf breeding populations still occur? Can MW be surveyed efficiently to distinguish between transient and breeding 

individuals? Under what conditions do MW successfully 

breed on agricultural land?

It is nearly impossible to acquire detailed behavioral 

data on many animals at once. The pioneering and best 

known behavioral ecology studies followed single social 

groups or small populations, where researchers could follow the relationships of individually known animals with 

each other and with the environment (e.g., the chimps of 

Gombe Stream, the lions of the Serengeti, the wolves of 

Isle Royale, and the elephants of Lake Manayra). Studies 

that began in the 1960s are in many cases still in progress, 

and they have acquired data on many animals by accumulating generations of longitudinal data. We followed far 

too few individuals for statistical inference of most parameters, but we relate for the first time the stories of a few 

free-living MW for a full maned wolf generation. We hope 

that these stories will inspire others to look more closely 

into the complex lives of individual families.
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Index

Figures in bold; Tables in italics.

Activity patterns, 15–24

Circadian activity, 16–19

resting behavior, 19–21

resting sites, 21–22

seasonal activity, 19, 30

travel to water, 21, 30

Anatomy, 3–4, 121

Anesthesia, 12, 78

Animal prey, 43–45, 121

Anthropocene, 119

Arboviruses, 88

Armadillos, 49, 53–54, 72, 89, 100, 118–119

Atlantic Forest (Mata Atlantica), 97

Avian prey, 40, 42–43, 44, 88

Beds, 21

Behavioral ecology, 4, 38, 57–58, 101

Behavioral flexibility, 97, 117–118

Birds (see Avian prey)

Caatinga biome, 121

Caching, 50

Calls (see Vocalizations)

Campo Cerrado, 6–7, 7, 10, 26, 39, 45, 48, 122

Campo de murunduns (Hummock Campo), 7

Campo Rupestre, 7

Campo Sujo, 7, 8, 10

Canine adenovirus (CAV-II), 79, 81, 84, 87, 98, 99

Canine coronavirus (CCV), 79, 84, 99

Canine distemper virus (CDV), 79, 81, 84, 87, 89, 99

Canine herpesvirus (CHV), 79, 84, 87

Canine parvovirus (CPV), 79, 81, 84, 87, 89, 99

Cavia, cavies, 23, 44, 47, 48–49

Cerradaõ, 6, 7

Cerrado, 1, 2, 5

Brazilian, 4
134 • smithsonian contributions to zoology

Cerrado (continued)

Canidae habitation, 1

climate changes, 117

ecological conditions, 1–2

ecoregion, 5

fauna, 5

flora, 5

mammals, 5

maned wolf in, 121

Chaco, 2, 5, 100, 121

Circadian activity, 16–19, 22–23

Climate

conservation and, 100–102

phenomena, 1

seasonality in wet ground habitat 

types, 9–12

unpredictable, 119

Conservation, 91–115

climate change, 100–102

cropland conversions, 97–98

domestic dogs, 98

fire and fire suppression, 100

folkloric medicine, hunting for, 

98–99

maned wolf habitat, threats to, 

102–103

Noel Kempff Mercado National Park, 

recommendations for, 103–107

population and geographic distribution, 93–97

retaliatory killing for livestock damage, 99–100

road traffic, 98

threats, 97

Crab-eating zorro vs. maned wolves, 

120–121

Creatinine kinase (CK), 81

Cropland conversion, 97–98

Deer, 39, 49–50

Dens, 21

Dentition, 4–5, 52–53

Density, 95–99

Department of Animal Health, National 

Zoological Park, 79

Diet, 38–40, 121–122

animal prey, 43–45

energetics, 46–48

food classes and seasonality, 40–43

frugivory, 45–46

qualitative analysis, 38

quantitative analysis, 38–39

resources and, variation in, 37–55

rodent, consequences of decline of, 

48–49

Dietary prey, 23, 121

Disease ecology, 123

Dispersal of young, 70–71, 73–74

Domestic dogs, 85, 87, 98

Dominance, 65, 73

Dry ground habitat types, 6–7

Ecology. See specific types of

Ectoparasites, 79, 81, 85, 88

El Niño Southern Oscillation (ENSO), 

5, 117

El Refugio Huanchaca Biological 

Station (ERH), 6, 6, 11, 120

Emas National Park, 34, 38, 78, 89, 

110

Endoparasites, 81, 85, 87–88

Energetics, 39–40, 46–48, 53–54

Ethiopian wolf, 3, 92, 118, 118

Falkland Island wolf, 5, 92

Field data analysis, 13–14

Fire and fire suppression, 46, 51–52, 55, 

75, 100

Folkloric medicine, 97, 98–99, 105

Food classes, 40–43

Fossil record, 5

Frugivory, 45–46, 51–53, 119

General movement patterns, 28–30, 

35–36

GPS

collars, 12–14, 16, 19, 26–27, 58, 61

fixes, 62, 65

PDOP, 14

sampling, 68

telemetry, 15–16, 26, 35, 57–58, 

61–65, 67, 107

Gray wolf, 3, 4, 118, 118

Helpers, 60–61, 70, 73, 117, 119

Hematology, 80–81, 82

Hidrovía, 98, 106, 107

Home range size, 27–28, 29, 34–35, 48, 

62, 123

Hummock Campo (Campo de 

murunduns), 7, 8, 9

Incremental cost of locomotion (ICL), 

40

Institutional Animal Care and Use 

Committees, National Zoological 

Park, 12

Intergovernmental Panel on Climate 

Change (IPCC), 100, 100, 101–102

International Species Information 

System (ISIS), 87

Kernel home range (KHR), 27, 28, 48, 

48, 60

Lactation, 62, 68–70, 72, 74, 87

Late Pleistocene extinctions, 5, 119

Listrophoridae, 81, 85, 88

Lobeira (Solanum lypocarpum), 38, 39, 

103, 121, 122

London Zoo, 92

Maned wolves (MW)

behavioral ecology of, 4

behavioral flexibility of, 117–118

in Cerrado, 121

crab-eating zorro vs., 120–121

dentition of, 4–5

free-living, 4, 23, 52, 53, 57–58, 78, 

80, 82–85, 86, 88

geriatric, 34, 61, 66, 81, 83, 86, 87, 89

interactions between adult pairs, 

61–65

as omnivore, 4, 4, 5, 38

omnivory, implications of, 118–119

pairs, 31, 33, 36, 48, 57–65, 59, 60, 

62, 71–72, 89, 92, 117, 123

physical characteristics of, 3–4

populations, 6, 6, 8, 26, 38–39, 55. 

78, 85, 87–89, 92–98, 94, 95, 

101–102, 103, 108–109, 108, 

109–115, 124

research on, 3–5

resting behavior, 19–21, 20, 23

resting sites, 16, 21–22, 23–24, 36

seasonal activity, 19

tallness of, 121–123

threats to, 97, 102–103

Mata Atlantica, 97

Maternal behavior, 68

Mato Grosso, 98, 110–113

Megafauna, 5, 119

Minas Gerais, 22, 35, 111–112

Minimum convex polygon (MCP), 

26–27, 30

Morbidity, 77–90. See also Mortality

ectoparasites, 81

endoparasites, 81

dental disease, 80, 81, 82

hematology, 80–81

materials and methods for, 78–80

physical findings, 80

results, 80–85

serologic testing, 81

serum chemistry, 81

spondylarthropy, 82, 86

urinary findings, 83

Mortality, 83–85. See also Morbidity

National Zoological Park, 12, 57, 79

Noel Kempff Mercado National Park

conservation, recommendations for, 

103–107

fauna of, 8

flora of, 8

geographic demographics of, 6

geology of, 8
number 639 • 135

habitats of, 8

population of, 6

rainfall at, 9–12

Omnivores, 4, 4, 5, 118

Packed blood cell volumes (PCV), 79, 

80–81, 82, 87, 89

Pampa arbolada, 7

Pampas de bajíos, 7–8

Pampa termitero (termite savanna), 7, 8, 

9, 10, 39, 45, 48, 51, 58

Paternal behavior, 68–70

Philopatry, 73

Pocock, Reginald, 92

Population viability analysis (PVA), 93, 

96, 108

Pozo Matt (PM), 8, 12, 28, 32, 33, 123

Prey, 39, 48. See also specific types of

Problem animals, 99–100

Qualitative analysis, 38

Quantitative analysis, 38–39

Rabies virus, 79, 84, 85, 89, 99, 

106–107, 123

Radio-tracking, 8, 12–13

Rainfall, 5, 9–12, 11, 14, 20, 51, 93, 

101

Ranging patterns, 25–36

general movement patterns, 28–30

home range size, 27–28

territoriality, 31–34

travel distance, 28–30, 121

travel rate, 28, 121

water, 30–31

Red fox, 118

Reproduction. See Social interactions 

and reproduction

Rest sites, 21–23

Resting, 19–21, 20

Resting energy expenditure (REE), 40

Resting energy requirement (RER), 

39–40

Retaliatory killing for livestock damage, 

99–100

Road traffic, 98

Roar-bark vocalizations, 65–67, 66, 72

Rocky Mountain spotted fever, 88

Rodents, 3, 23, 48–49, 97, 103

Sao Paulo, 95, 108, 112

Scavenging, 49–50

Seasonality, 9, 40–43, 67

Serologic testing, 79, 81

Serum chemistry, 81

Short-generation prey, 119

Size, value of, 119–123

Smithsonian Conservation Biology Institute, 4, 78, 89

Smithsonian National Museum of Natural History, see National Museum 

of Natural History

Smithsonian National Zoological Park, 

see National Zoological Park

Social groups, 119

Social interactions and reproduction, 

57–75

dispersal of young, 70–71

interactions between adult pairs, 

61–65

maternal behavior, 68

pair formation, 59–61

paternal behavior, 68–70

reproductive behavior, 67

results of, 59–71

roar-bark vocalizations, 65–67

seasonality, 67

territory acquisition, 59–61

Socioecology, 4, 75

Teeth, 52–53, 80–81, 83 

Termite Pampa, see Pampa termitero

Termite savanna, see Pampa termitero

Territoriality, 31–34, 36

Territory acquisition, 59–61

Trapping, 12–13, 54

Unpredictable climate, 54, 119

Urinary findings, 83

Vertebrate prey, 4, 47–48

VHF radio collars, 12

Viability analysis, 93

Viruses. See specific types of

Vocalization, 65–67

Water, 10, 21, 21, 23, 30–31, 31, 

35–36, 121

availability of, 2, 9, 16, 100–102

Wet ground habitat types, 7–12

climate and seasonality, 9–12

Hummock Campo, 7

Pampas de bajíos, 7–8

White blood cell (WBC) counts, 79

Wolf fruit, 38, 121
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References should be in alphabetical order, and in chronological order for same-author entries. Each reference should 

be cited at least once in main text. Complete bibliographic 

information must be included in all citations (e.g., author/editor, title, subtitle, edition, volume, issue, pages, figures). For 

books, place of publication and publisher are required. For 

journals, use the parentheses system for volume(number):pagination [e.g., “10(2):5–9”]. Do not use “et al.”; all authors/

editors should be included in reference citations. In titles, 

capitalize first word, last word, first word after colon, and all 

other words except articles, conjunctions, and prepositions. 

Examples of the most common types of citations are provided 

in the SISP Manuscript Preparation and Author Style Guide. 

For questions regarding the guidelines, please email SISP at 

schol_press@si.edu. 

requirements for smithsonian series publication