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smithsonian contributions to zoology • numb e r 6 4 8

The Annual Cycle and 

Natural History of a 

Subtropical Atlantic Forest 

Avifauna in Paraguay

Mercedes S. Foster and Ned K. Johnson

WASHINGTON D.C.

2017
ABSTRACT

Foster, Mercedes S., and Ned K. Johnson. The Annual Cycle and Natural History of a Subtropical Atlantic Forest Avifauna in Paraguay. Smithsonian 

Contributions to Zoology, number 648, viii + 84 pages, 8 figures, 2017. — We studied the avifauna in a subtropical humid forest around Hotel El 

Tirol, Department of Itapúa, Paraguay. The study site is part of the Atlantic Forest biome, a critically endangered biodiversity hot spot. We recorded 

205 species of birds in 45 families and provide information on their annual cycles and natural history from collected specimens and field observations. 

Increased knowledge will contribute to efforts to maintain and manage the bird species of this endangered biome. The annual cycle of the avifauna at El 

Tirol closely resembled that of birds at north temperate and subtropical latitudes. Birds entering reproductive phases were likely responding to increasing 

photoperiod and rainfall. In general, breeding was initiated in mid-August and began to decline in late November. Molt rose sharply in early December 

and continued into April, overlapping with breeding in 16 species. In some species, males replaced juvenal plumage with an immature plumage easily 

distinguishable from the adult form, which they acquired after several years. Most males in immature plumage bred. For most species skull pneumatization in young of the year was completed during their first year. In several species, however, the pneumatization process extended into year 2, and in 

other taxa, complete pneumatization requires multiple years or never occurs. The birds at El Tirol were predominantly insectivorous. About a quarter 

of the specimens in 134 species had noticeable body fat. In general, fat deposition peaked in June, with lesser peaks from February to mid-March and 

in late August and September. Twenty-seven of the species that we recorded were migratory. We compared the species of birds recorded at El Tirol with 

those recorded from San Rafael National Park, a large tract of Atlantic Forest farther north in Paraguay with a much more extensive avifauna. Some of 

the species we failed to record were likely overlooked. However, El Tirol is at the southwestern limit of the Atlantic Forest habitat; absences may reflect 

faunal attenuation as species reach the limits of their ecological ranges. The lower numbers may also indicate that diversity in forest patches is reduced. 

Regardless, such patches will play an important role in maintaining the Atlantic Forest avifauna.

RESUMEN

Foster, Mercedes S., and Ned K. Johnson. El Ciclo Anual y la Historia Natural de una Avifauna Subtropical, de Bosque Atlántico en Paraguay. Smithsonian Contributions to Zoology, número 648, viii + 84 páginas, 8 figuras, 2017. — Se estudió la avifauna en bosque húmedo subtropical alrededor del Hotel 

El Tirol, Departamento de Itapúa, Paraguay. El sitio de estudio es parte del bioma del Bosque Atlántico, un área de alta biodiversidad en estado crítico 

de conservación. Se registraron 205 especies de aves en 45 familias; se proporciona información sobre sus ciclos anuales e historia natural con base en 

los especímenes y las observaciones de campo. Un mayor conocimiento puede contribuir a los esfuerzos de conservación y manejo de las aves de este 

bioma amenazado. El ciclo anual de la avifauna en El Tirol se asemeja al de las aves en latitudes templadas y subtropicales del hemisferio norte. Las aves 

entrando en fase reproductiva probablemente responden al aumento del fotoperiodo y de la precipitación. En general, la época reproductiva comenzó a 

mediados de agosto y declinó a finales de noviembre. La ocurrencia de muda aumentó considerablemente a principios de diciembre y continúo todavía 

en abril. Muda traslapa con la cría en 16 especies. En algunas especies, los machos sustituyen el plumaje juvenil con un plumaje inmaduro fácilmente 

distinguible de la forma adulta, que adquieren después de varios años. La mayor parte de los machos en plumaje inmaduro se reprodujeron. Para la 

mayoría de las especies la neumatización (u osificación) del cráneo en juveniles se completó durante el primer año. En varias especies, sin embargo, el 

proceso de neumatización se extendió hasta el segundo año y en otros taxones la neumatización completa requirió varios años o nunca se completó. Las 

aves en El Tirol fueron predominantemente insectívoras. Aproximadamente una cuarta parte de los especímenes estudiados para 134 especies llevaba 

grasa corporal notable. El acúmulo de grasa alcanzó su máximo en junio, con picos menores desde febrero a mediados de marzo y a finales de agosto y 

septiembre. Veintisiete de las especies registradas eran migratorias. Comparamos las especies de aves registradas a El Tirol con éstas conocidas desde el 

Parque Nacional San Rafael, una gran extensión de Bosque Atlántico más al norte en el Paraguay y con una avifauna mucho más extensa. Algunas de las 

especies que no se registraron fueron probablemente pasadas por alto. Por otro lado, El Tirol está en el límite suroeste del Bosque Atlántico, y la ausencia 

de algunas especies pudiera reflejar la atenuación faunística que se presenta cuando las especies alcanzan los límites de sus rangos ecológicos. El menor 

número también puede indicar que la diversidad en los parches de bosques se reduce. Independientemente, dichos parches cumplen un papel importante 

en mantener la avifauna del Bosque Atlántico.

Cover image: Detail of Figure 2.

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Library of Congress Cataloging-in-Publication Data

Names: Foster, Mercedes S., author. | Johnson, Ned K., author. | Smithsonian Institution Scholarly Press, publisher.

Title: The annual cycle and natural history of a subtropical Atlantic Forest Avifauna in Paraguay / Mercedes S. Foster and Ned K. Johnson.

Other titles: Smithsonian contributions to zoology ; no. 648. 0081-0282

Description: Washington, D.C. : Smithsonian Institution Scholarly Press, 2017. | Series: Smithsonian contributions to zoology, ISSN 0081-0282 ; number 

648 | Includes bibliographical references and index.

Identifiers: LCCN 2016059155

Subjects: LCSH: Forest birds—Paraguay—Mata Atlântica—Identification. | Birds—Paraguay—Mata Atlântica—Identification.

Classification: LCC QL689 .P2 F67 2017 | DDC 598.17/88—dc23 | SUDOC SI 1.27:648

LC record available at https://lccn.loc.gov/2016059155

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

ZooBank registration: 19 April 2017 (LSID urn:lsid:zoobank.org:pub:82C5E94D-FF3B-4CB8-8885-D26BA168C93A)

Publication date (online): 1 May 2017

Ó 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.
Dedication

A favorite outing for people of all ages is a visit to a museum of natural history. There one can view 

examples of our natural world and learn about the characteristics of and interactions among the plants, 

animals, rocks, fossils, and other objects that make up our environment, and the innumerable ways 

they affect the human species. The mission of many natural history museums, however, extends far 

beyond this diffusion of knowledge, to include its creation. Much of the information relating to the 

natural world that is imparted by exhibits or through articles, books, documentaries, and other media 

is a product of scholarly research. This research is carried out by museum curators in the field when 

obtaining specimens and in the museum during the study of those specimens. The specimens upon 

which this report is based have been distributed among three such research-oriented museums.

Specimens in natural history museum collections are the basis of studies that touch every aspect 

of human lives. They are critical to our economic, political, and physical well-being. At the most 

fundamental level they tell us about the existence and distributions of organisms and their habitats, 

of geological formations, and the physical attributes of our world and the universe, through space and 

time. This information is used to chronicle biodiversity and extinctions, to locate mineral and energy 

deposits, to reconstruct the climate and ecological history of the Earth, and to monitor the evolution 

and movements of pests and pathogens and their effects on human health and agriculture.

In 1979, the Paraguayan National Forest Service, through the efforts of Ing. Hilario Moreno and Peace 

Corps (U.S.) volunteers David Wood and Diane Wood, initiated a program to inventory the flora and 

fauna of Paraguay as a basis for ensuring the conservation and proper management of Paraguay’s 

natural resources. This endeavor included the establishment of a National Museum of Natural History 

to house specimens that would be collected to document their findings and to provide materials for 

future research. Although early naturalists working in Paraguay, such as Moisés Bertoni (1857–1929), 

a botanist, meteorologist, and anthropologist, had maintained collections of specimens, many had been 

lost, and more recent material was needed. 

Planning for the museum began in 1979, and it was established in 1980. With the collaboration of 

individuals and support from institutions such as the U.S. Fish and Wildlife Service, the Peace Corps, 

the Carnegie Museum of Natural History, the Missouri Botanical Garden, the Smithsonian Institution, 

the World Wildlife Fund, the U.S. Agency for International Development, and many others, Paraguayan 

biologists were trained in field techniques and museum practices and studied for postgraduate degrees. 

Since that time, they have carried out scientific expeditions throughout the country and have built a 

collection of more than a million specimens, published checklists of organisms, named new species, 

and generally contributed to our knowledge of the systematics and ecology of the Paraguayan biota. 

They also promote the conservation and preservation of resources and encourage good management 

practices. They continue to do research, train successive generations of museum scientists, and develop 

educational and outreach programs for students and the general public.

In recognition of their unwavering efforts and significant contributions to scientific research, 

conservation, and education, we dedicate this work to the personnel and associates (past, present, 

and future), of the Museo Nacional de Historia Natural del Paraguay, Instituto Forestal Nacional, 

San Lorenzo, Paraguay.

Contents

LIST OF FIGURES vii

INTRODUCTION 1

STUDY AREA 2

METHODS 5

Specimens 5

Terminology and Aging 6

Analyses 6

RESULTS 6

Species Accounts 7

Hypotheticals 58

DISCUSSION 59

Skull Pneumatization 59

Reproduction 59

Plumage 60

Molt 61

Diet 61

Fat Deposition 62

Migration and Local Movements 62

Annual Cycle 63

Other Records from Hotel El Tirol 63

Comparison with Avifaunas at Other Sites 64

CONCLUSIONS 64

ACKNOWLEDGMENTS 65

APPENDIX A 67

APPENDIX B 71

REFERENCES 73

INDEX 77

Figures

Frontispiece. Looking east from Hotel El Tirol viii

1. Map of Paraguay 2

2. Network of forest patches and connecting corridors 3

3. Subtropical humid forest 4

4. Forest interior along a stream 4

5. Tung orchard 4

6. Mean monthly rainfall 5

7. Mean monthly temperatures 5

8. Timing of events in the annual cycles of birds 60
FRONTISPIECE. Looking east from the grounds of Hotel El Tirol, Department of Itapúa, Paraguay.
INTRODUCTION

When Foster first went to Paraguay in 1976 to study birds, she relied on Meyer 

de Schauensee’s A Guide to the Birds of South America (1970) to identify the species 

she encountered. The book included primarily plumage descriptions and information 

on habitat and geographic and elevational distributions. Basic? Yes. Incomplete? Yes 

again, but supremely useful. One can only admire and respect an individual who would 

endeavor to make the highly diverse avifauna of an entire continent accessible to everyone. Since then, superbly illustrated comprehensive field guides to birds in countries or 

regions of South America have proliferated, seemingly exponentially. The quality and 

accuracy of the information and images have increased markedly, as has the breadth of 

coverage, with notes on vocalizations, nesting, and migration included for many species 

(e.g., see Restall et al., 2007a, 2007b; Ridgely and Tudor, 2009). At the same time, flourishing communities of trained ornithologists, avian ecologists, and avian systematists in 

South America are publishing prolifically on the biology of species found in their countries, as are biologists from other continents. Studies tend to focus on the distributions, 

abundances, and systematics of birds, particularly threatened species and endemics. Such 

information is critical for identifying and prioritizing areas for protection.

Despite the rapid increase of available information, however, the ecology and natural history of most South American bird species remain poorly known (Marques-Santos 

et al., 2015). Equally limited are studies of the ecology and natural history of avian 

communities from single localities or habitats that present an avifauna as an integrated 

whole. Such information provides a critical baseline for the pursuit of more detailed studies of individual species, interactions among bird species, and interactions between birds 

and their prey, predators, or competitors. It also supports efforts to conserve or protect 

habitats and species or, if necessary, to manage them, through an understanding of how 

the latter function and persist (or not) in pristine and disturbed areas.

Avifaunal studies are concerned with species composition (phylogenetic or ecological) or functional activities (e.g., reproduction, molt, dispersal/migration) within the 

community and their timing (Miller, 1963; Willard et al., 1991). Most commonly, the 

functional activities of birds are completed in a single year and collectively are referred 

to as the annual cycle. A few species complete the events over a longer or shorter period 

(e.g., Miller, 1962). Our knowledge of annual cycles of South American birds is limited 

The Annual Cycle and Natural History 

of a Subtropical Atlantic Forest 

Avifauna in Paraguay

Mercedes S. Foster1* and Ned K. Johnson2†

1 U.S. Geological Survey Patuxent Wildlife 

Research Center and Division of Birds, National 

Museum of Natural History, Smithsonian Institution, P.O. Box 37012, MRC 111, Washington, 

D.C. 20013-7012, USA.

2 Museum of Vertebrate Zoology and Department of Zoology, 3101 Valley Life Science Building, University of California, Berkeley, California 

94720-3160, USA.

* Correspondence: M. S. Foster, fosterm@si.edu

† Deceased 11 June 2003.

Manuscript received 21 March 2016; accepted 

1 November 2016.
2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

The patch of forest at El Tirol is connected to other forest 

patches through a network of corridors. We provide information 

on the species composition of the avifauna of this forest network 

as well as information on the annual cycles, plumages, diets, behaviors, and other aspects of the natural history of the included species. 

Our study is based on field observations and collected specimens. 

Internal examination of specimens provided information on the 

timing of events (e.g., reproduction, fat deposition) in the annual 

cycle, on development of the cranium and reproductive systems, 

and on diet that cannot be obtained from field observations and 

revealed differences among species and within species between 

sexes and age groups. By increasing knowledge of individual species and the avifauna as a whole, we hope to contribute to efforts 

to maintain and manage the avifauna in remnant patches of this 

endangered biome as well as in large remaining areas of forest.

STUDY AREA

The study was conducted in the general area of Hotel El 

Tirol, 27°11′S, 55°47′W (main building, elevation ~250 m, 

Google Maps, 30 October 2015), and its surrounds (Figure 1) 

intermittently between 1976 and 2004. In 1976, when the study 

was initiated, the entrance to El Tirol was located along a dirt 

road ~19.5 km NNE of Encarnación, the closest city. The road, 

and can be subject to two biases. The first bias, which is common to many vertebrate classes and relevant to any geographic 

region, is the concentration of studies in the primary or expected 

breeding season. This limits understanding of activities during 

other parts of the annual cycle and their effects on those occurring during the breeding season (Marra et al., 2015). The second 

bias is a consequence of modern scientific ornithology having 

developed primarily in Northern Hemisphere temperate regions, 

which may unconsciously influence the ways in which studies are 

designed and data are analyzed and interpreted, through predetermined expectations. This bias can be eliminated only with a 

much greater knowledge of the natural history and annual cycles 

of species and avifaunas from all latitudes.

In this publication we report on the avifauna of an area of 

Southern Hemisphere subtropical humid forest in the vicinity of 

Hotel El Tirol del Paraguay, Department of Itapúa, Paraguay. 

The site lies at the southwestern limit of the Atlantic Forest 

biome of South America, a highly diverse and critically endangered habitat that has been reduced to 7.5% to 15% of its original extent (Myers et al., 2000; Galindo-Leal and de Gusmão 

Câmara, 2003; Ribeiro et al., 2009). Although efforts are being 

made to protect large areas of this habitat, smaller patches connected by riparian, windbreak, and other corridors will play a 

significant role in maintaining many species of birds and other 

organisms that comprise its diversity.

FIGURE 1. Map of Paraguay showing the location of Hotel El Tirol, various Paraguayan national parks, and other places mentioned in the text.
NUMBER 648 • 3

at the hotel, but the area had not been logged perhaps, since the 

time of the Jesuit reductions in the early 1700s. Trails had been 

cut through the forest for visitor access, and a dirt road accessed 

a small garden area with a stream diverted for irrigation. Brown 

capuchin monkeys (Sapajus cay) were sighted regularly; ninebanded armadillo (Dasypus novemcinctus), white-eared opossum 

(Didelphis albiventris), crab-eating fox (Cerdocyon thous), and 

lesser grison (Galictis cuja) were also recorded.

The El Tirol forest was continuous with other patches of 

forest or connected to them by broad corridors of forest along 

streambeds (Figure 4). In other areas, it abutted orchards of tung 

trees (Vernicia fordii, Euphorbiaceae; Figure 5) and castor beans 

(Ricinus communis, Euphorbiaceae), cultivated fields of yuca, or 

cassava (Manihot esculenta, Euphorbiaceae), tall second-growth 

forest originally planted in coffee or other crops, abandoned 

fields in early stages of regeneration, or pastures. Our work was 

concentrated in the El Tirol forest; the Becker forest, a larger 

patch of relatively undisturbed forest about ~1 km SSE of the 

hotel; other smaller forest patches; and the corridors connecting 

them, with occasional forays into the other habitats.

Foster visited the hotel briefly in 1995 and worked there 

again in 2004. Sometime in the late 1980s or early 1990s, the 

road from Encarnación was significantly widened, improved, 

paved, and extended to Ciudad del Este (formerly Puerto President Stroessner) via routes 6 and 7, ~285 km away by road. By 

which was closed when it rained, ended about ~55 km farther 

on at Capitán Meza. From there, relatively undisturbed tall 

humid forest, with few incursions and farms, extended NNE to 

the vicinity of Puerto Presidente Stroessner (renamed Ciudad del 

Este in 1989), some 165 km away as the crow flies.

The hotel property consists of rolling hills (moderately 

steep hillsides and level areas) spanning an elevational range 

from about 190 to 265 m above sea level (see Frontispiece and 

Figure 2). The area is dissected by streams fed by natural springs, 

rain, and runoff that flow east and northeast, eventually reaching 

the Paraná River. Natural seeps are also found in the forest and 

with the springs may give rise to small boggy areas. The soil is 

red clay with exposed sandstone outcroppings. When we worked 

there from 1976 to 1983, about 50 ha of hotel land were covered in humid forest with a 25-m canopy (Figure 3). This tall, 

humid forest formation is described in Lopez and Little (1987) 

and Keel et al. (1993), along with notes on the dominant tree 

species. Epiphytic Tillandsia usneoides (Bromeliaceae) commonly 

draped the trees. The relatively open understory was periodically interrupted by tangles of Chusquea (Poaceae) bamboo often 

mixed with lianas; the ground layer included a high diversity 

of ferns (Smith and Foster, 1984). Tree ferns, Nephelea setosa

(Cyatheaceae), occurred along the creeks, and monospecific 

stands were occasionally found on hillsides in the forest. At that 

time, selected trees had been removed to provide timber for use 

FIGURE 2. Network of forest patches and connecting corridors with interspersed pastures and cultivated 

fields in the vicinity of Hotel El Tirol, Department of Itapúa, Paraguay.
4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

1995, the habitat between El Tirol and Ciudad del Este, as far 

as one could see from the road, had been largely converted to 

commercial soybean production. Nevertheless, the forest around 

the hotel continued to interconnect along streambeds with other 

patches of forest, although some had been reduced in size or 

degraded with the removal of selected trees. No monkeys were 

encountered in the forest by three individuals during nearly a 

month of field work in 2004.

Daily rainfall data for January 1971 to September 1982 were 

obtained from records taken by Armando Reynaerts at Hotel El 

Tirol. Days with rain per month vary little (range of mean days/

month = 5.5–8.0) over the course of the year (Figure 6). The 

amount of rain falling each month is considerably more variable, 

with the rainiest season extending from October through December and the least rain falling in July. The most striking feature 

of the rainfall pattern is the great fluctuation in the amount of 

rain falling in any given month between years (Figure 6). Daily 

FIGURE 4. Forest interior along a stream near Hotel El Tirol, 

Department of Itapúa, Paraguay.

FIGURE 5. Tung (Vernicia fordii) orchard near Hotel El Tirol, 

Itapúa, Paraguay. This habitat is used by many species of birds, 

including Columbina talpacoti, Guira guira, and Sicalis flaveola.

Nests of a Patagioenas picazuro and a Troglodytes aedon were 

found here.

FIGURE 3. Subtropical humid forest in the vicinity of Hotel El 

Tirol del Paraguay, Department of Itapúa, Paraguay, which is 

located at the southwestern limit of the Atlantic Forest biome.
NUMBER 648 • 5

of collection, (4) soft-part colors, as noted by the person preparing the specimen, (5) mass determined with spring balances 

graduated in 0.2-, 0.5-, 1.0-, or 2.0-g increments, in accordance 

with the size of the bird, (6) fat condition, which is a subjective 

designation (but see Foster and Cannell, 1990), as light (includes 

slight), medium, or heavy, (7) skull pneumatization (or ossification) as a potential indication of age, (8) sex based on examination of the gonads, (9) reproductive condition, (10) presence 

and extent of molt, (11) plumage stage, (12) stomach contents, 

classified as mammals, insects, noninsect arthropods (e.g., spiders, millipedes), fruit, seeds, plant material, or “other” (e.g., 

nonarthropod invertebrates, corn), (13) habitat, and (14) miscellaneous observations on habitat, behavior, vocalizations, nests, 

or ecology. We used a single locality (i.e., El Tirol, 19.5 km by 

road ~NNE of Encarnación, Department of Itapúa, Paraguay, 

elevation 230 m) for all specimens taken on the hotel property 

or adjacent properties, unless otherwise noted. Skull pneumatization was loosely designated as juvenal skull or skull not pneumatized (little to no pneumatization), immature skull or skull with 

large windows (or noted as percent of the skull pneumatized), or 

adult skull or skull with small skull windows (pneumatization 

nearly complete) or completely pneumatized. For reproductive 

condition, male characteristics included length or length × width 

(mm) of the left testis, testis color if other than white or cream, 

and presence of a cloacal protuberance. Female characteristics 

included diameters (diam) of the largest ova, presence or absence 

temperature data for Capitán Miranda, a town ~4 km SW of El 

Tirol, were obtained for January 1964 to August 1982 from the 

Meteorological Service of the Ministry of Defense in Asunción 

(Figure 7). It is warmest during the summer months of November through February and coldest from May through August, 

when it may occasionally freeze. Mornings are often foggy, especially following a nighttime rain.

METHODS

For his study of the distribution and biogeography of Paraguayan birds, Hayes (1995) divided the country into seven 

geographical regions based on various environmental characteristics. El Tirol is located in his Alto Paraná region, which he 

characterized as having hilly terrain dominated by humid forest 

with abundant rainfall.

The El Tirol collections and observations were made from 

1976 to 1983 and in 2004 for a total of about 27 person-months. 

Because the work was carried out incidental to other research 

(e.g., Foster, 1981, 1987, 1990; Zink and Johnson, 1984; Johnson and Zink, 1985), collecting efforts were not evenly distributed over all months, and no collections were made in April or 

July. However, we were able to obtain a sample for many species 

from every calendar month in which we were present. We worked 

primarily in mature forest habitats, only occasionally collecting in 

pastures, croplands, orchards, and scrubby second growth.

Specimens

Bird specimens were prepared according to standard museum 

methods as round skins, flat skins, or skeletons or preserved in 

10% formalin buffered with MgCO3

. Standard data (see Foster 

and Cannell, 1990) were recorded for each specimen, including 

the following: (1) collector and field number, (2) locality, (3) date 

FIGURE 6. Mean monthly rainfall at Hotel El Tirol, Department 

of Itapúa, Paraguay, January 1971–September 1982. Ranges of 

the amount of rain falling in any given month illustrating the 

striking variability between years are noted adjacent to dots.

FIGURE 7. Mean monthly maximum and minimum temperatures at Capitán Miranda, a town ~4 km SW of Hotel El Tirol, 

Department of Itapúa, Paraguay, January 1964–August 1982.
6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

following hatching. The feathers are lax, often downy and dull, 

and recognizably different morphologically from subsequent 

plumages. The “immature” plumage follows and is distinct from 

the juvenal plumage; it may be equivalent to the definitive plumage or distinct from it in color and pattern. Finally, these descriptive terms are also used to refer to reproductive status. The 

gonads of juveniles are tiny and undeveloped, and the birds are 

not yet capable of breeding. Immatures have developed gonads, 

although they may be smaller than those of adults, but the birds 

have not yet bred. Adults have fully developed gonads (although 

testes especially may be small following postbreeding regression) 

and are either breeding or have bred previously. In north temperate birds the stages of development (juvenal, immature, adult) 

of the skull, plumage, and gonads generally coincide, and the 

terms are used with little confusion. However, in various tropical 

and subtropical bird taxa, the stages are not coincident (e.g., a 

breeding bird with mature gonads may have an immature skull 

or plumage). Investigators using the terms juvenal (juv), immature (imm), and adult (ad) in reference to a particular specimen 

often do not indicate the character(s) to which the designation 

refers. Until the ornithological community reaches a consensus 

about their implied meanings, readers should be careful to note 

the characteristic to which such adjectives have been applied.

Analyses

For the purposes of analysis, data were combined into 

bimonthly intervals (days 1–15 and 16–31) and (with the exception of diet) were considered on the basis of percentages of species for which at least one collected specimen showed evidence 

of the activity (e.g., breeding, molt) in question. Percentages of 

specimens that showed evidence of an activity generally closely 

track percentages for species, but use of the latter eliminates the 

influence of differences among species in numbers of individuals 

collected. For analyses of diet, specimens with empty stomachs 

were excluded from the calculations. Values are percentages of 

specimens with food items in the stomach or percentages of species for which at least one specimen contained food, not percentages of all specimens or species. Specimens with more than one 

type of food in the stomach were counted once in each food 

category represented, so combined percentages can exceed 100.

RESULTS

During the study, 1,887 specimens representing 187 species 

in 43 families were collected. An additional 17 species, including 

two additional families, were identified with confidence by sight. 

The latter species are indicated in the accounts with an asterisk. 

All species are listed in Appendix A. Eleven resident species were 

sampled in all 10 calendar months covered by our study (January–

March, May–June, August–December), 9 species were sampled 

in 9 months, and 8 were sampled in 8 months. Eight species of 

migrants were sampled in 6 to 8 calendar months. Specimens 

collected include 1,401 study skins, 384 skeletons, 94 fluid 

of yolk as indicated by color, presence of collapsed follicles, and 

enlargement of the oviduct. Surface texture of the ovary was 

noted if ova were not distinguishable (i.e., smooth, granular, or 

lumpy). For both sexes, the presence of an incubation patch was 

noted. Molt included the presence or absence of body, wing, and 

tail molt. The degree of body molt is a subjective designation as 

light (scattered feathers in several tracts, a few pin feathers at the 

beginning of molt or mostly remnant sheaths toward the end), 

moderate (more feathers in most tracts), or extensive or heavy 

(many feathers in all tracts). Molt was designated as prejuvenal (= 

postnatal), first prebasic (= postjuvenal), second and later prebasic (= postnuptial), or prealterate (= prenuptial), if distinguishable 

(see Humphrey and Parkes, 1959). Birds with unpneumatized 

skulls and tiny undeveloped gonads and/or extensive juvenal 

plumage were generally assumed to be undergoing their first prebasic molt. Those with fully pneumatized skulls and developed 

gonads were assumed to be in a later prebasic molt. Juvenal or 

immature plumages were described if different from the definitive 

plumage of adults, as were definitive plumage characteristics differing from those found in Ridgely and Tudor (2009). For stomach contents, taxa names of plants are provided if known but do 

not imply that these are the only taxa eaten.

Preliminary species identifications were made in the field and 

verified by comparison with museum specimens on our return. 

Scientific names, linear sequences, and common English names 

follow those of the American Ornithologists’ Union’s South 

American Classification Committee (Remsen et al., 2016). Plant 

names follow Tropicos (Missouri Botanical Garden, 2015–2016). 

Status as an Atlantic Forest endemic follows Brooks et al. (1999).

Specimens are deposited in the collections of the U.S. 

National Museum of Natural History (USNM) in Washington, 

D.C., Museum of Vertebrate Zoology (MVZ) at the University 

of California, Berkeley, and Muséo Nacional de Historia Natural del Paraguay (MNHNP) in San Lorenzo, Paraguay. Collections of tissues are deposited in MVZ’s Tissue Collection. Sound 

recordings are deposited in the Laboratory of Natural Sounds at 

MVZ. Field notes of Johnson (NKJ), Carla Cicero (CC), Robert 

E. Jones (REJ), and Robert M. Zink (RMZ) are available at the 

MVZ, and those of Foster (MSF) are at the USNM. Specimens 

were collected and exported from Paraguay and imported into 

the United States with permits issued by the Ministry of Agriculture, Secretaría del Ambiente, and Servicio Forestal Nacional of 

Paraguay and the U.S. Fish and Wildlife Service.

Terminology and Aging

A few comments about terminology and aging of passerines 

are in order. The term “adult” when referring to the skull signifies that the skull is fully pneumatized. An “immature” skull is 

partially pneumatized, and a “juvenal” skull shows very little 

to no pneumatization. When these same terms are used in relation to plumage, “adult” signifies the definitive basic plumage, 

whose aspect rarely changes except with the intermittent addition and loss of specialized feathers associated with breeding. 

The “juvenal” plumage is the first complete feather covering 
NUMBER 648 • 7

Notes. Groups of 1–3 feeding 3–5 m up in fruiting 

trees in Mar, Sep, and Oct.

Family Odontophoridae: New World Quails

Odontophorus capueira: Spot-winged 

Wood-quail

Specimens (MVZ). ♂ Jan (1), adult skull.

Mass (g). 335.

Iris. Brown.

Facial Skin. Orange.

Feet and Tarsi. Slate gray.

Gonads. Testis 6 × 12 mm.

Molt. Wing and body feathers.

Stomach Contents. Seeds.

Habitat. Mature forest and old second growth.

Notes. Observed in Feb, Mar.

Family Ardeidae: Herons

Syrigma sibilatrix: Whistling Heron

Specimens (MVZ). ♂ Feb (1).

Mass (g). 490, light fat.

Iris. White.

Bill. Pink proximally, black distally. Mouth lining pink.

Facial Skin. Bare skin around eyes powder blue.

Feet and Tarsi. Black.

Gonads. Testis 7 × 3 mm.

Molt. Wing and body feathers.

Stomach Contents. Orthopteran remains.

Habitat. Marshy pasture.

Notes. Generally observed as singles or pairs flying 

overhead, standing in wet grass or on stumps, or perched in 

snags in pasture areas. Flushed 8 or 9 birds roosting together in 

a stand of introduced Pinus sp. (Pinaceae) trees. Observed in Jan, 

Feb, Mar, Jun, Oct, and Nov.

Family Cathartidae: New World Vultures

Cathartes aura*: Turkey Vulture

Notes. Occasionally observed (NKJ, MSF, RMZ) 

soaring over fields and forest in groups of 1 to 4 individuals in 

Oct, Nov, Jan, Feb, Mar. Not observed at carcasses of a dead 

horse or a dead calf where black vultures were feeding.

Coragyps atratus: Black Vulture

Specimens (MVZ). ♂ Feb (1).

Mass (g). 1,735.

Iris. Brown.

Bill. Black basally, green distally. Mouth lining green, 

tinged white.

specimens, and 8 nests and/or eggs. Data for each species are summarized in the following accounts. Initials in parentheses following “Specimens” indicate the museum collections in which they 

are deposited. Sound recordings were made of the calls or songs 

of 55 of the bird species but are not considered in this paper.

Species Accounts

Family Tinamidae: Tinamous

Crypturellus tataupa: Tataupa Tinamou

Specimens (MVZ, MNHNP). ♂♂ Mar (1), Sep (1). 

♀ Jun (1).

Mass (g). ♂♂ 205 (Mar, light fat), 268 (Sep, extremely 

fat). ♀ 243.

Iris. Greenish or brown.

Bill. Pale purplish pink, reddish yellow, or orange with 

pale tip. Mouth lining light green.

Feet and Tarsi. Pale purple to purplish pink.

Gonads. ♂♂ Testis 14 × 8 mm (Mar), 24 × 13 mm 

(Sep). ♀ Ovary granular, ova ≤ 1 mm.

Molt. Body and flight feathers (Mar).

Stomach Contents. One with fruit; 1 with seeds.

Habitat. On the ground in mature forest with some 

undergrowth, but fairly open. Also occasionally flushed in cornfields and in dense, tall (≥1 m) grass in scrubby pasture.

Notes. Heard calling commonly in the early morning 

and late afternoon in all months. Birds often counter call, and 2 

birds are often seen together. ♂ tending a nest on 25 Sep, more than 

a week earlier than the earliest egg date reported by Hayes (2014) 

from Sapucái, a locality ~200 km NNW of El Tirol (Figure 1). The 

clutch was also larger, consisting of 6 smooth mauve-colored eggs 

with a dull lustrous finish. The eggs averaged 43.0 mm greatest 

length (standard deviation [SD] = 1.09, range = 41.2–44.0, N = 6) 

× 31.0 mm greatest width (SD = 0.88, range = 30.1–32.5, N = 6). 

Three young observed walking in the forest in Feb.

Family Cracidae: Guans

Penelope superciliaris: Rusty-margined Guan

Specimens (MVZ). ♂ Oct (1).

Mass (g). 640.

Iris. Chestnut brown.

Bill. Blackish brown.

Facial Skin. Skin around eyes and upper throat blue 

gray. Rest of throat and dewlap orange red.

Feet and Tarsi. Legs dusky with faint grayish-purple 

or grayish-pink cast. Toe pads yellowish green.

Gonads. Testis 12 × 5 mm.

Molt. No.

Stomach Contents. Two hard, brown fruits.

Habitat. Understory of mature forest and old second 

growth.
8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Stomach Contents. Small insects.

Habitat. Forest, old second growth; soaring over pasture and open areas.

Notes. A northern austral migrant. Species observed 

regularly from mid-Sep through Jan. Courtship flights over forest 

and fields observed in early Oct. Adult observed in Jan feeding 

a 10-cm-long stick insect (Phasmatodea) to a full-grown juvenile 

(but with a few down feathers remaining) perched at the top of a 

forest tree. Call a piercing whistle.

Rupornis magnirostris: Roadside Hawk

Specimens (MVZ). ♀♀ Oct (1), adult plumage; Feb 

(1), juvenal plumage.

Mass (g). 368 (adult); 345 (juvenile).

Iris. Dark brown.

Bill. Juvenile: Upper mandible bluish gray with black tip. 

Lower mandible yellow green at base, then bluish gray with black tip.

Facial Skin. Juvenile: cere orange; line around gape 

yellowish green; eyelid yellowish green; plate over eye olive green.

Tarsi. Juvenile: yellow orange with greenish tinge; toes 

orange yellow.

Gonads. Adult ♀ ready to lay, with orange ova 20 and 

11 mm diam. Juvenile ♀ with undeveloped double ovary.

Molt. No.

Stomach Contents. Insect remains, especially grasshoppers, and 1 large beetle.

Habitat. Forest; forest edge; scrubby, abandoned pasture; active pasture, cornfields.

Notes. Usually 1 or 2 birds perched at tops of trees or 

dead snags 3–17 m up or flying overhead. Often screaming; call 

a high-pitched single note followed by a shrill descending shree

or a single-note cry given repeatedly. Several perched together in 

Feb, calling, bill clicking, and chasing. Observed being mobbed 

by a great kiskadee (Pitangus sulphuratus) and chased by an 

American kestrel (Falco sparverius).

Buteo brachyurus*: Short-tailed Hawk

Notes. Seen in Oct, soaring over a forest clearing (MSF).

Family Rallidae: Rails

Aramides saracura: Slaty-breasted Wood-rail

Specimens (MVZ). ♂♂ Dec (1), Jan (1).

Mass (g). 536; 460 with light fat.

Iris. Pale green.

Bill. Green or olive green, brighter basally. Mouth lining whitish gray.

Facial Skin. Eye ring pink.

Feet and Tarsi. Reddish or purple.

Gonads. Testes enlarged (16 × 6 mm) in Dec; small 

(5 × 2 mm) in Jan.

Molt. Body (Dec, Jan) and flight (Jan) feathers.

Feet and Tarsi. Black dorsally to green on sides. Toe 

pads brown.

Gonads. Testis 4 × 2 mm.

Molt. Wing, tail, and body feather molt.

Notes. Seen regularly flying overhead in small groups 

of 1–6 or perched in dead trees in pastures. More than 55 feeding 

at a calf carcass in a pasture.

Family Accipitridae: Hawks

Elanus leucurus*: White-tailed Kite

Notes. Observed in Jan, Mar, and Nov flying over a 

clearing or hovering over a pasture (NKJ).

Elanoides forficatus*: Swallow-tailed Kite

Notes. Observed frequently in Sep through mid-Mar 

usually in groups of 2–7 (rarely alone), circling low over the 

hotel buildings or the forest canopy, occasionally over fields or 

clearings, or perched at the top of a 7–10 m dead snag. Their 

consistent close proximity to the forest canopy suggests that they 

may be hunting arboreal reptiles and amphibians. Presumed 

courtship flights observed in Nov. An austral migrant that breeds 

in Paraguay but moves north for the winter (Hayes, 1995).

Harpagus diodon: Rufous-thighed Kite

Specimens (MVZ). ♂♂ Jan (3), 2 adults, 1 juvenile.

Mass (g). X

_

 = 181.0 (SD = 1.73, range = 179–182, N = 3).

Iris. Adults: red orange; juvenile: dull yellow.

Bill. Adults: upper mandible olive green below nostrils; rest black. Lower mandible olive green. Juvenile: all black.

Facial Skin. Cere and gape at corners lemon yellow. 

Eye ring and bare orbital skin yellow, tinged green.

Feet and Tarsi. Adults: yellow orange. Juvenile: yellow.

Gonads. Testes small, range: 2 × 1–4 × 2.5 mm.

Molt. One adult replacing body and wing feathers.

Stomach Contents. Three with insect remains.

Habitat. Forest, woodland, and forest edge.

Notes. An austral migrant, breeding in Paraguay and 

moving north for the winter (Hayes et al., 1994). Birds have been 

observed chasing in Nov, and a juvenile exchanging screams with 

an adult in Jan may have been begging from a parent. The birds collected in Jan had small testes and likely were not breeding. El Tirol is 

farther south than previously reported localities (Hayes et al., 1994).

Ictinia plumbea: Plumbeous Kite

Specimens (MVZ). ♂ Sep (1), adult plumage.

Mass (g). 272, some fat.

Iris. Red.

Feet and Tarsi. Orange.

Gonads. Testes 12 × 8 mm.

Molt. No.
NUMBER 648 • 9

Patagioenas picazuro: Piacazuro Pigeon

Specimens (USNM, MVZ). ♂♂ Jan (1), Oct (1). 

Both with adult skulls.

Mass (g). 418 (Jan), 430 (Oct), neither with fat.

Iris. Outer ring orange; inner ring blue.

Bill. Dull bluish gray or gray at base and tan at tip.

Facial Skin. Nostril and skin around eye gray (Oct) 

or orbital skin anterior to eye and eye ring pinkish purple, and 

orbital skin above and below eye dull gray (Jan). Eye ring pinkish purple. Cere gray.

Feet and Tarsi. Rosy red.

Gonads. Testes 15 × 7 (Jan) and 23 × 7 mm (Oct).

Molt. Wing and body molt (Oct).

Stomach and Crop Contents. Large seeds and 

fruits (Jan) or corn (Oct).

Habitat. Mature forest, old second growth, secondgrowth scrub, and tung orchards.

Notes. Most common large pigeon at El Tirol; seen 

and heard frequently. Distinguished from other pigeons when 

flying by their size and a characteristic bend in the neck. Birds 

usually perch or roost fairly high up in the subcanopy of the 

forest. Call a 4-note whoo, who, who, whoo. Active nests 

were located in Oct, Nov (2), and Mar (2) in forest and tung 

orchards. The nests consisted of a simple, loose assemblage of 

sticks 5–15 m up in the crotch of a tree (see de la Peña, 2010). 

One parent tended the nest while the other perched nearby. 

Postbreeding birds may form large flocks. Although present 

year-round, some winter birds may fly south to breed.

Geotrygon violacea: Violaceous Quail-dove

Specimens (MVZ). ♂ Feb (1), adult skull.

Mass (g). 100, light fat.

Iris. Gold.

Bill. Red with purplish tinge. Mouth lining pink.

Facial Skin. Flesh around eye purplish red.

Feet and Tarsi. Red purple. Toe pads flesh color.

Gonads. Testes 4 × 2 mm.

Molt. Body feathers.

Stomach Contents. Fruit.

Habitat. Forest. Ground or low perches (≤2 m) in 

trees.

Notes. Observed in Feb and Mar.

Leptotila verreauxi: White-tipped Dove

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

Mar (2), May (1), Jun (2), Sep (2). ♀♀ Feb (1, fledgling), Jun (1), 

Dec (1). Egg Oct (1). Jan, May, 1 Sep ♂, and Jun ♀ with windows 

covering 10%–50% of the skull. Other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 182.3 (SD = 17.3, range = 154–203, 

N = 8), with light fat in Mar, May, Jun, Sep. ♀ adult (Dec) 172 g, 

with light fat.

Stomach Contents. Insect remains in 1.

Habitat. Along streams in mature forest, secondgrowth forest, and tall grass (to 2 m) at forest edge.

Notes. Generally keeps under cover, although occasionally seen on forest trails; on the ground or perched in small 

trees at about 2 m. Observed in pairs separated by up to 10 m. 

Vocalizations include strident calls, grunts, and chucks; birds 

counter call with a low-pitched note when alarmed.

Family Charadriidae: Plovers

Vanellus chilensis: Southern Lapwing

Specimens (USNM). ♀ Sep (1), adult skull.

Mass (g). 250, light fat.

Iris. Red.

Bill. Light red to purple to black at tip.

Facial Skin. Eye ring red.

Feet and Tarsi. Black

Gonads. Largest ovum 4 mm diam.

Molt. No.

Stomach Contents. Insects.

Habitat. Pastures.

Notes. Usually in pairs, occasionally in small groups. 

Conspicuous, loud, and aggressive; commonly dive-bomb 

intruders into their areas. Observed in Sep, Nov, Jan, Feb, Mar, 

and Jun. A breeding resident.

Family Scolopacidae: Sandpipers

Calidris subruficollis*: Buff-breasted Sandpiper

Notes. Observed (MSF) 19 August 1980, feeding in the 

drainage trough around the perimeter of a swimming pool; walked 

around and then flew to perch on the roof of an adjacent building. 

Myers and Myers (1979) observed small flocks of this migrant 

from North America in late Aug in the Paraguayan Chaco.

Family Columbidae: Pigeons

Columba livia: Rock Pigeon

Specimens (MNHNP). ♀ Jun (1), adult skull.

Mass (g). 345.

Iris. Pale orange.

Bill. Black.

Facial Skin. Around eye, pinkish tan. Operculum 

pale pink with black anteriorly.

Feet and Tarsi. Deep pink.

Gonads. Ovary active, largest ovum 5 × 5 mm, orange.

Molt. No.

Crop Contents. Corn and other seeds.

Notes. Introduced species. Specimen received from a 

local family that keeps pigeons; likely captive bred. Locality is 

2.25 km NNE Hotel El Tirol on Ruta 6, Department of Itapúa.
1 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Facial Skin. Eye ring creamy white. Fleshy skin at 

base of bill brown.

Feet and Tarsi. Pink or salmon color.

Gonads. ♂♂ Testes enlarged (9 × 5–11 × 5 mm) in 

Sep, Oct, Mar; smaller (4 × 1.5) in Jun. ♀♀ Largest ova 3.5 

(white) to 11 (yellow orange) mm diam; bird with smallest ova 

with slightly enlarged oviduct.

Molt. Light body molt in Oct (1).

Stomach and Crop Contents. Six with seeds.

Habitat. Open woods, tung orchard, scrubby abandoned pastures, along roads, cornfields.

Notes. Common, walking on the ground or perched 

in trees (especially in living fence rows) from 2 to 12 m up. 

Usually in pairs or small groups. Birds flushed from nests on 4 

Nov (1.3 m up in a bamboo thicket; 1 egg) and 15 Feb (2 white 

eggs; nest ~1.5 m up in a tree in a weedy field). A third bird was 

observed carrying a twig (nest material?) in late February. Gonad 

development along with the nest observations suggests a long 

breeding period. Hayes (2014) recorded nests of this species in 

every month from Oct to Feb.

Columbina squammata: Scaled Dove

Specimens (MVZ). ♀ Nov (1).

Mass (g). 52.

Bill. Grayish black.

Feet and Tarsi. Pale pink. Toe pads pale.

Gonads. Laying, largest ovum 3 mm diam, 1 collapsed follicle.

Molt. Scattered body.

Crop Contents. Full of tiny seeds.

Notes. Perched 4 m up in pasture tree.

Columbina picui: Picui Ground Dove

Specimens (USNM, MVZ). ♂♂ Jan (1), Mar (1), 

Oct (1). ♀♀ Jan (2), Nov (1). Oct ♂ skull partially pneumatized. 

All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 47.7 (SD = 4.51, range = 43.0–52.0, 

N = 3); light fat in Mar. ♀♀ X

_

 = 43.5 (SD = 2.18, range = 42.0–

46.0, N = 3).

Iris. White, lavender, gray lavender, or blue.

Bill. Upper mandible black. Lower mandible black or 

black with pale base.

Facial Skin. Eyelid buffy pink. Bare skin around eye 

purple pink. Operculum black.

Feet and Tarsi. Reddish purple, including toe pads.

Gonads. ♂♂ Testes enlarged in all (10 × 4–12 × 

5 mm). ♀♀ All with enlarged (2–6 mm) orange ova. Jan birds 

with early incubation patch or enlarged oviduct; 1 with mate.

Molt. Jan (2) and Mar (1).

Stomach and Crop Contents. All 6 with seeds.

Habitat. Tung orchards, scrubby early second growth, 

abandoned pastures, along roads, clearings.

Iris. Yellow, pale orange, or brown.

Bill. Black, blackish brown, brown, or dark purple.

Facial Skin. Eyelid and skin around eye reddish pink 

or purple with some gray above the eye or, in 2 birds, blue gray 

or powder blue.

Feet and Tarsi. Reddish, pinkish, or brownish purple or reddish gray. Toe pads sandy brown. Margins of toe and 

tarsal scutes whitish.

Gonads. ♂♂ Testes enlarged (11 × 8–15 × 6 mm) Mar 

through Jun, moderately enlarged (8 × 5 mm) in Sep, and small 

(3 × 1 mm) in Jan and Mar. One Sep ♂ with secretory crop. ♀♀

Largest ovum 6 mm diam, orange (Jun); nonreproductive (Dec).

Molt. Body and flight feathers in Mar (1) and May. Body 

molt only in Jan, Mar, Jun, Sep, and Dec. Prejuvenal molt in Feb.

Stomach and Crop Contents. Two each with 

fruit, fruit and corn, seeds, or seeds and grit; 1 with corn only.

Habitat. Forest, forest edge, tung orchards, cultivated 

fields (corn).

Notes. Common medium-size dove generally seen 

in small groups (1–4 individuals) or, in February and March, in 

postbreeding flocks (15–20 individuals). Perches 3–5 m up in 

trees, but often forages on the ground. Low-pitched 2-note call 

heard year-round. Skull pneumatization does not clearly indicate 

age, as large skull windows were present in some individuals that 

were obviously breeding. The timing of gonad enlargement and 

breeding activity suggests an extended reproductive period and an 

overlap of molt and breeding in some individuals. Nest with1 egg 

located 1 Oct 1980; nest deserted 2 days later, still only 1 egg.

Leptotila rufaxilla: Gray-fronted Dove

Specimens (MVZ). ♂ Mar (1).

Mass (g). 195, light fat.

Iris. Dark yellow.

Bill. Black.

Facial Skin. Eyelid and skin around eye red purple.

Feet and Tarsi. Deep red purple. Toe pads pinkish.

Gonads. Testes 7 × 3 mm.

Molt. Body and flight feathers.

Stomach Contents. Fruits.

Habitat. Netted in forest.

Columbina talpacoti: Ruddy Ground Dove

Specimens (USNM, MVZ, MNHNP). ♂♂ Mar 

(1), Jun (1), Sep (2), Oct (2). ♀♀ Sep (3). Oct ♂♂ with skull 

windows. All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 50.4 (SD = 3.07, range = 47.5–

54.5, N = 6). ♀♀ X

_

 = 47.0 (SD = 5.20, range = 44.0–53.0, 

N = 3). Light or moderate fat in some Sep (2 ♂♂, 1 ♀) and Oct 

(1 ♂) birds.

Iris. Red, orange, or purplish white.

Bill. Upper mandible brown, gray brown, or brownish yellow. Lower mandible gray, brown, or brownish yellow. 

Mouth lining black.
NUMBER 648 • 1 1

Iris. Black, dark brown, brown, or gray.

Bill. Black; ridge of culmen on upper mandible may be 

edged brown. Mouth lining black, grayish white, or slate gray blue.

Feet and Tarsi. Black. Toe pads dark brown.

Gonads. ♂♂ Testes enlarged Nov through Mar (12 × 

6–15 × 9 mm); regressing in May (8 × 3 mm); small in May, Jun (4.5 

× 1.0–3 × 2 mm), and enlarging again in Sep (6 × 3 mm). ♀♀ Jan 

birds with enlarged ova (2.5–5.0 mm diam), collapsed follicles, and/

or enlarged oviducts. Feb ♀ postbreeding with old incubation patch. 

Ovary granular, largest ovum ≤ 1.0 mm in Feb (1), Jun, and Oct.

Molt. Body, wing, and tail feathers molting in Jan (3), 

Feb (2), Mar (1), May (2), Jun (2), Sep (1), and Oct (1), plus 3 

Oct nestlings in prejuvenal molt.

Stomach Contents. Fourteen with insects remains, 

especially large orthopterans. Two Jun ♂♂ with fruit in stomach, 

and 1 Jun ♀ with insects and fruit.

Plumage. Juvenal feathers being acquired by nestlings 

are lax and dull brownish or sooty black with little or no scaling 

on breast, back, or abdomen.

Notes. Molt-breeding overlap present in several birds 

(i.e., body and flight feather molt with testis 9 × 15 mm or ovary 

with 5-mm ovum, 2 collapsed follicles, and enlarged oviduct). Perhaps the presence of helpers at the nest (Davis, 1940) allows these 

2 energy-consuming activities to coincide. The molting period for 

the species is clearly long. We do not know whether it is also long 

in individuals. Birds found in flocks in orchards, cultivated fields, 

and abandoned pastures. Groups of 2–5 adults common in Oct 

through Feb; probably breeding units. Larger flocks of 10–25 

more common in Feb to Oct. Active nest with 3 nestlings located 

on 13 Oct, 2 m up in an orange tree (Citrus sp., Rutaceae). Adults 

with fledglings and partly grown juveniles encountered in Nov, 

Jan, and Feb. Plumage of many birds has an unpleasant odor.

Tapera naevia: Striped Cuckoo

Specimens (USNM, MNHNP). ♂ Aug (1), adult 

skull. ♀ Jun (1), skull not pneumatized.

Mass (g). ♂ 54.0. ♀ 47.8, moderate fat.

Iris. Yellow or light brown.

Bill. Upper mandible black or gray with a black culmen. Lower mandible gray.

Facial Skin. Unfeathered region around eye, blue 

gray.

Feet and Tarsi. Gray.

Gonads. ♂ Testes 4 × 2.5 mm. ♀ Ovary granular, ova 

minute.

Molt. Light body molt (Aug).

Stomach Contents. Insect remains.

Habitat. Scrubby abandoned fields, pastures, 

cornfields.

Notes. Moves around in low shrubs and bushes, usually ≤3 m but has been noted calling 5 to 6 m up in the dead 

limbs of isolated trees. Call a 2-note whistle (NKJ). Registered 

only 4 times. Male has a distinct, unpleasant odor, especially in 

the area of the uropygial gland.

Notes. Much less common than C. talpacoti, but seen 

or heard at least weekly in pairs or small groups. Forage on the 

ground and perch in trees to ~7 m. Call is a low-pitched, 3-note, 

aspirated whistle with the second note emphasized and rising 

greatly (NKJ). Two adults with a nestling observed in early Mar. 

Reported by de la Peña (2010) to breed year-round.

Family Cuculidae: Cuckoos

Guira guira: Guira Cuckoo

Specimens (USNM, MVZ, MNHNP). ♂♂ Mar 

(1), Jun (2), Sep (1), Dec (1). ♀♀ Feb (1), Jun (2), Sep (1), Dec 

(1, juvenile).

Mass (g). ♂♂ X

_

 = 143 (SD = 8.16, range = 134–152, 

N = 5). ♀♀ X

_

 = 142 (SD = 13.66, range = 128–160, N = 4). Juvenal 

♀ = 106. All Jun birds and 1 Sep bird with light to moderate fat.

Iris. Pale orange or yellow.

Bill. Upper mandible reddish brown with orange tip and 

tomium, brownish yellow, or brown with a yellow tomium. Lower 

mandible dark yellow, orange, or orange with yellow sides at base.

Facial Skin. Light green, yellow green, or pale yellow 

around eye. Body skin black.

Feet and Tarsi. Greenish gray, pinkish brown with 

olive feet, or pinkish green with light brown toe pads and blue 

ankle joint.

Gonads. ♂♂ Testes enlarged (10 × 6–14 × 7 mm) in 

Sep, Dec, and Mar; moderately enlarged or small (7.5 × 1.5, 4 × 

2 mm) in Jun. ♀♀ Largest ova 2 mm (Feb, Sep); ovary granular, 

largest ovum ≤ 1.0 mm (Jun); ovary tiny, undeveloped (Dec).

Molt. Body and flight feather molt in Dec and Feb; 

light body molt in Sep. First prebasic molt in Dec.

Stomach Contents. Eight with arthropod remains, 

primarily Orthoptera (largest = 6 cm long) but also Coleoptera, 

other insects, and spiders.

Habitat. Forest edge, tung orchard, scrubby abandoned fields, pasture, around buildings.

Notes. Form loose flocks of 2–30 individuals; noisy, 

conspicuous, and appear clumsy as they move around and alight 

on branches. Generally in trees or bushes, but often forage on the 

ground; consequently, the breast, abdomen, and under surface 

of the tail are usually stained red with soil. Three-quarter grown 

nestling observed following an adult in February.

Crotophaga ani: Smooth-billed Ani

Specimens (USNM, MVZ, MNHNP). ♂♂ 11: Jan 

(1), Mar (1), May (2, one with small skull windows), Jun (3, one 

with small skull windows), Sep (1), Oct (2, both nestlings), Nov 

(1). ♀♀ Jan (2, imm skulls), Feb (2), Jun (3, one with small skull 

windows), Oct (2, one a nestling).

Mass (g). ♂♂ X

_

 = 101.2 (SD = 11.80, range = 87.0–

119.8, N = 9). ♀♀ X

_

 = 89.1 (SD = 12.00, range = 77.0–112, N = 8). 

All Jun and Sep birds with light to moderate fat. Nestlings = 55, 

51 (♂♂), and 44 (♀).
1 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Mass (g). ♂♂ X

_

 = 47.0 (SD = 2.16, range = 44.2–50.0, 

N = 5). ♀ = 64.3.

Iris. Brown, dark brown, or black.

Bill. Upper mandible black. Lower mandible black 

with flesh color at base. Mouth lining black in 1 adult ♂ (Nov), 

white in immature ♂ (Feb); not recorded for other birds.

Facial Skin. Eye ring black. Eyelids yellow green or 

yellow buff. Bare skin around eyes (especially below and behind) 

blue gray.

Feet and Tarsi. Gray, olive gray, or gray blue. Toe 

pads reddish brown or light green.

Gonads. ♂♂ Testes moderately large (6 × 4–8 × 4 

mm) in Nov–Dec; small (1.5 × 1 mm) in Feb. One Nov ♂ with 

well-developed brood patch. ♀ Laying, ovary with 2 collapsed 

follicles, shelled egg in oviduct, and incubation patch.

Molt. Body and flight feather molt (Feb immature). 

Body molt in mated pair (Dec), ♂ light and ♀ heavy.

Stomach Contents. Six with insect remains, 

including grasshoppers, cicadas, and caterpillars.

Habitat. Forest edge in dense vegetation, i.e., viny 

bamboo (Chusquea sp.) tangles, dense shrubs (e.g., Baccharis

sp., Asteraceae).

Notes. Reproduction and molt overlap in some specimens (e.g., Dec ♀ with heavy body molt was also laying). Bird 

observed twice on 20 Jan carrying food to presumed nest. The 

species, although uncommon, obviously breeds at El Tirol. The 

absence of sightings during the austral winter is consistent with 

it migrating and wintering to the north during that period (cf. 

Hayes et al., 1994). Sex-unknown specimen in mist net partially 

eaten by predator.

Coccyzus americanus: Yellow-billed Cuckoo

Specimens (MVZ). ♀♀ Jan (2), Mar (2). One Mar 

bird with adult skull; all others with small skull windows.

Mass (g). X

_

 = 60.8 (SD = 3.01, range = 58.0–63.5, 

N = 4). One Jan bird with some fat.

Iris. Dark brown.

Bill. Upper mandible black with yellow-orange sides 

near tomium and base. Lower mandible orange yellow with 

black tip. Tongue gray with black tip. Palate pale greenish yellow with slight black suffusion.

Facial Skin. Eye ring yellow or yellow orange. Eyelids bright orange. Orbital skin below eye gray or blue gray.

Feet and Tarsi. Gray, lead gray, or blue gray. Toe 

pads sandy olive, sandy brown, greenish tan, or blue gray.

Gonads. One Jan bird with undeveloped ovary. Other 

birds, ovary postreproductive.

Molt. General body and flight feather molt in Jan and 

1 Mar specimen. Body molt only in the other Mar specimen.

Stomach Contents. Insect remains in 3 birds 

(spiny caterpillars or grasshoppers). One Mar bird with large 

green fruits.

Habitat. Forest canopy, forest edge, tung orchard.

Dromococcyx phasianellus*: Pheasant Cuckoo

Notes. Observed once (MSF) in Oct, during the day, 

climbing around on a moderately large, recently fallen tree 

in an orchard. Not recorded from the Alto Paraná region by 

Hayes (1995), but Esquivel M. et al. (2007) found it in San 

Rafael National Park.

Piaya cayana: Squirrel Cuckoo

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), Mar (1), May (1), Jun (2). Jun birds with skull windows; all 

other ♂♂ with adult skulls. ♀♀ Jan (1), Feb (1), Jun (3), Sep (2). 

Jan and Feb birds with immature skulls; others with adult skulls.

Mass (g). ♂♂ X

_

 = 132 (SD = 16.08, range = 113–150, 

N = 5). ♀♀ X

_

 = 123.9 g (SD = 15.97, range = 109–153, N = 7). 

Five birds (Feb, 1; Jun, 4) with light to heavy body fat.

Iris. Red or reddish brown. Fleshy eye ring and bare 

skin around eye red, except gray patch below eye.

Bill. Yellow, yellow green, or pale green with yellow 

tomium. Gape gray or black. Mouth lining red purple or black.

Facial Skin. Fleshy eye ring, eyelid, and bare skin 

around eye red or purplish pink, except for a gray patch below 

the eye.

Feet and Tarsi. Gray, blue gray, or blue green. Toe 

pads yellow, yellow orange, or tan.

Gonads. ♂♂ Testes small (3 × 1–5 × 3 mm) Feb 

through Jun. ♀♀ Largest ovum 2 × 2 mm or shelled egg in oviduct in Sep. Ovaries smooth and undeveloped in Jan and Jun; 1 

ovary granular in Jun.

Molt. Body and flight feather molt in Feb (1), Mar (1), 

and May (1). Body feather only molt in Jan (1) and Jun (1). One 

bird with heavy tail molt observed in Nov.

Stomach Contents. Eight with insect remains, 

especially large orthopterans, caterpillars, and 1 praying mantis 

(60 mm long); 1 stomach with 2 snail shells also. Three Jun individuals with fruit and insect remains; the fruit in 1 = figs (Ficus

sp., Moraceae).

Habitat. Primarily in old forest but also found in second growth and in thickets in scrubby abandoned fields.

Notes. Usually in small groups of 2–4 individuals 

perched in uppermost quarter of the crown of tall trees but also 

as low as 1 m up in shrubs. Forage in trees but will swoop to the 

ground to recover a large insect. Call sounds like a creaky door 

opening slowly or a rusty spring uncoiling. Birds also make a lot 

of cackling or squabbling sounds. Twice (Nov, May) small birds 

were observed mobbing cuckoos, suggesting that the cuckoos eat 

eggs and/or nestlings of other species.

Coccyzus melacoryphus: Dark-billed Cuckoo

Specimens (USNM, MVZ). ♂♂ Feb (2), Nov (2), 

Dec (1). ♀ Dec (1). Sex? Dec (1). One Feb and 1 Nov bird with 

skull windows. Other birds with adult skulls.
NUMBER 648 • 1 3

Notes. Calls steadily in the morning from as early as 

3:00 am to ~10:00 am, at dusk, and in the evening, at least from 

Sep through Mar. Calls less on very cold nights. Call is a repeated 

wee wee wee with no apparent frequency modulation; whistlelike. Species is common, but birds appear to occupy specific, 

widely spaced areas. May bird attempted to grab a Trichothraupis melanops from a mist net.

Athene cunicularia: Burrowing Owl

Specimens (MNHNP). ♂♂ Jun (2). ♀ Jun (1).

Mass (g). ♂♂ 169, 179, with heavy and moderate fat, 

respectively. ♀ 162.5, fat.

Iris. Bright lemon yellow.

Bill. Yellowish green or yellowish gray.

Facial Skin. Cere gray.

Feet. Olive green or gray.

Gonads. ♂♂ Testes 4.5 × 2.5 and 4 × 2 mm. ♀ Ovary 

granular.

Molt. One ♂ with a trace of body molt.

Stomach Contents. Two with insect remains; 1 

with small-mammal hair and bones.

Notes. Part of a group of 6 individuals standing on the 

ground in scrubby pasture. One burrow noted (CC). Red dirt on 

feet and abdominal feathers. Groups seen occasionally standing 

around on the ground in active or abandoned pastures.

Aegolius harrisii: Buff-fronted Owl

Specimens (USNM). ♂ Aug (1), adult skull.

Mass (g). 123, light fat.

Iris. Greenish yellow.

Bill. Blackish, culmen gray.

Feet. Tan.

Facial Skin. Cere pale yellow.

Gonads. Testes 4 × 2 mm, 1 dark green, 1 orange.

Molt. No.

Stomach Contents. Hair; fragment of mammal 

bone.

Notes. Only individual encountered. In mature forest, 

perched about 3 m up in a small tree. Many subdermal nematodes on skull.

Family Nyctibiidae: Potoos

Nyctibius griseus: Common Potoo

Specimens (USNM, MVZ). ♂♂ Oct (2). ♀ Oct (1). 

All with completely pneumatized skulls.

Mass (g). ♂♂ 186, 177. ♀ 204.

Iris. Yellow.

Bill. Upper mandible black; lower mandible black or 

black with gray at the base. Mouth lining pink.

Feet. Brown or tan.

Notes. Migrant from North America and the Caribbean. For a discussion of molt in this species, including consideration of these Paraguay specimens, see Rohwer and Broms 

(2013). One Jan bird observed swallowing a lizard.

Family Strigidae: Owls

Megascops choliba: Tropical Screech-owl

Specimens (USNM, MVZ). ♂♂ Sep (1), Oct (1). 

♀♀ Feb (1), Oct (1). Sex? Aug (1).

Mass (g). ♂♂ 114, 104, respectively. ♀♀ 140, with 

light fat, and 147, respectively.

Iris. Yellow.

Bill. Creamy white, gray green, or greenish yellow.

Feet. Gray, pale green, or greenish gray. Toe pads 

lighter.

Gonads. ♂♂ Testes enlarged in Sep (14 × 8 mm) and 

Oct (10.5 × 8 mm). ♀♀ Laying in Oct: largest yolked ova 4, 4, 6, 

and 11 mm diam; 2 collapsed follicles; shelled egg in oviduct = 

30 mm greatest width, 10 g, all white. Feb bird, largest ovum = 

1.5 mm diam.

Molt. Body and wing in Feb.

Stomach Contents. Three with insect remains, 

including orthopterans and a 5.5-cm-long caterpillar.

Habitat. Mature forest, tall second-growth forest, 

woodland, and secondary scrub or pastures.

Notes. Species common; birds regularly call at dusk 

and at night, at least from Aug through Jan. Perch 3–6 m up in 

trees or on fence posts. Males are spaced out as if on territories. 

Gonadal development in accordance with Hayes’s (2014) record 

of 4 nests of this species in October in Sapucái (Figure 1). Birds 

appear to be sexually dimorphic, with females considerably 

heavier than males. Aug specimen eaten in a mist net; wings and 

tail saved. Eye socket of Oct male contained many nematodes.

Glaucidium brasilianum: Ferruginous 

Pygmy-owl

Specimens (USNM, MVZ). ♀♀ May (1), Oct (1), 

adult skulls.

Mass (g). 77.0, 85.0, moderate and light fat, 

respectively.

Iris. Bright yellow.

Bill. Yellow or pale greenish yellow.

Facial Skin. Cere yellow.

Feet. Yellow or pale greenish yellow.

Gonads. Oct ovary with 8-, 13-, and 15-mm-diam 

yolked ova; oviduct greatly enlarged. May ovary granular.

Molt. Body molt, May.

Stomach Contents. Both with insect remains; Oct 

bird also containing mammal hair.

Habitat. Forest, tall second growth, open secondgrowth scrub, woodland.
1 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Habitat. Scrubby pasture, forest edge.

Notes. On the ground or perched in small trees. Sep 

♂ and ♀ a mated pair. Oct ♂ calling regularly from a stump 

in scrubby pasture while ♀ rested on the ground nearby. Both 

males tape-recorded (MSF). Vocalizations a smooth “bubbling” 

or “gurgling” sound, suggestive of an extraterrestrial communication. Some birds with red dirt on the abdomen, underside of 

tail, under tail coverts, and throat.

Hydropsalis torquata: Scissor-tailed Nightjar

Specimens (MVZ). ♀ Sep (1), adult skull.

Mass (g). 63, light fat.

Bill. Brown

Feet and Tarsi. Brown

Gonads. Largest ovum 3 mm.

Molt. Yes.

Stomach Contents. Insect remains.

Habitat. Tall grassland with scattered trees and shrubs.

Antrostomus rufus: Rufus Nightjar

Specimens (MVZ). ♀ Nov (1). Broken egg shell, 

Nov (1).

Mass (g). 99, some abdominal fat.

Bill. Dull purplish brown with black tip and black culmen. Mouth lining pale greenish gray.

Feet. Toes pale brown at base, darker brown toward 

tips. Toe pads and unfeathered rear edge of tarsi sandy brown.

Gonads. Ova small; 2 collapsed follicles.

Molt. No.

Stomach. Jammed with insect parts.

Notes. Flushed at noon from a bare spot on the 

ground in forest edge near a weed field. Bird flew about 6 m 

and performed a distraction display, fluttering along on the 

ground. Broken egg shell on the ground, cream-colored background with irregular light brown markings. Nestling not 

located.

Family Apodidae: Swifts

Chaetura cinereiventris: Gray-rumped Swift

Specimens (MVZ). ♂ Jan (1), large skull windows.

Mass (g). 15.1.

Iris. Dark brown.

Bill. Black.

Feet. Black

Gonads. Testes 2 × 1 mm.

Molt. No.

Stomach Contents. Packed with tiny insects.

Notes. Regularly observed, along with Progne chalybea, feeding (even during heavy rains) over the hotel, clearings, 

cornfields, and forest in groups of 2–15 from Nov through Mar. 

Gonads. ♂♂ Testes 10 × 9 mm, 10 × 8 mm. ♀ largest 

ovum 25 mm diam, yolked, and two 3.5 mm diam, unyolked. 

Oviduct greatly enlarged.

Molt. ♀ With body molt.

Stomach Contents. Insect remains in all birds, plus 

grit in 1.

Habitat. Forest openings.

Notes. One male (prepared as skeleton) with very 

dark phase plumage. Calling regularly through the month of 

Oct, and occasionally seen at night flying across clearings near 

the hotel.

Family aprimulgidae: Nightjars

Nyctidromus albicollis: Common Pauraque

Specimens (MVZ). ♂♂ Jan (1), adult skull; Mar (1) 

skull not pneumatized. ♀♀ Jan (2), both with immature skulls.

Mass (g). ♂♂ 80.0, 78.0. ♀♀ 62.1, 69.0.

Iris. Brown.

Bill. Mouth lining pinkish flesh color.

Feet and Tarsi. Brown or light brown. Toe pads light 

brown.

Gonads. ♂♂ Testes 3 × 5 mm (Jan), 4 × 2 mm (Mar). 

♀♀ Ovaries immature.

Molt. All birds molting; ♀♀ with downy underparts.

Stomach Contents. All with insect remains, including beetle elytra.

Habitat. Forest opening; forest with cleared understory vegetation.

Notes. Red dirt on underparts and/or underside of tail.

Setopagis parvula: Little Nightjar

Specimens (USNM, MVZ). ♂♂ Sep (1), Oct (1), 

Dec (1). ♀♀ Jan (2), Sep (1), Oct (1). All except Dec ♂ with 

adult skulls.

Mass (g). ♂♂ X

_

 = 40.0 (SD = 1.80, range = 38.0–41.5, 

N = 3); Sep and Dec specimens with moderate and light fat, 

respectively. ♀♀ X

_

 = 40.7 (SD = 4.71, range = 37.2–45.5, N = 3); 

Sep ♀ not included in mean, specimen = 51 g, with moderate fat 

and fully shelled egg in oviduct.

Iris. Reddish brown, brown, or black. Eye shine red 

or yellow.

Bill. Black.

Feet. Gray, brown, or tan.

Gonads. ♂♂ Testes enlarged (12 × 5–15 × 7 mm) Sep 

through Dec. ♀♀ Breeding in Sep (largest ovum 11 mm diam, 

orange; all white shelled egg, 25 × 19 mm, in oviduct) and Oct 

(largest ovum 7 mm, yellow orange, oviduct enlarged). Jan birds 

with smooth or postbreeding ovaries.

Molt. Both Jan birds.

Stomach Contents. All specimens filled with insect 

remains, especially scarabs.
NUMBER 648 • 1 5

Gonads. ♂♂ Testes enlarged (3 × 1.5–3 × 2 mm) in 

1 Jan, 1 Feb, and 3 Oct birds. One Oct bird with well-developed 

brood patch. ♀♀ One Oct bird with yellow ova 1.5 mm diam 

and an enlarged oviduct. All other females, ovary granular or 

ova ≤ 1 mm except for 2 Nov birds in which the ovary is tiny 

and undeveloped.

Molt. Present in some birds in Nov, Dec, Jan, and Feb.

Stomach Contents. One Feb ♂ with insect 

remains. Birds were observed feeding at flowers of various forest 

shrubs and epiphytes, including Tillandsia stricta (Bromeliaceae), 

Calliandra foliolosa (Fabaceae), Ruellia angustifolia (Acanthaceae), Manettia luteorubra (Rubiaceae), Faramea cyanea (Rubiaceae), and Malvaviscus sp.

Habitat. Primarily forest, forest openings. Seen in 

disturbed areas and scrubby second growth in the nonbreeding 

season.

Notes. Moderately common in forest. Males observed 

primarily at leks in mature forest. The lek areas were bowl 

shaped, surrounded by mature forest, open to the sun above, 

and with dense, tangled vegetation below. Two leks first located 

in 1976 and occupied every year through 1983 consisted of 3 

males each. Each male had his own court, 6 to 10 m in diam 

and separated by 5 to 10 m. Within their courts, males had 3 

or 4 favorite perches, i.e., bare branches or vines in the open, 

2 to 6 m up, and ≤1 cm diam, which they used during the day. 

They defended the perches vigorously against other males with 

displays, distinct calls (sharp trill or buzz), and rapid chases. 

Males called from the perches throughout the day with only 

brief absences (2–3 min), presumably to feed. The call is high 

and squeaky and consists of several notes. It is repeated at a 

rapid rate (1 male gave 84 calls in 1 min). Calling males perch 

nearly erect, with the head/bill pointing upward at ~40° from 

horizontal, the posterior long plume feather pointing upward 

(but backward) at the same angle, and the purple crest elevated 

between them about 70° from the posterior horizontal. Males 

were active at the leks at least from Aug through Dec. These 

observations are generally consistent with those of Pizo (2012) 

at leks of this species in Brazil.

Thalurania furcata: Fork-tailed Woodnymph

Specimens (MNHNP). ♂♂ Jun (5); ♀♀ Jun (2).

Mass (g). ♂♂ X

_

 = 5.0 (SD = 0.19, range = 4.8–5.3, 

N = 5). ♀♀ 4.3, 4.8. Three ♂♂ and 1 ♀ with slight to moderate fat.

Iris. Brown or black.

Bill. Black.

Feet. Brown, black, or pink.

Gonads. ♂♂ Testes 0.5 × 0.5–1.0 ×1.0 mm. ♀♀ Ovary 

smooth or ovary granular.

Molt. One ♀ with a trace of body molt.

Stomach Contents. Three ♂♂ with insect remains; 

2 feeding at Malvaviscus sp. flowers.

Habitat. Old forest.

May be present year-round. Observed 1–5 individuals entering various hotel chimneys on different occasions in Nov, Feb, 

and Mar.

Family Trochilidae: Hummingbirds

Phaethornis eurynome: Scale-throated Hermit

Specimens (USNM, MVZ, MNHNP). ♂♂ May 

(1), Jun (2), Aug (1), Sep (1), Oct (1), Dec (2). ♀♀ Jun (3), Sep 

(2), Oct (3), Nov (1), Dec (1).

Mass (g). ♂♂ X

_

 = 4.2 (SD = 0.23, range = 4.0–4.6, 

N = 8); 1 Jun bird with moderate fat. ♀♀ X

_

 = 3.8 (SD = 0.31, 

range = 3.2–4.2, N = 10); 1 Jun bird with slight fat.

Iris. Brown or black.

Bill. Upper mandible black; lower mandible black 

with yellow-orange or yellow base or yellow or yellow orange 

with black tip.

Feet. Variously described as black, gray, pinkish gray, 

or reddish pink.

Gonads. ♂♂ Testes 2.5 × 2 mm (Sep); all other males 

testes ≤ 2 × 1 mm. ♀♀ Ovary granular with ova ≤ 1 mm in all 

except 1 Jun bird in which the ovary was smooth and undeveloped. Brood patch present (Nov) in 1 ♀ with ova ≤ 0.5 mm.

Molt. Three Dec birds molting, and light scattered 

body molt in May ♂.

Stomach Contents. Jun ♀♀, 1 with insect remains. 

Birds visit the red flowers of Malvaviscus sp. (Malvaceae; possibly M. penduliflorus), which is used widely in ornamental 

plantings around the hotel and in the region and appears to 

bloom over most of the year. They also visit the flowers of an 

ornamental Fuchsia sp. (Onagraceae). If the corolla tube of 

the latter species is particularly long, the birds may pierce the 

middle of the corolla just above the nectaries and “steal” the 

nectar (RMZ).

Habitat. Forest understory as well as ornamental 

plantings in open areas around buildings.

Notes. Nest with 2 young located in early February. 

On 11 Mar, two-thirds grown nestlings found dead (from exposure?) after several days of heavy rain. Moderately common.

Stephanoxis lalandi: Green-crowned 

Plovercrest

Specimens (USNM, MVZ, MNHNP). ♂♂ 11: Jan 

(2), Feb (2), Jun (2), Sep (1), Oct (3), Dec (1). ♀♀ 11: May (2), 

Sep (1), Oct (3), Nov (2), Dec (3).

Mass (g). ♂♂ X

_

 = 3.4 (SD = 0.52, range = 2.6–4.5, 

N = 11; fat present in 1 Jan and 1 Feb bird. ♀♀ X

_

 = 2.8 (SD = 

0.27, range = 2.5–3.25, N = 11).

Iris. Brown.

Bill. Black.

Feet. ♂♂ Black, brownish black, or brown; toe pads 

light green. ♀♀ Pink, pinkish gray, gray, or yellow.
1 6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Mass (g). ♂♂ X

_

 = 68.2 (SD = 3.27, range = 64.5–72.5, 

N = 5). ♀ mass on specimen label and in catalog = 168.5; likely 

a recording error.

Iris. Brown.

Bill. Gray, grayish green, grayish white, or greenish 

white. Mouth lining flesh color with blue in some areas.

Facial Skin. ♂♂ Eye ring and lid orange; naked skin 

below eye dirty white. ♀ Eye ring white.

Feet and Tarsi. Gray, blackish gray, black, or dark 

blue gray to slate. Toe pads light green or tan white.

Gonads. ♂♂ Testes moderately enlarged (7 × 4 mm) 

in Aug; small (2 × 1–4 × 2 mm) Feb to Jun. ♀ Ovary granular, 

ova ≤ 1 mm.

Molt. Extensive molt of body and flight feathers in 

Feb, Mar.

Stomach Contents. Insect remains, including 

beetles and caterpillars, in 1; fruit and insects in 3; only fruit 

in 2.

Habitat. Forest, old second growth.

Notes. Calling at least in Oct through Mar and Jun 

from perches 5–13 m up in open trees with little foliage or on 

horizontal vines. Call is a single note repeated many times in 

rapid succession; calling bouts may be long, up to 45 min, with 

brief pauses. Likely breeds from Aug through Jan/Feb. One nest 

located 21 Sep ~4 m up in the top of a dead snag. Also nests in 

tree cavities (de la Peña, 2010).

Trogon rufus: Black-throated Trogon

Specimens (MVZ). ♂♂ Mar (1), Sep (1). ♀ Mar (1).

Mass (g). ♂♂ 57, 59. ♀ 55.5.

Iris. Brown.

Bill. ♂♂ Greenish yellow. Mouth lining light green. ♀

Bill as in males but with black at base and dorsally on upper 

mandible.

Facial Skin. Eye ring blue; eyelid bluish purple.

Feet and Tarsi. Gray, green, or pinkish green. Toe 

pads tan.

Gonads. ♂♂ Testes 2 × 1 (Mar) and 5 × 4 (Sep) mm. 

♀ Largest ova ≤ 1 mm.

Molt. All birds with body molt; Mar birds also molting primaries.

Stomach Contents. Insects in 3, including Orthoptera, Coleoptera, and one 70-mm-long grub.

Habitat. Forest.

Notes. Call shorter than that of T. surrucura. Two 

Mar birds likely a mated pair.

Family Alcedinidae: Kingfishers

Megaceryle torquata*: Ringed Kingfisher

Notes. Heard calling near a scrubby abandoned clearing in Jan and seen flying over a pasture in Oct (NKJ).

Notes. Birds nonreproductive. Hummingbirds of 

various species regularly feed at ornamental plantings of Malvaviscus sp., which are common at El Tirol and flower most of 

the year. The absence of observations of this species outside of 

Jun suggests that it breeds elsewhere and may move around to 

exploit local food sources during the winter.

Amazilia versicolor: Versicolored Emerald

Specimens (USNM, MVZ). ♂♂ Sep (3), Oct (2). 

♀♀ Feb (1), Sep (1), Oct (1). Sex? Sep (1), Oct (1).

Mass (g). ♂♂ X

_

 = 3.5 (SD = 0.29, range = 3.25–4.0, 

N = 5). ♀♀ X

_

 = 3.1 (SD = 0.19, range = 2.9–3.25, N = 3), Feb ♀

with light fat. Sex? 3.5, 3.25.

Iris. Brown.

Bill. Upper mandible black. Lower mandible, basal 

half red or pink red, distal half black. Mouth lining yellow 

green.

Feet. Black. Toe pads light green.

Gonads. ♂♂ Testes 2.5 × 1.75–3.0 × 2.5 mm (Sep, 

Oct). ♀♀ Ovary smooth, undeveloped (Feb, Sep); ovary granular, ova ≤ 1 mm (Oct), with moderately enlarged oviduct.

Molt. Feb ♀ with body and wing molt.

Stomach Contents. Feb ♀ with insect remains.

Notes. Observed various times feeding from flowers of ornamental plantings of Malvaviscus sp. and at other red 

flowers in the forest. Solitary males occupy areas (territories?) 

in late second-growth forest. Areas contain favorite bare open 

branches (~1.5–3 m up) from which males call nearly nonstop 

over periods of weeks.

Hylocharis chrysura: Gilded Hummingbird

Specimens (USNM, MVZ). ♂ Sep (1). ♀♀ Oct (1), 

Dec (1).

Mass (g). ♂ 4.7, moderate fat. ♀♀ 4.0, 4.0.

Iris. Brown.

Bill. Proximal 60% pinkish red, distal 40% black.

Feet. Black.

Gonads. ♂ Testes 4 × 2 mm. ♀♀ Ova ≤ 0.5 mm (Oct); 

ovary tiny (Dec).

Molt. Sep ♂ molting.

Notes. Observed feeding from flowers of Ruellia 

angustifolia and Malvaviscus sp. The fact that observations of 

this hummingbird species feeding at Malvaviscus sp. flowers 

were confined to the spring/summer season suggests that it may 

be migratory, wintering elsewhere.

Family Trogonidae: Trogons

Trogon surrucura: Surucua Trogon

Specimens (MVZ, MNHNP). ♂♂ Feb (2), Mar (1), 

Jun (1), Aug (1). ♀ Jun (1).
NUMBER 648 • 1 7

Mass (g). ♂♂ 19.3 (SD = 1.35, range = 18.0–20.7, 

N = 3). ♀♀ 19 (SD = 1.38, range = 17.25–20.6, N = 4), Jun ♀

with moderate fat.

Iris. Brown.

Bill. Upper mandible black; lower mandible gray with 

black tip or basal half dull olive with distal half dull black. Base 

of tongue blue gray, tip glossy black. Mouth lining black or pinkish gray.

Facial Skin. Bare patch below eye bluish gray.

Feet and Tarsi. Gray.

Gonads. ♂♂ Testes 2 mm (Jan), 4 × 2 mm (Oct). ♀♀

Ova ≤ 1 mm (Jun, Nov); 1.5 mm diam (Oct); largest ovum 8 mm, 

orange (Nov), plus oviduct greatly enlarged, incubation patch 

present.

Molt. Body molt in a Jan and a Nov bird; tail molt in 

a Nov bird.

Stomach Contents. Six with insect (including 

grasshopper) remains.

Habitat. Forest, forest edge, orchard.

Notes. Male and female collected together in October 

and in Nov. Perch 2–8 m up in saplings, vines, and large trees. 

Make fly-catching sallies of ~1 m out from bare branches 2–3 cm 

in diam, returning to the perch to eat the insect.

Family Ramphastidae: Toucans

Ramphastos toco*: Toco Toucan

Notes. One individual observed in old second-growth 

forest in Oct 1980 (MSF).

Ramphastos dicolorus*: Red-breasted Toucan

Notes. Several birds, including a pair at a nest hole in 

a large tree, observed several times in Dec 1977 (MSF).

Pteroglossus castanotis: Chestnut-eared Araçari

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

Feb (1), Jun (1), Dec (1). ♀♀ Mar (1), May (1), Jun (1), Dec (1). 

Jan ♂ with immature skull.

Mass (g). ♂♂ X

_

 = 263.5 (SD = 19.67, range = 249–

292, N = 4). ♀♀ X

_

 = 251.9 (SD = 24.17, range = 232–283.5, 

N = 4). Heaviest ♀ (Jun) very fat.

Iris. White, creamy white, or greenish or yellowish 

white.

Bill. Narrow yellow band outlining the base of the bill, 

laterally and ventrally. Patches of reddish mahogany abut basal 

band distally on sides of bill. Upper mandible yellow with a wide 

black patch extending from the base of the bill and narrowing to 

a point about two-thirds down the length of the culmen; tomial 

margin irregularly “notched” distally in adults with alternating 

splotches of black and yellow. Lower mandible black or dark 

brown with yellow-green spot distally. Size and extent of color 

Family Momotidae: Motmots

Baryphthengus ruficapillus: Rufous-capped 

Motmot

Specimens (USNM, MVZ, MNHNP). ♂♂ Sep 

(1), Nov (1), Dec (1). ♀♀ Jan (1), Sep (1), Oct (1), Dec (2). All 

except 1 Dec female with adult skulls.

Mass (g). ♂♂ X

_

 = 134.7 (SD = 2.52, range = 132–137, 

N = 3). ♀♀ X

_

 = 128.0 (SD = 6.27, range = 121–136, N = 4).

Iris. Brick red or brown.

Bill. Black.

Feet and Tarsi. Gray or grayish brown.

Gonads. ♂♂ Testes 8 × 4, dark gray (Sep); 6 × 2, dark 

green (Dec); and 2 × 1 mm (Nov), with incubation patch. ♀♀

Sep ovary granular; breeding in Oct: largest ovum 4 mm diam, 

yellow orange, oviduct enlarging, brood patch developing. Jan 

ovary inactive. Ovary undeveloped in Dec immature.

Molt. Nov, Dec, and Jan birds with body and flight 

feather molt. Central rectrices continue growing after the molt 

of all other feathers is completed.

Stomach Contents. Six with insect (beetle, grasshopper) remains; 1 with fruit and insects.

Habitat. Forest.

Notes. Motmots perched low in the forest understory 

from 2 to 5 m up (most commonly 2–3 m). The birds were usually observed singly, often on a favorite perch that they used 

repeatedly. Their call was a resonant, hollow hoot given 5 or 6 

times. Occasionally, a bird gave a “long call” in which the hoot 

was repeated 15 to 20 times. The birds frequently called antiphonally, especially in the morning, with bouts lasting for 10 min 

or more. This may be intrapair communication. Occasionally, 

3 birds called antiphonally. One individual was observed with a 

snake (30–40 cm long × 1–1.5 cm in girth) in its bill. The bird 

changed perches a few times and then flew off with the snake.

Family Bucconidae: Puffbirds

Nystalus chacuru: White-eared Puffbird

Specimens (MVZ). ♂ Jun (1), adult skull.

Mass (g). 61, moderate fat.

Iris. Brown.

Bill. Upper and lower mandibles orange with black tip.

Feet and Tarsi. Gray green.

Gonads. Testes 4 × 1.5 mm.

Molt. No.

Stomach Contents. Full of insect parts.

Habitat. Scrubby abandoned field.

Nonnula rubecula: Rusty-breasted Nunlet

Specimens (USNM, MVZ). ♂♂ Jan (1), Oct (1), 

Nov (1). ♀♀ Jun (1), Oct (1), Nov (2). All birds with adult skulls.
1 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Molt. Molting birds were collected in Jan, Feb, Aug, 

Sep, and Dec. One bird in prejuvenal molt in Oct.

Plumage. Red tips on the fore crown feathers of ♂♂

acquired with the first prebasic molt.

Stomach Contents. Seventeen containing insect 

remains, including ants and ant larvae.

Habitat. Forest, second growth, forest edge, trees in 

scrubby abandoned fields and pastures. Birds frequent understory shrubs and trees, bamboo, vine tangles, thickets.

Notes. The reproductive cycle is not obvious because 

of the difficulty in aging birds and the absence of a clearly defined 

testis cycle. A male was observed over several days in early Jan 

excavating a nest cavity in a dead tree, with the female perched 

nearby. That plus observations of a fledgling in Oct and a family 

group in Jan and the association of body masses at the lower end 

of the range with tiny or undeveloped gonads and completely (as 

opposed to partially) unpneumatized skulls suggest that the birds 

breed from Sep at least through Jan. The birds perch l.5–7 m 

above the ground. They hammer, making a soft, distinctive taptap-tap, on small (7- to 20-mm-diam) hollow branches or bamboo stems, creating holes from which to remove eggs and larvae 

of ants or other insects. They also foliage glean, often hanging 

upside down to poke and probe. The birds make a woodpeckerlike call, which can be heard in most months, that sounds like a 

collection of glass beads bumping into each other.

Melanerpes candidus: White Woodpecker

Specimens (MVZ, MNHNP). ♂♂ Jan (1), Feb (1), 

Sep (1). ♀♀ Mar (1), Jun (1), Sep (1).

Mass (g). ♂♂ X

_

 = 123 (SD = 4.36, range = 120–128, 

N = 3), Feb bird with light fat. ♀♀ X

_

 = 114 (SD = 6.56, range = 

107–120, N = 3), Jun bird with slight fat.

Iris. White.

Bill. Black; lower mandible with gray or slate gray 

blue basally.

Facial Skin. Bright yellow around eye.

Feet and Tarsi. Olive green or blue green, with or 

without brownish tinge. Toe pads paler.

Gonads. ♂♂ Testes 7 × 4 mm (Sep), with incubation 

patch; 6 × 4 (Jan); and 4 × 2 (Feb). ♀ Ova ≤ 1 mm (Mar, Jun); 

ova 2 mm diam (Sep).

Molt. Body and flight feathers in Feb, Mar, and only 

body molt in Sep, Jan, and Jun.

Stomach Contents. Two with adult and larval 

insects, 1 with plant pulp, and 1 with corn. Observed feeding on 

fruit of Guarea (Meliaceae).

Habitat. Pastures, cultivated fields, clearings, tung 

orchards; less commonly in forest. Occupy snags and isolated 

trees in open areas.

Notes. Usually in groups of 2–5 during the breeding 

season. Flocks may double in size following breeding. Conspicuous, with loud calls, sometimes given antiphonally (Oct). Often 

with red dirt on breast feathers.

patches variable; colors duller in immatures. Mouth lining dark 

green or bright orange.

Facial Skin. Bare skin around eye black. Bare skin 

farther out above and/or posterior to eye sky blue or turquoise 

with purple tinge.

Feet and Tarsi. Olive green, green, or yellowish 

gray; ankle blue. Toe pads tan, olive brown, to yellow green.

Gonads. ♂♂ Testes enlarged (19 × 8 mm) in Dec; 

moderately enlarged (4 × 2–8 × 4 mm) in Jan, Feb, Jun. ♀♀ Ovaries granular or inactive in all.

Molt. Body and flight feather molt in Dec, Feb, and 

Mar. First prebasic molt in immature Jan ♂ of body feathers 

only.

Stomach Contents. All birds with fruit in stomach, often 2 or 3 species present. One stomach also contained 

2 spiders.

Habitat. Forest, forest edge, mature second growth, 

second-growth scrub.

Notes. Usually in groups of 2–6 (occasionally alone) 

in forest, although they will venture into scrub if there is a tree 

in fruit. Perches 10–15 m up in large trees; vocal and noisy. One 

Nov bird observed inspecting a tree cavity ~10 m up in a tree 

trunk, perhaps for a nest. Juvenile accompanying an adult in Jan.

Family Picidae: Woodpeckers

Picumnus temminckii: Ochre-collared Piculet

Specimens (USNM, MVZ, MNHNP). ♂♂ 14: Jan 

(2), Feb (2), May (1), Jun (1), Aug (1), Sep (3); Oct (3), Dec (1). 

♀♀ Feb (1), Sep (2), Oct (2), Nov (2), Dec (1). Sex? Feb (1). Of 

19 specimens with data, 3 are labeled as having an adult skull, 

3 as having a juvenal skull, and 13 as having partially pneumatized skulls. Pneumatization likely takes 2 or more years to 

complete, making stage of pneumatization unreliable for aging 

in this species.

Mass (g). ♂♂ X

_

 = 10.4 (SD = 1.0, range = 8.2–11.7, 

N = 14). ♀♀ X

_

 = 10.8 (SD = 0.89, range = 9.9–12.6, N = 8). 

Sex? = 10.5. One Sep bird with light fat; 1 Nov bird with 

some fat.

Iris. Brown or dark brown.

Bill. Upper mandible black or dark gray. Lower mandible black or gray or blue gray with a black tip. Mouth lining 

yellow to yellow green. Oct juvenile, bill yellow with blackish 

area at base of upper mandible.

Feet and Tarsi. Gray, blue gray, olive gray, or black. 

Toe pads tan.

Gonads. ♂♂ Testes were moderately developed (3 × 

2–5 mm long) in May, Aug, Sep, Oct, and Jan. Minimally developed (1 × 0.5–3 × 2 mm) in Jan, Feb, Jun, Oct, and Dec. Testes 

in Aug, Sep, and Oct were sometimes gray or black. One late 

Dec ♂ with a refeathering incubation patch. ♀♀ One Oct female 

had a 3-mm-diam yellow-orange ovum. All other females with 

undeveloped or granular ovaries with largest ova ≤ 1 mm.
NUMBER 648 • 1 9

Iris. Brown.

Bill. Black. Mouth lining gray.

Feet and Tarsi. Olive green, brown, or gray. Toe 

pads brown.

Gonads. ♂♂ Testes enlarged (10 × 6–14 × 10 mm) in 

Sep. Testes small (4 × 1–4 × 2 mm) in Dec (dark green in 1 ♂) and 

Feb. ♀♀ All ovaries tiny.

Molt. Body and flight feathers in Dec, Feb, and Mar, and 

body molt only in Nov and Dec (3). Nov bird in prejuvenal molt.

Stomach Contents. Nine with insects only, including small caterpillars, beetles, ants, and/or ant eggs (in 4). The 

stomach of 1 Dec bird also contained corn.

Habitat. Pastures, cultivated fields, clearings, tung 

orchards.

Notes. Usually found in small groups of 2–8 individuals. The birds make loud, shrill calls, chasing each other and 

interacting conspicuously. They perch on the ground, on stumps, 

and on snags up to ~7 m. Underparts (chin, breast, belly) often 

stained reddish brown by the soil, reflecting their habit of feeding 

frequently on areas of bare dirt. Hayes (2014) recorded a nest in 

Oct in Sapucái (Figure 1). A workman at El Tirol removed a ♀

nestling from a tree cavity on 4 Nov 1976. Feathers in all body 

tracts were with sheath as were both remiges and rectrices.

Dryocopus lineatus: Lineated Woodpecker

Specimens (MVZ). ♂ Jan (1). ♀ Feb (1).

Mass (g). ♂ 210. ♀ 207, light fat.

Iris. White.

Bill. Upper mandible black. Lower mandible dark 

gray green, lighter medially.

Feet and Tarsi. Gray. Toe pads greenish tan.

Gonads. Testes 4 × 2 mm, orange. Ova ≤ 1 mm.

Molt. Both birds with extensive body and flight 

feather molt.

Stomach Contents. ♂ packed with insects; ♀ with 

ants and fruit.

Habitat. Forest.

Notes. Observed feeding in and drumming on dead 

trees. Iris is an obvious and impressively bright white. Red dirt 

on belly of male. Two nests recorded at Sapucái (Figure 1) in Oct 

(Hayes, 2014).

Campephilus robustus: Robust Woodpecker

Specimens (MVZ). ♂♂ Jan (1), Feb (1).

Mass (g). 279, 267, respectively.

Iris. White or lemon yellow.

Bill. Upper mandible pale greenish brown, with sides 

greenish white at the base. Lower mandible greenish white, 

becoming pale greenish blue at sides of base.

Feet and Tarsi. Blackish gray or green. Toe pads 

brownish green.

Gonads. Testes 7 × 3 and 3 × 1 mm, respectively.

Veniliornis spilogaster: White-spotted 

Woodpecker

Specimens (USNM, MVZ, MNHNP). ♂♂ Mar 

(1), Jun (1), Aug (1) Sep (2), Oct (1). ♀♀ Jan (1), Feb (1), Mar (2), 

Jun (1), Sep (2), Oct (1). Mar ♂ and Sep ♀ with juvenal skulls.

Mass (g). ♂♂ X

_

 = 40.5 (SD = 1.52, range = 38.0–42.0, 

N = 6). ♀♀ X

_

 = 38.1 (SD = 1.56, range = 36.0–40.3, N = 8). Jun 

♀ with light fat.

Iris. Brown, dark brown, or red brown.

Bill. Upper mandible black; lower mandible light gray 

with dark tip. Mouth lining pinkish green. Tongue pinkish gray.

Feet and Tarsi. Black, gray, green, or olive gray. Toe 

pads light green, greenish brown, or tan.

Gonads. ♂♂ Testes enlarged (5 × 3–9 × 4 mm) in Aug, 

Sep; small (2 × 1 mm) in Mar, Jun. ♀♀ One Sep bird, largest ova = 

1.5 mm; 1 Feb bird with undeveloped ovary; all other females, 

ovary granular or largest ovum ≤ 1 mm.

Molt. Jan, Feb, and Mar ♀♀ with body and flight 

feather molt. Trace of body molt in Jun ♂.

Stomach Contents. Insects (including caterpillars) 

only, in 7; 1 with fruits and seeds.

Habitat. Forest, old second-growth forest, and forestpasture edge. One individual observed in a 3-m woody shrub in 

a pasture.

Notes. Perches 3–12 m up. Often seen in pairs. On 17 

Oct 1979, 1 bird was excavating a nest hole about 10 m up in a 

dead tree trunk (~11 m tall, broken off above, 30.5 cm diameter 

at breast height [DBH]); in forest with an open understory. Nest 

hole ~5 cm diam.

Colaptes melanochloros: Green-barred 

Woodpecker

Specimens (MVZ). ♂ Sep (1). ♀ Mar (1).

Mass (g). ♂ 125. ♀ 112.

Iris. Dark brown.

Bill. Grayish black. Palate and mouth lining dull pinkish purple. Tongue dull pink with gray-black tip.

Feet and Tarsi. Dull olive green. Toe pads olive brown.

Gonads. ♂ Testes 8 × 4 mm. ♀ Ovary postbreeding.

Molt. ♀ Heavy prebasic molt, including tail.

Stomach Contents. One with black ants.

Habitat. Forest and tung orchard.

Colaptes campestris: Campo Flicker

Specimens (MVZ). ♂♂ Feb (1, ad skull), Sep (2, ad 

skulls), Dec (2, imm skulls). ♀♀ Feb (1, imm skull), Mar (1), 

Nov (1, nestling), Dec (3, ad skulls).

Mass (g). ♂♂ X

_

 = 171.0 (SD = 7.26, range = 160–177, 

N = 5), Feb bird with light fat. ♀♀ X

_

 = 161.2 (SD = 5.22, range = 

156–170, N = 5), Feb, Mar, and 2 Dec birds with light fat. Nov. 

nestling = 108 g, with heavy fat along pterylae.
2 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Facial Skin. Around eye and cere, pale flesh color.

Feet and Tarsi. White, tinged green.

Gonads. Largest ovum of adult, 2 mm; of immature, 

≤ 1 mm.

Molt. Prebasic molt of adult, flight feathers and body; 

of immature, only body.

Stomach Contents. Immature with insect remains 

(including large ticks, Ixodidae) and hair.

Notes. Perches at or near the top of the tallest trees 

bordering scrubby, overgrown pastures or other open areas. Also 

observed flying overhead from Nov through Mar. Makes a loud, 

shrill scream.

Milvago chimango*: Chimango Caracara

Notes. Immature perched in a tree at the edge of a 

pasture in Feb (RMZ).

Falco sparverius: American Kestrel

Specimens (USNM, MVZ, MNHNP). ♂♂ Mar 

(1), Jun (1, dead on road), Sep (2: 1 ad, 1 imm plumage). ♀ Feb (1).

Mass (g). ♂♂ X

_

 = 104.0 (SD = 14.0, range = 93–120, 

N = 3). ♀ 122, light fat.

Iris. Dark brown or black.

Bill. Dark gray, lighter basally.

Facial Skin. Cere and skin around eye yellow green, 

brightest anterior to eye.

Feet and Tarsi. Yellow orange, yellow green, or 

black.

Gonads. Sep ♂ in immature plumage with enlarged 

(20 ×10 mm) testes; other ♂♂, testes small (2 × 1–5 × 4 mm). ♀

Ova ≤ 1 mm.

Molt. Prebasic molt of body, tail, and wing feathers 

(Feb, Mar).

Stomach Contents. Three with insect remains.

Habitat. Perched in trees or dead snags at the edge of 

or scattered in pastures, cultivated fields, open areas.

Notes. Present year-round. Two young in dead snag in 

scrubby pasture in Feb. Two adults perched in dead snag in Mar 

appeared to be molting.

Falco femoralis*: Aplomado Falcon

Notes. Observed clearly, flying from a perch in a tree 

in a pasture into an adjacent tung orchard, in Feb (NKJ).

Family Psittacidae: New World and African Parrots

Myiopsitta monachus: Monk Parakeet

Specimens (MVZ). ♂ Feb (1).

Mass (g). 110 (no fat).

Iris. Pale brown.

Molt. Both birds molting extensively.

Stomach Contents. Beetle larvae up to 4 cm long.

Habitat. Heavy forest.

Notes. Feb bird was with a conspecific; possibly a 

mated pair. Forage between 3–16 m up.

Family Falconidae: Falcons

Micrastur ruficollis: Barred Forest-falcon

Specimens (USNM, MVZ). ♂♂ Mar (1); Sep (1); 

Nov (1), immature plumage. ♀♀ Mar (2), 1 adult, 1 immature.

Mass (g). ♂♂ Adults 147, light fat, and 143, respectively; immature 128. ♀♀ Adult 170, immature 162.

Iris. Dark brown, tan, or tan with purple tinge.

Bill. Upper mandible black or brownish black with 

yellow, olive, or olive gray at base and below nostril. Lower 

mandible yellow, greenish yellow, or olive green with black tip. 

Base of tongue pale pinkish flesh; tip blue gray; palate bluish 

purple. Mouth lining dark purplish flesh color or green.

Facial Skin. Cere, fleshy tissue at gape, eyelids, eye 

rings, and bare skin around eyes yellow or greenish yellow; skin 

brightest anterior and posterior to eye and grayish below.

Feet and Tarsi. Front surfaces of tarsi greenish 

yellow or olive green; rear surfaces and toe pads bright lemon 

yellow.

Gonads. ♂♂ Testes enlarged (10 × 4 mm) in Sep; 

regressing? (5 × 2 mm) in Mar, and small (2 × 1 mm) in Nov 

immature. ♀♀ Ovary postbreeding (adult); double ovary, with 

discrete ova (immature).

Molt. Scattered body molt in Mar ♂ and 1 Mar ♀. 

Likely the end of the prebasic molt. Primary molt in immature 

♂ (Nov).

Stomach Contents. Orthoptera and other insect 

remains in crop and stomach of all birds. Stomach of immature 

♂ also contained mammal fur, and that of the adult ♀ a 10-mm 

stone.

Habitat. Deep forest.

Notes. Occupy low perches (2–4 m). Birds respond to 

squeaking and owl calling by human observers.

Caracara plancus*: Southern Caracara

Notes. Observed occasionally flying over open areas 

or perched in trees near grasslands, cultivated fields, or scrubby 

abandoned pastures (NKJ, MSF).

Milvago chimachima: Yellow-headed Caracara

Specimens (MVZ). ♀♀ Feb (2), 1 adult, 1 immature.

Mass (g). 295 (ad); 330 (imm); both with light fat.

Iris. Brown.

Bill. White, tinged green (ad); pale yellow green with 

wide gray tomium (imm).
NUMBER 648 • 2 1

Molt. Prebasic.

Stomach Contents. Orthopteran remains.

Habitat. Forest.

Notes. At the southern limit of the species range; also 

recorded from Misiones, Argentina (Canevari et al., 1991).

Batara cinerea*: Giant Antshrike

Notes. A male and female were observed with binoculars in Nov 1976 from a blind a short distance (≤5–7 m) away 

for several minutes (MSF). They were skulking around in forest undergrowth but observed clearly. This part of Paraguay has 

not previously been included in the range of the species (Hayes, 

1995; Guyra Paraguay, 2004; Ridgely and Tudor, 2009), nor 

has it been recorded from San Rafael National Park (Esquivel 

M. et al., 2007). However, Ridgely and Tudor (2009) noted its 

occurrence in adjacent Misiones, Argentina, some 200 km to the 

east (or ~105 km SE) of El Tirol, and Hayes (1995) recorded it 

from the central Paraguay geographical region, which abuts his 

Alto Paraná geographical region to the west.

Mackenziaena leachii: Large-tailed Antshrike

Specimens (MVZ). ♂♂ Jan (1), Feb (1), Mar (1). ♀♀

Feb (1), Mar (1), Nov (1). Skulls of Jan and Mar ♂♂ and Feb and 

Mar ♀♀ immature, with windows.

Mass (g). ♂♂ X

_

 = 68.8 (SD = 1.10, range = 67.5–69.5, 

N = 3). ♀♀ X

_

 = 68.9 (SD = 2.29, range = 67.2–71.5, N = 3). 

Feb ♀ with light fat.

Iris. Dark brown or brown.

Bill. Upper mandible black, brownish black, or grayish black. Lower mandible black, grayish black, or black proximally and gray distally. Palate and tongue grayish white or 

pinkish gray. Mouth lining pearl, pinkish flesh, pinkish gray, or 

grayish white.

Feet and Tarsi. Black or blackish brown. Toe pads 

green or olive brown.

Gonads. ♂♂ Testes all small (1 × 1–3 × 1 mm). ♀♀

Ovaries undeveloped (Feb), postbreeding (Mar), and with many 

ova 2 mm diam (Nov).

Molt. Molt in Feb (2) and Mar (2) birds.

Stomach Contents. All with remains of insects and 

other invertebrates, including Orthoptera, Coleoptera, Hemiptera (2 cm), Lepidoptera larva (7.6 cm), and Diplopoda.

Habitat. Border between forest and second-growth 

scrub.

Notes. In dense thickets of Baccharis shrubs, bamboo, 

and vine tangles.

Mackenziaena severa: Tufted Antshrike

Specimens (MVZ). ♂♂ Jan (1), Feb (1), May (1). ♀

Mar (1). Jan ♂ with adult skull. All others with only partly pneumatized skulls.

Facial Skin. Purplish around eye.

Feet and Tarsi. Gray brown. Toe pads light brown.

Gonads. Testis 2 × 1 mm.

Molt. Extensive on body.

Stomach and Crop Contents. Full of ground seeds.

Habitat. Area of farmland with scattered orchards, 

weedy fields, introduced eucalyptus (Myrtaceae), and native trees.

Notes. Specimen brought in by local individual. 

Actual locality is Capitán Miranda, ~4 km SW of El Tirol on 

Ruta 6. Observed several groups of 3 to 4 individuals and 1 flock 

of 12 flying around and perched 12–14 m up in trees. Several 

bulky nests 8 to 14 m up in eucalyptus trees.

Pionus maximiliani: Scaly-headed Parrot

Specimens (MVZ). ♀ Feb (1).

Mass (g). 275, light fat.

Iris. Brown.

Bill. Upper mandible yellow with black at base. Lower 

mandible yellow.

Feet and Tarsi. Black. Toe pads green.

Gonads. Largest ovum 2 mm.

Molt. Wing and body feathers.

Stomach and Crop Contents. Corn.

Habitat. Scrubby pasture, clearings, cultivated fields.

Notes. Flocks (7–11) flying over open areas or perched 

1–4 m up in snags.

Pyrrhura frontalis: Maroon-bellied 

Parakeet

Specimens (MVZ). ♂ Nov (1).

Mass (g). 75 (no fat).

Bill. Upper mandible olive brown. Lower mandible 

olive brown, becoming pale grayish brown at the base.

Facial Skin. Bare skin around eye pale bluish white.

Feet and Tarsi. Olive brown. Toe pads pale sandy 

brown.

Gonads. Testis 2 × 1 mm.

Molt. Scattered ensheathed feathers in body tracts.

Stomach and Crop Contents. Crushed seeds.

Notes. Two in the top of a fruiting tree, ~12 m up.

Family Thamnophilidae: Antbirds

Hypoedaleus guttatus: Spot-backed Antshrike

Specimens (MVZ). ♂ Feb (1), adult skull.

Mass (g). 40.5, light fat.

Iris. Brown.

Bill. Upper mandible black with blue streak ~1 mm 

wide just above tomium. Lower mandible blue.

Feet and Tarsi. Gray. Toe pads tan.

Gonads. Testis 4 × 2 mm.
2 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Gonads. ♂♂ Testes enlarged (8 × 4–12 × 5 mm) Aug 

through Feb; moderately enlarged (5.5 × 3–7.5 × 4 mm) Feb 

and May, which may represent regressing or enlarging gonads, 

respectively. Other males have small (1 × 1–3.5 × 1 mm) testes 

between Feb and Jun. Testis size has no apparent relationship to 

age, as indicated by degree of skull pneumatization. ♀♀ Largest 

ova 2–11 mm diam from Aug through Feb, accompanied by collapsed follicles, enlarged oviducts, and active incubation patches; 

1 additional ♀ had yolked 2-mm ova in May. Three Feb ♀♀ were 

designated postbreeding, 1 with an old incubation patch. Ten 

♀♀ from Feb, Mar, May, Jun, Oct, and Nov had granular ovaries 

with largest ova ≤ 1 mm. Two ♀♀ (Dec, Mar) with juvenal skulls 

had tiny, undeveloped ovaries. However, another 5 ♀♀ with only 

partially pneumatized skulls appeared to be breeding or postbreeding, and 1 had a developed but inactive ovary.

Molt. Presumed prebasic (in adults) and first prebasic 

(in birds of the year) molts recorded in Dec, Jan, Feb, Mar, and 

May. Light body molts recorded in 3 May ♂♂ with moderately 

enlarged testes could represent a prealternate molt or the end of 

a prebasic molt.

Plumage. ♂ from 16 May (USNM 599540) in juvenal plumage with limited black crown. Nape and back feathers 

and upper wing covers heavily spotted with black-edged whitish 

buff. Flanks gray or tawny banded white. Throat and breast gray 

with subtle white barring.

Stomach Contents. Thirty-four with insect remains, 

including caterpillars (1 = 35 mm long) and Coleoptera; 1 with 

insect remains and a 7-mm snail; and 1 with plant material 

and sand.

Habitat. Forest understory.

Notes. This was 1 of the most common species in the 

forest. The birds occupied low shrubby tangles and dense undergrowth (1–3 m; less commonly to 6 m) but also spent considerable 

time on the ground. Birds were paired and appeared to occupy 

territories year-round. Males sang year-round, females occasionally, and they sometimes countersang. They also made a singlenote whistle, and pairs communicated frequently with soft ah or 

sharper tsk position notes. Males bowed, bobbed, and fanned 

their tails when calling. The breeding season extended from Aug 

through Feb, although in any 1 of those months apparently nonbreeding adults were also present. May males had vascular testes 

of 7 × 3.5 and 7 × 4.0 mm and called continually. Family groups 

were observed in Mar. Males and females foraged together, at 

distances of 2–6 m. They also joined mixed-species flocks that 

included Phylloscartes eximius, Basileuterus culicivorus, and 

Trichothraupis melanops. One pair was observed feeding at an 

ant swarm.

Dysithamnus mentalis: Plain Antvireo

Specimens (USNM, MVZ, MNHNP). ♂♂ 24: Jan 

(1), Feb (2), Mar (1), May (2), Jun (6), Aug (2), Sep (4), Oct (3), 

Nov (1), Dec (2). ♀♀ 14: Mar (1), Jun (3), Oct (3), Nov (2), Dec 

(5). Sex? May (1), Nov (2, nestlings). Birds with juvenal skulls 

Mass (g). ♂♂ X

_

 = 54.8 (SD = 1.25, range = 53.5–56.0, 

N = 3); Feb bird with light fat. ♀ 53.0.

Iris. Brown or dark brown.

Bill. Black. Mouth lining yellow green.

Feet and Tarsi. Blue gray or light gray. Toe pads tan, 

bright green, or dull yellowish green.

Gonads. ♂♂ Testes small (1.5 × 1.5–4 × 1.5 mm), but 

increasing in size with date. ♀ Ovary undeveloped.

Molt. All birds molting.

Stomach Contents. Three with insect remains, 

including Coleoptera; 1 with insect remains and a fruit.

Habitat. Forest, forest edge, second-growth scrub.

Notes. In dense Chusquea bamboo and other low 

undergrowth; shy and nearly always behind cover. In May, part 

of a mixed-species flock following an ant swarm. Call an almost 

hawk-like whee; a high-pitched whistle going up slightly and then 

down. The female (MVZ 167304) is likely missexed. Its sooty 

black plumage, black crest, and lack of any barring suggest a male.

Thamnophilus ruficapillus: Rufous-capped 

Antshrike

Specimens (MVZ). ♂ Feb (1), adult skull.

Mass (g). 21.0.

Iris. Red orange.

Bill. Upper mandible black. Lower mandible blue 

gray. Mouth lining pale yellow green.

Feet and Tarsi. Slate gray tinged blue. Toe pads light 

green.

Gonads. Testis 4 × 2 mm.

Molt. Body molt.

Stomach Contents. Insect remains.

Habitat. Scrubby pasture.

Thamnophilus caerulescens: Variable 

Antshrike

Specimens (USNM, MVZ, MNHNP). ♂♂ 27: Jan 

(1), Feb (6), Mar (2), May (4), Jun (4), Aug (2), Sep (3), Oct (2), 

Nov (2), Dec (1). ♀♀ 29: Feb (6), Mar (2), May (2), Jun (5), Aug 

(2), Sep (4), Oct (5), Nov (1), Dec (2). Sex? Oct (1), Nov (1). 

Birds with partially pneumatized skulls in Jan (1), Feb (7), Mar 

(1), May (1), Sep (1), Oct (2), Nov (1), Dec (2).

Mass (g). ♂♂ X

_

 = 18.6 (SD = 1.13, range = 15.3–20.5, 

N = 27). ♀♀ X

_

 = 19.7 (SD = 1.55, range = 15.0–22.5, N = 28). 

Sex? 17.75, 21.75. Light fat in 2 Feb, 1 Jun, and 1 Nov ♀♀ and 

1 Feb ♂.

Iris. Brown or dark brown.

Bill. Upper mandible black. Lower mandible gray or 

blue gray, many with a black tip. Mouth lining greenish yellow, 

orange, ochre, pinkish flesh, or flesh color. Tongue yellowish or 

orangish flesh color.

Feet and Tarsi. Gray or bluish gray. Toe pads green, 

tan, greenish brown, or bright yellow.
NUMBER 648 • 2 3

Mass (g). ♂♂ X

_

 = 11.2 (SD = 1.03, range = 10.0–

12.5, N = 4). ♀♀ X

_

 = 10.5 (SD = 0.06, range = 10.5–10.6, 

N = 3).

Iris. Brown or dark brown.

Bill. Upper mandible black or dark brown. Lower 

mandible pale gray, whitish, white blue gray, gray with pinkish 

base, or black with a light base. Tongue, palate, mouth lining, 

and fleshy tissue at gape orange yellow in 2 Mar juvenal ♀♀.

Feet and Tarsi. Gray, greenish gray, or grayish tan. 

Toe pads green, tannish green, or sandy brown.

Gonads. ♂♂ Testes 3 × 2–5 × 2 mm. ♀♀ One Mar 

ovary undeveloped. Other Mar and Dec ovaries with small 

yolked ova ≤ 1 mm diam; Oct oviduct slightly enlarged.

Molt. Body and flight feather molt in Jan (1) and Mar 

(2) birds.

Plumage. Females lack the semiconcealed dorsal 

white interscapular patch (cf. Ridgely and Tudor, 2009).

Stomach Contents. Five with insect remains.

Habitat. Forest, forest edge, second-growth scrub 

in shrubby bamboo tangles and vine thickets near the ground 

(≤2 m).

Pyriglena leucoptera: White-shouldered 

Fire-eye

Specimens (USNM, MVZ). ♂♂ Feb (3), Mar (1), 

May (2), Sep (2), Dec (1). Two individuals from Feb with immature skulls, also 1 from Mar and 1 from May. ♀♀ 10: Jan (1), 

Feb (2), Mar (2), Sep (1), Oct (2), Nov (1), Dec (1). Both Mar 

♀♀ with skull windows.

Mass (g). ♂♂ X

_

 = 29.2 (SD = 1.94, range = 25.7–32.0, 

N = 9). ♀♀ X

_

 = 25.4 (SD = 1.45, range = 23.5–28.2, N = 9). Light 

fat in birds in Feb (2), May (2), and Sep (1).

Iris. Red.

Bill. Upper mandible black. Lower mandible black in 

males; pale gray, blue gray, or pinkish gray basally and gray distally in females. Mouth lining bright orange, orange yellow, or 

yellow green. Palate and tongue orange or orange yellow.

Feet and Tarsi. Black, blackish gray, gray, blue gray, 

or dull purple gray. Toe pads green, yellow green, olive brown, 

tan, grayish tan, or greenish tan.

Gonads. ♂♂ Testes of adult males enlarged (9 × 4–12 × 

7 mm) from Sep through Feb, and 1 ♂ with a cloacal protuberance; testes small (3.5 × 1.5 mm) in May and undeveloped (1 × 

1–2 × 1 mm) in juvenal males. ♀♀ Ova enlarged (2–8 mm diam), 

shelled egg in oviduct, enlarged oviduct, and/or incubation patch 

in adults, Sep to Jan. Feb ♀♀, largest ovum ≤ 1 mm diam. Juvenal ♀♀, ovaries undeveloped.

Molt. Recorded in Dec, Jan, Feb, and Mar. Some birds 

with body and flight feather molt; others with only body molt. 

The latter may be birds in their first prebasic molt.

Stomach Contents. Fourteen with insect remains. 

One breeding ♀ with a small snail in addition.

Habitat. Forest undergrowth.

are present in Nov (2), Dec (1), Feb (2), Mar (2), May (1), Aug 

(1), and Sep (1). All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 11.7 (SD = 0.94, range = 9.0–13.0, 

N = 23); light fat in 1 Aug bird. ♀♀ X

_

 = 11.3 (SD = 1.24, range = 

8.8–13.0, N = 13). Sex? 13.0; both nestlings = 10.25. Birds with 

light to moderate fat noted in Mar (1), Jun (2), Aug (1), and 

Dec (1).

Iris. Brown or dark brown.

Bill. Upper mandible black, dark gray, or gray. Lower 

mandible gray, blue gray, or gray basally with a black tip. Mouth 

lining gray or flesh color. In nestlings, upper mandible black and 

lower mandible rosy pink. Mouth lining bright orange, orange 

pink, flesh color, gray, or yellow green.

Feet and Tarsi. Adults: gray or yellowish or greenish 

gray; toe pads tan. Juveniles: blue gray or olive; toe pads tan, 

greenish brown, or yellow.

Gonads. ♂♂ Testes enlarging or enlarged (3.5 × 2–9 × 

5 mm) Aug through Dec; small (1 × 1–2.5 × 1 mm) Jan through 

Jun except for 1 May ♂ (5 × 2 mm). ♀♀ Ovary granular with ova 

≤ 1 mm, Mar through Jun plus some in Nov, Dec. Enlarged ova, 

shelled eggs, and/or active brood patches in Oct, Dec.

Molt. Prebasic molt of body and flight feathers 

recorded in Dec, Jan, May. First prebasic body molt recorded in 

Dec, Feb, Mar, May. Oct nestlings acquiring juvenal plumage.

Stomach Contents. Twenty-seven with insect 

remains, including Coleoptera; 1 with fruit and insect remains.

Habitat. Forest.

Notes. Common in dense vegetation of the forest 

understory. These foliage gleaners drop to a low perch (≤1 m) 

and then ascend by hopping up vertical vines and sapling trunks 

to 5 or 6 m and then drop down again, repeating the cycle. Generally in pairs or small family groups. Call continually while 

moving, giving a soft, oft-repeated aur or mew.

Herpsilochmus rufimarginatus: 

Rufous-winged Antwren

Specimens (USNM, MVZ). ♂♂ Oct (1), Dec (1). 

Adult skulls.

Mass (g). 10.5, 10.0, respectively.

Iris. Brown.

Bill. Upper mandible black. Lower mandible gray.

Feet and Tarsi. Pale gray.

Gonads. Testes in both 4 × 2 mm.

Molt. Dec bird in prebasic molt of body and flight feathers.

Stomach Contents. Insect remains in both, including 1 caterpillar.

Habitat. Forest.

Drymophila malura: Dusky-tailed Antbird

Specimens (USNM, MVZ). ♂♂ Jan (1), Sep (2), 

Oct (1). ♀♀ Mar (2), Oct (1). Mar ♀♀ with large lateral skull 

windows. All other birds with adult skulls.
2 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Gonads. ♂ Testes 14 × 7 mm. ♀ Largest ovum 1 mm 

diam, yellow orange; with brood patch.

Molt. No.

Stomach Contents. ♂ Seeds, crystalline grit, and 

insect remains. ♀ Insect remains.

Notes. Powerful muscular stomach with 10-mm-thick 

lining corrugated with 9 or 10 ridges. Call loud and tremulous 

and carries a long distance; somewhat ventriloquial and reminiscent of Glaucidium brasilianum. Birds call regularly from Sep 

through Mar and are more often heard than seen. They frequent 

the densest undergrowth using perches at 1–3 m but sometimes 

sing from higher perches (10 m) or from the tops of tall trees. 

Nests in tree cavities at least from Sep through Dec (Bodrati 

et al., 2014).

Family Furnariidae: Ovenbirds

Sclerurus scansor: Rufous-breasted 

Leaftosser

Specimens (USNM, MVZ). ♂ Oct (1), adult skull. 

♀♀ Mar (1), with skull windows; Oct (2), both with adult skulls.

Mass (g). ♂ 30. ♀♀ X

_

 = 37.7 (SD = 2.08, range = 

36–40, N = 3).

Iris. Brown or dark brown.

Bill. Upper mandible black. Lower mandible white to 

grayish white with a black tip. Mouth lining bluish gray.

Feet and Tarsi. Black. Toe pads reddish purple.

Gonads. ♂ Testes enlarged (9 × 5.5 mm). ♀♀ Largest 

ova 2 mm diam in Oct. Mar ovary undeveloped.

Molt. No.

Stomach Contents. Three with insect remains.

Habitat. Forest.

Notes. Found low in forest undergrowth and on 

ground, scratching in the leaf litter. One adult ♀ covered with 

hundreds of Mallophaga (bird lice) crawling everywhere.

Sittasomus griseicapillus: Olivaceous 

Woodcreeper

Specimens (USNM). ♂♂ 13: Jan (1), Feb (1), Mar 

(1), May (1), Aug (1), Sep (2), Oct (1), Nov (1), Dec (4). ♀♀ Jan 

(1), Feb (1), Mar (1), Oct (1), Dec (3). One Dec and 1 Jan ♂ and 

2 Dec and 1 Feb ♀ with partly pneumatized skulls. All others 

with adult skulls.

Mass (g). ♂♂ X

_

 = 12.4 (SD = 0.94, range = 11–14.3, N

= 13). ♀♀ X

_

 = 10.3 (SD = 0.69, range = 9.5–11.5, N = 6). Light 

fat in 1 Feb ♂.

Iris. Brown or dark brown.

Bill. Upper mandible black or brownish black. Lower 

mandible gray, blue gray, or silver gray with black tip. Mouth 

lining and tongue pinkish flesh color.

Feet and Tarsi. Gray or blue gray. Toe pads gray tan 

or olive brown.

Notes. Low in the vegetation, often near the forest floor. Once part of a mixed-species flock following an ant 

swarm; aggressive, chased away other birds (e.g., Trichothraupis melanops). Oviducal egg with unhardened shell (white with 

a few black dots) = 22 mm long × 18 mm at widest point. Molt 

overlaps with breeding in some males with enlarged testes 

(12 × 7 mm, Dec; 9 × 4 mm, Feb). Song a series of descending 

notes.

Family Conopophagidae: Gnateaters

Conopophaga lineata: Rufous Gnateater

Specimens (USNM, MVZ, MNHNP). ♂♂ 24: Feb 

(5), Mar (2), May (3), Jun (3), Aug (1), Sep (6), Oct (2), Dec (2). 

♀♀ 14: Jan (1), Feb (3), Sep (5), Oct (3), Dec (2). Two Dec, 5 

Feb, and 1 Mar bird with immature skulls; 1 Feb bird with small 

skull windows. All others with adult skulls.

Mass (g). ♂♂ X

_

 = 21.5 (SD = 1.15, range = 19.5–

24.0, N = 24). ♀♀ X

_

 = 19.9 (SD = 2.21, range = 16.0–24.0, 

N = 13). Two Jun ♂♂ and 1 Oct male with light to moderate fat.

Iris. Brown or dark brown.

Bill. Upper mandible black. Lower mandible white, 

pinkish white, flesh color, or tan. Soft, fleshy gapes of juveniles, 

orange or yellow. Mouth lining orange or yellow. Tongue and 

palate buffy orange.

Feet and Tarsi. Greenish or yellowish gray or tan, 

gray, tan, brown, or olive. Toe pads olive green, greenish tan, 

greenish brown, or tan.

Gonads. ♂♂ Testes small (1 × 1–4 × 3 mm) Dec 

through Jun; enlarged (8 × 5–17 × 7 mm), Aug through Oct. ♀♀

Ovaries granular in Dec and Jan; most ovaries with enlarged ova 

(1.5–11 mm diam) in Sep–Oct, and 1 Sep bird with an enlarging oviduct and developing incubation patch. Juvenal ♀♀ with 

small, undeveloped ovaries.

Molt. Adults in prebasic molt recorded in Dec, Jan, 

Feb, Mar. Immature birds in first prebasic molt in Feb and Mar.

Stomach Contents. Insect remains, including 

Coleoptera, Hemiptera, Orthoptera, and Lepidoptera larvae, in 

23. One with a large spider.

Habitat. Forest, forest edge.

Notes. Skulks around on the ground or in low understory vegetation. Uses both horizontal and vertical perches, 

especially vines in brushy tangles. Twice observed feeding at ant 

swarms. Call a harsh, buzzy trill or churrrp given repeatedly.

Family Formicariidae: Antthrushes

Chamaeza campanisona: Short-tailed 

Antthrush

Specimens (USNM, MVZ). ♂ Sep (1). ♀ Oct (1). 

Both with adult skulls.

Mass (g). ♂ 87. ♀ 91.
NUMBER 648 • 2 5

Gonads. ♂♂ Testes 3.5 × 2.0 (May), 8 × 5–15 × 9 Sep 

and Dec; 1 Dec bird with an incubation patch. ♀♀ Largest ovum 

2 mm (Oct); ovary of juvenile undeveloped.

Molt. Extensive. Prebasic, including flight feathers, 

May and Dec. First prebasic in Mar.

Stomach Contents. All with insect remains, including large cicadas.

Habitat. Forest, forest edge.

Notes. Found on trunks and (often on the underside 

of) large limbs in moderate to large trees; begins 2–3 m off the 

ground and moves up the trunk to about 8 m and then flies down 

to a low perch on the trunk of an adjacent tree and starts up 

again. Call a loud, raucous series of notes, almost a trill.

Xiphorhynchus fuscus: Lesser Woodcreeper

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (2), 

Jun (1), Sep (1), Oct (1), Dec (2). ♀♀ Jan (1), Feb (1), Aug (1), Sep 

(1), Oct (1), Dec (1). Sex? Dec (1). Jan, Sep, and Oct ♂♂ and Sep 

♀ with adult skulls. All others with partly pneumatized skulls.

Mass (g). ♂♂ X

_

 = 17.8 (SD = 1.39, range = 17.5–19.0, 

N = 6). ♀♀ X

_

 = 17.1 (SD = 1.96, range = 14.6–19.5, N = 6), Feb 

bird with light fat.

Iris. Brown or dark brown.

Bill. Upper mandible black or blackish brown. Lower 

mandible pink, white, or cream. Mouth lining peach color.

Feet and Tarsi. Gray, yellowish gray, or greenish 

with bright greenish toe pads.

Gonads. ♂♂ Testes small (4 × 2–2 × 1 mm) late 

Dec through Jun; enlarged in Sep (9 × 5 mm) and Oct (12 × 6 

mm). ♀♀ Enlarged ova in Aug (3 largest ova = 2 mm diam, yellow orange; oviduct enlarged) and Sep (largest ovum = 2 mm, 

orange). Ovaries in other ♀♀ tiny, with ova ≤ 1 mm.

Molt. In some Dec, Jan, and Feb birds.

Stomach Contents. Nine with insect remains.

Habitat. Forest.

Notes. In large trees, primarily on vertical surfaces. 

Complete skull pneumatization appears to take more than 1 

year. Apparent juveniles/immatures were present in Dec, Jan, 

and Feb. Other apparently adult birds with only partially pneumatized skulls were collected in Jun, Aug, Oct, and Dec, and 

some were in breeding condition. The unsexed bird was found 

on the forest floor, dead of unknown causes.

Campylorhamphus falcularius: Black-billed 

Scythebill

Specimens (MVZ). ♂ Mar (1), adult skull. ♀ Jan (1), 

adult skull. Sex? Mar (1), skull windows.

Mass (g). ♂ 33.2. ♀ 36.0.

Iris. Brown or dark brown.

Bill. Brownish black or black fading to dark olive 

brown at tip. Tongue and palate yellow orange. Mouth lining 

orange or pinkish flesh color.

Gonads. ♂♂ Testes enlarged (6 × 4–9 × 5.5 mm) Aug 

through Nov; small (1 × 1–2 × 1 mm) Dec through May. ♀♀

Largest ovum = 1 mm in Oct; all others ovary tiny or, in birds 

with imm skulls, smooth and undeveloped.

Molt. Prebasic molt including body and flight feathers 

recorded in Oct, Nov, Dec, Jan, Feb, Mar, May. First prebasic 

body molt recorded in Dec, Jan, Mar.

Stomach Contents. Ten with insect remains; 1 

with a spider.

Habitat. Forest, forest edge.

Notes. A common species found 10–15 m up on trunks 

and large limbs of tall trees. It sometimes hangs with its body 

horizontal from the underside of limbs. Often moves in pairs and 

may join mixed-species flocks. Makes a variety of calls, including 

a loud trill reminiscent of a cicada that increases in intensity as it 

progresses; also a series of raucous whees in a descending pattern.

Dendrocincla turdina: Plain-winged 

Woodcreeper

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

Jun (3). ♀ Jun (1). Jan ♂ with immature skull; all other birds 

with adult skulls.

Mass (g). ♂♂ Adults X

_

 = 44.0 (SD = 1.0, range = 

43.0–45.0, N = 3), all with moderate fat. Imm ♂ = 36.0. ♀ = 

37.8, moderate fat.

Iris. Brown.

Bill. Upper mandible black, dark gray, gray brown, or 

brown. Lower mandible gray, gray with tan tomium and tip, 

or light greenish gray.

Feet and Tarsi. Tarsi gray, gray brown, brown, or 

tan. Feet gray or gray brown.

Gonads. ♂♂ Testes small in adults (2.0 × 1.0–2.5 × 

1.5 mm) and immature (1 × 1 mm). ♀ Ovary granular, ova 

minute.

Molt. One adult ♂ molting the central rectrices (Jun); 

immature ♂ molting (Jan).

Stomach Contents. All with insect remains.

Habitat. Tall forest.

Dendrocolaptes platyrostris: Planalto 

Woodcreeper

Specimens (USNM, MVZ). ♂♂ May (1), Sep (2), 

Dec (2), all with adult skulls. ♀♀ Mar (1, juv skull), Oct (1, ad skull).

Mass (g). ♂♂ X

_

 = 57.5 (SD = 4.84, range = 52.0–64.0, 

N = 5). ♀♀ Adult, 61.0; immature, 59.5.

Iris. Brown.

Bill. Black with narrow yellow tomium basally and at 

tip. Mouth lining yellow green or orange green.

Facial Skin. Eyelids and bare skin below eyes pale 

greenish olive. Eye ring orange green.

Feet and Tarsi. Gray, brown, olive brown, olive 

green, or greenish gray. Toe pads olive orange.
2 6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Stomach Contents. Both with insect remains, 

including larvae.

Habitat. Old growth with vines.

Notes. Perches 5–6 m up in vines; hangs from twigs. 

Much less common at El Tirol than Xenops minutus.

Furnarius rufus: Rufous Hornero

Specimens (USNM, MVZ). ♂♂ Feb (1), Mar (1), 

Dec (1). ♀♀ Feb (1), May (1). May ♀ with adult skull. All other 

birds, skulls ≤ 50% pneumatized.

Mass (g). ♂♂ X

_

 = 54.1 (SD = 2.08, range = 52.8–56.5, 

N = 3). ♀♀ 54.5, 56.0. Both Feb and Mar birds with light fat.

Iris. Reddish or orangish brown.

Bill. Upper mandible black or brown. Lower mandible 

gray white at base and dark distally. Mouth lining light flesh blue 

or flesh green.

Feet and Tarsi. Brown, dark brown, or slate gray 

brown. Toe pads tan.

Gonads. ♂♂ Testes small (1 × 1–2 × 1 mm) in all 

birds. ♀♀ Feb, largest ova ≤ 1 mm diam. May ovary smooth and 

undeveloped.

Molt. Feb and Mar, only body or body and flight 

feathers.

Stomach Contents. Five with insect remains, 

including 2 with ants.

Habitat. Tung orchards, scrubby pasture, edges of 

fields, and clearings.

Notes. Move as pairs, duetting commonly. Also make 

a harsh tcha note, sometimes given repeatedly. Red dirt on ventral feathers of some.

Lochmias nematura: Sharp-tailed 

Streamcreeper

Specimens (USNM). ♀ Oct (1), skull 5% pneumatized.

Mass (g). 18.5.

Iris. Brown.

Bill. Upper mandible black. Lower mandible black 

with gray at base.

Feet and Tarsi. Brown.

Gonads. Largest ovum 1 mm diam. Oviduct enlarging.

Molt. No.

Stomach Contents. Insect remains.

Philydor atricapillus: Black-capped 

Foliage-gleaner

Specimens (MVZ). ♂♂ Dec (2), adult skull and juvenal skull.

Mass (g). 22.0 (adult); 23.0 (juv).

Gonads. Testis 2 mm (adult) and minute (juv).

Molt. Juvenile in first prebasic molt, growing body 

and flight feathers.

Stomach Contents. Insect remains in both.

Feet and Tarsi. Olive green. Toe pads olive brown 

or greenish orange.

Gonads. ♂ Testis 2.5 × 1.5 mm. ♀ Ovary tiny.

Molt. Prebasic molt Jan, Mar. First prebasic in Mar.

Stomach Contents. All with insect remains.

Habitat. Forest.

Notes. Forages on large trunks and heavy, woody 

vines in dense vegetation. Moves backward down bamboo vines 

using the tail extensively for support. Also forages on the undersides of horizontal limbs. Spends most of the time peering at 

surfaces rather than probing.

Lepidocolaptes angustirostris: Narrow-billed 

Woodcreeper

Specimens (MNHNP). ♂ Sep (1), fully pneumatized 

skull.

Mass (g). 13.0, no fat.

Gonads. Testis enlarged, 16 × 9 mm.

Molt. No.

Habitat. Tall forest.

Xenops minutus: Plain Xenops

Specimens (USNM, MVZ). ♂♂ Sep (1), Oct (1), 

Nov (1), Dec (3). All with fully pneumatized skulls except Nov 

♂ with small skull windows and 1 Dec ♂ with juvenal skull. ♀

Jan (1), adult skull. Sex? Nov (1), juvenal skull.

Mass (g). ♂♂ X

_

 = 8.2 (SD = 0.45, range = 7.4–8.6, 

N = 6); Dec juvenile with light fat. ♀ 6.8. Sex? = 8.3, moderate fat.

Iris. Black or brown.

Bill. Upper mandible black. Lower mandible pale or white.

Feet and Tarsi. Gray.

Gonads. ♂♂ Testes enlarged (5 × 3.5–7 × 4.5 mm) in 

Sep, Oct; small (≤1–1.5 × 0.75 mm) in Nov, Dec. ♀ Ovary tiny.

Molt. All Dec and Jan birds.

Stomach Contents. Five with insect remains.

Habitat. Forest, second-growth edge.

Notes. Uses primarily vertical perches, 3–10 m up in 

trees and vines. Taps and hammers branches like a woodpecker; 

forages like a nuthatch. Makes a single note pseuuut call over 

and over, with the last half upwardly inflected. Juvenile moving 

with adult ♂ in Dec.

Xenops rutilans: Streaked Xenops

Specimens (MVZ). ♀ Nov (1), adult skull. Sex? Nov 

(1), with large skull windows.

Mass (g). ♀ 11.8. Sex? 12.0.

Bill. Upper mandible brownish black. Lower mandible pinkish white grading to brownish at tip. Mouth lining 

brownish yellow.

Feet and Tarsi. Bluish gray. Toe pads greenish brown.

Gonads. ♀ Largest ova = 1 mm diam.

Molt. No.
NUMBER 648 • 2 7

Feb (1), Mar (1), May (1), Jun (1), Aug (1) Sep (3), Oct (1). One 

Sep and 1 Oct ♂ with adult skulls. All other birds with only 

partly pneumatized skulls.

Mass (g). ♂♂ X

_

 = 24.5 (SD = 1.59, range = 22.2–27.2, 

N = 16). ♀♀ X

_

 = 23.1 (SD = 1.72, range = 20.3–26.9, N = 9); 

Feb bird with light fat.

Iris. Brown, dark brown, and black.

Bill. Upper mandible black, blackish olive, or dark 

brown. Lower mandible gray, pinkish gray, grayish white, or 

white with brown, olive brown, or gray tomia and tip. Mouth 

lining lemon yellow, greenish yellow, brownish orange, or dark 

flesh color. Tongue and palate brownish orange or orange flesh 

color.

Feet and Tarsi. Yellowish tan, gray tan, gray green, 

olive green, olive brown, or yellow olive gray. Toe pads greenish 

yellow or bright yellow.

Gonads. ♂♂ Testes enlarged (10 × 5–13 × 7 mm) 

with cloacal protuberances, Sep, Oct; regressing (8 × 5 mm) 

in Nov; small (1 × 1–2 × 1.5 mm), Feb–May. ♀♀ Largest 

ova (2 mm diam) in Sep. All other birds, largest ova ≤ 1 mm, 

although an Oct ♀ has a well-developed incubation patch. One 

♀ with enlarging oviduct in Aug. Feb and Jun ♀♀ have smooth, 

undeveloped ovaries and are probably immatures that have not 

yet bred.

Molt. Adults and juveniles with molt in Jan, Feb, and 

Mar. One May ♀ with light molt on the head.

Stomach Contents. Seventeen with insect remains.

Habitat. Thickets, vines, and other dense vegetation 

in the forest understory.

Notes. Occupies the understory (1–7 m) but often 

stays low in the vegetation, 1–2 m up. Visits small (2–3 cm DBH) 

trees, scooting up the stem in woodcreeper fashion. Position note 

a squeaky, loud tschup. Full skull pneumatization in the species 

requires at least 2 years; birds breed while still retaining large 

skull windows. Common at El Tirol.

Automolus leucophthalmus: White-eyed 

Foliage-gleaner

Specimens (USNM, MVZ, MNHNP). ♂♂ 11: 

May (1), Jun (1), Sep (1), Oct (4), Nov (1), Dec (3). ♀♀ 13: 

Jan (1), Jun (4), Sep (1), Oct (1), Nov (2), Dec (4). Sex? Feb (1), 

Jun (1). All birds with adult skulls except 1 Dec ♂ and 1 Dec ♀, 

1 Jan ♀, and 1 Feb Sex?

Mass (g). ♂♂ X

_

 = 32.8 (SD = 1.80, range = 29.2–

35.5, N = 11). ♀♀ X

_

 = 29.6 (SD = 2.11, range = 26.0–32.5, 

N = 12), Feb bird with light fat.

Iris. Pearl, white, whitish brown, brown, gray, gray 

white, or golden white.

Bill. Upper mandible dark brown, brownish olive, or 

horn, with lighter tip. Lower mandible gray, yellow gray, gray 

green, ivory, or tan. Mouth lining and tongue pale pink.

Facial Skin. Skin around eye greenish yellow.

Feet and Tarsi. Olive, yellow, or gray green; greenish 

or grayish tan; or yellowish gray.

Philydor rufum: Buff-fronted 

Foliage-gleaner

Specimens (MVZ). ♂ Dec (1). ♀♀ Feb (1), Sep (1), 

Nov (1). ♂ and Nov ♀ with adult skulls; others with partly pneumatized skulls.

Mass (g). ♂ 26.0. ♀♀ X

_

 = 24.8 (SD = 1.25, range = 

23.4–25.8, N = 3).

Iris. Dark brown.

Bill. Upper mandible black. Lower mandible black, 

tinged brown. Mouth lining light green.

Feet and Tarsi. Pale green or olive green. Toe pads tan.

Gonads. ♂ Testes 5 × 3 mm. ♀♀ Largest ova ≤ 1 mm, 

Sep, Nov. Ovary of Feb ♀ smooth, undeveloped.

Molt. Feb body molt.

Stomach Contents. Insect remains in 2.

Habitat. Forest subcanopy, 6–9 m.

Anabacerthia lichtensteini: Ochre-breasted 

Foliage-gleaner

Specimens (USNM, MVZ, MNHNP). ♂♂ 13: Jan 

(3), Jun (1), Aug (1), Sep (3), Oct (3), Nov (1), Dec (1). ♀♀ Mar 

(1), May (1), Aug (1), Sep (1). Sex? Mar (1). Jun, Aug, Sep (2), 

and Dec ♂♂ with adult skulls. All other specimens with partly 

pneumatized skulls.

Mass (g). ♂♂ X

_

 = 21.6 (SD = 1.16, range = 19.5–

23.5, N = 13). ♀♀ X

_

 = 19.6 (SD = 1.00, range = 18.3–20.5, 

N = 4); Aug ♀ with light fat.

Iris. Brown or dark brown.

Bill. Upper mandible black, brown, brownish black, 

olive brown, or gray. Lower mandible black, brown, gray, grayish brown or white, bluish or greenish gray, or tan with brown 

tomium and tip. Mouth lining gray green, flesh green, or flesh 

color.

Feet and Tarsi. Olive, olive brown, olive green, yellow green, or yellow gray. Toe pads yellow brown, dark greenish 

brown, or brown.

Gonads. ♂♂ Testes enlarged (7.5 × 4–10 × 6.5 mm) 

Sep, Oct; regressing Nov, Dec (2 × 1–3 × 2 mm); small (1 mm) 

in Mar; and enlarging (2 × 2–3 × 1.5 mm) again in Jun, Aug. ♀♀

All with granular ovaries or largest ova ≤ 1 mm diam.

Molt. Prebasic molt of body and flight feathers in Dec 

and Mar.

Stomach Contents. Insect remains in 14.

Habitat. Forest.

Notes. Forages 1–10 m up in foliage or on stems 3–5 

cm diam; often in areas of bamboo or moderately dense saplings. 

May join mixed-species flocks. Call note a single, shrill scree.

Syndactyla rufosuperciliata: Buff-browed 

Foliage-gleaner

Specimens (USNM, MVZ, MNHNP). ♂♂ 16: Feb 

(1), Mar (5), May (2), Sep (4), Oct (3), Nov (1). ♀♀ 10: Jan (1), 
2 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Stomach Contents. Insect remains in 18.

Habitat. Forest understory, especially in very dense 

tangles of bamboo and vines.

Notes. Most commonly seen Synallaxis at El Tirol. 

One individual carrying nest material in Sep. Complete skull 

pneumatization appears to require at least 2 years, and many 

breeding birds have large skull windows. Bird begins foraging 

very low in vegetation, working its way up 1–2 m poking and 

probing; all stems 1–2 cm diam. Usually in pairs; 1 observation 

of foraging with a mixed-species flock. Call a long, ascending, 

reedy or nasal whistle followed by 2 short, abrupt notes at lower 

frequencies; wheee buz whit.

Synallaxis ruficapilla: Rufous-capped Spinetail

Specimens (USNM, MVZ). ♂♂ Feb (2), Mar (1), 

Oct (3), Dec (1). ♀♀ Jan (1), Mar (1), Sep (1), Oct (1). Sex? Sep 

(1). Skulls of all birds only partly pneumatized.

Mass (g). ♂♂ X

_

 = 12.7 (SD = 0.80, range = 12.0–14.1, 

N = 7). ♀♀ X

_

 = 12.3 (SD = 1.07, range = 10.9–13.5, N = 4).

Iris. Brown, red, or red brown.

Bill. Upper mandible black. Lower mandible black, 

gray, blue gray, white, or pale pinkish gray at base with gray tip. 

Tongue and palate pale pinkish flesh color. Mouth lining pinkish 

flesh color, greenish flesh color, or light green.

Feet and Tarsi. Yellowish gray, gray green, gray tan, 

brown, or olive green. Toe pads olive green or tan.

Gonads. ♂♂ Testes enlarged (6 × 4–9 × 6 mm) in 

Oct, regressing in Dec (5 × 2.5), and small (1 × 1–2 × 1 mm) in 

Feb, Mar. ♀♀ Enlarged ova (2–8 mm diam), enlarged oviduct, 

and/or developing incubation patch in Sep, Oct, Jan. Mar ovary 

postbreeding.

Molt. Body or body and flight feather molt in Dec, 

Jan, Feb, Mar.

Stomach Contents. Insect remains in 9.

Habitat. Thick forest undergrowth with vines and/or 

bamboo.

Notes. Moves about in pairs. Skulls require more than 

1 year to pneumatize if they ever do.

Synallaxis spixi: Spix’s Spinetail

Specimens (USNM, MVZ). ♂♂ Jan (1), Feb (1), 

May (1), Oct (1). ♀ Oct (1). Sex? Feb (1). Oct ♂ with adult skull. 

All others with partly pneumatized skulls.

Mass (g). ♂♂ X

_

 = 12.6 (SD = 0.30, range = 12.3–13.0, 

N = 4); Feb and May with light fat. ♀ 12.3, with light fat. Sex? 

11.7.

Iris. Brown, red, brick red brown, or pinkish or grayish white.

Bill. Upper mandible black. Lower mandible gray or 

blue gray. Mouth lining flesh color.

Feet and Tarsi. Olive tan, olive green, or greenish 

gray. Toe pads light green or grayish tan.

Gonads. ♂♂ Testes enlarged (10 × 5–15 × 8 mm) in 

Oct, Nov, Dec; small (1 × 1–3 × 1 mm) Dec to Jun; enlarging (8 × 

4 mm) in Sep. ♀♀ Enlarged ova, collapsed follicles, enlarged oviducts, and/or active incubation patches in Sep, Oct, Nov. Ovaries 

granular with ova ≤ 1 mm or ovaries undeveloped in birds with 

juvenal skulls in Dec, Jan, Feb, Jun.

Molt. Prebasic and first prebasic molts in Dec, Jan, 

Feb, May.

Stomach Contents. Sixteen with insect remains, 

including caterpillars.

Habitat. Heavy forest, old second growth.

Notes. Low (1–4 m) in vegetation on the trunks and 

branches of small trees, in bamboo thickets, tree ferns, vines. 

Often move in pairs; counter call. Common at El Tirol.

Cranioleuca obsoleta: Olive Spinetail

Specimens (MVZ). ♂ Oct (1), skull ~25% pneumatized.

Mass (g). 12.5, light fat.

Iris. Red brown.

Bill. Upper mandible black. Lower mandible flesh 

color.

Feet and Tarsi. Yellowish gray.

Gonads. Testis enlarged (9 × 5 mm).

Molt. No.

Stomach Contents. Insect remains.

Notes. At edge in scrubby vegetation, with bamboo 

and small trees.

Synallaxis cinerascens: Gray-bellied Spinetail

Specimens (USNM, MVZ, MNHNP). ♂♂ 18: 

Jan (2), Feb (2), Mar (1), May (2), Jun (2), Sep (2), Oct (3), Dec 

(4). ♀♀ Mar (3), Jun (1), Aug (1), Nov (1), Dec (1). One Dec 

♂ with an adult skull. All others birds with partly pneumatized 

skulls.

Mass (g). ♂♂ X

_

 = 11.8 (SD = 1.17, range = 10.0–14.0, 

N = 18). ♀♀ X

_

 = 11.4 (SD = 0.94, range = 10.0–12.5, N = 7). 

One Mar ♀ and 1 May and 1 Sep ♂ with light fat.

Iris. Red, red brown, or brown.

Bill. Upper mandible black. Lower mandible black, 

gray, gray brown, gray blue, or silver gray; may have a black tip. 

Mouth lining black, slate gray, or blue gray.

Feet and Tarsi. Tan, brown, gray tan, gray blue, 

olive brown, or yellowish or greenish gray. Toe pads light green, 

flesh green, olive tan, or tan.

Gonads. ♂♂ Testes of some enlarged (5 × 3–8 × 4 

mm) in Sep, Oct, Dec, and 1 bird in May. Testes medium size (4 × 

2 mm) in Jan, Feb, Mar, and May and small (1 × 1–2 × 1 mm) 

in Oct, Dec, Jan, Feb, May, and Jun. ♀♀ Nov ♀ with ova 

1.5 mm diam, enlarged oviduct, and brood patch; Aug ♀ with ova 

1.5 mm diam. All other ♀♀ with ova ≤ 1 mm.

Molt. Body and flight feather molt in Dec, Feb, Mar. 

Body only molt in Oct, Dec, Jan, and Mar.
NUMBER 648 • 2 9

Iris. Brown or gray brown.

Bill. Upper mandible black. Lower mandible black 

with light area at base. Mouth lining greenish orange.

Feet and Tarsi. Black or dark gray.

Gonads. ♂♂ Testes 3 × 2 (Jan), 7 × 3 (May), 5 × 3 mm 

(Oct). ♀ Ovary granular.

Molt. Prebasic molt of body and flight feathers in Jan 

and May.

Stomach Contents. All with insect remains, including caterpillars.

Habitat. Forest, forest edge.

Notes. Calls while moving through the foliage, foraging. Occasionally forages with a mixed-species flock. Moves in 

the understory (3–4 m) and up through the canopy (18 m). Testis 

size in May specimen suggests that breeding and molt overlap in 

this species. Also, full skull pneumatization requires more than 

a year.

Myiopagis viridicata: Greenish Elaenia

Specimens (USNM, MVZ). ♂♂ 14: Jan (1), Mar 

(3), Oct (3), Nov (6), Dec (1). ♀♀ Jan (2), Feb (1), Oct (4). Two 

Mar ♂♂ and Jan ♀♀ with skull windows. All others with adult 

skulls.

Mass (g). ♂♂ X

_

 = 11.7 (SD = 0.82, range = 10.3–

12.9, N = 14). ♀♀ X

_

 = 11.4 (SD = 1.20, range = 10.2–13.0, 

N = 7). Light fat in some Jan, Feb, and Mar birds.

Iris. Brown or dark brown.

Bill. Upper mandible black, blackish brown, or 

brown. Distal half of lower mandible black, blackish brown, 

or brown; proximal half pinkish purple, pinkish white, brown, 

or tan with black tomium. Mouth lining, tongue, and palate 

greenish orange, orange, or orangish flesh color.

Feet and Tarsi. Black, gray, bluish gray, slate gray, or 

brownish gray. Toe pads tan, gray, greenish gray, or gray brown.

Gonads. ♂♂ Testes enlarged (5 × 3–8 × 4 mm) Oct 

to Jan; small (1 × 1–3 × 2 mm) in Mar. ♀♀ Largest ova 0.5 to 

1.5 mm diam, Jan and Oct; Feb female with postbreeding ovary.

Molt. Prebasic molt in Nov, Dec, and Feb. First prebasic molt in Jan and Mar.

Plumage. Immature birds (with skull windows) have 

a pale reddish tan crown and lack the yellow coronal stripe.

Stomach Contents. Nine with only insect remains, 

9 with only fruit remains, and 1 with fruit and insect remains. 

Six in Oct and Nov with green caterpillars (to 3.8 cm long).

Habitat. Forest, cutover forest.

Notes. This northern austral migrant (Hayes et al., 

1994) calls steadily and repeatedly at least from Sep through 

Mar. In early Oct 1980, 6 individuals spaced out in a relatively 

small area of forest called nonstop as if establishing territories. 

Loud, rather harsh, 2-note call, the second note increasing in 

frequency, reminiscent of that of Lathrotriccus euleri. The call 

is sometimes preceded by a single shrill buzz. Birds call from 

perches at 4–8 m but may forage higher in the vegetation.

Gonads. ♂♂ Testes enlarged in May (6.5 × 4 mm) and 

Oct (5.5 × 4); small in Jan (3 × 2 mm) and Feb (1 mm). ♀ Largest 

ovum 1.5 mm diam.

Molt. Tail molt in Jan, Feb, Oct.

Stomach Contents. Insect remains in 6.

Habitat. Scrubby growth in abandoned pastures and 

fields. Frequents Baccharis shrubs, tall grass, and, especially, 

dense, tall (≤1 m) herbaceous growth.

Notes. Stays low within the vegetation, only occasionally emerging. Skull pneumatization takes a year or more and is 

not complete in most breeding birds. Vocalizes frequently, either 

a single note or a repeated series of similar notes.

Synallaxis frontalis: Sooty-fronted Spinetail

Specimens (MVZ). ♀ Jun (1), with large skull 

windows.

Mass (g). 14.3, light fat.

Iris. Light brown.

Bill. Upper mandible black. Lower mandible pinkish 

gray.

Feet and Tarsi. Tan.

Gonads. Ovary granular, ova minute.

Molt. No.

Stomach Contents. Insect remains.

Notes. Netted in scrubby field.

Family Tyrannidae: Tyrant Flycatchers

Phyllomyias burmeisteri: Rough-legged 

Tyrannulet

Specimens (MVZ). ♂♂ Mar (1), skull windows; 

Sep (1), first-year skull.

Mass (g). 10.6, 11.0, respectively.

Iris. Light brown.

Bill. Upper mandible black. Lower mandible pale pink 

with blackish tip. Mouth lining pinkish flesh color. Palate and 

tongue bright orange.

Feet and Tarsi. Black with faint purplish cast. Toe 

pads pale gray with greenish cast.

Gonads. Testes enlarged (6 × 4, 5 × 2 mm).

Molt. No.

Stomach Contents. Insect remains in 1.

Habitat. Forest.

Notes. Call and forage in the canopy.

Myiopagis caniceps: Gray Elaenia

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan 

(1), May (1), Oct (1). ♀ Jun (1). All birds with large skull 

windows.

Mass (g). ♂♂ X

_

 = 10.6 (SD = 0.86, range = 10.0–11.6, 

N = 3). ♀ 11.0.
3 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Mass (g). ♂♂ 16.9, 17.0. ♀ 15.0. All birds with light 

to moderate fat.

Iris. Brown.

Bill. Upper mandible black. Lower mandible tan or 

gray at base and black distally. Mouth lining orange or flesh 

green.

Feet and Tarsi. Black. Toe pads green.

Gonads. ♂♂ Testes small (2 × 1.5, 3 × 1.5 mm). ♀

Ova ≤ 1 mm.

Molt. ♀ With body molt.

Stomach Contents. Two with Ocotea puberula

fruits. Also observed feeding on Allophylus edulis pulp.

Habitat. Second-growth scrub.

Notes. An austral migrant that breeds in Paraguay and 

in temperate forests farther south in Argentina (Hayes, 1995; 

Jiménez et al., 2016). Winter birds may be resident breeders, winter residents from farther south, or both. The males we collected 

are likely passage migrants on their way south to the breeding 

grounds, although neither is in breeding condition. The female is 

likely a migrant on her way north to the wintering grounds.

Elaenia parvirostris: Small-billed Elaenia

Specimens (USNM, MVZ). ♂♂ Mar (1), May (2), 

Sep (5). ♀♀ May (2), Oct (2). Mar ♂ with skull windows. Others 

birds with adult skulls.

Mass (g). ♂♂ X

_

 = 16.3 (SD = 1.08, range = 14.75–

18.0, N = 8). Light to moderate fat in some Mar, May, and Sep 

♂♂. ♀♀ X

_

 = 20.3 (SD = 5.21, range = 14.0–26.1, N = 4). Light 

fat in 1 May ♀; very fat in 1 May and 1 Oct ♀.

Iris. Brown, dark brown, or black.

Bill. Upper mandible brown or black. Lower mandible 

brown or black distally and pale green, yellowish red, or flesh 

color basally. Mouth lining orange or yellow orange.

Feet and Tarsi. Black. Toe pads green.

Gonads. ♂♂ Testes small (3 × 2–2 ×1 mm) in all birds. 

♀♀ Ovaries granular or undeveloped.

Molt. No.

Plumage. Male with incompletely pneumatized skull 

lacks the white crown patch.

Stomach Contents. Two with insect remains. Five 

with fruit, including Ocotea puberula.

Habitat. Forest along creeks; forest edge adjacent to 

pasture.

Notes. Observed eating Ocotea puberula, Allophylus 

edulis, and Trema micrantha. Call note a whit or pit. Fairly common. Hayes (1995) and del Castillo et al. (2015) noted that this 

species is a breeding resident in Paraguay. However, populations 

that breed to the south in Argentina migrate north during the 

austral winter and pass through Paraguay (Capllonch and Lobo, 

2005; Ridgely and Tudor, 2009). Thus, although the species is 

likely present at El Tirol year-round, whether winter birds represent the local breeding population, migrants from farther south, 

or both is not known.

Elaenia flavogaster: Yellow-bellied Elaenia

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), Mar (1), May (1), Jun (2), Sep (1). ♀♀ Jun (2), Aug (1), Sep 

(1). All specimens with adult skulls.

Mass (g). ♂♂ X

_

 = 23.2 (SD = 2.07, range = 20.8–26.5, 

N = 6). ♀♀ X

_

 = 23.4 (SD = 1.68, range = 21.5–25.5, N = 4). Mar, 

Jun, and Sep birds with light to moderate fat.

Iris. Brown or dark brown

Bill. Upper mandible brown or dark brown with black 

tip. Lower mandible tan, brown, gray, or greenish flesh with 

dark brown or black tip. Mouth lining orange or yellow orange.

Feet and Tarsi. Black or dark gray. Toe pads green.

Gonads. ♂♂ Testes 5 × 3 mm (Feb) and small (1 × 

1–3 × 2 mm) in Mar through Sep. ♀♀ Ovaries granular, largest 

ova ≤ 1 mm.

Molt. Prebasic molt in Feb, Mar.

Stomach Contents. Six with fruits, including Capsicum sp. (Solanaceae) and Ocotea puberula (Lauraceae).

Habitat. Woodland edge, second-growth scrub, 

scrubby pasture; fence rows.

Notes. First heard singing in Oct and continuing 

through Mar. Call a single-note whistle similar to that of the western wood pewee (Contopus sordidulus) [RMZ]. Hayes (2014) 

located eggs from 13 nests in Nov–Jan at Sapucái (Figure 1). 

Observed feeding on fruits of Allophylus edulis (Sapindaceae) 

and Trema micrantha (Cannabaceae).

Elaenia spectabilis: Large Elaenia

Specimens (MVZ). ♂♂ Jan (1), Sep (3), Oct (2). 

♀ Oct (1). All birds with adult skulls.

Mass (g). ♂♂ X

_

 = 27.5 (SD = 1.05, range = 26.1–27.8, 

N = 6); light fat in Jan and 1 Sep ♂. ♀ 25.5.

Iris. Brown or dark brown.

Bill. Black; lower mandible light at base. Mouth lining 

orange or greenish orange.

Feet and Tarsi. Black.

Gonads. ♂♂ All testes enlarged (5 × 3–8 × 4 mm), 

Sep, Oct, and Jan. ♀ Three largest ova 1.5 mm diam; oviduct 

moderately enlarged.

Molt. Jan ♂ in heavy prebasic molt.

Stomach Contents. Five with fruit, including 

Ocotea puberula.

Habitat. Forest edge; second-growth scrub.

Notes. Makes a mournful, wheezy, descending preur

or peow call, similar to that of the western wood peewee, Contopus sordidulus (NKJ). Breeds in Paraguay and migrates north 

for the winter.

Elaenia albiceps: White-crested Elaenia

Specimens (MVZ). ♂♂ Sep (1), Oct (1). ♀ Mar (1). 

All birds with adult skulls.
NUMBER 648 • 3 1

Mass (g). ♂♂ X

_

 = 7.1 (SD = 0.77, range = 5.5–8.0, 

N = 10). ♀♀ X

_

 = 7.8 (SD = 0.98, range = 6.8–9.5, N = 6). Sex? 

6.35. One Feb and 2 Jun birds with light fat.

Iris. Brown, dark brown, or black.

Bill. Upper mandible black or brownish black. Lower 

mandible black, tan, or cream color with a black tip and broad 

black tomium. Mouth lining bright orange or orange olive. 

Tongue orange.

Feet and Tarsi. Dark gray, slate gray, brownish gray, 

or brown. Toe pads green, greenish gray, or olive tan.

Gonads. ♂♂ Testes enlarged (5 × 3–7 × 5 mm) Sep 

through Feb; small (3 × 2–1.5 × 1) Feb through Jun. ♀♀ Sep 

birds with enlarged (2–5 mm diam) yolked ova; 1 with enlarged 

oviduct. Mar birds also had enlarged ova and were with mates. 

Jun ♀ with granular ovary. Feb and May ♀♀ largest ova ≤ 1 mm; 

latter bird with a slightly enlarged oviduct.

Molt. Prebasic molt in Sep, Oct, Feb, Mar, and May.

Stomach Contents. Nine with insect remains, 

including a caterpillar; 1 with insect and fruit remains.

Habitat. Forest, forest edge, disturbed forest.

Notes. Flitted from branch to branch in dense shrubby 

growth, tangles of vines and Chusquea sp., and small trees, usually 1–4 m up. Made a high-pitched, short, single-note, upwardly 

inflected ripping or buzz call, which was given by 1 bird or in 

duet with a mate, year-round. Molt and breeding overlap in 

some individuals. A Sep ♀ with scattered body molt had a 5-mmdiam yolked ovum and a greatly enlarged oviduct, and an Oct ♂

also with body molt had a 7 × 4 mm testis.

Corythopis delalandi: Southern Antpipit

Specimens (USNM, MVZ, MNHNP). ♂♂ Jun 

(3), Sep (2), Oct (2), Dec (1). One Jun and 1 Sep ♂ with fully 

pneumatized skulls. Skulls of other ♂♂ with windows covering 

up to 60% of skull. ♀ Mar (1), juvenal skull.

Mass (g). ♂♂ X

_

 = 15.4 (SD = 0.61, range = 14.75–

16.5, N = 8); Jun birds with light to moderate fat. ♀ 11.9.

Iris. Brown.

Bill. Upper mandible brown, brownish black, or black. 

Lower mandible tan, flesh color, orange, or pinkish purple (♀). 

Both mandibles edged orange or yellow. Tongue, palate, mouth 

lining, and gape bright orange.

Feet and Tarsi. Gray or pinkish gray. Other birds, 

tarsi gray, tan, or flesh color, with gray, blue gray, or tan toes. 

Toe pads gray brown.

Gonads. ♂♂ Testes small (1.5 × 1–2 × 1 mm) in Jun 

birds, large (7 × 4–10 × 4 mm) in birds from Sep to Dec. ♀ Ovary 

undeveloped.

Molt. None recorded.

Stomach Contents. Six with insect remains. One 

bird observed with a caterpillar in its bill.

Habitat. Forest.

Notes. Many breeding males with incompletely pneumatized skulls. Birds hop around in open areas on the forest 

Suiriri suiriri*: Suiriri Flycatcher

Notes. The species occurs primarily in the Chaco 

in Paraguay, with El Tirol in the easternmost part of its range 

(Ridgely and Tudor, 2009). The bird was observed in Jan eating 

fruit in a tree in a clearing and was identified by its distinctive 

plumage and call (NKJ).

Serpophaga subcristata: White-crested 

Tyrannulet

Specimens (USNM). ♀ May (1), adult skull.

Mass (g). 5.5.

Iris. Brown.

Bill. Black.

Feet and Tarsi. Black.

Gonads. Ovary granular.

Molt. Light body molt in all tracts.

Plumage. Olive above and yellow on the abdomen.

Habitat. Scrubby second growth.

Notes. Appeared to be eating fruit when collected, 

but stomach was empty. The migratory status of the species is 

uncertain (Ridgely and Tudor, 1994). Some birds breeding to the 

south may move north in the winter (Hayes, 1995).

Serpophaga munda: White-bellied Tyrannulet

Specimens (USNM). ♂ Aug (1), adult skull.

Mass (g). 6.5, light fat.

Iris. Brown.

Bill. Black.

Feet and Tarsi. Black.

Gonads. Testis small (1.5 × 1 mm).

Molt. Body molt.

Plumage. Above, grayer than S. subcristata, and 

white on abdomen.

Stomach Contents. Full of insects.

Notes. Not recorded by Hayes (1995) from his Alto 

Paraná geographic region or by Esquivel M. et al. (2007) from San 

Rafael Park. Breeds farther south than S. subcristata, migrating 

north and east for the austral winter (Ridgely and Tudor, 1994, 

2009; Hayes, 1995). This flycatcher has been variously considered 

to be a species distinct from S. subcristata, a subspecies of S. subcristata, or a color morph of the latter (Short, 1975; Belton, 1985; 

Hayes, 1995; Stotz et al., 1996; Rheindt et al., 2008; Ridgely and 

Tudor, 2009; Krabbe, 2016; Remsen et al., 2016). A definitive 

resolution of its systematic status requires additional investigation.

Capsiempis flaveola: Yellow Tyrannulet

Specimens (USNM, MVZ, MNHNP). ♂♂ 10: 

Feb (2), Jun (3), Sep (3), Oct (2). ♀♀ Feb (1), Mar (1) May (1), 

Jun (1), Sep (2). Sex? Jun (1). All with adult skulls except 1 Feb 

♂ with 2 small windows.
3 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Mass (g). ♂♂ X

_

 = 8.5 (SD = 0.68, range = 8.0–9.5, N = 

5); Aug ♂ with light fat. ♀♀ X

_

 = 7.8 (SD = 1.0, range = 7.0–10.3, 

N = 9).

Iris. Brown or brick red.

Bill. Upper mandible black. Lower mandible tan or tan 

with flesh color at base and black at tip. Mouth lining pale orange.

Feet and Tarsi. Gray. Toe pads sandy brown.

Gonads. ♂♂ Testes enlarged (6 × 3–7 × 4 mm) in Aug, 

Sep, small (2 × 1 mm) in Jan, May. ♀♀ Aug ♀ with largest ova 

2 mm diam, 1 collapsed follicle, and oviduct greatly enlarged. 

Ovaries small and granular or smooth and undeveloped in May, 

Sep, and Oct birds.

Molt. No.

Stomach Contents. Ten with insect remains, 

including caterpillars.

Habitat. Forest.

Notes. Skull pneumatization clearly requires more 

than 1 year, if it is ever achieved. Foliage gleans among the dense 

leaves toward the tops of understory to midstory trees.

Mionectes rufiventris: Gray-hooded Flycatcher

Specimens (USNM, MVZ, MNHNP). ♂♂ Jun 

(1), Sep (1), Oct (2), Nov (1). ♀ Dec (1). All birds with large 

skull windows.

Mass (g). ♂♂ X

_

 = 15.0 (SD = 0.57, range = 14.5–15.8, 

N = 5). ♀ 11.2.

Iris. Brown, dark brown, or blackish brown.

Bill. Upper mandible black. Lower mandible with 

black or brownish black distal half; basal half yellowish tan or 

pinkish brown. Mouth lining black or grayish black; tongue 

grayish black with white tip.

Feet and Tarsi. Gray or pale bluish brown. Toe pads 

greenish brown.

Gonads. ♂♂ Testes enlarged (6 × 3–8 × 3 mm) in Sep, 

Oct; regressing (4 × 2 mm) in Nov; and small (2.5 × 1.5 mm) in 

Jun. ♀ Largest ovum 2 mm diam.

Molt. No.

Stomach Contents. Three with fruit and seeds.

Habitat. Forest understory.

Notes. Skull pneumatization apparently takes more 

than 1 year to complete in this species; however, birds with only 

partly pneumatized skulls had enlarged gonads and appeared to 

breed their first year. Bird observed feeding on Allophylus edulis and Phoradendron piperoides (Loranthaceae) fruits; chased 

away from the latter by Euphonia violacea.

Leptopogon amaurocephalus: Sepia-capped 

Flycatcher

Specimens (USNM, MVZ, MNHNP). ♂♂ 24: Jan 

(1), Feb (1), May (3), Jun (2), Aug (2), Sep (5), Oct (2), Nov (5), 

Dec (3). Some Jan, Feb, Sep, Oct, and Dec ♂♂ with adult skulls; 

others with partially (~40%–90%) pneumatized skulls. ♀♀ 15: 

floor and fallen logs. Perch on vines and saplings usually ≤ 0.5 m; 

occasionally up to 2 m. Call very loud.

Euscarthmus meloryphus: Tawny-crowned 

Pygmy-tyrant

Specimens (MVZ). ♀ Oct (1), adult skull.

Mass (g). 8.8.

Gonads. Largest ova 1.5 mm; with incubation patch.

Stomach Contents. Insect remains.

Molt. No.

Notes. Pair calling repeatedly from dry thicket; acted 

as if they had a nest. Not reported from the Alto Paraná geographical region of Hayes (1995), but recorded subsequently 

from San Rafael National Park (Esquivel M. et al., 2007).

Phylloscartes eximius: Southern Bristle-tyrant

Specimens (USNM, MVZ). ♂♂ Mar (1), Jun (1), 

Sep (1), Oct (2), Nov (1). ♀♀ Mar (1) Sep (2), Oct (1), Nov (1). 

The Jun ♂ and 1 Sep ♀ have adult skulls. All other birds, skull 

pneumatization ≤ 50%.

Mass (g). ♂♂ X

_

 = 7.8 (SD = 0.43, range = 7.3–8.2, 

N = 6). ♀♀ X

_

 = 7.0 (SD = 0.64, range = 6.7–8.0, N = 4). Jun ♂

with light fat.

Iris. Brown, dark brown, or red.

Bill. Upper mandible black or horn color. Lower mandible tan, pinkish tan, or pinkish white; some with black tip. 

Mouth lining and tongue flesh or greenish flesh color; palate gray.

Feet and Tarsi. Gray, blue gray, or black. Toe pads 

light green or light olive brown.

Gonads. ♂♂ Testes Sep through Nov enlarged (4 × 

2–6 × 3.5 mm); Mar and Jun small (1 mm diam). ♀♀ Sep birds 

breeding (enlarged ova and oviduct; 1 with shelled egg in oviduct). Oct and Nov largest ova ≤ 0.5 mm and postbreeding. Mar 

ovary undeveloped.

Molt. Prebasic in Nov and Mar. First prebasic in Mar.

Stomach Contents. Ten with insect remains, including larvae and a 31-mm-long caterpillar.

Habitat. Forest, especially with open understory.

Notes. Several breeding individuals with large skull 

windows; complete pneumatization likely takes more than 1 

year. Moderately common; seen and heard regularly. Call is a 

buzz of varying length. Foliage gleans in the understory, 3–6 m 

up. The International Union for Conservation of Nature (IUCN, 

2015) listed this species as Near Threatened; a moderately rapid 

decline in numbers due to habitat loss is suspected.

Phylloscartes ventralis: Mottle-cheeked 

Tyrannulet

Specimens (USNM, MVZ). ♂♂ Jan (1), May (1), 

Aug (1), Sep (2). ♀♀ May (2), Aug (1), Sep (2), Oct (4). All birds 

with partly pneumatized skulls.
NUMBER 648 • 3 3

Gonads. ♂♂ Testes enlarged (3 × 1–7 × 3 mm) Aug 

through Nov. Small or undeveloped (0.5 × 0.5–1.5 × 0.75 

mm) Feb through Jun. ♀♀ Two Aug birds breeding (enlarged 

yolked ova to 5 mm diam, collapsed follicle, enlarged oviduct). Ovaries small, undeveloped in Jan, Jun, and Oct 

specimens.

Molt. Likely prebasic molt in Feb, Jun, and Nov. First 

prebasic molt in Mar. Crown molt only in late Sep breeding male 

may be a prealternate molt.

Stomach Contents. Fourteen with insect remains 

(including caterpillars).

Habitat. Forest undergrowth; dense woodland; isolated trees in scrubby second growth.

Notes. The species is fairly common and often heard 

rather than seen. Pairs move together, calling back and forth 

with high-pitched double tsk or teek notes. They also make a 

single-note, oft-repeated dik, dik, dik, sometimes followed by 

a short trill. The birds forage in thickets, at the tops of saplings or small trees, and in bamboo tangles, Baccharis shrubs, 

and vines, from 2 to 10 m. The skull in this species does not 

appear to pneumatize fully, so this character cannot be used to 

age individuals. Birds with unpneumatized skulls are in breeding 

condition.

Hemitriccus diops: Drab-breasted 

Pygmy-tyrant

Specimens (USNM, MVZ). ♂♂ Oct (3), Dec (2). 

♀♀ Jan (2), Dec (2). Skulls only partially pneumatized in all 

birds.

Mass (g). ♂♂ X

_

 = 8.8 (SD = 0.74, range = 8.0–9.5, 

N = 5). ♀♀ X

_

 = 8.3 (SD = 1.64, range = 6.8–10.0, N = 4).

Iris. Black, brown, or red.

Bill. Upper mandible black. Lower mandible gray.

Feet and Tarsi. Gray.

Gonads. ♂♂ Oct birds with enlarged (7.5 × 3.5–8 × 

4 mm) testes. Dec birds with small (1 × 1–3.5 × 2.5 mm) testes. 

♀♀ Ovaries tiny or granular.

Molt. All Dec and Jan birds molting.

Stomach Contents. Four with insect remains.

Habitat. Dense growth in forest understory, near 

ground.

Notes. Several males in breeding condition have 

incompletely pneumatized skulls.

Hemitriccus margaritaceiventer: Pearly-vented 

Tody-tyrant

Specimens (MVZ). ♂ Sep (1), with large skull 

windows.

Mass (g). 8.9.

Iris. Pale gold.

Gonads. Testis 6 × 3 mm.

Molt. No.

Jan (1), Mar (1), Jun (3), Aug (1), Sep (1), Oct (3), Nov (1), 

Dec (4). One Jan, 1 Mar, and 1 Dec ♀ with juvenal skull, i.e., 

no evidence of any pneumatization. Others with skulls partially 

(~40%–60%) pneumatized; none with adult skulls. Sex? May 

(1), skull 50% pneumatized.

Mass (g). ♂♂ X

_

 = 11.9 (SD = 0.97, range = 10.0–

13.2, N = 24). ♀♀ X

_

 = 11.2 (SD = 0.91, range = 10.0–13.5, 

N = 15). Sex? = 12.75. Birds with light fat in Jan (1), Jun (3), Aug 

(1), and Dec (2).

Iris. Brown, dark brown, or gray brown.

Bill. Upper mandible black. Lower mandible with distal two-thirds black and basal one-third light (gray, white, pinkish 

white, or tan); occasionally with light tip and/or tomium. Tongue 

and mouth lining flesh color.

Feet and Tarsi. Gray, gray brown, brown, or slate. 

Toes same as tarsi or blue gray. Toe pads tan or greenish tan.

Gonads. ♂♂ Testes enlarging in Aug (4 × 2.5 mm), 

enlarged (6 × 3–8 × 4 mm) in Aug to Dec, regressing in Jan (4 × 

2 mm), and small from Feb to Jun (1 × 0.5–3 × 1 mm). In one 

Dec ♂ with a juvenal skull, testis minute. Jan, Jun, Sep, and 1 

Dec ♀♀ with undeveloped ovaries. Other Jun and some Oct and 

Dec ♀♀ with granular ovaries. Some ♀♀ with enlarged ova, collapsed follicles, enlarged oviducts, and/or incubation patches in 

Aug, Oct, and Dec.

Molt. Prebasic molt in Nov, Dec, and Feb. First prebasic molt in Dec, Jan, and Mar.

Stomach Contents. Nineteen with insect remains, 

including caterpillars and grasshoppers. Two with mashed fruit 

or seeds.

Habitat. Forest.

Notes. One of the most common birds in the forest 

understory or midstory, sometimes in vine tangles, saplings, or 

bamboo thickets. Perches 2–10 m up. Skull pneumatization data 

suggest that the process takes 2 years to complete but that birds 

breed their first year. Call a series of short falling notes or soft 

buzzy trill. May hover-pluck insects; observed beating a caterpillar against a branch to subdue it.

Myiornis auricularis: Eared Pygmy-tyrant

Specimens (USNM, MVZ, MNHNP). ♂♂

14: Feb (1), Mar (1), May (2), Jun (2), Aug (2), Sep (1), Oct 

(4), Nov (1). ♀♀ Jan (1), Jun (1), Aug (2), Oct (1). All birds 

with skull windows of varying size; no skulls more than 50% 

pneumatized.

Mass (g). ♂♂ X

_

 = 5.25 (SD = 0.24, range = 5.0–5.8, 

N = 14). ♀♀ X

_

 = 5.3 (SD = 0.93, range = 4.0–6.5, N = 5). Some 

individuals with light to moderate fat in May, Jun, Aug, Oct.

Iris. Red, brick red, red brown, or white.

Bill. Upper mandible black. Lower mandible whitish 

or tan with black tomium or black with tan, white, or yellow 

patch at base. Mouth lining orange or yellow green.

Feet and Tarsi. Brown, tan, or flesh color (also pinkish green, grayish pink, greenish purple, yellowish, or maroon).
3 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Notes. Birds with unpneumatized skulls in breeding 

condition. Female with juvenile in Oct. Call a full-bodied buzz.

Platyrinchus mystaceus: White-throated 

Spadebill

Specimens (USNM, MVZ, MNHNP). ♂♂ Jun 

(2), Aug (1), Sep (2), Oct (3). ♀♀ Feb (1), Mar (1), Jun (1), Sep 

(1), Dec (2). All but 1 bird with skull windows of varying size; 

none >50% pneumatized.

Mass (g). ♂♂ X

_

 = 9.2 (SD = 1.26, range = 8.3–12.0, 

N = 8). ♀♀ X

_

 = 7.25 (SD = 0.54, range = 6.4–8.0, N = 6). Slight 

or moderate fat in Jun birds.

Iris. Dark brown or brown.

Bill. Upper mandible black. Lower mandible tan, 

cream color, flesh color, or yellow. Mouth lining and tongue yellow orange or orange flesh color.

Feet and Tarsi. Tan, gray, pinkish gray, pinkish 

white, or flesh color. Toe pads yellowish white or pinkish or 

greenish tan.

Gonads. ♂♂ Testes enlarged (8 × 3–9 × 4 mm) in Sep–

Oct; small (1 × 0.5–3.5 × 2 mm) in Jun, Aug, and 1 Sep bird. ♀♀

All ovaries small or minute; 2 in Feb–Mar, undeveloped.

Molt. Feb ♀ with late body molt.

Plumage. The yellow coronal patch was well developed in all males. The patch was either completely absent from 

females or consisted of a small buffy area on 1 or 2 crown 

feathers.

Stomach Contents. Ten with insect remains.

Habitat. Forest undergrowth, shrubs, and vines.

Notes. Rarely above 1.5–2 m. Many breeding birds 

with unpneumatized skulls.

Lathrotriccus euleri: Euler’s Flycatcher

Specimens (USNM, MVZ). ♂♂ (48): Feb (2), Mar 

(3), Aug (6), Sep (7), Oct (14), Nov (14), Dec (2). ♀♀ (27): Jan 

(2), Feb (2), Mar (2), Sep (6), Oct (2), Nov (9), Dec (4). Sex? Feb 

(1), Dec (1). Birds with juvenal skulls in Nov (4), Dec (1), Jan (2), 

Feb (1), and Mar (1). All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 11.0 (SD = 0.81, range = 8.7–12.75, 

N = 48). ♀♀ X

_

 = 10.9 (SD = 1.06, range = 9.0–13.8, N = 27). 

Sex? = 10.4, 9.0. Birds with light fat in Feb (3), Aug (1), Nov (5), 

and Dec (1); moderate to heavy fat in Mar (3).

Iris. Brown, dark brown, or black.

Bill. Upper mandible black. Lower mandible orange, 

yellow, white, tan, or flesh color; tomium may be orange. Mouth 

lining, tongue, and palate bright orange, sometimes with an olive 

tinge or white.

Feet and Tarsi. Black; brownish, grayish, or reddish 

black; blue gray; gray; or brown. Toe pads tan, brown, gray, or 

pinkish gray.

Gonads. ♂♂ Testes of 27 of 31 adult ♂♂ from midSep to mid-Dec are enlarged (range 5 × 3–9.5 × 4.5 mm). Testes 

Poecilotriccus plumbeiceps: Ochre-faced 

Tody-flycatcher

Specimens (USNM, MVZ). ♂♂ Mar (1), Sep (1), 

Oct (2), Dec (1). ♀ Sep (1). All birds with skull windows of varying size; none more than 50% pneumatized.

Mass (g). ♂♂ X

_

 = 5.8 (SD = 0.19, range = 5.5–6.0, 

N = 5). ♀♀ 5.5.

Iris. Brown, chestnut brown, or red.

Bill. Black. Mouth lining, tongue, and palette pale 

flesh or yellowish flesh color.

Feet and Tarsi. Gray or blue gray. Toe pads brownish gray.

Gonads. ♂♂ Testes enlarged (5 × 3–6 × 4 mm) in Sep, 

Oct, decreasing in size in Dec (4 × 2.5 mm), and small in Mar 

(1 × 1 mm). ♀ Largest ovum 1 mm, oviduct enlarging, and incubation patch developing.

Molt. Mar ♂ in heavy body and tail molt.

Stomach Contents. Insect remains in 2.

Habitat. Forest, forest edge.

Notes. Birds often move as pairs. Birds without fully 

pneumatized skulls breed. Occupy dense undergrowth (1–2 m) 

of viny tangles and bamboo thickets, but also may call from 

higher perches 3–5 m up in saplings and small trees. Call a lowpitched guttural trill (repeated note). Birds calling everywhere in 

forest in May.

Tolmomyias sulphurescens: Yellow-olive 

Flycatcher

Specimens (USNM, MVZ, MNHNP). ♂♂ Jun (1), 

Sep (2), Oct (3). ♀♀ Feb (1), Oct (1), Nov (1). One Sep ♂ with 

an adult skull. All other birds with skull ≤ 50% pneumatized.

Mass (g). ♂♂ X

_

 = 14.7 (SD = 0.86, range = 13.5–15.9, 

N = 5). ♀♀ X

_

 = 16.2 (SD = 1.08, range = 15.0–17.1, N = 3); Nov 

♀ with light fat.

Iris. Brown.

Bill. Upper mandible black. Lower mandible gray 

or white or pale greenish gray at base with double purple lines 

forming a diamond and bluish gray near tip. Mouth lining and 

tongue pink.

Facial Skin. Bare skin below eye gray.

Feet and Tarsi. Gray, dark blue gray, or brown with 

blue gray or purple gray tinge. Toe pads tan.

Gonads. ♂♂ Testes increasing in size in Sep (3 × 2–5 × 

3 mm), enlarged in Oct (8 × 4–9 × 4 mm), and small in Jun (2 × 

1 mm). ♀♀ Nov ♀ recently laid; Oct and Nov ♀♀ with active 

incubation patches. Ovary small in Feb.

Molt. Feb ♀ with body molt.

Plumage. Ear covert patch blackish as reported in 

Ridgely and Tudor (2009).

Stomach Contents. Seven with insect remains, 

including 2 with stink bugs (Pentatomidae, Hemiptera).

Habitat. Forest.
NUMBER 648 • 3 5

Habitat. Forest, forest edge.

Notes. On scrubby, viny bamboo, often low (1 m) 

in vegetation. This species is reportedly a rare breeder in Paraguay and even rarer in the winter, when it migrates to the north 

(Hayes et al., 1994; Hayes, 1995). However, the species occurred 

regularly at El Tirol, and we collected 2 winter specimens (8 and 

21 May).

Contopus cinereus: Tropical Pewee

Specimens (USNM). ♂ Jun (1).

Mass (g). 13.5, very fat.

Iris. Brown.

Bill. Upper mandible black. Lower mandible yellow 

orange. Mouth lining bright orange.

Feet and Tarsi. Black.

Gonads. Testis 2 × 1 mm.

Molt. No.

Plumage. Fits the description in Ridgely and Tudor 

(2009:450) of birds from southeastern Brazil, i.e., darker and 

grayer than birds in the rest of the range, with darker lores and 

weak wing bars.

Stomach Contents. Insect remains.

Habitat. Forest.

Colonia colonus: Long-tailed Tyrant

Specimens (USNM, MVZ). ♂♂ Feb (3), 1 adult 

skull, 1with skull windows, and 1 skull not pneumatized. ♀ Aug 

(1), adult skull.

Mass (g). ♂♂ X

_

 = 15.8 (SD = 0.58, range = 15.5–16.5, 

N = 3), all with light fat. ♀ 16.5, heavy fat.

Iris. Brown.

Bill. Black. Mouth lining yellow green or yellow 

orange.

Feet and Tarsi. Black. Toe pads green or gray green.

Gonads. ♂♂ Testes of all = 1 mm. ♀ Ovary granular.

Molt. Adult ♂ with prebasic body and flight feather 

molt; immature ♂♂ in first prebasic body molt.

Plumage. Central rectrices of males with incompletely 

pneumatized skulls truncated; crown and nape black; white 

superciliary absent.

Stomach Contents. All with insects, including 

coleopterans.

Habitat. Forest edge or dense second-growth scrub.

Notes. Pairs and family groups on open branches or in 

dead trees. Once 3 observed moving with a mixed-species flock.

Machetornis rixosa: Cattle Tyrant

Specimens (MVZ). ♂ Mar (1). ♀ Sep (1). Both with 

adult skulls.

Mass (g). ♂ 37.5. ♀ 33.5.

Iris. Brown.

decrease in size in Dec (4 × 2 mm), are small in Feb and Mar 

(1 × 1–1.5 × 1 mm), and increase in size again in Aug and Sep 

(2 × 1–3.5 × 1.5 mm). ♀♀ Nine of 10 adult females in Oct and 

Nov have enlarged ova, enlarged oviducts, and/or active brood 

patches. Ovaries small, granular, and postbreeding, and incubation patches refeathering in Nov, Dec, Jan, and Mar. Testes or 

ovaries of birds with juvenal skulls minute and undeveloped.

Molt. Prebasic molt of adults in Dec, Jan, Feb, including body and flight feathers. Capllonch and Zelaya (2006) 

reported that Argentine birds begin the body molt on the breeding grounds but found no evidence of flight feather molt, which 

they speculated occurs during migration or on the wintering 

grounds. First prebasic molt in Jan, Feb, appeared to involve 

only body feathers.

Stomach Contents. Insect remains (predominantly 

beetles but also caterpillars) in 54; insect and fruit remains in 2; 

only fruits in 2.

Habitat. Forest, forest edge, mature second growth.

Notes. An austral migrant arriving from the north in 

mid- to late Aug. Some individuals stay to reproduce; others are 

likely in passage to breeding grounds in Argentina (Capllonch 

and Zelaya, 2006). Males arrive 7 to 10 days before ♀♀ and set 

up well-spaced territories, concentrated along creeks and ravines. 

May occupy thickets with dense sapling growth, vines, and thick 

ground cover of ferns. Perch from 1 to 10 m, usually at 3–5 m. 

Often seen in pairs or family groups. Calls of both males and 

females are heard from Aug through Mar. The primary call is a 

buzz followed by 2 (or 3) notes, the last at a higher frequency: 

buzz pee wheet or buzz pee o wheet. Feb and Mar birds make a 

2-note descending call. The species was gone from El Tirol by the 

end of Mar. A primary focus of research of NKJ in Paraguay (see 

Zink and Johnson, 1984). Song recordings deposited at MVZ.

Cnemotriccus fuscatus: Fuscous Flycatcher

Specimens (USNM, MVZ, MNHNP). ♂♂ Mar 

(1), May (1), Sep (4), Oct (2). ♀♀ Mar (1), May (1). Sex? Jan 

(1). All birds with adult skulls except Sex?, which has tiny skull 

windows.

Mass (g). ♂♂ X

_

 = 14.0 (SD = 1.50, range = 12.0–16.3, 

N = 8); May ♂ with heavy fat. ♀♀ 10.5, 12.7. Sex? 15.8.

Iris. Brown or dark brown.

Bill. All black or upper mandible black or brown and 

lower mandible dark brown with whitish area at base. Mouth 

lining orange or, along with palette and tongue, pinkish flesh 

color.

Feet and Tarsi. Gray, bluish gray, or tarsi purplish 

gray and feet gray black. Toe pads light gray or grayish yellow.

Gonads. ♂♂ Testes enlarged (4 × 2–9 × 4 mm) Sep 

and Oct; small (2 × 1 mm) Mar and May. ♀♀ Mar ovary postbreeding; May ovary granular.

Molt. Body molt in Jan Sex?.

Stomach Contents. Eight with insect remains; 2 

with fruit remains; 1 with fruit and insect remains.
3 6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

patch. Adults in Dec through Sep largest ova 1–2 mm diam; Feb 

ovary postbreeding. Ovary of Dec immature tiny.

Molt. Prebasic molt in Nov, Dec, Feb, and May specimens. First prebasic molt in Dec.

Stomach Contents. Eight with fruit, 3 with insect 

remains, and 2 with insect and fruit remains.

Habitat. Forest edge, tung orchards, scrubby second 

growth, trees around clearings, gardens, around buildings.

Notes. Often in small groups. Noisy and conspicuous. 

Perches in the open. Observed feeding on the fruits of several 

species, including Ocotea puberula, Trema micrantha, Allophylus edulis, Guarea sp., and Cupania vernalis (Sapindaceae). Nest 

located 14 Sep 1978 in second-growth scrub. Bird carrying nest 

material 10 Oct 1979. Earliest egg clutch from Sapucái (Figure 1) 

on 10 Oct (Hayes, 2014). Body cavity of Nov ♂ filled with white 

nematodes (~150).

Myiodynastes maculatus: Streaked 

Flycatcher

Specimens (USNM, MVZ). ♂♂ Jan (1), Feb (1), Sep 

(2), Oct (2), Nov (3). ♀♀ Feb (1), Sep (1). Feb ♂ with immature 

skull; all other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 43.8 (SD = 3.95, range = 38.0–52.0, 

N = 9); Feb immature with light fat, 1 Oct bird with moderate 

fat. ♀♀ 57.0, heavy fat (Feb); 44.5, light fat (Sep).

Iris. Brown or black.

Bill. Black. Mouth lining flesh color.

Feet and Tarsi. Black or gray. Toe pads green.

Gonads. ♂♂ Testes enlarged or enlarging (6 × 2.5–12 × 

5 mm) Sep through Nov; regressing (6 × 3 mm) in Jan; immature 

Feb ♂ small (3 × 1 mm). ♀♀ Ovaries developed; largest ova ≤ 1 

mm diam.

Molt. Jan, Feb.

Stomach Contents. Four with only insect remains; 

5 with only fruit (including Ocotea puberula); 2 with fruit and 

insect remains.

Habitat. Forest, forest edge.

Notes. A northern austral migrant (Hayes et al., 

1994). The species was not observed at El Tirol during the winter months. The birds occupy the forest canopy, often on bare 

branches at the very tops of the trees, from which they make 

long fly-catching sallies. They also fly down from high perches 

to pluck fruits (including Allophylus edulis) that they carry back 

up to their original sites. They are usually seen in pairs. Vocalize 

a lot in late Dec and still appear to be on territories; also seen 

carrying twigs in late Dec.

Megarynchus pitangua: Boat-billed Flycatcher

Specimens (USNM, MVZ, MNHNP). ♂ Feb (2), 

Mar (2), Jun (1), Oct (2), Dec (1). One Mar ♂ with skull windows. Other males with adult skulls. ♀♀ Jan (1), Feb (1), Dec 

(2). All with adult skulls.

Bill. Black. Mouth lining yellow green.

Feet and Tarsi. Black. Toe pads tan.

Gonads. ♂ Testis 9 × 4 mm. ♀ Largest ovum 1 mm.

Molt. ♂ With prebasic body and flight feather molt.

Plumage. Tail feathers lack white tips.

Stomach Contents. One with Coleoptera.

Habitat. Pasture edge. Isolated trees in scrubby 

pasture.

Legatus leucophaius: Piratic Flycatcher

Specimens (MVZ). ♂♂ Nov (2), adult skulls.

Mass (g). 21.1, 22.9.

Gonads. Testes 4 × 3, 7 × 4 mm.

Molt. No.

Stomach Contents. Fruit in 1.

Habitat. Pasture adjacent to forest.

Notes. Singing in small isolated trees near a natural 

spring in pasture. Breeds in Paraguay and migrates north for the 

winter (Hayes et al., 1994).

Myiozetetes similis: Social Flycatcher

Specimens (MVZ). ♀ Jun (1), adult skull.

Mass (g). 34.5, moderate fat.

Iris. Light brown.

Bill. Black.

Feet and Tarsi. Blackish.

Gonads. Ovary granular, ova minute.

Molt. No.

Stomach Contents. Fruit pulp and seeds. Observed 

feeding in Guarea sp.

Habitat. Forest edge, scrubby second growth, isolated 

trees in pastures, roadsides, around buildings.

Pitangus sulphuratus: Great Kiskadee

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), May (1), Sep (3), Nov (2), Dec (1). Dec ♂ with large skull 

windows; other ♂♂ with adult skulls. ♀♀ Feb (1), May (1), Jun 

(2), Sep (2), Oct (1), Dec (2). One Dec ♀ with immature skull; 

others with adult skulls.

Mass (g). ♂♂ X

_

 = 62.8 (SD = 4.98, range = 56.5–70.5, 

N = 8). ♀♀ X

_

 = 67.3 (SD = 5.89, range = 58.0–77.0, N = 8). Two 

Jun and 1 Sep ♀ with light to moderate fat.

Iris. Brown.

Bill. Black. Mouth lining and gape yellow orange or 

yellow green.

Feet and Tarsi. Black. Toe pads light green or olive 

brown.

Gonads. ♂♂ Testis of adults enlarged (8 × 4–9 × 

3 mm) in Nov and small (2 × 1–3 × 2 mm) in Feb through Sep. 

Dec immature, testis small (3 × 1 mm). ♀♀ Oct ♀ breeding, 

largest ovum 12 mm diam, 1 collapsed follicle, with incubation 
NUMBER 648 • 3 7

Tyrannus melancholicus: Tropical Kingbird

Specimens (USNM, MVZ). ♂♂ Sep (2), Nov (2); all 

with adult skulls. ♀♀ Jan (1), Mar (1), Oct (1); Jan and Oct with 

adult skulls; Mar ♀ likely immature.

Mass (g). ♂♂ X

_

 = 42.1 (SD = 1.76, range = 40.0–

44.3, N = 4), 1 Sep bird with light fat. ♀♀ Adults: Jan 50 g, 

with light fat; Oct 47 g. Immature 38 g, with light to moderate fat.

Iris. Dark brown, brown, or gray brown.

Bill. Black. Mouth lining and tongue pale pinkish flesh 

color or whitish, tinged beige.

Feet and Tarsi. Black. Toe pads green.

Gonads. ♂♂ Testis enlarging in Sep (4 × 2, 5 × 2 mm), 

enlarged in Nov (11 × 4, 11 × 6 mm). ♀♀ Oct, ovary with 3 collapsed follicles, and ♀ with incubation patch. Jan ♀ with 3 postovulatory follicles, an enlarged oviduct, and a well-developed 

incubation patch. Ovary of immature undeveloped.

Molt. Body feather molt recorded in Jan, Mar, Sep, 

Nov.

Plumage. Immature ♀ (Mar) lacks the orange crown 

patch.

Stomach Contents. Four with insect remains, 

including ants. One with insect and fruit remains. Two with 

only fruit remains. Fruits include Solanum sp. (Solanaceae) and 

Ocotea puberula.

Habitat. Forest, forest edge, tung orchard, scrubby 

second growth, isolated trees in and around pastures, cultivated 

areas, and weedy fields around clearings.

Notes. This austral migrant arrives from the north in 

Sep, occasionally in moderate- to large-size groups with most of 

the birds continuing on to the south. In early Mar smaller groups 

of birds begin to go through, migrating north. The species is gone 

by the end of the month. During the breeding season, one sees 

up to 4 birds perched together, chasing, and giving shrill, highpitched trills. The birds prefer open trees, often without leaves, 

generally perching near the top.

Tyrannus savana: Fork-tailed Flycatcher

Specimens (USNM, MVZ). ♂♂ Aug (1), Sep (2), 

Oct (1), Nov (1), Dec (1). ♀♀ Oct (2). All birds with adult 

skulls.

Mass (g). ♂♂ X

_

 = 35.4 (SD = 3.33, range = 32.0–39.5, 

N = 6). Two heaviest ♂♂ (Sep, Nov) moderately to extremely fat. 

♀♀ 34.5, 34.7, both with moderate fat.

Iris. Brown or black.

Bill. Upper mandible black. Lower mandible black or 

black with gray at base. Tongue and mouth lining pinkish flesh 

color.

Feet and Tarsi. Black or grayish black. Toe pads pale 

grayish brown.

Gonads. ♂♂ Testis Aug through Dec, range = 4 × 2–8 × 

4 mm. ♀♀ Ova tiny, 0.5–1.0 mm diam.

Mass (g). ♂♂ X

_

 = 62.4 (SD = 5.96, range = 54.5–72.5, 

N = 8), 1 Feb ♂ with light fat. ♀♀ X

_

 = 63.8 (SD = 5.63, range = 

58.5–70.7, N = 4).

Iris. Brown or dark brown.

Bill. Black. Palate and mouth lining flesh color or yellow green.

Feet and Tarsi. Black or gray. Toe pads green or gray 

brown.

Gonads. ♂♂ Testis enlarged (10 × 4–12 × 6 mm) Oct 

to Dec, regressing (4 × 2–5 × 2 mm) in Feb, and small (2 × 1–3 × 

1.5 mm) Mar to Jun. ♀♀ Jan ovary postbreeding; others, largest 

ova = 1–2 mm diam.

Molt. Prebasic molt of body and flight feathers in Dec, 

Jan, Feb, Mar. First prebasic body molt in immature Mar ♂.

Stomach Contents. Five with only insect remains, 

1 with only fruit, and 4 with insect and fruit remains. Insects 

include caddis flies, homopterans, ants, coleopterans, and 

lepidopterans.

Habitat. Forest, disturbed forest, forest edge, tung 

orchard, scrubby second growth, roadsides.

Notes. Often in small groups. Frequently observed 

feeding in fruiting trees. Males were displaying in Oct. Body cavity of Dec male full of nematodes.

Empidonomus varius: Variegated Flycatcher

Specimens (USNM, MVZ). ♂♂ 12: Feb (2), Mar 

(1), Sep (4), Oct (3), Nov (2). All with adult skulls. ♀♀ Sep (1), 

Oct (1); adult skulls.

Mass (g). ♂♂ X

_

 = 27.4 (SD = 2.89, range = 23.8–

32.3, N = 12). ♀♀ Both = 26.5. Some Sep and Oct birds with 

light to moderate fat; a few with heavy fat in Feb, Mar, and 

Sep.

Iris. Brown or dark brown.

Bill. Upper mandible black. Distal half of lower mandible black; basal half pale pinkish brown. Mouth lining, palate, 

and tongue pinkish flesh color.

Feet and Tarsi. Black or brownish black. Toe pads 

pale gray brown, tan, or green.

Gonads. ♂♂ Testes enlarging (4 × 2–7 × 2.5) in Sep, 

Oct; enlarged (9 × 3–10 × 4 mm) in Oct, Nov; and small (3 × 1–3 × 

2 mm) in Feb, Mar. ♀ Largest ova 2 mm diam.

Molt. Body molt in Feb ♂♂; 1 also molting the tail.

Stomach Contents. Four with only insect remains; 

6 with only fruits; 3 with a mixture of fruits and insects.

Habitat. Forest, forest edge, tung orchards, isolated 

trees in pastures, and cultivated fields.

Notes. Generally seen in pairs, often perched and foraging at the tops of large trees and dead snags. Seen carrying 

nest materials in Oct and twice in Nov, and another pair seen 

building a nest in Nov. Observed feeding on Allophylus edulis

and Ocotea puberula fruits. The birds with heavy fat probably 

represent migrants recently arrived from or about to depart to 

northern wintering areas.
3 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

fat. ♀♀ X

_

 = 26.3 (SD = 2.15, range = 24.6–28.7, N = 3). 

Sex? = 21.3.

Iris. Brown, dark brown, or red brown.

Bill. Upper mandible black or blackish brown. Lower 

mandible brown or dark brown at base, darkening to blackish 

brown or black at tip. Mouth lining, palate, and tongue bright 

orange or greenish orange.

Feet and Tarsi. Black, brownish black, or grayish 

black. Toe pads greenish white, greenish black, grayish brown, 

or tan.

Gonads. ♂♂ Testes enlarging (4 × 2 mm) in Sep, large 

(11.0 × 4.5 mm) in Oct, and small (1.5 × 1–2 × 1 mm) in Mar. 

♀♀ Old incubation patch, ova = 0.5 mm (Jan); active incubation 

patch, ova = 2 mm (Oct); and active incubation patch, recently 

laid (Nov).

Molt. Prebasic molt recorded in Jan and Mar.

Stomach Contents. Four with insect remains, 4 

with fruit remains (including Ocotea puberula), and 1 with fruit 

and insect remains.

Habitat. Forest, second-growth scrub, isolated trees 

in fields and pastures.

Notes. Perches at tops of open trees. Migrates to the 

north to winter. The extreme fall date reported by Hayes et al. 

(1994) is 1 Mar; we obtained a specimen on 10 Mar 1980 (MVZ 

167435).

Family Cotingidae: Cotingas

Pyroderus scutatus: Red-ruffed Fruitcrow

Specimens (USNM, MVZ). ♂ Jun (1). ♀♀ Jun (1), 

Oct (1).

Mass (g). ♂ 540, very fat. ♀♀ 350 (light fat), 330, 

respectively.

Iris. Brown.

Bill. Silvery gray or upper mandible gray, darker at 

base and whitish at tip, and lower mandible lighter gray, tinged 

purple, with whitish tip.

Feet and Tarsi. Black or bluish gray.

Gonads. ♂ Testis 5 × 2 mm, black. ♀♀ Ovary granular (Jun); ova 0.5 mm (Oct).

Molt. Primaries and body, Jun ♀.

Stomach Contents. Three with fruit and insects, 

including orthopteran and caterpillar. Fruits eaten by the Oct 

bird included 2 species of Sapindaceae, Allophylus edulis (6 

whole fruits, 47 seeds [1 seed/fruit], and pulp) and Cupania vernalis (7 seeds and pulp).

Habitat. Forest, including moderately disturbed 

areas and an area from which much of the understory had been 

cleared.

Notes. Perch 10 to 15 m up. Regularly observed in 

Jun 2004. The Jun ♀ plucked an orthopteran from the ground 

and carried it to a tree to ingest. One mobbed and chased by a 

group of red-rumped caciques (Cacicus haemorrhous).

Molt. No.

Stomach Contents. Three with fruits (Ocotea 

puberula), 2 with insect remains, 1 with fruit and insect 

remains.

Habitat. Second-growth scrub, tall trees at the edges 

of pasture and cultivated fields, and around buildings.

Notes. The species began arriving at El Tirol in late 

Aug in small numbers. By mid-Sep and for the ensuing 3 weeks, 

large flocks of as many as 50 birds moved through, flying farther 

south. By mid-Oct only a few birds remained, and they persisted 

through the breeding season. In late Jan the northward migration 

began, with flocks of 10 to 80 birds moving through throughout 

Feb. While at El Tirol, the birds perch in the perimeter at the tops 

of dead trees or deciduous trees that have lost their leaves. These 

highly maneuverable birds swoop out from their perches, pluck 

insects from the air (or fruits from an adjacent tree), and return 

to their perches, often hovering in front of them before landing. The birds interact aggressively, chasing and displacing each 

other and giving a harsh, single-note, buzzy call. They eat a lot 

of Ocotea puberula fruits, which they pluck and swallow whole. 

A mated pair was collected in Oct.

Sirystes sibilator: Sibilant Sirystes

Specimens (MVZ). ♂ Feb (1), adult skull. ♀♀ Feb 

(1), juvenal skull; Sep (1), adult skull.

Mass (g). ♂ 30.8. ♀ 27.4 and 33.5, respectively.

Iris. Brown or dark brown.

Bill. Upper mandible black; lower mandible dark 

brown. Mouth lining greenish orange.

Feet and Tarsi. Grayish black. Toe pads brownish 

gray or grayish tan.

Gonads. ♂♂ Testis 1.5 × 1 mm. ♀♀ Adult with 7-mmdiam orange ovum and incubation patch. Ovary undeveloped in 

immature.

Molt. Feb: ♂ rectrices 6-6 in sheath, growing; ♀

immature in first prebasic molt.

Plumage. Upper wing coverts edged rufous buff in the 

immature; edging grayish buff in adults.

Stomach Contents. Insect remains in 2.

Habitat. Forest, forest edge.

Notes. In the canopy, sometimes in dead snags. Frequents riparian areas. In pairs or family groups; occasionally 

part of mixed-species flocks. Adult attending young in Feb. Begging young made pip-pip-pip or pur-pur-pur notes.

Myiarchus swainsoni: Swainson’s 

Flycatcher

Specimens (USNM, MVZ). ♂♂ Mar (3), Sep (1), 

Oct (1). ♀♀ Jan (1), Oct (1), Nov (1). Sex? Mar (1). All with 

adult skulls except Sex?, with skull windows.

Mass (g). ♂♂ X

_

 = 24.1 (SD = 1.68, range = 22.5–

26.5, N = 5). Some Mar and Sep ♂♂ with light to moderate 
NUMBER 648 • 3 9

Notes. Moderately common in tall, old forest. Many 

leks present. Birds can breed before their skulls are fully pneumatized. For information on vocalizations, reproductive behavior, and social organization, see Foster (1981). Nest with 3 eggs 

located 4 Dec 1977, preyed on 6 Dec; 88 cm above ground in a 

2-m-tall sapling (DBH = 13 mm). Inner and outer heights and 

diameters of the nest were 50 and 56 and 47 and 65 mm, respectively. One egg = 22 × 17 mm. A ♂ in definitive plumage observed 

foraging with a mixed-species flock (including Hemithraupis 

guira, Trichothraupis melanops, and other species) once in Mar 

and once in May.

Pipra fasciicauda: Band-tailed Manakin

Specimens (USNM, MNHNP). ♂ Oct (1). ♀ Jun 

(1). Both with adult skulls.

Mass (g). ♂ 14.0, ♀ 15.5, light fat.

Iris. ♂ White. ♀ Gray.

Bill. Upper mandible black, lighter at base in ♀. Lower 

mandible maroon with gray tip (♂) or grayish tan at base with 

black tip (♀).

Feet and Tarsi. Pinkish gray or maroon.

Gonads. ♂ Testis 4.5 × 2.0 mm; no cloacal protuberance. ♀ Ovary granular.

Molt. No.

Habitat. Forest.

Notes. The male is in subadult plumage indicative of 

a 2-year-old male; his testes, although enlarged, are somewhat 

smaller than those normally present in breeding males (MSF, 

unpublished data). The species is more common in Cerro Corá 

National Park, Department of Amambay (~500 km N El Tirol) 

and Ybycuí National Park, Department of Ybycuí (~160 km to 

the NW) but uncommon in San Rafael National Park and rare 

this far south in Paraguay (Figure 1). No leks were located at El 

Tirol, nor were any birds heard calling.

Family Tityridae: Tityras

Tityra inquisitor: Black-crowned Tityra

Specimens (MVZ). ♂ Mar (1). ♀ Oct (1). Both with 

adult skulls.

Mass (g). ♂ 42.5. ♀ 44.0.

Iris. Dark brown.

Bill. Upper mandible black. Lower mandible blue gray.

Facial Skin. Bluish gray below eyes.

Feet and Tarsi. Grayish black. Toe pads tan gray.

Gonads. ♂ Testis 5 × 2.5 mm. ♀ Ovary with 1 collapsed follicle, 1 ovum 10 mm diam, and other enlarged ova; 

oviduct huge; with mate.

Molt. No.

Stomach Contents. Insects in both, including a 

large orthopteran.

Habitat. Forest, forest edge, forest clearing.

Family Pipridae: Manakins

Chiroxiphia caudata: Swallow-tailed 

Manakin

Specimens (USNM, MVZ, MNHNP). ♂♂ 27: Jan 

(5), May (1), Jun (4), Aug (1), Sep (6), Oct (8), Dec (2). ♀♀ 14: 

Jan (2), Feb (1), Mar (1), May (1), Jun (3), Sep (2), Oct (3), Nov 

(1). Egg: Dec (1). Birds with partially pneumatized skulls in Feb, 

May, Jun, Aug, Sep, Oct.

Mass (g). ♂♂ X

_

 = 22.6 (SD = 1.12, range = 20.0–25.0, 

N = 26); some individuals with light fat in Jan, Aug, Sep, Oct, 

Dec. ♀♀ X

_

 = 22.6 (SD = 1.51, range = 21.0–26.0, N = 14); some 

with light fat in Jun, Sep.

Iris. Brown.

Bill. Upper mandible dark brown, with or without yellowish tinge on tomium and tip, or horn color. Lower mandible 

horn color, with or without yellow tip; maroon; or brown with 

a light tip or purplish tinge. Tongue and palate dull olive green. 

Mouth lining flesh color, orange, or light green.

Feet and Tarsi. Maroon. Toe pads sandy brown 

with greenish tinge.

Gonads. ♂♂ Testes enlarged (5 × 2–10 × 3 mm) in 

Sep, Oct, Dec, and Jan; regressing (3 × 2–4 × 3.75 mm) in Jan; 

small (1.5 × 1–3.5 × 1.5 mm) and sometimes black or dark green 

in May, Jun, and Aug. ♀♀ Ova enlarged (1.5–8.0 mm diam) 

and yellow orange, oviduct enlarged, and/or developing incubation patch in Sep, Oct, and Jan. Ovary granular with largest ova 

≤ 1.0 mm in Nov, Jan, Feb, Mar, May, and Jun. Ovary smooth 

and undeveloped in Jun, Sep.

Molt. Prebasic body and flight feather molt in Jan, 

Feb, Mar. Light scattered body molt only, in Sep, Oct, Dec, May, 

and Jun; in some individuals this likely represents the onset or 

end of a more substantial molt. Molt in spring months may be 

a limited prealternate molt. Body molt may be present in some 

breeding individuals.

Plumage. Juvenal males are green like females. They 

maintain a green plumage following the first prebasic molt but 

add a well-developed bright red crown. Females sometimes have 

a red crown, although it is generally duller and considerably less 

extensive than that of males and often has a bronze cast. With 

the second prebasic molt, males acquire an immature or subadult 

plumage intermediate between that of the definitive plumages of 

males and females. It includes varying amounts of blue in the 

dorsal feathers and black in the ventral feathers and on the face. 

Males acquire the definitive male plumage with the third prebasic molt.

Stomach Contents. Thirty with only fruit, including Allophylus edulis, Eugenia uniflora (Myrtaceae), Psychotria

carthagenensis (Rubiaceae), Guarea sp., Trema micrantha, 

Trichilia catigua (Meliaceae), Casearia silvestris (Salicaceae), 

Dendropanax cuneatus (Araliaceae), Cecropia pachystachya

(Urticaceae), Ficus sp., and various others. One stomach contained fruit plus a spider.
4 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

bird with 8- and 13-mm-diam, vascular, yellow-orange ova and 

well-developed incubation patch. Ova minute in Dec.

Molt. Body and flight feather molt in Oct, Dec, Jan. 

First prebasic body molt in Dec.

Stomach Contents. Six with insect remains, including 3 with only caterpillars (up to 38 mm long). Only fruit remains 

in 2. Breeding ♀ (Oct) with pieces of egg shell in stomach.

Habitat. Tall old forest.

Notes. Usually seen in the understory moving inconspicuously 1–4 m up in saplings or vines. Oct ♂ in breeding condition (testis = 9 × 6.5 mm) but molting flight feathers. Call with 

a sibilant quality; 4 notes, whoo whoo tui tui.

Pachyramphus polychopterus: 

White-winged Becard

Specimens (MVZ). ♂♂ Oct (2). ♀♀ Feb (1), Mar (1), 

Oct (1), Nov (1). All birds with adult skulls.

Mass (g). ♂♂ Both 21.5. ♀♀ X

_

 = 24.2 (SD = 1.55, 

range = 23.1–26.5, N = 4).

Iris. Dark brown.

Bill. Upper mandible black. Lower mandible whitish blue or pinkish white with brown sides and bluish gray tip. 

Mouth lining yellow orange.

Feet and Tarsi. Gray or purplish slate gray. Toe pads 

light gray or tan.

Gonads. ♂♂ Testes enlarged (both 8 × 5 mm), 1 ♂

with mate. ♀♀ Largest ova = 2 mm, ♀ with incubation patch 

(Oct); ≤ 1 mm (Feb, Mar); and ≤ 1 mm, postbreeding (Nov).

Molt. ♀♀ Molting in Feb, Mar.

Plumage. Ridgely and Tudor (2009:482) noted that 

except in western Amazonia, males have a gray nuchal collar, 

rump, and underparts; 2 bold white wing bars; and white edging 

on the scapulars and flight feathers. In addition, they reported 

that males in all areas lack the white or pale gray lores characteristic of other members of the genus. The gray nuchal collar is 

limited or absent from the males from El Tirol, and some pale 

gray is present in the lores.

Stomach Contents. Three with only insect remains, 

1 with only fruits, and 1 with remains of both fruit and insects. 

Insect remains include grubs and caterpillars.

Habitat. Forest, forest edge, tung orchard.

Notes. In the canopy or tree tops of tall and mediumheight forest. Mated pair collected in Oct; both birds calling. 

Song a rather long run of triple or quadruple notes: whew, whew, 

whew, whew, or chuck, chuck, chuck, chuck. Birds call regularly 

Oct through Mar. Paul Smith photographed a nest of this species 

at El Tirol in Jan (Smith, 2006).

Piprites chloris: Wing-barred Piprites

Specimens (USNM, MVZ). ♂♂ Sep (2), Oct (2). ♀

Aug (1). One Sep ♂ with an adult skull. All other birds, skull 

partly pneumatized.

Notes. Perches at the top of canopy trees. One Feb 

adult accompanied by a juvenile. Another Feb bird moving with 

a mixed-species canopy flock.

Tityra cayana: Black-tailed Tityra

Specimens (USNM, MVZ). ♂♂ Mar (1), Oct (4), 

all with adult skulls. ♀ Feb (1), skull immature.

Mass (g). ♂♂ X

_

 = 77.9 (SD = 5.92, range = 72–87, 

N = 5), 3 Oct birds with light fat. ♀ = 82.0, heavy fat.

Iris. Brown.

Bill. Both mandibles rosy to wine red at base. Distal 

part of upper mandible black. Distal part of lower mandible gray 

with a black tip. Tongue, palate, and mouth lining orange or 

dark orangish flesh color.

Facial Skin. Pale gray green or rosy red above and 

below eyes; rosy to wine red in front of and behind eyes. Flesh at 

gape red to wine red.

Feet and Tarsi. Gray, slate gray, or black. Toe pads 

light green or brownish yellow.

Gonads. ♂♂ Testis enlarged (12 × 7–15 × 6 mm) in 

Oct, small (3 × 2 mm) in Mar. One Oct ♂ with an active brood 

patch. ♀ Ova ≤ 1.0 mm.

Molt. March ♂ in heavy prebasic molt.

Stomach Contents. Two with only fruit, 1 with 

only insects, and 2 with fruit and insect remains. Insects include 

5-cm-long sphinx moth (Sphingidae), caterpillar, 6.4-cm katydid, 

and praying mantis. Fruit includes Cupania vernalis and Ocotea 

puberula. Other birds observed feeding in Ficus sp. in Jan.

Habitat. Forest, forest edge.

Notes. Often seen in pairs perching and moving 

together; 3 birds together in Mar, possibly parents and young. 

Observed in Feb as part of a mixed-species canopy flock. Occupy 

the tops of the tallest trees, often on bare branches. Call like a 

grinding, unwinding spring, similar to that of Tityra semifasciata.

Schiffornis virescens: Greenish Schiffornis

Specimens (USNM, MVZ). ♂♂ 14: Jan (2), Aug 

(1), Sep (2), Oct (6), Dec (3). Birds with small skull windows 

found in Sep, Dec, and Jan. The former appear to have hatched 

in the previous year and the latter 2 to have hatched in the previous few months. ♀♀ Oct (1), Dec (1), both with adult skulls.

Mass (g). ♂♂ X

_

 = 22.1 (SD = 1.64, range = 18.5–25.5, 

N = 14); 1 breeding Oct bird with extensive fat along pterylae 

and in furculum. ♀♀ 28.75 (contains multiple enlarged ova) and 

22.0, respectively.

Iris. Brown.

Bill. Upper mandible black. Lower mandible gray or 

black with gray at base.

Feet and Tarsi. Black, gray, or tarsi black and feet 

gray.

Gonads. ♂♂ Testis enlarged (6 × 4–10 × 6 mm) in 

Aug, Sep, Oct and small (2 × 1–3 × 2 mm) in Dec, Jan. ♀♀ Oct 
NUMBER 648 • 4 1

Bill. Upper mandible black, dark gray, or brown. 

Lower mandible pale pinkish gray, pale gray, or brown. Mouth 

lining pale greenish yellow.

Feet and Tarsi. Gray or blue gray. Toe pads pale 

greenish tan.

Gonads. ♂♂ Testis enlarged (4 × 3.5–6 × 4 mm) Aug–

Oct. ♀♀ Oct and Nov birds, largest ova ≤ 2.0 and ≤ 1.5 mm, 

respectively. Dec and Jan birds with tiny ovaries.

Molt. Dec and Jan.

Stomach Contents. Four with insect remains, 

including a 2.5-cm spiny caterpillar. One with fruit.

Habitat. Forest, tung orchard.

Notes. Family groups in Mar. Foliage glean, foraging 

singly or in pairs; may join mixed-species flocks.

Vireo olivaceus: Red-eyed Vireo

Specimens (USNM, MVZ). ♂♂ 22: Feb (3), Sep (5), 

Oct (4), Nov (10). ♀♀ Jan (1), Feb (1), Mar (1), Oct (1), Nov (4). 

All birds with adult skulls except Mar ♀, with immature skull.

Mass (g). ♂♂ X

_

 = 15.3 (SD = 0.86, range = 13.9–

17.1, N = 20). ♀♀ X

_

 = 14.9 (SD = 1.31, range = 12.8–17.0, 

N = 8). Light or moderate fat in 1 bird each in Feb, Mar, Sep, 

and Nov.

Iris. Brown or dark brown.

Bill. Upper mandible black, brownish black, or gray 

brown with paler tomium. Lower mandible gray or blue gray; 

sometimes whitish at base. Mouth lining yellow green or pinkish 

gray.

Feet and Tarsi. Gray, blue gray, or tan. Toe pads tan, 

grayish, or greenish.

Gonads. ♂♂ Testis moderately to greatly enlarged 

from Sep to Nov (5 × 3–11 × 6 mm); several birds with large 

cloacal protuberances, singing, or with a mate. Small in Feb (1 × 

1–3 × 2 mm). ♀♀ Oct and Nov birds with enlarged ova, collapsed follicles, enlarged oviducts, and/or incubation patches. 

Jan and Feb, largest ova ≤ 1 mm diam. Mar immature, ovary 

small and undeveloped.

Molt. Only Jan ♀.

Stomach Contents. Thirteen with insect remains, 

including caterpillars, beetles, and a praying mantis. Three with 

fruit and insect remains, and 4 with only fruit remains, including 

Ocotea puberula.

Habitat. Forest, forest edge, tung orchard. In winter, 

in viny-shrub thickets at margins of abandoned fields.

Notes. Common at El Tirol, calling steadily from Sep 

through Mar at midstory to canopy levels. Female laid an egg 

in a holding bag in Oct. Family groups seen in Jan and Feb, 

with adults feeding juveniles. Flocks of ~10 birds begin to appear 

in Jan. It is not clear whether these are young or postbreeding 

adults from the area mobilizing to migrate north or migrants 

arriving from farther south. Birds observed feeding on fruits of 

various species, including Allophylus edulis; also acrobatically 

foraging for insects, including spending several minutes pulling 

Mass (g). ♂♂ X

_

 = 16.8 (SD = 0.85, range = 16.0–17.9, 

N = 4). ♀ 19.0, light fat.

Iris. Brown.

Bill. Upper mandible black, gray, or blue gray. Lower 

mandible gray or blue gray. Mouth lining black.

Feet and Tarsi. Gray or blue gray.

Gonads. ♂♂ Testis enlarged (7 × 3–8 × 4 mm), 1 with 

cloacal protuberance. ♀ Largest ovum 1.5 mm, yellow orange.

Molt. One Oct ♂ with extensive body but no flight 

feather molt.

Stomach Contents. Three with insect remains, 

including caterpillars (one 5 cm long) and a tick.

Notes. The development of the gonads indicates that 

these birds breed before skull pneumatization is complete. The 

molting Oct ♂ (testis 7 × 3 mm) suggests that molt-breeding 

overlap may also occur in this species. The call of 1 Sep male 

consisted of a rising series of 7–8 “pip-like” whistles (NKJ).

Family Vireonidae: Vireos

Cyclarhis gujanensis: Rufous-browed 

Peppershrike

Specimens (MVZ). ♂♂ Jan (1), Mar (1), Sep (1), Oct 

(1), Nov (1). ♀♀ Feb (1), Mar (1), Sep (1). Mar ♂ with juvenal 

skull; all other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 28.1 (SD = 1.97, range = 25.8–30.1, 

N = 5). ♀♀ X

_

 = 30.3 (SD = 1.91, range = 28.5–32.3, N = 3). Sep 

♂ with moderate fat.

Iris. Red, red brown, or chestnut brown.

Bill. Upper mandible blue gray or gray with pale 

brown base. Lower mandible blue gray, grayish white, or 

pinkish gray. Mouth lining pinkish flesh color. Tongue pinkish gray.

Feet and Tarsi. Blue gray. Toe pads tan or greenish 

tan.

Gonads. ♂♂ Testes enlarged (6 × 4 mm) Oct–Nov, 

regressing in Jan (4 × 2 mm), and small in Mar and Sep (2 × 

1 mm). ♀♀ All with largest ova ≤ 1 mm.

Molt. Prebasic molt of body and flight feathers in Jan, 

Feb, and Mar. First prebasic molt in Mar.

Stomach Contents. Seven with insect remains.

Habitat. Forest.

Notes. Males singing year-round from the tree tops in 

mature forest.

Hylophilus poicilotis: Rufous-crowned Greenlet

Specimens (USNM, MVZ). ♂♂ Aug (1), Sep (2), 

Oct (1). ♀♀ Jan (1), Oct (1), Nov (1), Dec (1). Jan ♀ with large 

skull windows. All other birds with adult skulls.

Mass (g). ♂♂ 9.6, 10.0. ♀♀ X

_

 = 10.6 (SD = 0.70, 

range = 9.9–11.5, N = 4). Jan ♀ with moderate fat.

Iris. Brown.
4 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Notes. The female was netted as she left a nest under 

the roof at the hotel, where the birds nested commonly from 

1976 to 1978. Sometime during the winter of 1979, entries to the 

attic were blocked. Although the birds were observed around the 

hotel in subsequent years, their numbers were greatly reduced, 

although the species is still common at El Tirol between Sep and 

Mar. In Mar, flocks of 5 to 30 individuals of this migratory species can be seen flying north. These birds often forage in heavy 

rain in loose mixed flocks with Chaetura cinereiventris.

Petrochelidon pyrrhonota: Cliff Swallow

Specimens (MVZ). ♀ Mar (1), adult skull.

Mass (g). 19.5, light fat.

Iris. Brown.

Bill. Black. Mouth lining flesh green.

Feet and Tarsi. Dark purple. Toe pads pink.

Gonads. ♀ Largest ova ≤ 1 mm.

Molt. Body and flight feathers.

Stomach Contents. Insect remains, including 

coleopterans.

Notes. Loose flocks (4–60+ individuals) of this migrant 

were seen regularly from Nov to Mar flying high over pastures, 

cultivated areas, and clearings. Nearctic migrant present during 

the austral spring, summer, and fall, although a few individuals may be found in winter (Hayes, 1995; Hayes et al., 1994). 

Not recorded by Hayes (1995) from his Alto Paraná geographic 

region but known from San Rafael National Park (Esquivel M. 

et al., 2007).

Family Troglodytidae: Wrens

Troglodytes aedon: House Wren

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), Mar (1), May (1), Jun (1), Aug (1), Oct (1), Nov (2), Dec 

(1). ♀♀ Mar (1), Jun (2), Sep (1), Dec (1). Sex? Dec (3 nestlings). 

Birds with juvenal skulls recorded in Nov (1), Feb (1), Mar (1), 

and May (1); 2 Jun birds with small skull windows.

Mass (g). ♂♂ X

_

 = 12.2 (SD = 1.20, range = 10.6–13.75, 

N = 8). ♀♀ X

_

 = 12.4 (SD = 0.90, range = 11.3–13.8, N = 5). 

Sex? All = 11.0. Light to moderate fat in Feb, Jun, Aug, and Dec 

♂♂ and Jun (2), Sep, and Dec ♀♀.

Iris. Brown.

Bill. Upper mandible black or dark brown. Basal half 

of lower mandible whitish cream, pale gray, or tan with gray 

or brown distal half. Tongue and palate dull greenish orange. 

Mouth lining dull greenish orange or yellow orange. Nestling bill 

with dark tip; mouth lining bright orange.

Feet and Tarsi. Olive orange, brown, tan, or gray 

brown. Toe pads tan, gray tan, or brown. Nestling feet and tarsi 

gray.

Gonads. ♂♂ Testes enlarged (4 × 2.5–7 × 4 mm) 

from Aug through Nov and small (1 × 0.5–3 × 1 mm) from Nov 

apart a large silky cocoon and extracting the pupa. See Johnson 

and Zink (1985) for discussion of the taxonomic status of this 

species in Paraguay.

Family Corvidae: Jays

Cyanocorax chrysops: Plush-crested Jay

Specimens (USNM, MVZ). ♂♂ Oct (1), Dec (1), 

both with adult skulls. ♀♀ Mar (2), Sep (2), Oct (1), Dec (2). All 

females with adult skulls except 1 Mar bird with juvenal skull.

Mass (g). ♂♂ 149.0 (Oct); 165.0 (Dec). ♀♀ X

_

 = 160 

(SD = 7.30, range = 148–169, N = 7). Masses of 3 birds (MVZ 

165668, 165669, 165670) collected and prepared on the same 

day by the same individual were listed as 64, 65, and 67 g. The 

birds were full grown and had completely pneumatized skulls. 

We assume that the masses were recorded incorrectly and have 

included them in our sample as 164, 165, and 167 g, respectively.

Iris. Bright yellow.

Bill. Black or grayish black. Palate and mouth lining 

grayish black or whitish flesh color. Tongue gray or whitish flesh 

color.

Feet and Tarsi. Black or brownish black. Toe pads 

greenish yellow or reddish brown.

Gonads. ♂♂ Testes 12 × 6 mm (Oct), 4 × 1 mm (Dec). 

♀♀ Adults, ovaries tiny (Dec) or postbreeding (Mar); largest ova 

≤ 1 mm (Sep) or 1–2 mm diam (Sep, Oct). Ovary of juvenile 

undeveloped.

Molt. Prebasic molt in Dec, Mar. First prebasic molt 

in Mar.

Stomach Contents. Three birds with insect remains, 

including a grasshopper; 3 with insect remains and seeds from 

fruits; 1 with fruit pulp and skin.

Habitat. Forest, forest edge, woods, tung orchards.

Notes. Noisy, conspicuous, and common in midcanopy, 11–13 m. Usually seen in groups of 2–15 individuals at any 

time of year. However, pairs and small groups are most common in Sep–Nov, followed by family groups (3–5) in Dec–Jan, 

and then larger groups. Observed eating Allophylus edulis and 

Eugenia uniflora fruits but also being mobbed by small birds in 

Sep, suggesting that they may also rob nests. Many varied calls.

Family Hirundinidae: Swallows

Progne chalybea: Gray-breasted Martin

Specimens (MVZ). ♀ Nov (1), adult skull.

Mass (g). 51.0, light fat.

Gonads. Largest ovum 4 mm, yellow orange.

Molt. None.

Stomach Contents. Insect remains.

Habitat. Commonly seen flying overhead, above pastures, cultivated fields, and scrubby second growth; occasionally 

over forest; around buildings.
NUMBER 648 • 4 3

Bill. Upper and lower mandibles brown, dark olive 

brown, gray, or black with light green or yellow tomium. Mouth 

lining yellow or yellow green.

Facial Skin. Eye ring pale olive brown.

Feet and Tarsi. Gray, gray green, or brown. Toe pads 

brownish green or tan.

Gonads. ♂♂ Testes enlarging to enlarged (4 × 2–10 × 

6 mm) in Sep; small (1 × 1–3 × 2 mm) in Jan through Jun and 

occasionally dark gray or black. ♀♀ Largest ova 1.5 mm diam 

in Oct; adults in other months with granular ovaries or largest ova ≤ 1.0 mm diam. Ovaries of immature birds smooth and 

undeveloped.

Molt. Adults with prebasic molt in Feb, May, Jun. All 

immature birds (Jan, Mar) with first prebasic body molt.

Stomach Contents. Twelve with fruits or fruit 

remains, including Trema micrantha, Psychotria carthagenensis, 

Allophylus edulis, Cupania sp., Solanum sp., and unidentified 

others. Birds often had more than 1 species of fruit in their stomachs. One with only insects, and 1 with insects and fruit.

Habitat. Forest, forest edge, dense second-growth 

scrub, tung orchard.

Notes. Common. Often in pairs in austral spring and 

family groups in summer. Two nests located in Nov, 1 under the 

eaves at the hotel and one 3 m up on the top of a cut tung tree 

in which new shoots formed a bowl. Birds observed feeding on 

fruits in all months. Ventral feathers of many stained with red 

soil. One bird with nematodes in kidneys and body cavity.

Turdus rufiventris: Rufous-bellied Thrush

Specimens (USNM, MVZ, MNHNP). ♂♂ 15: 

Feb (2), May (2), Jun (2), Sep (5), Oct (2), Dec (2). ♀♀ 17: Feb (3), 

Mar (3), Jun (4), Aug (1), Sep (1), Oct (4), Nov (1). Sex? Jun (1). 

Two Feb and 1 Mar ♀ with juvenal skulls. All other birds with 

adult skulls.

Mass (g). ♂♂ X

_

 = 68.4 (SD = 4.25, range = 61.0–75.0, 

N = 15). ♀♀ X

_

 = 73.9 (SD = 5.0, range = 64.0–80.0, N = 15). 

Birds with light or moderate fat recorded in Feb (2), Mar (1), 

Jun (4), and Aug (1).

Iris. Brown or black.

Bill. Yellow, grayish yellow, olive brown, or brownish horn color with brighter yellow or greenish yellow tomium; 

mandibles darker at base. Mouth lining bright orange yellow, 

yellow green, or olive green. Tongue bright orange.

Facial Skin. Eyelid and fleshy eye ring orange or 

orange yellow.

Feet and Tarsi. Olive green, gray, tan, or brown. Toe 

pads light brown, red brown, or olive tan.

Gonads. ♂♂ Testes enlarged (10 × 7–19 × 9 mm) in 

Sep, Oct, Dec; small (1 × 1–4 × 2.5 mm) and sometimes gray in 

Feb, May, Jun. ♀♀ Ovaries granular, ova ≤ 1 mm (Mar, Jun); ova 

and oviducts beginning to enlarge (Aug, Sep); ova and oviducts 

greatly enlarged (Oct, Nov); ovary postbreeding, old incubation 

patch (Feb). Ovaries of juveniles smooth and undeveloped.

through Jun. ♀♀ Ovary of Mar juvenile undeveloped; Jun ovaries smooth. Largest ovum of Sep ovary 2.5 mm diam, yellow 

orange; Dec ovary granular.

Molt. Feb and Mar ♂♂ with prebasic body and flight 

feather molt.

Stomach Contents. Twelve with insect remains.

Habitat. Tung orchard, scrubby fields, edges of cultivated fields, around buildings, and in gardens.

Notes. The progression of skull pneumatization suggests that birds complete the process in their first year. A nest 

with 3 nestlings was located on 28 Dec 1977 in the hollow 

stub of a limb in a tung tree ~1 m above ground. One nestling 

had 3 and another nestling 5 large botfly larvae in the tissue 

on the head. An adult with stub-tailed young was located at 

another nest in a stump surrounded by a pile of branches on 

8 Nov 1981. Hayes reported egg sets from Sapucái (Figure 1) 

from Sep through Feb. The males sing year-round, even when 

not in breeding condition. Birds often with red dirt on ventral 

feathers.

Family Polioptilidae: Gnatcatchers

Polioptila lactea: Creamy-bellied Gnatcatcher

Specimens (USNM). ♂ Mar (1), adult skull.

Mass (g). 5.8, light fat.

Iris. Dark brown.

Bill. Upper mandible black. Lower mandible blue gray 

basally and black distally.

Feet and Tarsi. Slate gray blue. Toe pads light 

green.

Gonads. Testes 1 mm.

Molt. Prebasic body and flight feather molt.

Stomach Contents. Insect remains.

Habitat. Forest.

Notes. The IUCN (2015) designates this Atlantic 

Forest endemic species as Near Threatened. Esquivel M. et al. 

(2007) noted that it was fairly common at several locations in 

San Rafael National Park. Willis and Bosso (1997) recorded a 

pair building a nest in Iguazú National Park, Misiones Province, 

Argentina, in mid-August.

Family Turdidae: Thrushes

Turdus leucomelas: Pale-breasted Thrush

Specimens (USNM, MVZ, MNHNP). ♂♂ 14: Jan 

(1, skull imm), Feb (1), Mar (2, skulls imm), May (2), Jun (4), 

Sep (4). ♀♀ 10: Jan (1, juv skull), Mar (1, imm skull), Jun (5), 

Sep (1), Oct (2).

Mass (g). ♂♂ X

_

 = 70.9 (SD = 4.95, range = 61–79, N = 

14). ♀♀ X

_

 = 71.0 (SD = 4.19, range = 65–78, N = 9). Some with 

light fat in Mar, May, Jun.

Iris. Brown or reddish brown.
4 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

breeders as well as some breeding birds from populations farther 

to the south. Nematodes in body cavity of 1 bird.

Turdus nigriceps: Slaty Thrush

Specimens (USNM). ♂ Oct (1). ♀ Oct (2). All with 

adult skulls.

Mass (g). ♂ 51. ♀♀ 48, light fat; 65.0, moderate fat.

Iris. Brown.

Bill. ♂ Yellow. ♀♀ Brownish, 1 with yellow at corners 

of gape.

Facial Skin. Fleshy eye ring orange.

Feet and Tarsi. Tan or light brown.

Gonads. ♂ Testis 9 × 6 mm. ♀♀ Largest ova = 1.5 

mm diam.

Molt. No.

Plumage. Ridgely and Tudor (1989) recognized the 

birds in the eastern part of the range, T. n. sublaris, as a separate species, Turdus subalaris (eastern slaty-thrush), which they 

noted differed in plumage and song from T. nigriceps. The plumages of our specimens fit the description of subalaris except for 

the absence of a prominent white crescent on the upper chest of 

females.

Stomach Contents. Fruit in 2.

Habitat. Forest.

Notes. This rare species may be a northern austral migrant (Hayes, 1995; Ridgely and Tudor, 2009). It was 

observed at El Tirol only in Oct (6–18); the male was in breeding 

condition.

Turdus albicollis: White-necked Thrush

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb (1), 

May (2), Jun (3), Aug (1). Jun and Aug ♂♂ with adult skulls; 

Feb and May ♂♂, skulls partially pneumatized. ♀♀ 10: Feb (2), 

Mar (2), May (1), Jun (4), Aug (1). Two Feb, 1 Mar, and 1 Jun 

♀♀ with juvenal or immature skulls; other ♀♀ with adult skulls.

Mass (g). ♂♂ X

_

 = 62.1 (SD = 2.23, range = 59.5–

65.0, N = 7). ♀♀ X

_

 = 62.1 (SD = 3.78, range = 55.8–67.5, 

N = 10). Some birds with light or moderate fat in Feb, Mar, Jun.

Iris. Brown or red brown.

Bill. Upper mandible black, brownish black, brown, 

or olive brown with narrow yellow, olive yellow, or orange yellow tomium; some with yellowish tip (cf. Ridgely and Tudor, 

2009:543). Lower mandible olive brown, yellow, or yellow 

orange with dark tip and olive-yellow tomium. Mouth lining 

greenish yellow or dark flesh color. Tongue greenish yellow or 

bright orange. Palate olive with orange ridges.

Facial Skin. Fleshy eye ring yellow orange to orange.

Feet and Tarsi. Gray, gray brown, olive brown, or 

pink brown. Toe pads flesh green, brown, or tan.

Gonads. ♂♂ Testes small (1 × 1–2 × 1 mm) in all males 

and gray or black in some. ♀♀ Ovaries of adults postbreeding 

(Mar), granular (May, Jun), or early reproductive, i.e., largest 

Molt. Prebasic in Dec, Feb, Mar. First prebasic in Feb, 

Mar.

Stomach Contents. Sixteen with only fruit, including Psychotria carthagenensis and Allophylus edulis; 5 with only 

insects; and 4 with fruit and insects. Observed feeding in Cupania vernalis.

Habitat. Forest, forest edge, second-growth woodland, around buildings. Frequent at fruiting trees.

Notes. Most common thrush at El Tirol; seen most 

days. Nest located 10 Oct 1980; female incubating 1 blue-green 

egg with brown specks but had been about to lay another. The 

nest was in the terminal crotch of a small (DBH = 2 cm) tree 

that had been topped at ~151 cm; 5 new branches grew from 

the top and 1 side of the trunk to form a basketlike structure 

in which the nest was sitting. Inner dimensions of the nest were 

10 × 7 cm by 10 cm deep; outer dimensions were 15 × 13 cm by 

14 cm high (cf. de la Peña, 2010). Plant debris (leaves, pieces of 

vines, fungal hyphae, etc.) hung another 10 cm below the nest, 

making the entire structure look like a pile of debris that had 

fallen and caught on the branches. The 6- to 10-mm-thick inner 

layer of the nest was composed of tiny twigs, leaf veins, vine tendrils, rootlets, hyphae of Marasmius sp. (Marasmiaceae) fungus, 

and grass fibers. Surrounding this was a 10- to 20-mm layer of 

mud containing a lot of grass fibers and forming a sort of adobe; 

there were also thin strips of papery bark and dabs of moss. 

The thicker (20–30 mm) outermost layer of the nest consisted of 

larger twigs, stems, pieces of bark (3.5 × 5 cm), and whole leaves. 

Some of the nest material was interwoven, but most of the pieces 

were simply laid around in a coil. Not observed in large flocks 

as were the other Turdus spp. Several individuals had red dirt on 

their ventral feathers.

Turdus amaurochalinus: Creamy-bellied Thrush

Specimens (USNM, MVZ, MNHNP). ♂♂ Aug (1), 

Sep (4). ♀♀ Jun (1), Sep (2), Oct (1). All with adult skulls.

Mass (g). ♂♂ X

_

 = 62.5 (SD = 5.63, range = 59.0–72.5, 

N = 5); birds with light or moderate fat in Aug, Sep. ♀♀ X

_

 = 

66.8 (SD = 10.44, range = 53.0–78.0, N = 4). Jun and Oct ♀♀

with heavy fat (without the latter 2 birds, X

_

 = 59.5).

Iris. Brown.

Bill. Upper and lower mandibles brown, yellow, or 

brownish yellow.

Feet and Tarsi. Gray, grayish brown, or tan.

Gonads. ♂♂ Testes small (1 × 1–3 × 1 mm) in all 

males and gray, dark green, or black in some. ♀♀ Ovary granular (Jun); largest ova ≤ 1 mm (Jun, Sep) or 1.5 to 2 mm (Oct).

Molt. None.

Stomach Contents. Three with fruit, including Psychotria carthagenensis and Ocotea puberula; 1 with fruit and 

insects. Observed feeding in Allophylus edulis.

Habitat. Forest.

Notes. Present year-round, although some breeders 

may move farther north in winter. Winter birds may include local 
NUMBER 648 • 4 5

common in his Alto Paraná geographic region, but this was the 

only time we recorded it.

Neothraupis fasciata*: White-banded Tanager

Notes. Perched 10 m up in a patch of light in a forest 

tree on 22 Nov 1981 (NKJ). The southernmost locality for the 

species recorded by Hayes (1995), who reported it from humid 

tall forest, is about 200 km to the north of El Tirol. Not recorded 

from San Rafael National Park (Esquivel M. et al., 2007). 

Ridgely and Tudor (2009) noted that the species is usually found 

at higher elevations and in the cerrado rather than forest habitat. 

Designated as Near Threatened by IUCN (2015).

Nemosia pileata: Hooded Tanager

Specimens (MVZ, MNHNP). ♂ Nov (1). ♀♀ Jun (1), 

Nov (1). All birds with adult skulls.

Mass (g). ♂ 15.2. ♀♀ 19.5, moderate fat (Jun); 20.7 

(Nov).

Iris. Yellow.

Bill. Upper mandible black, brownish black, or gray 

brown. Lower mandible pale pinkish flesh color or with basal 

half pinkish gray or pinkish tan and distal half black. Mouth lining and tongue glossy black.

Feet and Tarsi. Dull orange or orange yellow; toe 

pads also.

Gonads. ♂ Testes enlarged (7 × 4 mm), with mate. ♀♀

Nov bird with egg forming in oviduct and incubation patch; with 

mate and carrying a 15.5-cm-long plant fiber (nest material?). 

Jun bird with granular ovary, largest ovum ≤ 1 mm.

Molt. No.

Stomach Contents. All with insect remains, 

although also reported to eat fruit (Isler and Isler, 1987).

Habitat. Forest edge, orchard.

Notes. Jun ♀ moving with a mixed-species flock 

including Hemithraupis guira and Conirostrum speciosum. Nov 

birds a mated pair. Male sang from 5–9 m up, a listless series of 

high-pitched notes; ♀ perched nearby with the plant fiber in her 

bill.

Pyrrhocoma ruficeps: Chestnut-headed Tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ 28: Jan 

(2), Feb (1), Mar (1), May (2), Jun (1), Aug (1), Sep (6), Oct (10), 

Dec (4). ♀♀ 19: Jan (1), Feb (2), Mar (4), May (2), Jun (1), Sep 

(1), Oct (7), Dec (1). Birds with only partly pneumatized skulls in 

Jan, Mar, and May likely represent birds of the year. Birds with 

small skull windows and developed gonads in Feb, Aug, and Oct 

are likely in their second year.

Mass (g). ♂♂ X

_

 = 14.4 (SD = 1.50, range = 12.2–18.5, 

N = 27). ♀♀ X

_

 = 14.7 (SD = 2.01, range = 12.0–19.5, N = 18). 

Birds (5) with light fat in Jan, Mar, Jun, Oct, and Dec; with moderate fat in Sep (1), Oct (1).

ova 0.5 mm (Aug). Ovaries of ♀♀ with immature skulls smooth 

and undeveloped (Feb, Mar) or granular (Jun).

Molt. First prebasic molt in Feb.

Plumage. Rufous flanks, as described by Ridgely and 

Tudor (2009:543) for birds from southeastern Brazil.

Stomach Contents. Only fruit (including Allophylus edulis and Psychotria carthagenensis) in 12; fruit and 

insects in 1.

Habitat. Forest, old second growth.

Notes. Birds were recorded regularly at El Tirol from 

Feb through Aug but not during the austral spring, and none was 

in breeding condition. In May they formed single-species flocks 

(≤10 individuals). These birds, which have partially yellow bills 

and rufous flanks (see Ridgely and Tudor, 2009), perched from 

2 m up into the canopies of the tallest trees. Often seen feeding in 

fruit trees (including Trema micrantha) and once following and 

feeding at an ant swarm.

Family Mimidae: Mockingbirds

Mimus saturninus: Chalk-browed Mockingbird

Specimens (MVZ, MNHNP). ♂♂ Feb (1), Mar (1), 

Jun (1). ♀ Jun (1). Jun birds with adult skulls; Feb and Mar ♂♂

with immature skulls.

Mass (g). ♂♂ 58.2 (Feb), 72.5 (Mar), 72.0 (Jun); all 

with light fat. ♀ = 71.0, moderate fat.

Iris. Brown, brownish green, or whitish.

Bill. Upper mandible black. Lower mandible black, 

in some with gray or blue gray at base. Mouth lining yellow 

green.

Feet and Tarsi. Black or dark brown. Toe pads 

brown.

Gonads. Testes not enlarged (1 × 1–3.5 × 2 mm); left 

testis of Jun ♂ black. ♀ Ovary granular, ova minute.

Molt. First prebasic body molt in Feb and Mar ♂♂.

Plumage. The Feb ♂ is in juvenal plumage, heavily 

spotted brown on the breast and flanks. The Mar ♂ has already 

replaced those feathers and resembles the adult. The younger age 

of the Feb bird may explain its lower body mass.

Stomach Contents. One with only insect remains, 

including Coleoptera; 1 with insects and seeds; 2 with fruits and 

seeds of several species.

Habitat. Small trees in scrubby pasture or at edges of 

fields.

Notes. In small family groups in Feb and Jun.

Family Thraupidae: Tanagers

Cissopis leverianus*: Magpie Tanager

Notes. In Oct perched quietly 2–3 m up in a tree in a 

closed-canopy, wooded area from which the undergrowth had 

been removed (MSF). Hayes (1995) designated this species as 
4 6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

tsees with a rising inflection. One individual with nematodes in 

the body cavity, 1 with ticks on the eyes, and 3 with scaly legs 

and feet.

Trichothraupis melanops: Black-goggled 

Tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ 38: Jan 

(2), Feb (3), Mar (3), May (3), Jun (7), Aug (2), Sep (4), Oct (9), 

Nov (1), Dec (4). ♀♀ 22: Feb (1), Mar (2), May (3), Jun (3), Aug 

(4), Sep (3), Oct (3), Nov (2), Dec (1). Birds with only partly 

pneumatized skulls in Oct, Dec, Feb, Mar, May, and Jun likely 

represent birds of the year. Birds with small skull windows in Oct 

and Dec are likely in their second year.

Mass (g). ♂♂ X

_

 = 20.8 (SD = 1.98, range = 16.6–25.7, 

N = 35). ♀♀ X

_

 = 22.2 (SD = 1.43, range = 17.75–24.5, N = 20). 

Birds with light fat in Feb, May, Jun, and Aug; with moderate or 

heavy fat in Jun and Aug.

Iris. Brown or black.

Bill. Upper mandible black, dark gray, or blue gray, 

with blue-gray or silver-gray tomium. Lower mandible gray, silver gray, or blue gray, sometimes with white or gray tomium. 

Mouth lining ochre or flesh color. Tongue flesh color.

Feet and Tarsi. Gray or blue gray. Toe pads light 

green, tan gray, or sandy brown.

Gonads. ♂♂ Males with adult skulls had enlarged 

testes (12 × 8–5 × 4.5 mm) from Aug through Jan and regressed 

testes (2 × 1–1 × 1 mm) from Feb through Aug. Some males 

breed before skull pneumatization is completed. All males with 

juvenal skulls had tiny testes (2 × 1–1 × 0.5 mm). ♀♀ Granular ovaries or those with largest ova ≤ 1 mm were recorded 

in most months, although many of the Aug through Dec birds 

were likely about to breed or postbreeding. Birds with enlarged, 

yellow-orange ova and enlarged oviducts were recorded in Aug, 

Sep, Oct, and Nov. Ovaries of all ♀♀ with juvenal skulls were 

smooth and undeveloped.

Molt. Prebasic molt recorded in Dec, Jan, Feb, and 

Mar. First prebasic molt recorded in Oct, Feb, Mar, and May.

Plumage. Birds in juvenal plumage resemble the 

female. Following the first prebasic molt, males acquire a plumage with characteristics of the definitive-male plumage, but the 

extent of those characteristics varies widely. Some first-year birds 

have a fully definitive plumage. However, most first-year males 

lack the black mask (or goggles) and have dusky wings and 

tail and a limited yellow crown patch. A single female (MVZ 

165627) with a moderately well-developed yellow crown may 

have been missexed.

Stomach Contents. Only insects in 25 birds; only 

fruit in 8; a mix of fruit and insect remains in 6. One ♂ had 

remains of a snail shell, and 1 ♀ had remains of an egg shell.

Habitat. Forest, disturbed forest, occasionally in open 

scrub.

Notes. One of the most common birds at El Tirol. 

Usually 2–8 m up in understory (often fruiting) trees, but 

Iris. Brown, dark brown, or reddish brown.

Bill. Upper mandible brown, black, or grayish black 

with narrow pale gray tomium. Lower mandible lighter than 

upper mandible: gray (whitish gray, blue gray, purplish gray), 

white, tan, flesh color. Mouth lining flesh color, gray, slate gray 

blue. Tongue flesh color or purplish at base and white distally; 

palate purplish pink.

Feet and Tarsi. Gray, brownish gray, or blue gray. 

Toe pads green, tan, yellowish tan, or greenish brown.

Gonads. ♂♂ Males with adult skulls had enlarged testes (6 × 4–12 × 8 mm) from Aug into Dec, when they began to 

regress. Testes were regressed (1 × 1–2.5 × 1.5 mm) from late 

Dec through Jun. Males with skulls ≥50% pneumatized or with 

only small skull windows had enlarged (7.5 × 5.5–10 × 5 mm) 

testes and apparently bred. Males with juvenal skulls (Oct, Mar, 

May) had tiny (≥ 1 × 1 mm) testes. ♀♀ in Oct, Nov, and Dec 

had enlarged ova (2–10 mm, many yolked), enlarged oviducts, 

incubation patches, and/or were accompanied by juveniles. From 

Jan through Jun and Sep, ovaries were granular, had largest ova 

≤ 1 mm, or were postreproductive. Ovaries of all females with 

juvenal skulls were smooth and undeveloped.

Molt. Prebasic molt recorded in Oct, Dec, Jan, Feb, 

and Mar. First prebasic molt recorded in Jan and May. Two adult 

Sep birds (♂, ♀) with body molt; possibly prealternate. Molt in 

the Sep ♂ (testis 7 × 3 mm) may overlap with breeding.

Plumage. Birds in juvenal plumage resemble the 

female, but with lax rufous feathers on the upper back and 

breast. Following the first prebasic molt, males acquire a plumage closely resembling the adult female or one that is a mixture of 

adult male and adult female characteristics. In males with mixed 

plumage the crown is yellowish chestnut, the throat about half 

chestnut and half yellow, and the black foreface has olive feathers 

scattered through it; the dorsal and ventral body feathers range 

from one- to two-thirds gray, with the rest of the feathers olive. 

The variation in the plumage may reflect the date of hatching 

and the relative ages of the males, with older individuals looking more like adult males. Males with a mixed plumage have 

only partly pneumatized skulls, whereas those with the definitive 

plumage have fully pneumatized skulls. Birds in mixed plumage 

had enlarged testes and apparently breed (Belton, 1985).

Stomach Contents. Only insects, including a caterpillar and ticks, in 14; only fruit remains in 7; a mix of fruit 

and insect remains in 2. Observed feeding on fruits of Allophylus 

edulis (Foster, 1987, 1990).

Habitat. Forest, old second growth.

Notes. Common in forest undergrowth, thickets, and 

bamboo patches, using both horizontal and vertical perches, 

usually below 4 m. Some males in immature plumage have developed testes and may breed. Small groups (3–4) of birds seen from 

Jan to Mar are likely family groups. The birds fly up to pluck 

fruits, rapidly returning to their perches, or they foliage glean on 

terminal branches and twigs. The birds flit around, rarely still, 

giving a single high-pitched pseet note or soft chup like glass 

beads colliding. Their calls are whistle-like whe whes or tsee 
NUMBER 648 • 4 7

than in older birds. The birds breed in this plumage and also may 

retain small skull windows.

Stomach Contents. Thirteen with only insect 

remains (including ants); 8 with only fruit, including Ficus sp.; 8 

with mixed insect, fruit, and plant remains.

Habitat. Forest and forest edge, occasionally in 

orchards or thick scrub adjacent to forest.

Notes. Occupy the densest growth in the forest 

understory, including bamboo, dense stands of saplings, and 

dense brush, as well as trees 6–8 m up. Prebasic molt may 

begin in some males while they are still in breeding condition. 

Males and females often move and forage together or with 

mixed-species flocks. Known to feed on Allophylus edulis and 

Eugenia uniflora and to follow ant swarms from low perches 

(1–1.5 m).

Stephanophorus diadematus*: 

Diademed Tanager

Notes. A male of this species was observed clearly 

while it fed on Eugenia uniflora fruits in an isolated 3-m-tall tree 

near the hotel (MSF). This species is distributed primarily to the 

east and south of Paraguay in Argentina and Brazil (Ridgely and 

Tudor, 2009). Hayes (1995) suggested that it may be a southern austral migrant to Paraguay, whereas R. P. Clay (Western 

Hemisphere Shorebird Reserve Network, Manomet, Inc., personal communication, 18 January 2016) speculated that it may 

“invade” Paraguay only during periods of population irruption. 

Del Castillo et al. (2015) considered it a “vagrant” to Paraguay. 

A single individual of this species was recorded by Smith et al. 

(2005) but may have been misidentified (P. Smith, FAUNA Paraguay, personal communication, 8 Sep 2016).

Pipraeidea melanonota: Fawn-breasted 

Tanager

Specimens (USNM, MNHNP). ♂♂ Jun (1), Sep 

(2). ♀ Aug (1). All birds with adult skulls.

Mass (g). ♂♂ X

_

 = 22.9 (SD = 2.43, range = 20.3–25.0, 

N = 3), Jun bird with light fat, Nov bird with moderate to heavy 

fat. ♀ 21.0, light fat.

Iris. Brown or red.

Bill. Upper mandible black. Lower mandible gray; 

with black tip in some birds.

Feet and Tarsi. Black, gray brown, or gray.

Gonads. ♂♂ Testes enlarged (7 × 3.5, 5.5 × 4 mm) in 

Sep; small (2 × 1 mm) in Jun. ♀ largest ovum = 0.5 mm, oviduct 

beginning to enlarge.

Molt. Body molt in Aug ♀.

Stomach Contents. Insect remains in 2; plant 

remains in 1; plant and insect remains in 1.

Habitat. Forest.

Notes. May join mixed-species flocks including such 

birds as Setophaga pitiayumi.

sometimes in viny bamboo tangles. During the breeding season, 

birds occur mostly in pairs or, later, in family groups. Firstyear males, including those with female-like plumage, appear to 

breed. For example, 5 males (2 with small skull windows) collected in Oct and Nov had testes ranging from 8 × 5 to 9.5 × 

6 mm. Four males in full adult plumage from the same period 

had testes ranging from 8 × 6 to 10 × 7 mm. From Mar through 

August female-plumaged birds (both ♀♀ and young ♂♂) form 

small flocks of 4–7 birds. Males in adult plumage seem to be 

solitary. The Trichothraupis in the flocks seem to be the nuclear 

species for the formation of mixed-species understory flocks that 

may include Basileuterus culicivorus and Hemithraupis guira. 

Whether solitary or part of a flock, both ♂♂ and ♀♀ repeatedly 

give a harsh, single-note chup or chuck as they move around in 

the vegetation. When perched, a bird may flick its tail up and 

down vertically. The species was observed feeding on Allophylus 

edulis and Trema micrantha fruits (Foster, 1987, 1990) and following an ant swarm.

Tachyphonus coronatus: Ruby-crowned 

Tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ 33: Jan 

(1), Feb (1), Mar (3), May (1), Jun (7), Aug (4), Sep (4), Oct (7), 

Nov (4), Dec (1). ♀♀ 17: Jan (1), Feb (1), Mar (1), May (3), Jun 

(3), Aug (2), Sep (4), Nov (1), Dec (1). Birds with juvenal/immature skulls in Jan (1), Feb (1), Mar (2), Jun (3). One Oct and 1 

Nov bird with small skull windows and greatly enlarged testes 

likely represent birds in their second year. All other specimens 

with completely pneumatized skulls.

Mass (g). ♂♂ X

_

 = 26.3 (SD = 2.88, range = 22.0–35.0, 

N = 32). ♀♀ X

_

 = 26.2 (SD = 1.99, range = 23.0–29.0, N = 15). 

Light or moderate fat present in some birds in Feb (1), Mar 

(1), May (1), Jun (6), Aug (3), Sep (1). One very fat bird 

in Sep.

Iris. Brown, dark brown, or black.

Bill. Upper mandible black. Lower mandible gray or 

white with black tip. Mouth lining lemon yellow, yellow orange, 

or pink. Soft gape tissue in juveniles yellow orange.

Feet and Tarsi. Black, various shades of dark gray, 

or dark purple. Toe pads green or tan.

Gonads. ♂♂ Testes of adults small (≤2.5 × 1.5 mm) 

from Mar to Aug, enlarging in Sep (3 × 2–6 × 4 mm), and 

enlarged from Sep through Feb (8 × 4–15 × 9 mm), often with a 

large cloacal protuberance. Testes of immature ♂♂ ≤ 1.5 × 1.0 

mm, sometimes black. ♀♀ Ovaries granular, May into early Sep. 

Sep ♀♀, ova = 1 mm diam; Nov ♀ laying, with incubation patch. 

Ovaries of ♀♀ in their first year, smooth and undeveloped.

Molt. Prebasic molt in Jan (1), Feb (1), Mar (1), and 

Jun (1). First prebasic molt in Jan (1), Feb (1), Mar (1).

Plumage. First-year males that have completed their 

first prebasic molt may retain yellowish brown feathers on the 

flanks, rump, and lower abdomen and occasionally on the upper 

wing coverts or breast. The primaries are also dull and browner 
4 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Gonads. ♂♂ Testes enlarged in Dec (6.5 × 4 mm) and 

Jan (8 × 6, 6 × 4 mm) or beginning to decline in Jan (4 × 3 mm) 

and small in May (2 × 1.5 mm). ♀♀ Feb ovary postreproductive, 

incubation patch old. Oct largest ovum 1.5 mm diam.

Molt. Prebasic molt in Jan, Feb; first prebasic molt in 

Jan.

Stomach Contents. Four with fruits, including 

Allophylus edulis and Eugenia uniflora; 2 with “plant material.”

Habitat. Forest, forest edge, woodland, gardens.

Notes. Perches in the canopy, often on bare branches. 

May join mixed-species foraging flocks. Birds give a single pseet

note. Isler and Isler (1987) reported that the species has a subadult plumage in which the birds probably breed. We did not 

encounter any birds in this plumage.

Tersina viridis: Swallow Tanager

Specimens (USNM, MVZ). ♂♂ Sep (3), Nov (1). 

♀♀ Oct (3). All with adult skulls.

Mass (g). ♂♂ X

_

 = 33.4 (SD = 1.60, range = 31.0–34.5, 

N = 4). ♀♀ X

_

 = 34.9 (SD = 0.81, range = 34.0–35.5, N = 3). Light 

or moderate fat in 1 Sep ♂ and 2 Oct ♀♀.

Iris. Brown.

Bill. Black. Palate and tongue pale pinkish purple. 

Floor of mouth dull yellowish pink.

Feet and Tarsi. Black or brownish black. Toe pads 

gray.

Gonads. ♂♂ Testes enlarging (4 × 3– 6 × 4 mm) in Sep 

and enlarged in Nov (10 × 5 mm). Reproductive states of Oct 

♀♀ varied from largest ovum ≤ 1–5 mm with oviduct moderately 

enlarged to shelled egg in oviduct.

Molt. No.

Plumage. The nonmolting Nov male (MVZ 168911) 

had an adult skull and a mixture of adult female and male plumages. Although males breed at age 1 year, they do not acquire the 

full adult plumage until their second or even later prebasic molt 

(Schaefer, 1953).

Stomach Contents. Six with only fruit, including 

Alchornea iricurana and Ocotea puberula; 1 with an orthopteran.

Habitat. Forest, forest edge, woodland.

Notes. Frequently observed in pairs or small groups 

feeding in fruiting trees and occasionally making fly-catching 

sallies. Use generally bare perches from 2 to 15 m up. A pair 

observed on 11 Oct 1978 was going in and out of a hole in a 

bank adjacent to a creek through undisturbed forest. The hole 

was ~3 m above the streambed in an area of soft sandstone. In 

1979, a female gathered and carried away moss (possibly for lining a nest?) from ~3 m up on the trunk of a tree in the vicinity of 

the nest hole located the previous year. The species is reported to 

breed in holes in banks (Schaefer, 1953; J. C. Chebezas in Ortiz, 

2009) as well as in tree holes (Canevari et al., 1991). The species is reportedly migratory in Venezuela (Schaefer, 1953). Hayes 

(1995) also regarded it as a migrant, breeding in Paraguay and 

moving north in the austral winter. Ridgely and Tudor (1989), 

Thraupis sayaca: Sayaca Tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(2), Jun (3), Aug (1), Sep (1), Oct (2). ♀♀ Jan (1), Feb (2), Jun 

(1), Sep (2), Nov (1). Birds with juvenal skulls in Feb (3) and Jun 

(3). One Oct ♂ with tiny skull windows and breeding is likely in 

his second year.

Mass (g). ♂♂ X

_

 = 32.1 (SD = 1.81, range = 30.0–35.2, 

N = 8). ♀♀ X

_

 = 32.9 (SD = 1.35, range = 31.5–35.0, N = 7). 

Light or moderate fat recorded in Feb (2), Jun (2), Sep (2), Oct 

(1), and Nov (1).

Iris. Brown.

Bill. Upper mandible black distally with gray or blue 

gray at base. Lower mandible gray or blue gray, some with black 

tip. Mouth lining flesh color.

Feet and Tarsi. Gray or gray blue. Toe pads tan or 

green.

Gonads. ♂♂ Testes enlarged (8.5 × 5–9 × 6 mm) Sep–

Oct; 1 ♂ with large cloacal protuberance. Testes of immatures 

and adults small (1 × 0.5– 2 × 1 mm), Feb through Aug. ♀♀ Ovaries with enlarged ova (≥2 mm diam) or collapsed follicles, oviduct enlarged, and/or incubation patch (Sep, Nov, Jan). Adults 

and immatures largest ovum ≤ 1 mm (Feb, Jun, Sep),

Molt. Prebasic molt in Jan (1) and Feb (4); first prebasic molt in Feb (1).

Stomach Contents. Seven with fruits and seeds; 2 

with insects and plant material (e.g., flowers); 1 with only insect 

remains. Feeds routinely on Allophylus edulis, Cupania vernalis, 

Eugenia uniflora, and Ocotea puberula fruits.

Habitat. Forest, forest edge, open woodland, tung 

orchard, forest clearings.

Notes. Generally in pairs or in family groups following breeding (Jan–Mar), usually from 2 to 7 m up. Birds were 

found in the same areas over and over through the breeding 

season, as if on territories, although agonistic interactions with 

conspecifics were not observed. Birds were observed bathing in 

water in a hole in the crotch of a tall tree in the forest. A bird 

entered the water, fluttered its wings and tail, and flipped water 

all over its body several times and then left. That bird or another 

returned to bathe again after about 1 min. Bathing was observed 

on 22 Sep and 23 Oct 1980 and in earlier years at the same tree 

hole.

Tangara seledon: Green-headed Tanager

Specimens (USNM, MVZ). ♂♂ Jan (4), May (1), 

Dec (1). ♀♀ Feb (1), Oct (1). One Jan ♂ with juvenal skull; all 

other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 18.5 (SD = 1.18, range = 16.5–20.0, 

N = 6). ♀♀ Both 20.5. One Jan ♂, 1 Oct ♀ with light fat.

Iris. Dark brown or brown.

Bill. Black. Mouth lining black.

Feet and Tarsi. Gray, blue gray, or slate gray. Toe 

pads gray or tan.
NUMBER 648 • 4 9

Nov (2). All birds with adult skulls except a Sep ♀ = skull 60 % 

pneumatized and 1 Nov ♀ = juvenal skull.

Mass (g). ♂♂ X

_

 = 12.5 (SD = 1.09, range = 9.5–14.0, 

N = 14). ♀♀ X

_

 = 13.4 (SD = 1.15, range = 11.8–15.5, N = 8). 

Light to moderate fat present in some birds in Jan, Feb, May, 

Jun, Sep, Oct, and Nov.

Iris. Brown or dark brown.

Bill. Upper mandible black (or brown) with yelloworange tomium. Lower mandible yellow orange or greenish yellow. Mouth lining and tongue pinkish flesh color.

Feet and Tarsi. Black, gray, or blue gray. Toe pads 

pale gray, light green, or pale greenish tan.

Gonads. ♂♂ Testes small ≤ 1.5 mm diam in May and 

Jun; enlarged (8 × 5.5–5 × 4 mm) in Aug to Feb, some ♂♂ with 

large cloacal protuberances. ♀♀ Aug bird, largest ovum yellow 

orange and 3 mm diam, 1 collapsed follicle, and oviduct enlarging. Bird with juvenal skull (Nov), ovary undeveloped. All other 

♀♀ with granular ovaries and largest ova ≤ 1.0 mm.

Molt. Prebasic molt in Jan (1), Feb (2), and May; first 

prebasic molt in Nov.

Stomach Contents. Nine with only insect remains, 

including 4 with caterpillars (to 3 cm long); 4 with only fruit; 3 

with insect, fruit, and other plant remains.

Habitat. Forest, forest edge, disturbed forest with a 

cleared understory; occasionally in orchard near forest.

Notes. Occur in pairs year-round in the canopies of 

forest trees or in family groups in the latter half of the breeding season. In Feb a pair was followed by and attended to a 

fully grown juvenile. During the austral winter (Mar–Aug), 

pairs may join subcanopy, mixed-species flocks, which include 

Nemosia pileata, Hemithraupis guira, Basileuterus culicivorus, 

and Trichothraupis melanops. The birds foliage glean like warblers, hopping, flitting, and hanging upside down while probing 

among flowers and leaves. They also appear to take nectar and 

have been observed feeding on fruits of Allophylus edulis and 

Trichilia catigua.

Conirostrum speciosum: Chestnut-vented 

Conebill

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), May (1), Jun (2), Oct (1). ♀ Jun (1). Feb ♂ with unpneumatized skull; all others with adult skulls.

Mass (g). ♂♂ X

_

 = 9.0 (SD = 0.14, range = 8.8–9.2, 

N = 5), Feb specimen with light fat. ♀ 8.4, light fat.

Iris. Brown.

Bill. Upper mandible black with gray or blue gray 

tomium. Lower mandible gray or blue gray. Mouth lining flesh color.

Feet and Tarsi. Gray or blue gray.

Gonads. ♂♂ Testes enlarged (5 × 4 mm) in Oct; small 

(3 × 2–1 × 0.5 mm), Feb through Jun. ♀ Ovary granular.

Molt. Prebasic molt in May; first prebasic molt in Feb.

Stomach Contents. Four with insect remains, 

including a caterpillar; 1 with seeds and plant material.

in contrast, described it as nomadic, appearing erratically from 

1 place and 1 year to the next. We recorded it only during the 

breeding season (Sep–Nov) and only in 1978, 1979, and 1981, 

although someone was present and collecting during the breeding seasons of 1976–1977, 1980, 1982, and 1983.

Dacnis cayana: Blue Dacnis

Specimens (USNM, MVZ, MNHNP). ♂♂ 10: Feb 

(2), Mar (1), May (1), Jun (3), Sep (1), Oct (1), Dec (1). With 

juvenal skulls in Dec, Feb (1), May, and Jun (1). ♀♀ Jan (1), May 

(2), Jun (3), Oct (2). With small skull windows in May (1), Jun 

(1), and Oct (1), and 1 bird with juvenal skull in Jun.

Mass (g). ♂♂ X

_

 = 16.1 (SD = 0.80, range = 15.0–17.5, 

N = 9). ♀♀ X

_

 = 16.0 (SD = 1.04, range = 14.5–17.6, N = 8). 

Occasional birds with light or moderate fat Jan (1), May (1), Jun 

(2), Dec (1).

Iris. Brown, reddish brown, or brick red.

Bill. Upper mandible black. Lower mandible black or 

gray with black tip. Mouth lining green, yellow, or flesh color. 

Tongue yellow flesh color.

Feet and Tarsi. Gray, maroon, tan, or dull red. Toe 

pads tan or pink.

Gonads. ♂♂ Testes of adults enlarged in Sep (5 × 

3 mm) and Oct (8 × 5 mm, ♂ with moderate cloacal protuberance); small (≤2 × 1 mm) from Feb through Jun. Testes of juveniles small (1 × 0.5–1.5 × 1 mm) Dec to Jun. ♀♀ Largest ova 

2 mm diam in Oct (2); 1 bird with a developing brood patch. ♀

with an enlarged oviduct and brood patch in Jan. Ovaries granular in May, Jun. Jun juvenile with smooth, undeveloped ovary.

Molt. Some birds with prebasic molt in Feb, Mar, 

May. First prebasic molt in Dec, Feb, May.

Stomach Contents. Fifteen with fruit pulp and 

seeds, including Trema micrantha; 1 with fruit and insect 

remains, including a 27-mm-long caterpillar; 1 with only insect 

remains.

Habitat. Forest, disturbed forest, forest edge, isolated 

fruit trees in fields.

Notes. Commonly observed during the austral winter 

moving with mixed-species flocks high in the forest canopy and 

in fence row trees between pastures. Also seen in small flocks 

(5–6) of conspecifics. Foliage glean for insects and feed on fruits 

of Allophylus edulis and Trema micrantha. Ridgely and Tudor 

(2009) reported that these birds feed mainly on insects and, 

to a lesser extent, small fruits, in contrast to the results from 

the stomach contents we analyzed. One breeding male (MVZ 

166356) with a healed broken leg. Juvenile being attended by 

female in May.

Hemithraupis guira: Guira Tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ 14: Jan 

(1), Feb (1), May (1), Jun (2), Aug (2), Sep (2), Oct (3), Nov 

(1), Dec (1). ♀♀ 10: Jan (1), May (1), Jun (3), Aug (1), Sep (2), 
5 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Mass (g). ♂♂ X

_

 = 16.0 (SD = 0.52, range = 15.4–

16.75, N = 5); Dec bird with light fat. ♀♀ 16.5, 15.8.

Iris. Brown or black.

Bill. Upper mandible brown. Lower mandible brown, in 

some birds yellow or grayish white at base. Mouth lining flesh pink.

Feet and Tarsi. Brown or green with tan toe pads.

Gonads. ♂♂ Testes enlarged (6 × 4–9 × 6 mm) Sep 

through Jan. ♀♀ Ovaries small, undeveloped.

Molt. Prebasic molt in 2 Mar ♀♀. Oct male replacing 

entire tail (possibly adventitious loss).

Plumage. Adult plumage conforms to the “southern 

form” described by Ridgely and Tudor (2009). Males are more 

olive above and on the breast and have less orange on the crown 

than birds from northern and northwestern South America. 

Females are more brownish above and whiter below. Both sexes 

have more streaking. One adult male from El Tirol had considerable dusky streaking on the breast and flanks. The Oct and Dec 

males, with adult skulls (95% and 100% pneumatized, respectively), are in full female plumage.

Stomach Contents. Six with seeds.

Habitat. Tung orchards, cultivated fields, scrubby 

pastures, along roadsides.

Notes. Males singing regularly in Oct through Feb. One 

♂ displaying to a ♀ and juveniles being fed by adults in Feb. Males 

appear to require 2 years to complete skull pneumatization and 

acquire the adult male plumage but are in breeding condition (testes 

8 × 4 and 7.5 × 6.5 mm) and singing after their first year. Observed 

in flocks of up to 20 individuals (mostly young) beginning in Mar. 

Abdominal feathers of all individuals soiled with red dirt.

Volatinia jacarina: Blue-black Grassquit

Specimens (MVZ). ♂♂ Feb (2), 1 with adult skull 

and plumage; 1 with a juvenal skull and immature plumage (like 

female).

Mass (g). Adult 10.5, light fat; juvenile 8.8.

Iris. Brown.

Bill. Adult: Upper mandible black, lower mandible 

blue. Immature: Upper mandible brown, lower mandible gray 

blue. Mouth lining dull yellow.

Feet and Tarsi. Black or dark brown (juvenile). Toe 

pads tan.

Gonads. Testis of adult, 6 × 4 mm; juvenile, 1 × 1 mm.

Molt. Adult with body molt.

Stomach Contents. Both with seeds.

Habitat. Scrubby pasture, tall grass with scattered bushes.

Sporophila angolensis: Chestnut-bellied 

Seed-finch

Specimens (USNM). ♀ Oct (1), skull partly pneumatized.

Mass (g). 13.25.

Iris. Brown.

Bill. Black.

Habitat. Forest, forest edge, orchards, scrubby fields 

adjacent to forest.

Notes. Inhabits forest canopy and tops of small fruiting trees. Visits flowers from which it appears to be taking 

insects. Joins mixed-species flocks including Hemithraupis guira

and Nemosia pileata.

Haplospiza unicolor: Uniform Finch

Specimens (USNM, MVZ, MNHNP). ♂♂ May 

(1), Sep (2), Oct (2). ♀♀ Jun (1), Sep (6), Oct (1). Birds with 

juvenal/immature skulls in Sep (2 ♂♂ and 2 ♀♀) and Oct (1♂). 

All other specimens with skulls completely pneumatized.

Mass (g). ♂♂ X

_

 = 14.9 (SD = 1.60, range = 13.0–16.8, 

N = 5). ♀♀ X

_

 = 15.0 (SD = 1.89, range = 12.1–18.3, N = 8). Light 

fat in May (1) and Sep (1), and moderate to heavy fat present in 

Sep (3).

Iris. Brown.

Bill. Upper mandible black or brown. Lower mandible 

black or brown distally, yellow or yellow tan at base.

Feet and Tarsi. Brown, tan, grayish tan, or flesh color.

Gonads. ♂♂ With adult skulls, 5 × 3.5 mm (May, 1) 

and 3.5 × 2 mm (Oct, 1); with immature skulls, 2 × 1 mm (Sep) 

and 3.5 × 3–2.5 × 2 mm (Oct). ♀♀ Ova of 1 Sep bird >1 mm; all 

other ♀♀ with ova ≤ 1 mm diam. A Sep bird with an unpneumatized skull had a smooth, undeveloped ovary and likely had 

recently hatched. In contrast, a Sep bird with a 70% pneumatized skull and a granular ovary likely hatched during the previous breeding season.

Molt. None noted.

Plumage. Immature males that have completed 

their first prebasic molt have a plumage somewhat intermediate 

between those of adult males and females. Females are yellowish 

ventrally and heavily streaked with dusky on the throat, breast, 

and flanks and with gray on the abdomen. Young males (e.g., 

USNM 599171, MVZ 167499) are pale gray ventrally (less yellow than females) with darker gray or dusky streaks on the throat, 

breast, and flanks. The abdomen is whitish, streaked gray. Dorsally, young males are paler gray than adult males with irregular 

spots and blotches of dusky olive brown. They have some darker 

streaking on the crown and nape. Tail is brown as in females.

Stomach Contents. Insect remains in 2 birds, seeds 

in 2. One of the birds with insects, both of those with seeds, and 

an additional 3 birds whose stomachs lacked food remains had 

grit in their stomachs.

Habitat. Brush and dense bamboo low in the forest 

understory.

Notes. Has a harsh, sharp, single-note call.

Sicalis flaveola: Saffron Finch

Specimens (USNM, MVZ). ♂♂ Jan (1), Sep (1), 

Oct (1), Nov (1), Dec (1). Oct bird with small skull windows; all 

others, adult skulls. ♀♀ Mar (2), juvenal skulls.
NUMBER 648 • 5 1

(1), Jun (1, juvenal skull), Aug (2), Sep (2), Oct (2), Nov (2), Dec 

(2). Sex? Sep (1, nestling; MSF 2069). Nest Sep (1); MSF 2073. 

One Oct and 1 Nov ♂ and May, Jun, and 1 Sep ♀♀ with small 

skull windows. One Nov ♂ with large skull windows.

Mass (g). ♂♂ X

_

 = 14.9 (SD = 1.34, range = 11.8–17.3, 

N = 22). ♀♀ X

_

 = 14.8 (SD = 1.87 range = 10.9–17.0, N = 13). 

Some birds with light fat in almost every month. One Jun and 1 

Nov bird with moderate to heavy fat.

Iris. Brown or dark brown.

Bill. Upper mandible black or dark brown. Lower 

mandible gray or gray blue, with black tip in some. Mouth lining 

flesh color, reddish, or pale yellowish white. Tongue and palate 

pale yellowish white.

Feet and Tarsi. Gray, brown, or black. Toe pads 

brown or reddish brown.

Gonads. ♂♂ Testes enlarging in Aug–Oct (4 × 2.5–5 × 

3 mm), enlarged in Sep–Jan (6 × 4.5–10 × 5 mm), including 

in ♂♂ with small skull windows. Regressed in May–Jun (≤2 × 

1 mm, some black). Mar juveniles with tiny testes (1 mm diam). 

♀♀ Ovaries granular or largest ova ≤ 1 mm in Dec through Sep 

plus 1 Oct bird. An Oct ♀ and a Nov ♀ with enlarged (2–2.5 mm 

diam), yellow-orange ova, and 1 with an enlarged oviduct. 

Another Nov bird with postbreeding ovary.

Molt. Two Mar ♂♂ in first prebasic molt. One Jan, 

2 Oct, and 1 Dec adults with light scattered body molt. Birds 

observed (but not captured) in Feb appear to be molting heavily.

Stomach Contents. Eleven with only insects, Aug–

Dec; 10 with only seeds, Dec–Jun; suggests a seasonal shift in 

diet. Known to feed in Allophylus edulis.

Habitat. Scrubby second growth with many small 

trees, thickets at the edges of forests and fields, tung orchard, 

weedy road sides.

Notes. Very common at El Tirol. Birds generally in 

pairs or family groups but may form flocks (10–15 birds) in 

the nonbreeding season. They frequent small trees, shrubs, and 

vine tangles a few meters off the ground, although singing males 

may perch on bare limbs10–12 m up in large trees. Copulation 

observed in Oct; nest located Sep; pairs feeding young in Nov, 

Jan, Feb.

Nest (cf. de la Peña, 2010) located 19 Sep 1982, 18 days 

earlier than the earliest egg date reported by Hayes (2014) for 

Sapucái (Figure 1). The nest was in a vine (Relbunium hypocarpium, Rubiaceae) tangle hanging from a small tree (4 m tall) in 

second-growth-edge scrub. The viny mass hung to about 75 cm 

above the ground, which was covered with weedy annuals and 

some woody perennials 75 to 100 cm tall. The bottom of the 

nest was 111 cm above ground, 13 cm from the tree trunk, and 

easily accessible to climbing mammalian or reptilian predators. 

The nest incorporated 5 vertical vine stems that ran through it 

and held it up. Its outer height was 6.0 cm, and inner depth was 

4.5 cm; the outer diameter at the rim was ~8.0 cm, and the inner 

diameter was 5.5 cm, although the outer (somewhat) and inner 

(especially) diameters decreased toward the bottom (inner diameter = 3.6 cm). The nest was essentially round at the rim. The 

Feet and Tarsi. Dark gray.

Gonads. Ovary smooth and undeveloped.

Molt. No.

Stomach Contents. Seeds in crop and stomach.

Habitat. Scrubby second growth in abandoned clearing.

Sporophila caerulescens: Double-collared 

Seedeater

Specimens (MVZ, MNHNP). ♂♂ Feb (2), Mar (1), 

Jun (1), Nov (2). One Nov bird with tiny skull windows; all others, skulls fully pneumatized. Sex? Mar (1), juvenal skull.

Mass (g). ♂♂ X

_

 = 10.3 (SD = 1.36, range = 8.8–12.0, 

N = 6). Nov bird with skull windows, very fat. Sex? 7.8.

Iris. Dark brown to brown.

Bill. Greenish yellow or greenish gray with yellow at 

base and along tomia. Or upper mandible gray brown or gray 

green and lower mandible paler bluish gray brown with yellow 

orange at base and along tomia. Mouth lining pale red brown 

or yellow.

Feet and Tarsi. Dark brownish black, dark gray, or 

grayish brown. Toe pads tan, gray brown, or gray. In juvenile, 

pinkish green with pink toe pads.

Gonads. Testis sizes suggest breeding from Nov 

through Mar, although gonad enlargement does not appear to 

be synchronous in the population. ♂♂ Testes in Nov = 5 × 4 and 

3 × 2 mm; Feb = 9 × 5 mm, with large cloacal protuberance, male 

singing, and 2 × 1 mm; Mar = 6 × 5 mm, large cloacal protuberance; and Jun = 1 × 0.5 mm.

Molt. Body molt in Feb (1), Mar (1), and Nov (1); 

body and flight feather molt in Mar Sex? bird. Molting and 

breeding in Mar ♂ may overlap.

Plumage. Two Nov males in first-year plumage with 

only a hint of the pectoral band, upper throat with only a few 

black feathers, and white malar stripe limited; brown dorsally. 

Degree of skull pneumatization indicates that the birds hatched 

the previous year, and their testes sizes suggest that they may 

breed in this plumage. The Sex? bird from Mar is in lax juvenal plumage: brown dorsally; throat buff, breast pinkish brown 

grading into whitish belly.

Stomach Contents. Four birds with only seeds, 1 

with seeds and grit, and the juvenile with seeds and white eggshell fragments. One bird with small insects.

Habitat. Orchards, shrubby pasture, dense grass 

scrub, open fields, and roadsides.

Notes. Usually found in small groups in bushes or 

small trees, from 1 to 3 m, or on the ground. Ventral feathers 

often soiled with red dirt.

Coryphospingus cucullatus: Red-crested Finch

Specimens (USNM, MVZ, MNHNP). ♂♂ 27: Jan 

(1), Feb (1), Mar (3, all with juvenal skulls), May (1), Jun (4), 

Aug (1), Sep (4), Oct (5), Nov (5), Dec (2). ♀♀ 13: Jan (1), May 
5 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Bill. Black.

Feet and Tarsi. Dark gray.

Gonads. Testis 2 × 1 mm.

Molt. No.

Habitat. In a field.

Stomach Contents. Full of seeds and other plant 

material.

Family Emberizidae: Sparrows

Zonotrichia capensis: Rufous-collared Sparrow

Specimens (USNM, MVZ). ♂♂ 22: Feb (1, imm 

skull), Mar (1), Aug (1), Sep (7), Nov (11, one with small skull 

windows), Dec (1). ♀♀ Jan (1, imm skull), Feb (1, imm skull), 

Mar (1), Oct (1), Nov (3). Sex? Mar (1).

Mass (g). ♂♂ X

_

 = 21.0 (SD = 1.33, range = 16.7–23.0, 

N = 22), no fat. ♀♀ X

_

 = 21.2 (SD = 1.36, range = 20.4–22.8, 

N = 3 ad); slight fat in 2 Nov birds. Sex? 20.8.

Iris. Brown or red brown.

Bill. Upper mandible dark brown or brown. Lower 

mandible gray or green gray. Mouth lining flesh color.

Feet and Tarsi. Brown. Toe pads brown or tan.

Gonads. ♂♂ Testes enlarged (5 × 4–10 × 6 mm) Aug 

through Dec; many ♂♂ with a large cloacal protuberance. Testis small (1 × 1 mm) in Mar. ♀♀ Oct–Nov birds with various 

combinations of enlarged ova (to 6 mm diam), collapsed follicles, enlarged oviducts, and active incubation patches; 2 with 

unshelled eggs in their oviducts. Mar adult, largest ova ≤ 1 mm. 

Jan and Feb immatures with small, undeveloped ovaries.

Molt. Feb and Mar birds with body and flight feather 

molt.

Plumage. Head striping bold and conspicuous (cf. 

Ridgely and Tudor, 2009). Jan ♀ in juvenal plumage: yellowish tan on throat, breast, anterior abdomen, and flanks densely 

streaked dusky; posterior abdomen buffy; dorsally brown with 

bold dusky streaks but lacking the rufous collar. None of the 

specimens has a noticeable yellow bend to the wing (cf. Chapman, 1940; Bó, 1972; Hayes, 1995).

Stomach Contents. Seven with only seeds; 11 with 

only insects, including a caterpillar; 4 with seeds and insects.

Habitat. Tung orchard, pastures, cultivated fields, 

clearings, around buildings.

Notes. On the ground and in shrubs and small trees. 

Ventral feathers frequently soiled with red dirt. Observed feeding 

on Allophylus edulis fruits, but it was not clear whether it was 

eating the pulp or extracting the seed.

Family Cardinalidae: Cardinal Grosbeaks

Habia rubica: Red-crowned Ant-tanager

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

Jun (2), Sep (2), Oct (3), Nov (1). ♀♀ Jun (2), Oct (3). Sex? 

bulk of the nest consisted of an inner layer (10–12 mm thick) of 

circularly but irregularly interwoven very fine pale fibers, smooth 

and round in cross section. An outer layer (3–5 mm thick) consisted of a hodgepodge of materials, including strips of bark (4–5 

mm wide), small twigs (to 55 mm long × 1 mm diam) pieces of 

leaf and grass blades (dry and brown), leaf midribs, and lots of 

moss woven together and sometimes anchored with spider web.

The 2 eggs were white with no external markings and measured 19.2 × 13.6 mm, 1.5 g and 20.0 × 13.8 mm, 1.6 g. They 

were rounded at 1 end and narrowed to a point at the other. The 

eggs likely hatched on 23 Sep. On 25 Sep the nestlings weighed 

4.3 and 4.0 g (their bellies were enormous and full of food) and 

had completely sheathed primaries ~2 mm long; their eyes were 

closed. The bill was brown with a white tomium and yellow at 

the corners of the gape; the mouth lining was yellow gold. No egg 

tooth was apparent. The skin was dark gray with the maroon of 

muscles showing through. Very fluffy grayish white down was 

present in the superciliary region, in a horizontal line across the 

back of the head, in the scapular region, in the femoral tract (with 

a few around the ankles), in the posterior two-thirds of the spinal 

tract, in the posterior ventral tract (a few), and at the site of the 

secondaries. The down feathers lacked a rachis, with the barbs 

emerging directly at the skin surface. Down feathers were 8–10 

mm long except in the ventral tract, where they were only 1 to 

2 mm. A few tiny wisps of down were also present in the tail or 

tail-covert region. All feather tracts were well defined with barely 

emerging pin feathers or pin feathers visible under the skin.

When the nest was next checked on 28 Sep, the feathers of 

the adult female were on the ground everywhere around it. One 

nestling was half eaten (bitten through) suggesting a mammalian 

predator, and the other was dead. The conditions of the nestlings 

suggested that predation occurred on the night of 27 Sep.

Coereba flaveola: Bananaquit

Specimens (USNM). ♂ Jun (1), adult skull.

Mass (g). 9.7.

Iris. Brown.

Bill. Black.

Feet and Tarsi. Gray.

Gonads. Testis 2 × 1 mm.

Molt. No.

Plumage. Dusky olive gray above with yellow-olive 

rump. Crown darker blackish gray. Lacks a white wing speculum.

Notes. Observed on several occasions in Jun feeding 

in blossoms of ornamental Malvaviscus sp. shrubs, abutting the 

forest.

Saltator similis: Green-winged Saltator

Specimens (MVZ). ♂ Jun (1), immature skull with 

large windows.

Mass (g). 62.0, light fat.

Iris. Brown.
NUMBER 648 • 5 3

Mass (g). X

_

 = 18.1 (SD = 0.86, range = 17.0–19.5, 

N = 7). Oct immature with light fat.

Iris. Brown.

Bill. Upper mandible black. Lower mandible gray or 

gray at base with black tomium and tip.

Feet and Tarsi. Brown or black.

Gonads. Testes of adults small (2 × 1–3 × 2 mm, some 

black) in Aug, Sep and somewhat enlarged (4 × 3–6.5 × 3.5 mm) 

in Oct. Testes of immature ♂♂ small (1 × 1– 3 × 2 mm).

Molt. Light body molt in Sep ♂♂.

Plumage. The May immature ♂ has a female-type 

plumage. The Oct immature has a mixed plumage resembling 

that of a female except for a few blue feathers on the breast and 

throat and blue feathers covering about two-thirds of the chin, 

the sides of the face, the forecrown, and most of the top of the 

head. Neither bird was molting.

Stomach Contents. One with fruit and seeds of 

Trema micrantha; 2 with seeds of other species; 1 with seeds and 

insects; 1 with only insects; 1 with corn. Seeds crushed.

Habitat. Scrubby forest-pasture edge in shrubs and 

vine and bamboo tangles.

Notes. Birds usually ≤1 m from the ground. Locals 

report that this species is a pest on corn crops. The immature 

Oct ♂ with mixed plumage had a small testis (3 × 2 mm) relative 

to the Oct adults. Males apparently require at least 2 molts to 

acquire the definitive plumage. Hayes et al. (1994) considered 

this species to be a “southern austral migrant,” breeding in more 

temperate areas to the south and migrating to Paraguay during 

the colder months. The absence of records of females from El 

Tirol suggests that wintering locations of the sexes may differ. 

Hayes et al. (1994) reported an extreme date of 4 Oct. We collected 3 males in mid-Oct (15–19).

Cyanoloxia brissonii: Ultramarine Grosbeak

Specimens (USNM, MVZ). ♂♂ Jan (1), Feb (1), Sep 

(1), Oct (1). ♀♀ Feb (1), May (1), Jun (1), Sep (1), Oct (1). Jun ♀

with partly pneumatized skull. All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 21.5 (SD = 1.26, range = 20.5–23.2, 

N = 4). ♀♀ X

_

 = 21.0 (SD = 1.24, range = 19.5–22.5, N = 5).

Iris. Brown or dark brown.

Bill. Upper mandible black. Lower mandible black, 

gray, or black distally and gray basally. Mouth lining flesh color.

Feet and Tarsi. Black, brown, or dark brown. Toe 

pads light green.

Gonads. ♂♂ Testes enlarged (7 × 4–12 × 7 mm) Sep 

through Feb; large cloacal protuberance in some. ♀♀ Largest 

ova of Feb, Sep, and Oct birds ≤ 1 mm. May and Jun ♀♀ had 

smooth, undeveloped ovaries indicating first-year birds.

Molt. Prebasic molt of body and flight feathers in Feb 

adults.

Plumage. The Sep and Oct males have a female-type 

plumage, although the latter bird has a trace of blue on the 

crown feather.

Sep (1, fledgling). Nest, egg shell Sep (1). All birds except fledgling with adult skulls.

Mass (g). ♂♂ X

_

 = 34.6 (SD = 2.30, range = 31.5–37.0, 

N = 9). ♀♀ X

_

 = 31.2 (SD = 2.36, range = 28.0–34.0, N = 5). 

Fledgling = 24.5. Three Jun birds with light fat.

Iris. Brown or gray.

Bill. All black or blackish brown or with lower mandible gray at base; upper mandible black with tan tomium, lower 

mandible blackish brown; bill mottled brown and yellowish tan 

with tan tomium.

Feet and Tarsi. Dark gray, brown, reddish brown, 

or tan.

Gonads. ♂♂ Testes enlarged (8 × 4–13 × 6.5 mm) 

from Sep to Jan; small (≤2 × 1 mm, 1 blackish) in Jun. ♀♀ One 

Oct bird with multiple yellow-orange ova (2–6 mm diam) and a 

greatly enlarged oviduct; 2 other Oct ♀♀, largest ovum ≤ 1 mm. 

Jun ♀♀, ovaries granular (1) or smooth and undeveloped (1).

Molt. Jan (1) and Jun (1), prebasic molt.

Stomach Contents. Nine with insect remains, 

including a cicada; 1 with fruit remains.

Habitat. Forest.

Notes. An understory species that moves in pairs or 

small groups, often as part of mixed-species flocks. Skull pneumatization in this species appears to be completed rapidly. A Jun 

♀ with an adult skull had the smooth, undeveloped ovary of a 

bird that has never bred. Likewise, 1 nonmolting ♂ in complete 

female plumage that was collected on 11 Nov 1981 had a completely pneumatized skull and was seemingly in breeding condition (testis 8 × 4 mm). A nest and an egg shell were collected 

from the forest in Sep 1982 along with a just-fledged nestling (see 

Foster et al., 1989).

Amaurospiza moesta: Blackish-blue Seedeater

Specimens (MVZ). ♀ (by plumage) Jun (1), adult 

skull.

Mass (g). 13.5, slight fat.

Iris. Brown.

Bill. Upper mandible black. Lower mandible tan with 

brown tomium.

Feet and Tarsi. Gray, feet slightly paler.

Gonads. Not located.

Molt. No.

Stomach Contents. Insect parts.

Habitat. Forest understory.

Notes. Listed as Near Threatened on the IUCN (2015) 

Red List.

Cyanoloxia glaucocaerulea: Glaucous-blue 

Grosbeak

Specimens (USNM, MNHNP). ♂♂ May (1) Aug 

(1), Sep (2), Oct (3). May and 1 Oct bird with partly pneumatized immature skulls. Others with adult skulls.
5 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Molt. Two Feb ♀♀ first prebasic molt of body feathers.

Stomach Contents. Twelve with insect remains, 

often caterpillars. Two with fruit remains.

Habitat. Forest, forest edge, dense secondary growth 

scrub.

Notes. Usually in the forest canopy, often moving as 

part of mixed-species flocks through the tops of the tallest trees, 

but sometimes feeding with understory flocks (including Pipraeidea melanonota and Trichothraupis melanops) or alone, only 3 

to 4 m up or in shrubs. Gleans insects from bare branches of 

trees; moves down limbs head first, hangs upside down, probes 

flowers and moss on tree trunks and large limbs. Makes a chattering, buzzy call or loud trill. Juvenile seen following adult in 

Feb.

Myiothlypis leucoblephara: White-browed 

Warbler

Specimens (USNM, MVZ, MNHNP). ♂♂ 31: Jan 

(1), Feb (3), Mar (2), May (2), Jun (3) Aug (3), Sep (5), Oct (6), 

Nov (1), Dec (5). ♀♀ 19: Feb (3), Mar (2), May (2), Jun (4), Aug 

(1), Sep (2), Oct (2), Nov (1), Dec (2). Sex? Nov (1). Birds with 

only partly pneumatized skulls present in Dec, Feb, Mar, and 

May. Nest/egg Oct (1).

Mass (g). ♂♂ X

_

 = 14.2 (SD = 1.09, range = 11.4–

16.0, N = 31). ♀♀ X

_

 = 13.4 (SD = 0.89, range = 12.0–15.0, 

N = 18). ♀♀ With light fat in Feb (1), Jun (1), Aug (1), and 

Oct (1) and with moderate or heavy fat in Jun (3).

Iris. Brown, dark brown, or black.

Bill. Upper and lower mandibles black; lower mandible browner at base in some. Mouth lining and tongue pinkish 

flesh or dark flesh color. Palate yellow white.

Feet and Tarsi. Tan; tan, olive, or orange brown; 

orange; yellow; yellow tan; or flesh color. Toe pads brighter yellow orange, yellow green, yellow tan, tan, or greenish brown.

Gonads. ♂♂ Testes enlarged (6 × 3–10 × 7 mm) Aug 

through Nov; many birds with large cloacal protuberances. Testes small (1 × 1–3 × 3 mm) Jan through Jun. ♂♂ with juvenal 

skulls, testes ≤ 2 mm. ♀♀ Most adults with enlarged ova, shelled 

eggs, enlarged oviducts, and/or active incubation patches in Sep, 

Oct, Nov; a few with largest ova ≤ 1 mm. Ova not enlarged Feb 

through Aug. Ovaries of ♀♀ with immature skulls undeveloped.

Molt. First prebasic molt noted in some Dec, Feb, 

Mar, and May birds.

Stomach Contents. Insect remains in 29.

Habitat. Forest, late second growth.

Notes. Common in the lowest levels of the forest understory, ≤1.5 m, in shrubs, vine tangles, and Chusquea

sp.; usually in the stratum below that used by Basileuterus 

culicivorus. Also pokes through the leaf litter when foraging. 

Males sing year-round, although less frequently in winter. Both 

sexes make a single whistle-like note. Most often move as pairs 

or occasionally in small groups. Bird collecting nest material in 

late Sep. Nest with 1 egg located 2 Oct; accompanying ♀ had 

Stomach Contents. Three with only seeds, 1 with 

only insects, and 4 with seeds and insects.

Habitat. Forest edge, woodland, tung orchard.

Notes. Occupies the scrubby edge between field and 

forest, thickets, bamboo tangles, small trees, and shrubs (e.g., 

Baccharis), often low to the ground. Sometimes forages in the 

debris captured in leaf axils. The Sep and Oct ♂♂ have enlarged 

testes and apparently breed in an immature, female-like plumage.

Family Parulidae: Wood-warblers

Geothlypis aequinoctialis: Masked 

Yellowthroat

Specimens (MVZ). ♂♂ Feb (1), Mar (1), Nov (1). 

♀ Feb (1). Nov ♂ with adult skull. All other birds with juvenal 

skulls.

Mass (g). ♂♂ X

_

 = 11.8 (SD = 0.47, range = 11.3–12.2, 

N = 3). ♀ 11.4. Nov ♂ and ♀ light fat.

Iris. Dark brown or brown.

Bill. Upper mandible black or brownish black. Lower 

mandible gray white or pinkish gray with black tip. Mouth lining flesh color.

Feet and Tarsi. Brown or pale gray brown. Toe pads 

green or pale brownish gray.

Gonads. ♂♂ Testis of adult 5 × 3 mm; of juveniles 1 × 

1 mm. ♀ Ovary undeveloped.

Molt. Feb ♂ First prebasic body molt.

Stomach Contents. All with insect remains.

Habitat. Second-growth scrub, pasture.

Notes. In small, isolated trees, tall grass. Calling in 

March.

Setophaga pitiayumi: Tropical Parula

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

May (1), Jun (2), Aug (1), Sep (2). ♀♀ Feb (2), Mar (1), Jun (2), 

Sep (2), Nov (1). Sex? Jun (1). Two Feb and 1 Jun ♀ with skulls 

only partly pneumatized. All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 8.5 (SD = 0.68, range = 7.4–9.5, 

N = 7). ♀♀ X

_

 = 7.9 (SD = 4.3, range = 7.3–8.5, N = 7). Sex? = 6.5. 

Light or moderate fat in some birds in Jan, Mar, Jun, Aug, Sep.

Iris. Brown or dark brown.

Bill. Upper mandible black or brownish black. Lower 

mandible yellow, yellowish tan, or flesh color, some with black 

or dusky tip. Mouth lining light green or flesh color.

Feet and Tarsi. Dark brown, tan, or orange; toes 

lighter than tarsi. Toe pads tan or orange yellow.

Gonads. ♂♂ Testes enlarged (6 × 4–7 × 5 mm), with 

pronounced cloacal protuberance, in Sep, Jan; small (1 × 0.5–2.5 × 

1.5 mm) in May, Jun, Aug. ♀♀ Breeding in Sep (largest ovum 

1.5 mm, early incubation patch) and Nov (enlarged yolked ova, 

huge oviduct, incubation patch). Other Sep ♀ largest ovum 

1 mm. Feb and Jun immatures with small, undeveloped ovaries.
NUMBER 648 • 5 5

toward the end of summer, when they also may form small flocks 

of 4–7 individuals. When not singing, the birds chup, chip, and 

chatter continuously. Bird gathering fibers for nest material on 10 

Nov. Pair of birds carrying food (caterpillars and large grasshoppers) 21–24 Oct 1980 to a nest finally located on 26 Oct. One 

adult did a broken wing display along the ground to draw the 

observer from the nest. Holding its open wings, tail, and head 

down, it hopped along as if injured until about 10 m from the 

nest and then flew away. The nest held 4 downy nestlings with 

short pin feathers. However, the nestlings were able to locomote 

rapidly on foot and tumbled out of the nest when disturbed. They 

stayed in the vicinity of the nest peeping continuously. By 29 Oct 

they could almost fly, lifting ~10 cm off the ground and flying 

for ~75 cm. The nest was on the ground in a depression ~6 cm 

deep at the edge of a small man-made drainage channel. The nest 

was angled at about 15° with the horizontal, the opening directed 

laterally. It was conical, 6.0–6.8 cm deep, with outer and inner 

diameters of 9.0 and 4 cm, and made of twigs and coiled plant 

fibers. The nest was under a pile of leaf litter, itself beneath a 

loose network of fallen sticks and branches. A large nematode 

was present in the body cavity of 1 May adult. Red dirt was present on the breast and belly of some birds.

Family Icteridae: Blackbirds

Cacicus haemorrhous: Red-rumped Cacique

Specimens (USNM, MVZ, MNHNP). ♂♂ Jan (1), 

Mar (2), Jun (2), Sep (3), Oct (1). Eight with adult skulls; 1 Jun 

bird with small skull windows.

Mass (g). Adults X

_

 = 100.6 (SD = 8.36, range = 91.0–

113, N = 8). Light or moderate fat in 2 Jun and 1 Sep birds. Bird 

with immature skull = 83.5, light fat.

Iris. Blue, purplish blue, blue gray, or brown.

Bill. Lime green, greenish yellow, yellowish ivory, 

ivory, yellow basally fading to white, or lime brown fading to 

gray at tip. Mouth lining bluish or dark flesh color. Palate dark 

blue gray; tongue pinkish at base fading to gray in center and 

whitish gray at tip.

Feet and Tarsi. Black. Toe pads brown or yellowish 

brown.

Gonads. Testes enlarged (9 × 6–12 × 8 mm) in most 

birds in Sep, Oct; 1 Sep ♂ testis small (2.5 × 2.0 mm). Testes 

small (1.5 × 1.0–3 × 2 mm) Jan through Jun.

Molt. Prebasic molt of body and flight feathers in Jan 

and Mar.

Stomach Contents. Three with insect remains, 

including larvae; 3 with fruit pulp and seeds, including Alchornea glandulosa. Observed tearing open pods of Inga marginata

(Fabaceae) to extract the aril-covered seeds; also seen eating 

Cupania vernalis and Allophylus edulis.

Habitat. Forest, forest edge, second-growth scrub. 

Nests in isolated trees (especially palms) in clearings, pastures, 

and around buildings.

a shelled (20 × 15 mm) egg and a large unshelled ovum (4 × 

4 mm) in the oviduct, suggesting a clutch size of at least 3. Massive 

nematode infection in body cavity of 1 Aug ♀. Feet of 1 Oct male 

with heavy “scaly leg” disease likely caused by an infection of 

mites. Feathers of a Nov bird heavily infested with parasite eggs.

Basileuterus culicivorus: Golden-crowned 

Warbler

Specimens (USNM, MVZ, MNHNP). ♂♂ 37: Jan 

(1), Feb (2), Mar (3), May (3), Jun (6), Aug (3), Sep (3), Oct (7), 

Nov (4), Dec (5). ♀♀ 12: Jan (1), Feb (1), Jun (1), Aug (1), Sep 

(1), Oct (1), Nov (3), Dec (3). Sex? Mar (2), Oct (2, nestlings). 

Nest (1, Nov). Birds with juvenal skulls in Nov, Dec, Feb, Mar, 

and Jun. An Oct bird with small skull windows, presumably 

hatched the previous year. All other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 9.2 (SD = 0.85, range = 7.0–11.0, 

N = 37). ♀♀ X

_

 = 8.5 (SD = 1.11, range = 7.0–11.5, N = 12). Sex? 

7.7, 8.8; nestlings 7.5, 8.1. Light to moderate fat in Feb, Jun, 

Nov, and Dec.

Iris. Dark brown or brown.

Bill. Upper mandible black, dark brown, or brown. 

Lower mandible brown, tan, horn color, or flesh color; often 

lighter at base with dark tip. Mouth lining flesh color, tongue 

pinkish flesh, and palate yellowish. Juveniles’ mouths and fleshy 

gapes yellow or orange.

Feet and Tarsi. Brown, olive brown, tan, orange, or 

yellow. Toe pads greenish, brownish, or yellow.

Gonads. ♂♂ Testes of adults enlarged (4.5 × 3–10 × 

8 mm, with cloacal protuberances) Aug through Nov; small (1 × 

0.5–2.5 × 1.5 mm) Nov through Jun. Testes of juveniles ≤ 1 mm. 

♀♀ Adults with enlarged ova, collapsed follicles, enlarged oviducts, or at nest in Oct (1), Nov (1). Oct ♀ with shelled egg in 

cloaca; mass = 1.75 g. Eggshell white, marked with small purplish brown dots and splotches, densest at the large end. Other 

adults from all months, largest ova ≤ 1 mm. Females with juvenal 

skulls, ovaries smooth and undeveloped.

Molt. Prebasic molt of body and flight feathers in 

Nov, Dec, and Jan. First prebasic molt of body feathers in Nov, 

Dec. Two Oct nestlings in prejuvenal molt.

Plumage. Juvenal feathers soft and lax; olive green on 

back; yellowish brown or khaki color on breast and scattered 

over the abdomen. Lacking orange crown and black coronal 

stripes. Upper wing coverts edged khaki.

Stomach Contents. Thirty-four with insect 

remains, including an ant and 35- and 38-mm-long caterpillars.

Habitat. Forest, woodland.

Notes. One of the most common birds at El Tirol. 

Generally seen in pairs or family groups but also joins mixedspecies flocks (with Trichothraupis melanops). Birds foliage glean 

in understory vegetation but also poke in ground cover and leaf 

litter. One pulled an 8-cm-long earthworm from the litter, carried 

it to a branch, and after much effort, swallowed it. Birds sing at 

least from Aug through Mar, although with reduced frequency 
5 6 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Gonads. ♂♂ Testes 12 × 7 (Dec) and 12 × 8 mm (Jan). 

All ♀♀ with tiny ovaries, largest ova ≤ 1.0 mm.

Molt. Jan ♀ molting.

Stomach Contents. Four birds with insect remains; 

1 with insect remains and seeds.

Habitat. Forest edge, tung orchard, second-growth 

scrub, pasture, cornfields.

Notes. Frequents tops of dead snags in pasture and 

scrub. Flocks of 15–50 seen in Feb and Mar. Males still singing 

in March.

Agelaioides badius: Grayish Baywing

Specimens (MVZ). ♀♀ Jan (2), skulls not 

pneumatized.

Mass (g). 39.5, 42.0 (slight fat).

Iris. Black.

Bill. Brown; lower mandible lighter at base.

Feet and Tarsi. Brown.

Gonads. Ovaries tiny, not developed.

Molt. One ♀ in first prebasic molt.

Stomach Contents. Both with insect and plant 

remains.

Notes. Hayes (1995) did not report this species from 

the Department of Itapúa. These individuals may represent postbreeding season wanderers.

Molothrus rufoaxillaris: Screaming Cowbird

Specimens (MVZ). ♂ Sep (1), adult skull.

Mass (g). 62.0.

Bill. Black.

Feet and Tarsi. Blackish brown.

Gonads. Testis 8 × 5 mm.

Molt. No.

Notes. Several observed in Oct.

Molothrus bonariensis: Shiny Cowbird

Specimens (USNM, MVZ). ♂♂ Oct (2), adult 

skulls. ♀♀ Sep (3), Oct (2), Nov (2). One Nov ♀ with juvenal 

skull; other ♀♀ with adult skulls.

Mass (g). ♂♂ 53.0, 54.0. ♀♀ X

_

 = 44.7 (SD = 2.37, 

range = 42.0–49.0, N = 7); light or moderate fat in 1 Sep and 1 

Nov ♀.

Iris. Brown.

Bill. Black. Juvenal ♀ with yellow at fleshy corners of 

gape.

Feet and Tarsi. Black.

Gonads. ♂♂ Testes 9 × 5, 8 × 5 mm. ♀♀ One Sep 

adult with largest ova ≤ 1 mm. Other adult ♀♀ with multiple 

enlarged (2–11 mm diam) yellow or orange ova and enlarged 

oviducts. Juvenile with minute ova.

Molt. First prebasic molt in Nov.

Notes. Occurs in noisy groups of 4–10 individuals. Nests in colonies in Sep, Oct. A nest colony active in Oct 

was completely empty by late Dec. Birds observed pulling large 

masses of fibers off the rachises of palm fronds in early Oct and 

flying away with them; presumably the fibers were used to build 

their long, pendulous nests (see de la Peña 2010). The birds are 

extremely aggressive toward one another when incubating eggs 

and feeding young. A group mobbed a Pyroderus scutatus and 

chased it away from a fruit tree.

Icterus cayanensis: Epaulet Oriole

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), May (1), Aug (1), Oct (3), Nov (1). ♀♀ Jan (1), Feb (1), Mar 

(3), May (1), Jun (1). Feb ♂ and ♀ and 1 Mar ♀ with immature 

skulls; all others with adult skulls.

Mass (g). ♂♂ X

_

 = 31.4 (SD = 2.11, range = 28.0–34.0, 

N = 7). ♀♀ X

_

 = 29.9 (SD = 1.54, range = 27.0–31.9, N = 7). All 

Feb and Mar birds with light fat.

Iris. Brown, reddish brown, or chestnut brown.

Bill. Black. Mouth lining black, dark purplish 

black, or pale greenish flesh color. Palate gray; tongue brownish gray.

Feet and Tarsi. Gray, brown gray, blue gray, or deep 

slate gray. Toe pads light green or gray tan.

Gonads. ♂♂ Testes enlarged (6 × 4–11 × 7.5 mm) and 

vascular in Oct–Nov; small Jan through Aug (1 × 1–3 × 2 mm), 

sometimes black. ♀♀ Adult ovaries postbreeding in Jan, Mar; 

Jan bird with old incubation patch; ovaries granular in May, Jun. 

♀♀ Immatures with undeveloped ovaries.

Molt. Prebasic molt in Mar and May. First prebasic 

molt recorded in Feb and Mar.

Plumage. Feb ♂ and ♀ in dull brownish juvenal 

plumage.

Stomach Contents. Eight with insect remains, 

including caterpillars and other larvae; 2 with insect and fruit 

remains; 2 with only fruit.

Habitat. Forest, forest edge, tung orchard, secondgrowth scrub, pasture.

Notes. In pairs. Found in bushes and small trees in 

pasture and high in the canopy in forest and forest edge. Feeding 

on fruit of Trema micrantha and Ficus sp. Birds appear to impale 

a fig, open the bill to split the fruit, and then take bites of the soft 

center pulp and larvae. Makes a single-note whistle.

Gnorimopsar chopi: Chopi Blackbird

Specimens (USNM, MVZ). ♂♂ Jan (1), Oct (1). 

♀♀ Jan (1), Sep (2). All with adult skulls.

Mass (g). ♂♂ 79.0 (Jan), 84.0 (Oct). ♀♀ X

_

 = 71.2 

(SD = 2.57, range = 69.0–74.0, N = 3). Sep birds with light fat.

Iris. Black or brown.

Bill. Black.

Feet and Tarsi. Black.
NUMBER 648 • 5 7

of a large tree on 21 Jan 1980. Another pair was observed with 

3 juveniles on 22 Feb 1980. The male of the latter pair was displaying for the female, moving along a branch in front of her and 

forcefully dropping his rear end. The males and females of both 

pairs gave 2-note calls.

Euphonia violacea: Violaceous Euphonia

Specimens (USNM, MVZ). ♂♂ Sep (2), Oct (3). 

♀♀ Sep (1), Oct (4). Two Oct (♂, ♀) specimens with skulls about 

75% pneumatized. Other birds with adult skulls.

Mass (g). ♂♂ X

_

 = 14.1 (SD = 0.70, range = 13.5–15.0, 

N = 4); 1 Sep bird with light fat. ♀♀ X

_

 = 15.6 (SD = 1.30, range = 

14.0–16.75, N = 4).

Iris. Brown.

Bill. Upper mandible black. Basal half of lower mandible gray or silver gray, distal half black, and tomium black.

Feet and Tarsi. Gray.

Gonads. ♂♂ Testes enlarged (8.5 × 6.5–11 × 6 mm), 

including in ♂ with skull windows. ♀♀ Largest ovum 2 mm 

diam, oviduct slightly enlarged (Sep). Three Oct ♀♀ with multiple enlarged (4–8 mm diam) orange-yellow, vascularized ova, 

collapsed follicles, and/or an enlarged oviduct; 2 of these birds 

with eggs (15, 18 mm long) in the oviduct, shells forming. ♀

With skull windows, ovary granular.

Molt. Sep ♀ with light body molt.

Stomach Contents. Three with Allophylus edulis

(Sapindaceae) fruits and seeds.

Habitat. Forest.

Notes. Fed commonly on mistletoe (Phoradendron 

piperoides) berries, which seem to be available over several 

months. They grab the berries whole, whereas they merely 

remove bites from A. edulis fruits that remain attached to the 

tree (Foster, 1987). They were also observed feeding on Eugenia uniflora and Rhipsalis shaferi fruits. The birds are extremely 

acrobatic while feeding, as well as aggressive, chasing away other 

species of birds (e.g., Mionectes rufiventris) that attempt to feed. 

They sometime join mixed-species foraging flocks. The birds are 

generally in pairs. Copulation was observed toward the end of 

Sep, and a ♂ and ♀ built a nest in a very dense clump of epiphytic 

orchids on the side of a tree trunk.

Euphonia pectoralis: Chestnut-bellied Euphonia

Specimens (USNM, MVZ). ♂♂ Jan (1), Feb (1), 

Sep (1), Oct (1). ♀ Sep (1). All specimens with adult skulls.

Mass (g). ♂♂ X

_

 = 13.8 (SD = 0.80, range = 13.0–14.9, 

N = 4); Feb and Sep birds with light fat. ♀ 13.8.

Iris. Brown or dark brown.

Bill. Upper mandible black with gray at base; lower 

mandible gray or blue gray. Mouth lining yellow orange.

Feet and Tarsi. Gray or gray green. Toe pads green.

Gonads. ♂♂ Testes enlarged (8 × 5 mm) Sep through 

Feb (5 × 3 mm). ♀ Largest ovum 1.5 mm diam.

Stomach Contents. Two with only insect remains; 

3 with insect and seed remains; 1 with insect and fruit remains.

Habitat. Second-growth scrub, pasture, fence rows.

Notes. Feeds on ground. Occupies isolated trees and 

may perch high up in large trees. Pairs displaying and courting in 

Oct. Fully grown juvenile begging from a pair of Vireo olivaceus

“parents” in Nov.

Family Fringillidae: Finches

Spinus magellanicus: Hooded Siskin

Specimens (MVZ). ♂ Jun (1), adult skull.

Mass (g). 13.0.

Iris. Brown.

Bill. Upper mandible dark gray with black tip. Lower 

mandible gray.

Feet and Tarsi. Black.

Gonads. Testis small (1 × 0.5 mm).

Molt. Trace body molt.

Stomach Contents. Throat, crop, and stomach full 

of tiny (~1 mm) seeds.

Habitat. In a field.

Notes. Bird was in a flock of conspecifics.

Euphonia chlorotica: Purple-throated Euphonia

Specimens (USNM, MVZ, MNHNP). ♂♂ Feb 

(1), Sep (1), Oct (1). ♀♀ Jun (1), Oct (1). All specimens with 

adult skulls.

Mass (g). ♂♂ X

_

 = 11.6 (SD = 1.20, range = 10.3–12.7, 

N = 3); Oct bird with light fat. ♀♀ 11.2, 12.0, both with 

light fat.

Iris. Brown.

Bill. Both mandibles black centrally and at tip; blue 

gray or light gray area on each side at base.

Feet and Tarsi. Gray, dark gray, or black. Toe pads 

light green.

Gonads. ♂♂ Testes enlarged (5 × 3–6 × 4 mm). ♀♀

Ovaries granular, ova minute.

Molt. Prebasic molt in Feb; trace of body molt (Jun).

Stomach Contents. Two birds with mistletoe 

(Phoradendron piperoides) berries and seeds.

Habitat. Forest, forest edge, scrubby field.

Notes. Birds move in pairs or occasionally in small 

groups year-round. They are frequent members of mixed-species 

flocks including E. violacea. They use a wide range of heights 

in the forest vegetation, from 3 to 18 m, in part determined by 

the location of the plant material they consume. In addition to 

eating mistletoe berries, they have been observed taking fruits of 

epiphytic cacti (Rhipsalis cereuscula, R. shaferi) and Allophylus 

edulis. It appears that they also eat flower petals, although they 

may merely be robbing nectar. A ♂ carried sticks and displayed 

for and interacted with a female at ~13 m up under the crown 
5 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Seems to prefer the shorter grasses, although occasionally seen in 

tall growth. Whistles on flushing. Also reported by Smith et al. 

(2005) from the fields surrounding El Tirol.

Family Threskiornithidae: Ibises

Mesembrinibis cayennensis: Green Ibis

RMZ observed a flock of 3 flying overhead on 24 Feb 1980; 

all dark brown with fairly sharply decurved bills.

Family Recurvirostridae: Avocets and Stilts

Himantopus mexicanus: Black-necked Stilt

One flying high overhead on 7 Feb 1980 (RMZ). Often 

treated as a separate species, H. himantopus (Remsen et al., 

2016).

Family Strigidae: Owls

Pulsatrix koeniswaldiana: Tawny-browed Owl

On 30 Oct 1976 MSF flushed a medium to large owl, light 

brown ventrally without obvious markings, from a perch about 

4 m up in a forest tree. Smith et al. (2005) reported possibly 

seeing this owl at El Tirol in the early 2000s and have since 

confirmed its presence (Smith, pers. comm., 8 Sep 2016). On 1 

Jan 1980 NKJ observed a nestling high up in a nest in a forest 

tree near Villarrica, ~42 km NE of El Tirol. Known from several localities farther to the north in eastern Paraguay (Hayes, 

1995).

Family Psittacidae: New World and African Parrots

Pionopsitta pileata: Pileated Parrot

Observed 11 Mar 1980 (RMZ). Pionus build and tail, but 

not maximiliani; smaller and browner.

Amazona aestiva: Turquoise-fronted Parrot

Flock flew high overhead on 8 Jan 1978 (MSF). One or 2 

individuals flushed from large trees in the forest/forest edge on 

21–24 Sep (MSF).

Forpus xanthopterygius: Blue-winged Parrotlet

Large flock flying overhead 1 Sep 1978 (MSF).

Aratinga nenday: Nanday Parakeet

Large green parrot with a dark, charcoal head, flying over 

scrubby pasture, 1 Sep 1978 (MSF).

Molt. Prebasic molt in Feb. One ♂ undergoing the 

first prebasic molt at the end of Jan.

Stomach Contents. One bird with tiny seeds of 

Phoradendron piperoides. Observed feeding on Allophylus 

edulis.

Habitat. Forest, woodland.

Notes. Birds occur in pairs. Feed on fruits but also 

poke around in the bases of leaves, presumably searching for 

insects.

Chlorophonia cyanea: Blue-naped 

Chlorophonia

Specimens (USNM, MVZ). ♂♂ Sep (1), Oct (1). 

♀♀ Sep (1), Oct (1). All specimens with adult skulls.

Mass (g). ♂♂ 13.5 (Sep), 14.0 (Oct). ♀♀ 14.5 (Sep), 

moderate fat; 16.0 (Oct), light fat.

Iris. Brown.

Bill. Upper mandible dark gray, gray at base with 

black at tip, black, or black with silver gray spot on each side 

at base. Lower mandible dark gray, gray, or silver gray at base 

with black tip.

Feet and Tarsi. Gray.

Gonads. ♂♂ Testes 6 × 4 (Sep), 4 × 4 (Oct) mm. 

♀♀ Largest ova 0.5 (Sep) and 2.0 (Oct) mm diam. Oct ♀ with 

enlarged oviduct.

Molt. No.

Stomach Contents. Two with fruit pulp and seeds.

Habitat. Forest, forest with cleared understory.

Notes. Move as pairs. Eat Allophylus edulis fruits and 

Phoradendron piperoides; also nibble around blossoms in large 

flowering trees, presumably taking nectar. On 30 Oct a ♂ and ♀

gathered moss growing about 1.5 m up on a tree trunk (for nest 

lining?).

Hypotheticals

The following species are represented only by sight records. 

These birds flew very high overhead or were observed only 

briefly. Unlike the species whose sight records are included in 

the species accounts, we cannot positively confirm their identities and, consequently, list them as hypotheticals. They are not 

included in any of the species numbers or calculations. Every 

species, however, is listed by Hayes (1995) as occurring in the 

area, and all except Aratinga nenday and Amazona aestiva have 

been recorded at San Rafael National Park (Esquivel M. et al., 

2007; Figure 1).

Family Tinamidae: Tinamous

Nothura maculosa: Spotted Nothura

Seen repeatedly over several months (NKJ) in grass and 

weeds along the road, in tung orchard, and in scrubby pasture. 
NUMBER 648 • 5 9

chloris and Platyhincus mystaceus are disputed, although their 

close relationship to the abovementioned group of species is not 

(Tello et al., 2009; Ohlson et al., 2013; Dickinson and Christidis, 2014). In these two species also, skull pneumatization is 

only partial.

A number of species in the Furnariidae (as delineated by 

Cracraft, 2014 and Dickinson and Christidis, 2014) also exhibited only partial skull pneumatization. These included the four 

species of Synallaxis (i.e., spixi, cinereus, ruficapilla, frontalis) 

and Cranioleuca obsoleta in the Synallaxinae as well as Syndactyla rufosuperciliata and Anabacerthia lichtensteini in the 

Philydorinae. In the latter two species, however, many breeding 

birds had pneumatized skulls. On the other hand, skull pneumatization in Automolus leucophthalmus, Philydor rufum, and 

P. atricapillus, also in the Philydorinae, was complete, as it was 

in the species of Xenops in the Xenopinae. Our collections were 

insufficient to allow us to draw conclusions about the patterns of 

skull pneumatization for species in the Furnariinae which require 

additional study.

The speed and degree of skull pneumatization in other 

unrelated species, a piculet (Picumnus temminckii), an antbird 

(Thamnophilus caerulescens), a flycatcher (Myiopagis caniceps), 

and a manakin (Chiroxiphia caudata), in which breeding individuals frequently lack fully pneumatized skulls, also require 

additional examination. A better understanding of the distribution of incomplete skull pneumatization across all suboscine 

taxa may help us to explain the evolution and function of the 

different degrees and patterns of pneumatization.

Reproduction

The percentage of species for which collected specimens 

show evidence of breeding (e.g., enlarged gonads, active brood 

patch, nest building or attendance, feeding of fledglings) is 

plotted for biweekly intervals in Figure 8. This curve is closely 

tracked by the percentages of specimens collected that represent 

breeding individuals but eliminates the influence of differences 

among species in numbers of individuals collected.

Breeding is seasonal, beginning in early to mid-August, continuing through September and October, and gradually declining 

from late November through May. Some species, such as Phylloscartes ventralis, Leptopogon amaurocephalus, and Myiornis 

auricularis, appear to be “early” breeders, with large gonads 

and nests in August, whereas most species begin breeding in 

September. Other species, such as Baryphthengus ruficapillus, 

appear to have short breeding seasons, whereas those of species 

such as Thamnophilus caerulescens are extended. The breeding 

periods of some pigeons and doves also appear to be especially 

long. Active nests of Patagioenas picazuro, for example, were 

located in October, November, and March. A female Columbina 

talpacoti had an 11-mm-diameter ovum on 4 September, indicating incipient laying, and active nests of the species were located 

in November and February. Although we have no sample from 

July, some species of pigeons appear to be reproductively active 

Psittacara leucophthalmus: White-eyed 

Parakeet

Large flock flying over scrubby pasture 25 Oct 1982 (MSF). 

Several flocks sighted this month.

DISCUSSION

Skull Pneumatization

Skull pneumatization in north temperate birds follows a 

fairly standard pattern (Pyle et al., 1987; Ralph et al., 1993). At 

hatching, the frontals and parietals are thin and single layered; 

gradually, a second layer forms underneath, with reinforcing 

trabeculae between the layers. Skull pneumatization in most of 

the El Tirol species for which young of the year were collected 

followed this pattern. Pneumatization took several months and 

was generally completed prior to the onset of the next breeding 

season, which marks the beginning of the “second year.” Because 

pneumatization was completed between March and May, it was 

possible to age birds in their first year well into the austral summer months or later.

In a number of species, however, the pneumatization process differed from this pattern, extending into the second year. 

These birds, recognized by the presence of obvious “windows” 

(areas where the skull is single layered and/or lacks trabeculae) 

in the posterior frontal and dorsal parietal regions as well as fully 

developed, active reproductive organs, fall into two groups. In 

the first group, individuals with completely pneumatized skulls 

are also present, and only a few breeding individuals with incompletely pneumatized skulls (small to tiny skull windows) were 

recorded, indicating that the pneumatization process is eventually completed, likely early in year 2. The birds with skull windows may have hatched later in the breeding season than those 

with completely pneumatized skulls. This group included oscine 

taxa such as Tachyphonus coronatus, Thraupis sayaca, and Pyrrhocoma ruficeps.

In the second group, in contrast, birds with completely 

pneumatized skulls were rare or absent, and pneumatization 

rarely exceeded 50% of the skull in any individuals. This suggests that a full 2 years or more are required to complete the 

pneumatization process, if indeed it is completed at all. This 

group comprised primarily suboscine taxa that align in particular clades. For example, Corythopis delalandi, Phylloscartes 

ventralis, P. eximius, Mionectes rufiventris, Leptopogon amaurocephalus, Tolmomyias sulphurescens, Myiornis auricularis, 

Hemitriccus diops, H. margaritaceiventer, and Poecilotriccus 

plumbeiceps are all placed in the same family (Rhynchocyclidae 

by Tello et al., 2009 and Ohlson et al., 2013; Pipromorphidae 

by Cracraft, 2014 and Dickinson and Christidis, 2014), subfamily, or other taxonomic unit (see Remsen et al., 2016: note 1 

in the Tyrannidae section) and are separated from the rest of 

the flycatcher genera. The taxonomic placements of Piprites 
6 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

testes is sometimes black or dark green (which it also may be in 

adult males with regressed testes).

Plumage

Males of a number of species replace the juvenal plumage 

with an immature or subadult plumage easily distinguishable 

from the definitive or adult form, which they acquire with the 

second or third prebasic molt, depending on the species. The 

immature plumage may resemble that of the female, or it may be 

intermediate between those of the adult male and female. In several species, including Pipra fasciicauda, Chiroxiphia caudata, 

Cyanoloxia brissonii, Habia rubica, Sicalis flaveola, Trichothraupis melanops, Tachyphonus coronatus, Tersina viridis, and 

Pyrrhocoma ruficeps, the testes of males in the immature plumage were enlarged to breeding size. Some of those males also 

had large cloacal protuberances and/or brood patches. We do 

not know, of course, whether they were successful at obtaining 

mates. The presence of a subadult plumage was not necessarily 

linked to the degree of skull pneumatization. Immature-plumaged 

male Pipra fasciicauda, Cyanoloxia brissonii, Habia rubica, and 

through the austral winter. Females of both Columba livia and 

Leptotila verreauxi had enlarged (5 and 6 mm diameters, respectively), yolked ova in June (one of the coldest months), and males 

of the latter species had greatly enlarged testes (to 13.5 × 7 mm) 

in the same month. Hayes (2014) reported a comparable breeding season for 63 species of birds from the humid forest around 

Sapucái (Department of Paraguarí; ~200 km NNW of El Tirol; 

Figure 1) based on 454 clutches of eggs collected by William T. 

Foster from 1900 to 1908. All the eggs were collected between 

September and February. The peak of breeding was in October 

and November, with many fewer species reproducing in September and February.

Ovaries of young of the year are easily distinguished from 

those of older females in most species. Although generally tiny, 

ovaries may reach lengths of 4–7 mm before the birds’ skulls 

are completely pneumatized. However, the surface of the ovary 

is smooth and white, and incipient ova are not distinguishable. 

Consequently, females with only partially pneumatized skulls 

but with well-developed ova are assumed to be at least in their 

second year. Testes of males of the year are tiny, generally only 

1–2 mm long. The fibrous capsule surrounding the immature 

FIGURE 8. Timing of events in the annual cycles of birds at Hotel El Tirol, Department of Itapúa, 

Paraguay, as indicated by percentages of species for which collected specimens show evidence 

of breeding (circles), molting (squares), or fat deposition (stars), during each 2-week calendar 

period. Dashed lines cross periods (April, July, and early August) during which no specimens were 

collected.
NUMBER 648 • 6 1

smaller trees, shrubs, and vines (e.g., Cecropia pachystachya; 

Sorocea bonplandii, Moraceae), most of which we did not identify. The percentage of species eating insects is high from October 

through December, whereas the percentage eating fruits is lower. 

This likely reflects an increase in insect availability in response to 

the warmer temperatures, increased rainfall, and associated leaf 

flush. It also coincides with the period when adults are feeding 

nestlings, which may require more protein for growth than is 

generally contained in fruit.

A quarter of the species (N = 49%, 26.1%), including 13 

species of Tyrannidae, 8 of Thraupidae, 4 of Turdidae, and 3 

each of the Cuculidae, Picidae, Tityridae, and Icteridae, ate both 

fruit and insects. Some of these taxa are primarily insectivorous 

but occasionally take fruits (e.g., Lathrotriccus euleri: 54 of 56 

stomach samples [N] contained insect [I] remains and 4 contained fruit [F]; Leptopogon amaurocephalus: N = 21, I = 19, F = 

2); others are primarily frugivorous but occasionally take insects 

or other arthropods (e.g., Chiroxiphia caudata: N = 30, I = 1, 

F = 30; Dacnis cayana: N = 17, I = 2, F = 16), and some appear to 

be truly omnivorous (e.g., Myiopagis viridicata: N = 19, I = 10, F = 

10; Myiodynastes maculatus: N = 11, I = 6, F = 7).

Relatively few of the birds collected were eating seeds (X

_

 = 

5.3% of the species in any 2-week period, range 0%–14%). 

This result reflects the focus of our work on forest birds rather 

than on those in pastures, grasslands, and other open habitats. 

Columbina talpacoti, C. picui, and a few other species ate only 

seeds, but other species consumed a mixed diet. Some were 

primarily granivorous, only occasionally taking an insect (e.g., 

Sporophila caerulescens: N = 7, S [seeds] = 6, I = 1); others 

appeared to be primarily insectivorous but occasionally taking 

seeds (e.g., Conirostrum speciosum: N = 5, S = 1, I = 4), and 

some appeared to be truly omnivorous (e.g., Coryphospingus 

cucullatus: N = 22, S = 10, I = 13; Zonotrichia capensis: N = 22, 

S = 10, I = 15).

Stomachs of three species of owls (Aegolius harrisii, Athene 

cunicularia, Glaucidium brasilianum) and two raptors (Milvago 

chimachima, Micrastur ruficollis) contained mammal remains. 

The latter four species also contained insect remains. No other 

vertebrate remains were found in any stomachs, but we did 

observe a Baryphthengus ruficapillus eating a snake and a Coccyzus americanus eating a lizard, and we captured a Glaucidium 

brasilianum attempting to remove a bird from a mist net.

A parrot (Pionus maxamiliani), three pigeon species 

(Columba livia, Leptotila verreauxi, Patagioenas picazuro), two 

woodpeckers (Melanerpes candidus, Colaptes campestris), and 

a grosbeak (Cyanoloxia glaucocaerulea) had eaten corn and are 

considered pests by the local farmers. The stomachs of six species contained grit, which is not surprising for species such as 

L. verreauxi (3 individuals), Haplospiza unicolor (5), Sporophila 

caerulescens (1), and Chamaeza campanisona (1), which are at 

least partially granivorous. However, Nyctibius griseus (1) and 

Thamnophilus caerulescens (1) also contained grit but are not 

known to eat grain, and the stomach of one Micrastur ruficollis

contained a stone.

Tersina viridis had pneumatized skulls, whereas the immatureplumaged male Pyrrhocoma ruficeps, Sicalis flaveola, and Tachyphonus coronatus did not. Males with and without pneumatized 

skulls were found among immature-plumaged Chiroxiphia caudata and Trichothraupis melanops. These observations suggest 

that the definitive states of these traits are acquired independently and that the timing of acquisition of each is responding to 

different selective forces.

Molt

The percentages of species collected that were molting are 

plotted in Figure 8 for biweekly intervals. Because it was not 

always possible to distinguish between the first and subsequent 

prebasic molts, data for the two were combined. The percentages 

of species with molting individuals rose sharply in early December to high levels that continued through March and probably 

into April. By May, the numbers of species with molting individuals had decreased by nearly two-thirds, dropping even lower 

in June with the tail end of most prebasic molts.

Molt and breeding overlapped in some individuals of 16 

species. In eight species only body molt was involved (e.g., 

Picumnus temminckii, Capsiempis flaveola, Thraupis sayaca, 

Sporophila caerulescens) and ranged from limited (e.g., Coryphospingus cucullatus, Guira guira) to extensive (e.g., Coccyzus melacoryphus, Piprites chloris) replacement. In other species 

(e.g., Leptotila verreauxi, Crotophaga ani, Myiopagis caniceps, Tachyphonus coronatus, Pyriglena leucoptera), wing and 

sometimes tail feathers were also being replaced. The overlap 

in some of these individuals likely represents the onset of prebasic molt before the completion of a late renesting attempt following the loss of a brood. In other species (e.g., Chiroxiphia 

caudata, Schiffornis virescens, Pyrrhocoma ruficeps), however, 

overlap occurred at the beginning of the breeding season, long 

after prebasic molts would be expected to have been completed. 

Such molts may be prealternate molts, although it is somewhat 

surprising that they occur only in some individuals and involve 

anywhere from limited numbers of body feathers to all body and 

flight feathers.

Diet

The birds at El Tirol were predominantly insectivores, with 

an average of 78% (range = 62%–95%) of the species in any 

2-week period eating insects (including noninsect arthropods). 

Ants were recorded in the diets of nine of those species (13 individuals), including four woodpeckers (Colaptes campestris, C. 

melanochloros, Dryocopus lineatus, Picumnus temminckii) and 

an ovenbird (Furnarius rufus). Frugivory was much less common, 

with an average of only 28% (range = 14%–40%) of the species 

in any 2-week period eating fruit. Multiple species of birds congregated to feed in medium to large trees such as Allophylus edulis, Ocotea puberula, Trichilia catigua, and Ficus spp. that were 

heavily laden with fruit. Birds also removed fruits from many 
6 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

73. Presumably, these birds were depositing fat in anticipation 

of migration or had retained fat after arriving on their breeding grounds. Nevertheless, they do not account for the fall and 

spring peaks of fat deposition in the avifauna because so few 

migrant species were present in the samples at those times. For 

example, from February to mid-March, representatives of 60 

species were recorded with fat. However, only 10 of those species were migrants. Likewise, in mid-September to mid-October, 

only 11 of 44 species recorded with fat were migrants.

Migration and Local Movements

Twenty-seven of the species that we recorded, including 

two that we did not collect (Calidris subruficollis and Elanoides 

forficatus), are migrants (Appendix A). The bulk of these species (19), designated northern austral migrants (BN) by Hayes 

(1995), breed in Paraguay, after which all or part of the population migrates north for the winter (Ridgely and Tudor, 1989, 

1994, 2009; Hayes, 1995). Other populations of these same species that breed to the south of El Tirol also migrate north for the 

winter. Consequently, birds wintering at El Tirol may have bred 

there, or they may have bred in areas to the south. In contrast, 

Patagioenas picazuro, Serpophaga munda, and S. subcristata are 

southern austral migrants (BS), including some birds that breed 

and winter in Paraguay and others that winter in Paraguay but 

migrate farther south to breed (Hayes, 1995). Both P. picazuro

specimens (October, January) had enlarged testes, and active 

nests of the species were located in October, November, and 

March. The Serpophaga species were taken in winter, and neither 

individual was in breeding condition. Two other species, Cyanoloxia glaucocaerulea and Elaenia albiceps, reside in Paraguay 

only in winter (WR), migrating south to breed (Hayes, 1995). 

We collected three mid-October males of C. glaucocaerulea with 

enlarging testes. None of the E. albiceps was in breeding condition. The remaining three migrant species, Calidris subruficollis,

Coccyzus americanus, and Petrochelidon pyrrhonota, are longdistance Nearctic migrants (NM) that breed in North America 

and on Caribbean Islands and winter in South America.

The nature of the seasonal movements of five other species remains in question. Canevari et al. (1991), Sick (1993), 

and Hayes (1995) reported that Tersina viridis was a partial or 

irregular northern migrant, appearing in widely varying numbers 

in some years and being totally absent in others. The designation 

of this species by Ridgely and Tudor (1989) as nomadic may be 

more accurate. We recorded it only in the breeding season and 

in only 3 of 8 years. The migratory status of Stephanophorus 

diadematus is equally enigmatic. The species may be a southern 

migrant (Hayes, 1995), although its irregular occurrences in Paraguay have also been interpreted as population irruptions (Clay, 

pers. comm., 18 January 2016).

Hylocharis chrysura and Thalurania furcata are not known 

to be migratory, but we recorded them at El Tirol for only limited periods. Specimens of H. chrysura were taken during the 

breeding season (September, October, December), and birds were 

One breeding female each of Schiffornis virescens (October) 

and Trichothraupis melanops (November) and a juvenile (sex 

undetermined) of Sporophila caerulescens (March) had remains 

of eggshells in their stomachs; breeding female Pyriglena leucoptera (September) and Piaya cayana (September), a breeding male 

T. melanops (November), and a juvenile female Thamnophilus 

caerulescens (March) had remains of snail shells in their stomachs, and a postbreeding female Mackenziaena leachii (March) 

had eaten a millipede (Diplopoda). Eggshells, snail shells, and 

millipedes are high in calcium and may be important sources of 

this mineral for shell formation in laying females or bone pneumatization in growing young (Foster, 2014).

Fat Deposition

About 24% (N = 444) of the specimens distributed among 

72% (N = 134) of the species had noticeable body fat. The percentages of species with fat are shown for biweekly intervals 

in Figure 8. Individuals with fat were not evenly distributed 

throughout the year; numbers peaked in June when 56% and 

61% of all specimens taken in the two 2-week periods carried fat 

and 73% and 75% of the species collected in those same periods 

included individuals with fat. Lesser peaks were present from 

February to mid-March (ranges = 27%–39% of individuals and 

36%–49% of species) and in the latter halves of August (35% 

and 44%) and September (26% and 40%). The fat was designated as light in 44% (N = 194) of the individuals, moderate in 

50% (N = 220), and heavy in just 7% (N = 30). About a third of 

the birds with moderate fat (30%) and more than a third (37%) 

with heavy fat were taken in June.

Despite the broad representation of birds with fat among 

species, some species seemed more inclined to deposit fat than 

others. Considering only species for which we had 10 or more 

specimens (N = 59 species), more than 25% of individuals of 

25 species were designated with fat, and of those, in seven species 50% or more of individuals were so designated: Elaenia flavogaster (70%, N = 10), Elaenia parvirostris (67%, N = 12), 

Empidonomus varius (64%, N = 14), Guira guira (60%, N = 

10), Colaptes campestris (55%, N = 11), Thraupis sayaca (50%, 

N = 16), and Leptotila verreauxi (50%, N = 12). Only Elaenia 

parvirostris and Empidonomus varius are migrants, but all of 

the species except Guira guira ate large quantities of fruit. Conversely, individuals in four species with samples of 10 or more 

showed no evidence of fat at any time of the year: Automolus 

leucophthalmus (N = 26), Syndactyla rufosuperciliata (N = 26), 

Synallaxis ruficapilla (N = 12), and Euphonia violacea (N = 10). 

Samples of the former three species included eight, eight, and 

four specimens, respectively, taken during the peak periods of fat 

occurrence in the avifauna. In this group, only E. violacea is a 

frugivore. The others ate only insects.

Peaks of fat deposition among migrants (252 specimens 

among 25 species) were in February to mid-March, when 

77% of migrant species present included individuals with fat, 

and mid-September to mid-October, when the percentage was 
NUMBER 648 • 6 3

farther south or as a residuum of fat in those that have already 

arrived on their breeding grounds. Perhaps of greater interest is 

the regular presence of body fat in nonmigratory species in the 

late fall and especially during winter that disappears as breeding 

activity increases in the spring. It is generally assumed that breeding and molt are confined to periods of food abundance, suggesting that food availability during winter is insufficient to support 

those resource-demanding activities, particularly if the cost of 

thermoregulation increases at that time. Even so, available food 

may exceed requirements for maintenance during winter. For 

any organism experiencing such circumstances, deposition of fat 

reserves in anticipation of prospective breeding activities would 

be advantageous. Our data suggest that fat deposition may be 

associated with a frugivorous diet (see “Fat Deposition” section 

above), an observation that merits additional study.

Other Records from Hotel El Tirol

In 2005, Smith et al. published an avifaunal inventory of 

Hotel El Tirol. According to Smith (pers. comm., 2 September 

2016), the inventory was intended to provide a basis for future 

studies, combining the results from the inventory team, reports 

from any ornithologists and birdwatchers who had visited the 

site over the years, and an earlier species list maintained by 

Guyra Paraguay, a conservation group; it was not meant to be 

a scientific document but rather a working list subject to modification. In the publication, the earlier species list was erroneously attributed to MSF. Although the list may include some of 

MSF’s records, she was not involved in its compilation, and the 

source(s) of its contents remains unknown.

With additions and corrections from 2006 to 2009 (added 

directly to the online publication by Smith or in Smith, pers. 

comm., 8 September 2016), the Smith et al. (2005) amended 

list now includes 236 species, although the occurrence of Lepidocolaptes falcinellus still requires confirmation (Smith et al., 

2005). We recorded 194 (82%) of their 236 species (195 if we 

include Nothura maculosa, a species on our hypothetical list 

whose presence at Tirol they confirmed). Of the 42 species that 

we did not record (Appendix B), 33 were recorded by Smith and 

his colleagues (Smith et al., 2005, and updates), and 9 species 

are attributable only to the earlier Guyra Paraguay list. That we 

both had probable sightings of P. koeniswaldiana strengthens 

the likelihood that it also is present at El Tirol.

Conversely, we recorded 11 species not included in the Smith 

et al. updated list. Ten of these species are represented by only 

one or two specimens or sight records and are likely rare at the 

site. However, the absence of the 11th species, Sittasomus griseicapillus, from their list is surprising. Between 1976 and 1983, we 

collected 20 specimens of the species, which was common in the 

El Tirol forest, and sighted it numerous additional times. We did 

not record it in 2004, although Smith recorded it once in August 

2004 and noted (pers. comm., 8 September 2016) that it is still 

present at the site but rare, a change in abundance for which we 

have no explanation.

observed feeding in flowers of Malvaviscus sp., planted as an 

ornamental around the hotel, only during that same time period, 

although we routinely observed other hummingbird species feeding in those shrubs at other times of year. The timing of these 

observations suggests that the species may be migratory or that 

it may wander during the nonbreeding season, exploiting other 

local food resources. We collected T. furcata and observed it 

feeding in Malvaviscus sp. flowers only in June, suggesting that 

it also may migrate or at least wander during the nonbreeding 

season. Individuals of Stephanoxis lalandi were present at El 

Tirol year-round, although Sick (1993) has reported that some 

populations in Brazil may undergo elevational migrations, seeking lower elevations in winter.

Annual Cycle

The annual cycle of the avifauna in the austral subtropical 

humid forest at El Tirol follows a pattern closely resembling that 

found among birds at north temperate and subtropical latitudes 

(Figure 8). Breeding is seasonal (cf. Hayes, 2014), with gonads 

developing and the first signs of reproduction appearing in early 

spring (latter half of August); testes generally remain enlarged 

through midsummer, when they begin to regress in some species. Testis size continues to decrease through the austral fall. 

A few species maintain enlarged and seemingly active gonads 

(Columba livia, Leptotila verreauxi) into the winter months.

Birds entering their reproductive phase are likely responding 

to changes in photoperiod and lengthening days. At El Tirol, the 

shortest (21 June) and longest (21 December) days of the year 

differ by 3 h and 27 min (U.S. Naval Observatory, 2015). Breeding also coincides with the rainiest part of the year. Although 

rain falls consistently in every month, it increases to a high in 

October, followed by slight decreases in November and December. However, rainfall in every month is highly variable between 

years (Figure 6), which could advance or delay the onset of breeding in any given year. Breeding also coincides with the warmest 

months of the year, from October through March (Figure 7).

As breeding wanes, the numbers of individuals and species 

in molt increase, so that breeding and molt are inversely timed. 

This temporal separation reinforces the general observation that 

these two resource-demanding activities are incompatible (but 

see Foster, 1975a). Individuals in a few species seem to deviate 

from this pattern with molt and breeding overlapping, as has 

been reported for some tropical areas (Foster, 1974, 1975b). In 

Pyriglena leucoptera and Sporophila caerulescens, for example, 

the prebasic molt begins before breeding is completed, whereas 

in Piprites chloris and Capsiempis flaveola an apparent prealternate molt overlaps the beginning of the breeding season.

Deposition of body fat seems to be of regular occurrence in 

the El Tirol species. Southern Hemisphere migrants store energy 

for migration, as do their Northern Hemisphere counterparts. 

Fat present in migrants in February–March likely represents fat 

deposited in anticipation of fall migration. In September–October it is likely present in migrants in transit to breeding sites 
6 4 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

the park: Tyrannidae (11 sp. = 18% of tyrannid species recorded 

at San Rafael), Picidae (5 sp. = 42% of picids), Thraupidae (5 sp. = 

30% of thraupids), and Furnariidae (4 sp. = 15% of furnariids). The remaining 24 species are scattered among 17 families. 

Again, it is likely that some of these species, several of which are 

rare in Itapúa or Paraguay as a whole (Guyra Paraguay, 2004, 

2005), were simply overlooked.

On the other hand, El Tirol is located at the southwestern 

limit of the Atlantic Forest habitat, and species absences may 

reflect faunal attenuation as species reach the limits of their ecological ranges. It may also be that the lower species numbers 

simply reflect the lower diversity supported by a forest fragment, 

even one connected to other fragments along riparian or other 

corridors (cf. dos Anjos, 2001). Most of the fragments where 

we worked comprised fewer than 100 ha, and the majority of 

those probably ranged from 40 to 50 ha. Nevertheless, both 

Penelope superciliaris and Crypturellus tataupa were seen regularly, as were at least two species of grassland tinamous, which 

are usually vulnerable to overhunting. Forest hawks were present, but we did not record the largest raptors and eagles. Large 

frugivores, such as Pyroderus scutatus, Pteroglossus castanotis, 

Ramphastos toco, and Ramphastos dicolorus, apparently can 

persist in fragments, although the latter two species were rare. 

We also recorded two of the large woodpeckers (Dryocopus 

lineatus, Campephilus robustus). Dendrocincla turdina was 

observed regularly, as was Lepidocolaptes fuscus, another forest 

specialist. Eighty of the ~200 species of Atlantic Forest endemics 

(Stotz et al., 1996) are known from Paraguay (Fragano and Clay, 

2003; Esquivel M., 2006). Forty-five of them were recorded at El 

Tirol plus an additional two if we include hypotheticals. We also 

recorded four species (Phylloscartes eximius, Polioptila lactea, 

Neothraupis fasciata, Amaurospiza moesta) designated by the 

IUCN (2015) as Near Threatened.

The 17 species recorded at El Tirol that were not included 

on the San Rafael list are as follows (names followed by a dagger 

[†] are from Smith et al., 2005, and Smith, pers. comm., 8 September 2016; others are from this study): Calidris subruficollis, 

Coccyzus americanus, Aegolius harrisii, Heliomaster furcifer†, 

Thalurania furcata, Batara cinerea, Thamnophilus ruficapillus, Phacellodromus rufifrons†, Schoeniophylax phryganophilus†, Elaenia obscura†, Serpophaga munda, Xolmis irupero†, 

Paroaria capitata†, Neothraupis fasciata, Coereba flaveola, 

Piranga flava†, and Agelaioides badius. Most of these species are 

rare, uncommon, or previously unrecorded in the Alto Paraná 

region (Hayes, 1995; Guyra Paraguay, 2004). Although the birds 

recorded may simply have been wandering individuals, the species are likely to appear again in the Alto Paraná Region.

CONCLUSIONS

The highly diverse Atlantic Forest biome has been reported 

to house between 21,300 and 21,700 species of trees, shrubs, 

and terrestrial vertebrates (Mittermeier et al., 1999; Ministério 

Combining our list and the updated list of Smith et al. 

(2005, plus additions; Smith, pers. comm., 8 September 2016), 

247 species, including 45 Atlantic Forest endemics, have been 

recorded from the El Tirol forest and adjacent orchards, fields, 

and second-growth scrub. Confirmation of the presence of Pulsatrix koeniswaldiana would bring the totals to 248 and 46, 

respectively. This number is impressive, especially given the limited size of the forest patch and its lack of formal protection. 

However, an avifaunal list is always in flux, and we anticipate 

that additional species will be recorded and, unfortunately, that 

rare or uncommon species may be lost as the level of disturbance 

increases.

Comparisons with Avifaunas at Other Sites

The Atlantic Forest ecosystem originally spanned 28° of 

latitude in Brazil from Rio Grande do Norte to Rio Grande do 

Sul, extending westward from the Atlantic coast to the cordilleras separating the Paraná and Paraguay river basins in eastern 

Paraguay (Ribeiro et al., 2009). Eighty-five percent or more of 

this biome has been cleared for cattle ranches and sugar cane, 

oil palm, and soybean plantations, and destruction and degradation continue (Galindo-Leal and de Gusmão Câmara, 2003; 

Silveira et al., 2003). The largest remnant of this habitat in Paraguay is located in San Rafael National Park in the departments 

of Itapúa and Caazapá, some 83 km north (heading ~4.21°) of 

El Tirol (Figure 1). The park is located in the “Cordillera San 

Rafael” (elevation up to 500 m above sea level) and covers an 

area of approximately 748 km2

 distributed among seven types 

of habitat. Lowen (Lowen et al., 1996), Madroño (Madroño N. 

et al., 1997), and their collaborators surveyed birds in the park 

in the mid-1990s. Together, they recorded a total of 295 species 

(Madroño N. et al., 1997; they reported a total of 294 species 

but included 295 on their list). Additional bird surveys carried 

out between 1996 and 2006 brought the species total to 406 

(Esquivel M. et al., 2007).

Combining our data and the updated information from 

Smith et al. (2005; Smith, pers. comm., 8 September 2016), we 

recorded 230 (~57%) of those species at El Tirol, plus another 

17 species that they did not record in San Rafael. Nighty-nine 

of the species we did not record occupy aquatic, marshland, or 

grassland habitats that are not associated with El Tirol and that 

we did not sample, which brings our total to about 75% of the 

rest of the San Rafael avifauna. The remaining 77 species, representing 30 families, were regularly observed in or above forest 

habitats at San Rafael. Nearly a third (23 = 30%) of those species 

belong to groups that generally fly or soar high overhead (Cathartidae, 2 sp.; Accipitridae, 8; Psittacidae, 6) or are active at night 

(Tytonidae, 1 sp.; Strigidae, 4; Nyctibiidae, 1; Caprimulgidae, 

1). We spent little time trying to identify such birds at Tirol, and 

it is likely that many were actually present. The three cracid and 

two tinamou species (5 = 6%) missing from El Tirol may have 

succumbed to hunting pressure. Of the remaining 49 species, 25 

(32%) belong to four families that are among the most diverse in 
NUMBER 648 • 6 5

Management, National Parks, and Wildlife; and Lic. Ana Beatriz 

Pin, Department of Protection and Conservation of Biodiversity.

Armando and Miguelita Reynaerts and Eric Reynaerts, the 

owners of Hotel El Tirol at the time of our studies, were gracious 

and supportive hosts during our extended stays. They and hotel 

employees Rita and Ramón Diez made every effort to accommodate our work and the often unusual requests associated with 

it. Nancy López and John Kochalka, Peg and Phil Myers Sr., and 

Jim and Nancy Talbot were gracious hosts during our stays in 

Asunción, assisted with logistics, and helped in numerous other 

ways.

We are especially indebted to the many individuals who 

helped with the field work and the collection and preparation 

of specimens, including Robert M. Zink, Robert E. Jones, Carla 

Cicero, Nancy E. Lopez, Anne D. Jacobberger, Anne Inderbitzin, 

Eugene W. Schupp, Jill M. Hanna, Rebecca Zarza, Elena Escobar, and Vicki Dziadosz (who made most of the recordings of the 

bird vocalizations).

Carla Cicero and Nancy López provided access to specimens and information housed at the MVZ and the MNHNP, 

respectively, and answered a multitude of questions. Steven 

Smith (National Museum of Natural History) identified the 

plants. Fiona Wilkinson significantly improved the photographs 

and figures. Jose Tello corrected the Spanish translation of the 

abstract. Other individuals, including Pedro Acevedo, L. Amarilla, D. Cadena, Rob Clay, Nigel Cleere, Gen. Alejando Fretes 

Davalos, Nicky and Lee Donnell, Christina Fidler, Lee Fitzgerald, Amy Johnson, Carla Johnson, Mary Keith, G. M. Kirwan, 

Gary Krauss, P. Lasker, Mary LeCroy, Roy McDiarmid, Cristina 

Morales, Martha Motte P., Hilario Moreno O., Phil Myers Jr., 

Larry Naylor, J. V. Remsen, Paul Smith, Jose Tello, Col. Charles 

R. Wallis, Mary Walter, David Wood, Diane Wood, and Addison 

Wynn helped in a variety of ways. R. T. Chesser and two anonymous reviewers kindly read the manuscript and offered very helpful comments and suggestions. We offer our sincere thanks to all 

of these individuals.

M.S.F. thanks the National Geographic Society, Alexander Wetmore Fund of the Bird Division at the USNM, U.S. Fish 

and Wildlife Service, U.S. Geological Survey Patuxent Wildlife 

Research Center, and the Museum of Vertebrate Zoology for support of her research. N.K.J. thanks the American Philosophical 

Society, the National Science Foundation (DEB #7909807), and 

the Museum of Vertebrate Zoology for support of his research.

do Meio-Ambiente, 2000; de Gusmão Câmara, 2003) and some 

6% to 7% of all currently recognized bird species (Goerck, 1997; 

BirdLife International, 2015), about 20% of which are endemics (Tabarelli et al., 2003). It originally covered some 1.0 to 1.5 

million km2

 of Brazil, Argentina, and Paraguay, but only about 

7.5% to 15% of that area remains (Myers et al., 2000; GalindoLeal and de Gusmão Câmara, 2003; Ribeiro et al., 2009). 

Ribeiro et al. (2009) reported that the Atlantic Forest remaining 

in Brazil is distributed among 245,173 forest fragments, 83.4% 

and 97% of which are smaller than 50 and 250 ha, respectively. 

Although similar habitat surveys and calculations have not been 

done for Paraguay, the situation is likely similar. Currently, only 

two large fragments of Atlantic Forest in Paraguay enjoy some 

level of protection (Figure 1), the San Rafael National Park, of 

which about 80% is forest (Esquivel M. et al., 2007), and the 

Mbaracayú Forest Nature Reserve, covering ~644 km2

, of which 

about 87% is terra firme forest (Keel et al., 1993).

Several authors have suggested that the Atlantic Forest avifauna is resistant to the effects of forest fragmentation (Benke 

and Kindel, 1999; Protomastro, 2001). Brooks et al. (1999) disputed this, suggesting rather that this is a false impression resulting from the lag time between fragmentation and extinction. 

Additional time will be required to evaluate these alternative 

views. Regardless of the outcome, it is clear that forest fragments 

will be important in the maintenance of the Atlantic Forest avifauna, if not as breeding refuges for given species (e.g., Aguilar et 

al., 1999), then as parts of a network of corridors linking larger 

areas (e.g., Dornelas de Andrade and Marini, 2001). It is important that we obtain as much information as possible about the 

biology of species in these fragments as a basis for future management and that owners of these small patches be apprised of 

their importance and encouraged to protect and maintain them.

Acknowledgments

It would have been impossible to carry out this study without the considerable help of numerous individuals and institutions. Permits to collect and export specimens were authorized 

by the following Paraguayan officials: Ing. Hernando Bertoni, 

Minister of Agriculture; Ing. Gricelda Marín, Director of Wildlife, Ministry of the Environment; Ing. Alfredo Silvo Molinas 

Maldonado, Executive Secretary, Ministry of the Environment; 

Ing. Hilario Moreno O., Chief of the Department of Forest 

This appendix includes the species of birds recorded at El Tirol, Department of Itapúa, 

Paraguay, and the numbers of months (in parentheses) in which each species was collected.Species known only from sight records are indicated by an asterisk. AFE indicates Atlantic Forest endemic (after Brooks et al., 1999). Note that for Turdus nigriceps,

only the subspecies T. n. sublaris, which is considered by some to be a separate species 

(Ridgely and Tudor, 2009), is an Atlantic Forest endemic. Designations of breeding or 

migrant status (modified from Hayes, 1995) are as follows: BR = breeding permanent resident; BN = breeding resident, less abundant or absent during winter when birds migrate 

north; BS = breeding resident but some birds migrate farther south to breed; WR = winter 

resident that migrates south of Paraguay to breed; NM = Nearctic migrant that breeds in 

North America and/or the Caribbean but winters in South America.

Tinamidae

Crypturellus tataupa (3) BR

Cracidae

Penelope superciliaris (1) BR

Odontophoridae

Odontophorus capueira (1) AFE, BR

Ardeidae

Syrigma sibilatrix (1) BR

Cathartidae

Cathartes aura* BR

Coragyps atratus (1) BR

Accipitridae

Elanus leucurus* BR

Elanoides forficatus* BN

Harpagus diodon (1) BN

Ictinia plumbea (1) BN

Rupornis magnirostris (2) BR

Buteo brachyurus* BR

Rallidae

Aramides saracura (2) AFE, BR

Appendix A
6 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Alcedinidae

Megaceryle torquata* BR

Momotidae

Baryphthengus ruficapillus (5) AFE, BR

Bucconidae

Nystalus chacuru (1) BR

Nonnula rubecula (4) BR

Ramphastidae

Ramphastos toco* BR

Ramphastos dicolorus* AFE, BR

Pteroglossus castanotis (6) BR

Picidae

Picumnus temminckii (9) AFE, BR

Melanerpes candidus (4) BR

Veniliornis spilogaster (7) AFE, BR

Colaptes melanochloros (2) BR

Colaptes campestris (4) BR

Dryocopus lineatus (2) BR

Campephilus robustus (2) AFE, BR

Falconidae

Micrastur ruficollis (3) BR

Caracara plancus* BR

Milvago chimachima (1) BR

Milvago chimango* BR

Falco sparverius (4) BR

Falco femoralis* BR

Psittacidae

Myiopsitta monachus (1) BR

Pionus maximiliani (1) BR

Pyrrhura frontalis (1) AFE, BR

Thamnophilidae

Hypoedaleus guttatus (1) AFE, BR

Batara cinerea* BR

Mackenziaena leachii (4) AFE, BR

Mackenziaena severa (4) AFE, BR

Thamnophilus ruficapillus (1) BR

Thamnophilus caerulescens (10) BR

Dysithamnus mentalis (10) BR

Herpsilochmus rufimarginatus (2) BR

Drymophila malura (4) AFE, BR

Pyriglena leucoptera (8) AFE, BR

Conopophagidae

Conopophaga lineata (10) AFE, BR

Formicariidae

Chamaeza campanisona (2) BR

Charadriidae

Vanellus chilensis (1) BR

Scolopacidae

Calidris subruficollis* NM

Columbidae

Columba livia (1) BR

Patagioenas picazuro (2) BS

Geotrygon violacea (1) BR

Leptotila verreauxi (6) BR

Leptotila rufaxilla (1) BR

Columbina talpacoti (4) BR

Columbina squammata (1) BR

Columbina picui (4) BR

Cuculidae

Guira guira (5) BR

Crotophaga ani (8) BR

Tapera naevia (1) BR

Dromococcyx phasianellus* BR

Piaya cayana (6) BR

Coccyzus melacoryphus (3) BN

Coccyzus americanus (2) NM

Strigidae

Megascops choliba (3) BR

Glaucidium brasilianum (2) BR

Athene cunicularia (1) BR

Aegolius harrisii (1) BR

Nyctibiidae

Nyctibius griseus (1) BR

Caprimulgidae

Nyctidromus albicollis (2) BR

Setopagis parvula (4) BR

Hydropsalis torquata (1) BR

Antrostomus rufus (1) BR

Apodidae

Chaetura cinereiventris (1) BR

Trochilidae

Phaethornis eurynome (6) AFE, BR

Stephanoxis lalandi (8) AFE, BR

Thalurania furcata (1) BR

Amazilia versicolor (3) BR

Hylocharis chrysura (3) BR

Trogonidae

Trogon surrucura (4) AFE, BR

Trogon rufus (2) BR
NUMBER 648 • 6 9

Pitangus sulphuratus (7) BR

Myiodynastes maculatus (5) BN

Megarynchus pitangua (6) BR

Empidonomus varius (5) BN

Tyrannus melancholicus (5) BN

Tyrannus savana (5) BN

Sirystes sibilator (2) BR

Myiarchus swainsoni (5) BN

Cotingidae

Pyroderus scutatus (2) AFE, BR

Pipridae

Chiroxiphia caudata (10) AFE, BR

Pipra fasciicauda (2) BR

Tityridae

Tityra inquisitor (2) BR

Tityra cayana (3) BR

Schiffornis virescens (5) AFE, BR

Pachyramphus polychopterus (4) BN

Piprites chloris (2) BR

Vireonidae

Cyclarhis gujanensis (6) BR

Hylophilus poicilotis (6) AFE, BR

Vireo olivaceus (6) BN

Corvidae

Cyanocorax chrysops (4) BR

Hirundinidae

Progne chalybea (1) BN

Petrochelidon pyrrhonota (1) NM

Troglodytidae

Troglodytes aedon (9) BR

Polioptilidae

Polioptila lactea (1) AFE, BR

Turdidae

Turdus leucomelas (7) BR

Turdus rufiventris (9) BR

Turdus amaurochalinus (4) BR

Turdus nigriceps (1) AFE, BR

Turdus albicollis (5) BR

Mimidae

Mimus saturninus (3) BR

Thraupidae

Cissopis leverianus*BR

Neothraupis fasciata* BR

Furnariidae

Sclerurus scansor (2) AFE, BR

Sittasomus griseicapillus (9) BR

Dendrocincla turdina (2) AFE, BR

Dendrocolaptes platyrostris (5) BR

Xiphorhynchus fuscus (6) AFE, BR

Campylorhamphus falcularius (2) AFE, BR

Lepidocolaptes angustirostris (1) BR

Xenops minutus (4) BR

Xenops rutilans (1) BR

Furnarius rufus (4) BR

Lochmias nematura (1) BR

Philydor atricapillus (1) AFE, BR

Philydor rufum (4) BR

Anabacerthia lichtensteini (9) AFE, BR

Syndactyla rufosuperciliata (9) BR

Automolus leucophthalmus (8) AFE, BR

Cranioleuca obsoleta (1) AFE, BR

Synallaxis cinerascens (10) BR

Synallaxis ruficapilla (6) AFE, BR

Synallaxis spixi (4) BR

Synallaxis frontalis (1) BR

Tyrannidae

Phyllomyias burmeisteri (2) BR

Myiopagis caniceps (3) BR

Myiopagis viridicata (6) BN

Elaenia flavogaster (5) BR

Elaenia spectabilis (3) BN

Elaenia albiceps (2) WR

Elaenia parvirostris (4) BN

Suiriri suiriri* BR

Serpophaga subcristata (1) BS

Serpophaga munda (1) BS

Capsiempis flaveola (6) BR

Corythopis delalandi (4) BR

Euscarthmus meloryphus (1) BR

Phylloscartes eximius (5) AFE, BR

Phylloscartes ventralis (5) BR

Mionectes rufiventris (5) AFE, BR

Leptopogon amaurocephalus (10) BR

Myiornis auricularis (9) AFE, BR

Hemitriccus diops (3) AFE, BR

Hemitriccus margaritaceiventer (1) BR

Poecilotriccus plumbeiceps (4) BR

Tolmomyias sulphurescens (5) BR

Platyrinchus mystaceus (7) BR

Lathrotriccus euleri (8) BN

Cnemotriccus fuscatus (4) BN

Contopus cinereus (1) BR

Colonia colonus (1) BR

Machetornis rixosa (2) BR

Legatus leucophaius (1) BN

Myiozetetes similis (1) BR
7 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Icteridae

Cacicus haemorrhous (5) BR

Icterus cayanensis (8) BR

Gnorimopsar chopi (3) BR

Agelaioides badius (1) BR

Molothrus rufoaxillaris (1) BR

Molothrus bonariensis (3) BR

Fringillidae

Spinus magellanicus (1) BR

Euphonia chlorotica (4) BR

Euphonia violacea (2) BR

Euphonia pectoralis (4) AFE, BR

Chlorophonia cyanea (2) BR

Hypotheticals

Tinamidae

Nothura maculosa*

Threskiornithidae

Mesembrinibis cayennensis*

Recurvirostridae

Himantopus mexicanus*

Strigidae

Pulsatrix koeniswaldiana* AFE

Psittacidae

Pionopsitta pileata* AFE

Amazona aestiva*

Forpus xanthopterygius*

Aratinga nenday*

Psittacara leucophthalmus*

Nemosia pileata (2) BR

Pyrrhocoma ruficeps (9) AFE, BR

Trichothraupis melanops (10) BR

Tachyphonus coronatus (10) AFE, BR

Stephanophorus diadematus* BR

Pipraeidea melanonota (3) BR

Thraupis sayaca (7) BR

Tangara seledon (4) AFE, BR

Tersina viridis (3) BN

Dacnis cayana (8) BR

Hemithraupis guira (9) BR

Conirostrum speciosum (4) BR

Haplospiza unicolor (4) AFE, BR

Sicalis flaveola (6) BR

Volatinia jacarina (1) BR

Sporophila angolensis (1) BR

Sporophila caerulescens (4) BR

Coryphospingus cucullatus (10) BR

Coereba flaveola (1) BR

Saltator similis (1) BR

Emberizidae

Zonotrichia capensis (8) BR

Cardinalidae

Habia rubica (5) BR

Amaurospiza moesta (1) AFE, BR

Cyanoloxia glaucocaerulea (4) WR

Cyanoloxia brissonii (6) BR

Parulidae

Geothlypis aequinoctialis (3) BR

Setophaga pitiayumi (8) BR

Myiothlypis leucoblephara (10) AFE, BR

Basileuterus culicivorus (10) BR
This appendix includes bird species (N = 42) recorded by Smith et al. (2005) at Hotel El 

Tirol, Department of Itapúa, Paraguay, that we did not record during our study. Note 

that Synallaxis albescens (pale-breasted spinetail) and Elaenia chiriquensis (lesser elaenia) have been deleted from the Smith et al. (2005) list at the request of Smith (pers. 

comm., 8 September 2016), who indicated that they likely represent misidentifications. 

Smith et al. also noted sightings of owls tentatively identified as Pulsatrix koeniswaldiana (tawny-browed owl; an Atlantic Forest endemic), which needs confirmation. Names 

have been updated to follow Remsen et al. (2016). AFE indicates Atlantic Forest endemic 

(after Brooks et al., 1999).

Tinamidae

Crypturellus obsoletus: Brown Tinamou

Nothura maculosa: Spotted Nothura

Ardeidae

Nycticorax nycticorax: Black-crowned Night-heron

Bubulcus ibis: Cattle Egret

Ardea cocoi: Cocoi Heron

Ardea alba: Great Egret

Threskiornithidae

Plegadis chihi: White-faced Ibis

Phimosus infuscatus: Bare-faced Ibis

Accipitridae

Leptodon cayanensis: Gray-headed Kite

Rostrhamus sociabilis: Snail Kite

Accipiter striatus: Sharp-shinned Hawk

Columbidae

Patagioenas cayennensis: Pale-vented Pigeon

Geotrygon montana: Ruddy Quail-dove

Zenaida auriculata: Eared Dove

Cuculidae

Crotophaga major: Greater Ani

Dromococcyx pavoninus: Pavonine Cuckoo

Appendix B
7 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Caprimulgidae

Lurocalis semitorquatus: Short-tailed Nighthawk

Antrostomus sericocaudatus: Silky-tailed Nightjar

Apodidae

Chaetura meridionalis: Sick’s Swift

Trochilidae

Anthracothorax nigricollis: Black-throated Mango

Heliomaster furcifer: Blue-tufted Starthroat

Chlorostilbon lucidus: Glittering-bellied Emerald

Alcedinidae

Chloroceryle americana: Green Kingfisher

Ramphastidae

Selenidera maculirostris: Spot-billed Toucanet, AFE

Falconidae

Herpetotheres cachinnans: Laughing Falcon

Falco rufigularis: Bat Falcon

Furnariidae

Lepidocolaptes falcinellus: Scalloped Woodcreeper, AFE

Phacellodomus rufifrons: Rufous-fronted Thornbird

Schoeniophylax phryganophilus: Chotoy Spinetail

Tyrannidae

Elaenia obscura: Highland Elaenia

Myiophobus fasciatus: Bran-colored Flycatcher

Xolmis irupero: White Monjita

Conopias trivirgatus: Three-striped Flycatcher

Myiarchus ferox: Short-crested Flycatcher

Oxyruncidae

Oxyruncus cristatus: Sharpbill

Tityridae

Pachyramphus validus: Crested Becard

Hirundinidae

Pygochelidon cyanoleuca: Blue-and-white Swallow

Progne tapera: Brown-chested Martin

Tachycineta leucopyga: Chilean Swallow

Thraupidae

Paroaria capitata: Yellow-billed Cardinal

Saltator coerulescens: Grayish Saltator

Cardinalidae

Piranga flava: Hepatic Tanager
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Conservation Publications.

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Index

Page numbers in italics indicate figures and captions.

Acanthaceae, 15

Accipiter striatus, 71

Accipitridae (Hawks), 8, 64, 67, 71

Aegolius harrisii, 13, 61, 64, 68

African Parrots (Psittacidae), 20–21, 58–59, 

64, 68, 70

Agelaioides badius, 56, 64, 70

Alcedinidae (Kingfishers), 16, 68, 72

Alchornea

glandulosa, 55

iricurana, 48

Allophylus edulis, 61

Cacicus haemorrhous, 55

Chiroxiphia caudata, 39

Chlorophonia cyanea, 58

Coryphospingus cucullatus, 51

Cyanocorax chrysops, 42

Dacnis cayana, 49

Elaenia, 30

Empidonomus varius, 37

Euphonia, 57, 58

Hemithraupis guira, 49

Mionectes rufiventris, 32

Myiodynastes maculatus, 36

Pitangus sulphuratus, 36

Pyroderus scutatus, 38

Pyrrhocoma ruficeps, 46

Tachyphonus coronatus, 47

Tangara seledon, 48

Thraupis sayaca, 48

Trichothraupis melanops, 47

Turdus, 43, 44, 45

Vireo olivaceus, 41

Zonotrichia capensis, 52

Alto Paraná region, 45, 64

Amaurospiza moesta, 53, 64, 70

Amazilia versicolor, 16, 68

Amazona aestiva, 58, 70

American Ornithologists’ Union’s 

South American Classification 

Committee, 6

Anabacerthia lichtensteini, 27, 59, 69

Ani

Greater (Crotophaga major), 71

Smooth-billed (Crotophaga ani), 11, 

61, 68

Antbirds (Thamnophilidae), 21–24, 68

Anthracothorax nigricollis, 72

Antpipit, Southern (Corythopis delalandi), 

31–32, 59, 69

Antrostomus

rufus, 14, 68

sericocaudatus, 72

Antshrike

Giant (Batara cinerea), 21, 64, 68

Large-tailed (Mackenziaena leachii), 21, 

62, 68

Rufous-capped (Thamnophilus 

ruficapillus), 22, 64, 68

Spot-backed (Hypoedaleus guttatus), 21, 

68

Tufted (Mackenziaena severa), 21–22, 68

Variable (Thamnophilus caerulescens), 22, 

59, 61, 62, 68

Ant-tanager, Red-crowned (Habia rubica), 

52–53, 60–61, 70

Antthrushes (Formicariidae), 24, 68

Antvireo, Plain (Dysithamnus mentalis), 

22–23, 68

Antwren, Rufous-winged (Herpsilochmus 

rufimarginatus), 23, 68

Apodidae (Swifts), 14–15, 68, 72

Araçari, Chestnut-eared (Pteroglossus 

castanotis), 17–18, 64, 68

Araliaceae, 39

Aramides saracura, 8–9, 67
7 8 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Aratinga nenday, 58, 70

Ardea

alba, 71

cocoi, 71

Ardeidae (Herons), 7, 67, 71

armadillo

nine-banded armadillo 

(Dasypus novemcinctus), 3

Asteraceae, 12

Asunción, map, 2

Athene cunicularia, 13, 61, 68

Atlantic Forest ecosystem, 

64–65

Automolus leucophthalmus, 

27–28, 59, 62, 69

Avocets and Stilts 

(Recurvirostridae), 58, 70

Baccharis sp., 12, 21, 29, 33, 54

Bananaquit (Coereba flaveola), 

52, 64, 70

Band-tailed Manakin (Pipra 

fasciicauda), 39, 60–61, 69

Bare-faced Ibis (Phimosus 

infuscatus), 71

Barred Forest-falcon (Micrastur 

ruficollis), 20, 61, 68

Baryphthengus ruficapillus, 17, 

59, 61, 68

Basileuterus culicivorus, 22, 47, 

49, 54, 55, 70

Batara cinerea, 21, 64, 68

Bat Falcon (Falco rufigularis), 72

Baywing, Grayish (Agelaioides 

badius), 56, 64, 70

Becard, Crested (Pachyramphus 

validus), 72

Becard, White-winged 

(Pachyramphus 

polychopterus), 40, 69

Black-billed Scythebill 

(Campylorhamphus 

falcularius), 25–26, 69

Blackbird, Chopi (Gnorimopsar 

chopi), 56, 70

Blackbirds (Icteridae), 55–57, 

61, 70

Bosso, A., 43

breeding. see reproduction

Bristle-tyrant, Southern 

(Phylloscartes eximius), 22, 

32, 59, 64, 69

Bromeliaceae, 3, 15

Broms, K., 13

Brooks, T., 6, 65

brown capuchin monkeys, 3

Bubulcus ibis, 71

Bucconidae (Puffbirds), 17, 68

Buteo brachyurus, 8, 67

Caazapá (department). see San 

Rafael National Park

Cacicus haemorrhous, 38, 

55–56, 70

Cacique, Red-rumped (Cacicus 

haemorrhous), 38, 55–56, 

70

Calidris subruficollis, 9, 62, 

64, 68

Calliandra foliolosa, 15

Campephilus robustus, 19–20, 

64, 68

Campylorhamphus falcularius, 

25–26, 69

Canevari, M., 62

Cannabaceae, 30

Capitán Miranda, Paraguay, 

5, 21

Capllonch, P., 35

Caprimulgidae (Nightjars), 14, 

64, 68, 72

Capsicum sp., 30

Capsiempis flaveola, 31, 61, 

63, 69

capuchin monkeys, 3

Caracara

Chimango (Milvago 

chimango), 20, 68

Southern (Caracara plancus), 

20, 68

Yellow-headed (Milvago 

chimachima), 20, 61, 68

Caracara plancus, 20, 68

Cardinal, Yellow-billed 

(Paroaria capitata), 72

Cardinal Grosbeaks 

(Cardinalidae), 52–54, 

70, 72

Cardinalidae (Cardinal 

Grosbeaks), 52–54, 70, 72

Casearia silvestris, 39

Cathartes aura, 7, 67

Cathartidae (New World 

Vultures), 7–8, 64, 67

Cecropia pachystachya, 39, 61

Cerdocyon thous, 3

Cerro Corá National Park, 2, 

39

Chaco region, 31

Chaetura

cinereiventris, 14–15, 42, 68

meridionalis, 72

Chamaeza campanisona, 24, 

61, 68

Charadriidae (Plovers), 9, 68

Chiroxiphia caudata, 39, 59, 

60, 61, 69

Chloroceryle americana, 72

Chlorophonia, Blue-naped 

(Chlorophonia cyanea), 

58, 70

Chlorophonia cyanea, 58, 70

Chlorostilbon lucidus, 72

Chusquea sp., 3, 12, 22, 31, 54

Cissopis leverianus, 45, 69

Citrus sp., 11

Ciudad del Este, 2

Clay, R. P., 47

Cnemotriccus fuscatus, 35, 69

Coccyzus

americanus, 12–13, 61, 62, 

64, 68

melacoryphus, 12, 61, 68

Coereba flaveola, 52, 64, 70

Colaptes

campestris, 19, 61, 62, 68

melanochloros, 19, 61, 68

Colonia colonus, 35, 69

Columba livia, 9, 60, 61, 63, 68

Columbidae (Pigeons)

annual cycle, 63

diet, 61

reproduction, 59–60

species list, 9–11, 68, 71

Columbina

picui, 10–11, 61, 68

squammata, 10, 68

talpacoti, 4, 10, 11, 59, 61, 68

Conebill, Chestnut-vented 

(Conirostrum speciosum), 

45, 49–50, 61, 70

Conirostrum speciosum, 45, 

49–50, 61, 70

Conopias trivirgatus, 72

Conopophaga lineata, 24, 68

Conopophagidae (Gnateaters), 

24, 68

Contopus

cinereus, 35, 69

sordidulus, 30

Coragyps atratus, 7–8, 67

Cordillera San Rafael, 64

Corvidae (Jays), 42, 69

Coryphospingus cucullatus, 

51–52, 61, 70

Corythopis delalandi, 31–32, 

59, 69

Cotingas (Cotingidae), 38, 69

Cotingidae (Cotingas), 38, 69

Cowbird

Screaming (Molothrus 

rufoaxillaris), 56, 70

Shiny (Molothrus 

bonariensis), 56–57, 70

crab-eating fox (Cerdocyon 

thous), 3

Cracidae (Guans), 7, 64, 67

Cranioleuca obsoleta, 28, 59, 

69

Crotophaga

ani, 11, 61, 68

major, 71

Crypturellus

obsoletus, 71

tataupa, 7, 64, 67

Cuckoo

Dark-billed (Coccyzus 

melacoryphus), 12, 61, 68

Guira (Guira guira), 4, 11, 

61, 62, 68

Pavonine (Dromococcyx 

pavoninus), 71

Pheasant (Dromococcyx 

phasianellus), 12, 68

Squirrel (Piaya cayana), 12, 

62, 68

Striped (Tapera naevia), 11, 68

Yellow-billed (Coccyzus 

americanus), 12–13, 61, 

62, 64, 68

Cuckoos (Cuculidae), 11–13, 

61, 68, 71

Cuculidae (Cuckoos), 11–13, 

61, 68, 71

Cupania sp., 43

Cupania vernalis, 36, 38, 40, 

44, 48, 55

Cyanocorax chrysops, 42, 69

Cyanoloxia

brissonii, 53–54, 60–61, 70

glaucocaerulea, 53, 61, 62, 70

Cyatheaceae, 3

Cyclarhis gujanensis, 41, 69

Dacnis, Blue (Dacnis cayana), 

49, 61, 70

Dacnis cayana, 49, 61, 70

Dasypus novemcinctus, 3

de la Peña, M. R., 11

del Castillo, H., 30, 47

Dendrocincla turdina, 25, 64, 

69

Dendrocolaptes platyrostris, 

25, 69

Dendropanax cuneatus, 39

Didelphis albiventris, 3

diet, 6, 61–62

Dove

Eared (Zenaida auriculata), 71

Gray-fronted (Leptotila 

rufaxilla), 10, 68

Picui Ground (Columbina 

picui), 10–11, 61, 68

Ruddy Ground (Columbina 

talpacoti), 4, 10, 11, 59, 

61, 68

Scaled (Columbina 

squammata), 10, 68

Violaceous Quail- (Geotrygon 

violacea), 9, 68

White-tipped (Leptotila 

verreauxi), 9–10, 60, 61, 

62, 63, 68

Dromococcyx

pavoninus, 71

phasianellus, 12, 68

Drymophila malura, 23, 68

Dryocopus lineatus, 19, 61, 

64, 68

Dysithamnus mentalis, 22–23, 

68

eggs, 7, 52, 59–60

Egret

Cattle (Bubulcus ibis), 71

Great (Ardea alba), 71
NUMBER 648 • 7 9

Elaenia

Gray (Myiopagis caniceps), 

29, 59, 61, 69

Greenish (Myiopagis 

viridicata), 29, 61, 69

Highland (Elaenia obscura), 

64, 72

Large (Elaenia spectabilis), 

30, 69

Lesser (Elaenia chiriquensis), 

71

Small-billed (Elaenia 

parvirostris), 30, 62, 69

White-crested (Elaenia 

albiceps), 30, 62, 69

Yellow-bellied (Elaenia 

flavogaster), 30, 62, 69

Elaenia

albiceps, 30, 62, 69

chiriquensis, 71

flavogaster, 30, 62, 69

obscura, 64, 72

parvirostris, 30, 62, 69

spectabilis, 30, 69

Elanoides forficatus, 8, 62, 67

Elanus leucurus, 8, 67

El Tirol. see Hotel El Tirol del 

Paraguay

Emberizidae (Sparrows), 52, 70

Emerald

Glittering-bellied 

(Chlorostilbon lucidus), 72

Versicolored (Amazilia 

versicolor), 16, 68

Empidonomus varius, 37, 62, 69

Encarnación, Paraguay, 2, 3

Esquivel M., 12, 43

Eugenia uniflora, 39, 42, 47, 

48, 57

Euphonia

Chestnut-bellied (Euphonia 

pectoralis), 57–58, 70

Purple-throated (Euphonia 

chlorotica), 57, 70

Violaceous (Euphonia 

violacea), 32, 57, 62, 70

Euphonia

chlorotica, 57, 70

pectoralis, 57–58, 70

violacea, 32, 57, 62, 70

Euphorbiaceae, 3

Euscarthmus meloryphus, 32, 

69

Fabaceae, 15

Falco

femoralis, 20, 68

rufigularis, 72

sparverius, 8, 20, 68

Falcon

Aplomado (Falco femoralis), 

20, 68

Barred Forest- (Micrastur 

ruficollis), 20, 61, 68

Bat (Falco rufigularis), 72

Laughing (Herpetotheres 

cachinnans), 72

Falconidae (Falcons), 20, 68, 72

Falcons (Falconidae), 20, 68, 72

Faramea cyanea, 15

fat deposition, 60, 62, 63

Ficus sp., 39, 40, 47, 56, 61

Finch

Chestnut-bellied Seed- 

(Sporophila angolensis), 

50–51, 70

Red-crested (Coryphospingus 

cucullatus), 51–52, 61, 70

Saffron (Sicalis flaveola), 4, 

50, 60, 61, 70

Uniform (Haplospiza 

unicolor), 50, 61, 70

Finches (Fringillidae), 57–58, 

70

Fire-eye, White-shouldered 

(Pyriglena leucoptera), 

23–24, 61, 62, 63, 68

Flycatcher

Boat-billed (Megarynchus 

pitangua), 36–37, 69

Bran-colored (Myiophobus 

fasciatus), 72

Euler’s (Lathrotriccus euleri), 

29, 34–35, 61, 69

Fork-tailed (Tyrannus 

savana), 37–38, 69

Fuscous (Cnemotriccus 

fuscatus), 35, 69

Gray-hooded (Mionectes 

rufiventris), 32, 57, 59, 69

Piratic (Legatus leucophaius), 

36, 69

Sepia-capped (Leptopogon 

amaurocephalus), 32–33, 

59, 61, 69

Short-crested (Myiarchus 

ferox), 72

Social (Myiozetetes similis), 

36, 69

Streaked (Myiodynastes 

maculatus), 36, 61, 69

Suiriri (Suiriri suiriri), 31, 69

Swainson’s (Myiarchus 

swainsoni), 38, 69

Three-striped (Conopias 

trivirgatus), 72

Variegated (Empidonomus 

varius), 37, 62, 69

Yellow-olive (Tolmomyias 

sulphurescens), 34, 59, 69

Foliage-gleaner

Black-capped (Philydor 

atricapillus), 26, 59, 69

Buff-browed (Syndactyla 

rufosuperciliata), 27, 59, 

62, 69

Buff-fronted (Philydor 

rufum), 27, 59, 69

Ochre-breasted (Anabacerthia 

lichtensteini), 27, 59, 69

White-eyed (Automolus 

leucophthalmus), 27–28, 

59, 62, 69

Forest-falcon

Barred (Micrastur ruficollis), 

20, 61, 68

Formicariidae (Antthrushes), 

24, 68

Forpus xanthopterygius, 58, 70

Foster, William T., 60

fox, crab-eating (Cerdocyon 

thous), 3

Fringillidae (Finches), 57–58, 70

Fruitcrow, Red-ruffed 

(Pyroderus scutatus), 38, 

56, 64, 69

Fuchsia sp., 15

Furnariidae (Ovenbirds), 24–29, 

59, 64, 69, 72

Furnariinae, 59

Furnarius rufus, 26, 61, 69

Galictis cuja, 3

Geothlypis aequinoctialis, 54, 70

Geotrygon

montana, 71

violacea, 9, 68

Glaucidium brasilianum, 13, 

24, 61, 68

Gnatcatcher, Creamy-bellied 

(Polioptila lactea), 43, 64, 

69

Gnatcatchers (Polioptilidae), 

43, 69

Gnateater, Rufous 

(Conopophaga lineata), 

24, 68

Gnateaters (Conopophagidae), 

24, 68

Gnorimopsar chopi, 56, 70

gonads, enlarged, 59–60, 63

Grassquit, Blue-black (Volatinia 

jacarina), 50, 70

Greenlet, Rufous-crowned 

(Hylophilus poicilotis), 

41, 69

grison, lesser (Galictis cuja), 3

Grosbeak

Glaucous-blue (Cyanoloxia 

glaucocaerulea), 53, 61, 

62, 70

Ultramarine (Cyanoloxia 

brissonii), 53–54, 60–61, 

70

Ground Dove

Picui (Columbina picui), 

10–11, 61, 68

Ruddy (Columbina talpacoti), 

4, 10, 11, 59, 61, 68

Guan, Rusty-margined 

(Penelope superciliaris), 7, 

64, 67

Guans (Cracidae), 7, 64, 67

Guarea sp., 36, 39

A Guide to the Birds of South 

America (Meyer de 

Schauensee), 1

Guira Cuckoo (Guira guira), 4, 

11, 61, 62, 68

Guira guira, 4, 11, 61, 62, 68

Guyra Paraguay (conservation 

group), 63

Habia rubica, 52–53, 60–61, 70

Haplospiza unicolor, 50, 61, 70

Harpagus diodon, 8, 67

Hawk

Roadside (Rupornis 

magnirostris), 8, 67

Sharp-shinned (Accipiter 

striatus), 71

Short-tailed (Buteo 

brachyurus), 8, 67

Hawks (Accipitridae), 8, 64, 

67, 71

Hayes, F. E.

Batara cinerea, 21

on breeding season, 60

Cissopis leverianus, 45

Colaptes campestris, 19

Columbina talpacoti, 10, 11

Coryphospingus cucullatus, 

51

Crypturellus tataupa, 7

Cyanoloxia glaucocaerulea, 

53

Elaenia flavogaster, 30

Elaenia parvirostris, 30

hypotheticals, 58

Megascops choliba, 13

on migrants, 62

Neothraupis fasciata, 45

Stephanophorus diadematus, 

47

Tersina viridis, 48

Troglodytes aedon, 43

Heliomaster furcifer, 64, 72

Hemiptera, 21, 24, 34

Hemithraupis guira, 39, 45, 47, 

49, 50, 70

Hemitriccus

diops, 33, 59, 69

margaritaceiventer, 33, 59, 69

Hermit, Scale-throated 

(Phaethornis eurynome), 

15, 68

Heron

Black-crowned Night- 

(Nycticorax nycticorax), 71

Cocoi (Ardea cocoi), 71

Whistling (Syrigma sibilatrix), 

7, 67

Herons (Ardeidae), 7, 67, 71

Herpetotheres cachinnans, 72

Herpsilochmus rufimarginatus, 

23, 68
8 0 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Himantopus

himantopus, 58

mexicanus, 58, 70

Hirundinidae (Swallows), 42, 

69, 72

Hornero, Rufous (Furnarius 

rufus), 26, 61, 69

Hotel El Tirol del Paraguay, 2, 

2–4, 5

Hummingbird, Gilded 

(Hylocharis chrysura), 16, 

62–63, 68

Hummingbirds (Trochilidae), 

15–16, 62–63, 68, 72

Hydropsalis torquata, 14, 68

Hylocharis chrysura, 16, 62–63, 

68

Hylophilus poicilotis, 41, 69

Hypoedaleus guttatus, 21, 68

hypotheticals, 58–59, 70

Ibis

Bare-faced (Phimosus 

infuscatus), 71

Green (Mesembrinibis 

cayennensis), 58, 70

White-faced (Plegadis chihi), 

71

Ibises (Threskiornithidae), 58, 

70, 71

Icteridae (Blackbirds), 55–57, 

61, 70

Icterus cayanensis, 56, 70

Ictinia plumbea, 8, 67

Iguazú National Park, 

Argentina, 43

Inga marginata, 55

International Union for 

Conservation of Nature 

(IUCN)

Near Threatened species, 32, 

43, 45, 53, 64

Isler, M. L., 48

Isler, P. R., 48

Itapúa (department), Paraguay. 

see San Rafael National Park

IUCN. see International Union 

for Conservation of Nature

Ixodidae, 20

Jay, Plush-crested (Cyanocorax 

chrysops), 42, 69

Jays (Corvidae), 42, 69

Johnson, Ned K., 42

Kestrel, American (Falco 

sparverius), 8, 20, 68

Kingbird, Tropical (Tyrannus 

melancholicus), 37, 69

Kingfisher

Green (Chloroceryle 

americana), 72

Ringed (Megaceryle 

torquata), 16, 68

Kingfishers (Alcedinidae), 16, 

68, 72

Kiskadee, Great (Pitangus 

sulphuratus), 8, 36, 69

Kite

Gray-headed (Leptodon 

cayanensis), 71

Plumbeous (Ictinia plumbea), 

8, 67

Rufous-thighed (Harpagus 

diodon), 8, 67

Snail (Rostrhamus sociabilis), 

71

Swallow-tailed (Elanoides 

forficatus), 8, 62, 67

White-tailed (Elanus 

leucurus), 8, 67

Lapwing, Southern (Vanellus 

chilensis), 9, 68

Lathrotriccus euleri, 29, 34–35, 

61, 69

Lauraceae, 30

Leaftosser, Rufous-breasted 

(Sclerurus scansor), 24, 69

Legatus leucophaius, 36, 69

leks, 15, 39

Lepidocolaptes

angustirostris, 26, 69

falcinellus, 63, 72

fuscus, 64

Leptodon cayanensis, 71

Leptopogon amaurocephalus, 

32–33, 59, 61, 69

Leptotila

rufaxilla, 10, 68

verreauxi, 9–10, 60, 61, 62, 

63, 68

Lochmias nematura, 26, 69

Loranthaceae, 32

Lowen, J. C., 64

Lurocalis semitorquatus, 72

Machetornis rixosa, 35–36, 69

Mackenziaena

leachii, 21, 62, 68

severa, 21–22, 68

Madroño N., A., 64

Mallophaga, 24

Malvaceae, 15

Malvaviscus

penduliflorus, 15

sp., 15, 16, 52, 63

Manakin

Band-tailed (Pipra 

fasciicauda), 39, 60–61, 69

Swallow-tailed (Chiroxiphia 

caudata), 39, 59, 60, 61, 69

Manakins (Pipridae), 39, 69

Manettia luteorubra, 15

Mango, Black-throated 

(Anthracothorax 

nigricollis), 72

Manihot esculenta, 3

Marasmiaceae, 44

Marasmius sp., 44

Martin

Brown-chested (Progne 

tapera), 72

Gray-breasted (Progne 

chalybea), 14, 42, 69

Mbaracayú Forest Nature 

Reserve, 2, 65

Megaceryle torquata, 16, 68

Megarynchus pitangua, 36–37, 

69

Megascops choliba, 13, 68

Melanerpes candidus, 18, 61, 68

Meliaceae, 39

Mesembrinibis cayennensis, 

58, 70

Meyer de Schauensee, R., 1

Micrastur ruficollis, 20, 61, 68

migration and local movements, 

62–63

Milvago

chimachima, 20, 61, 68

chimango, 20, 68

Mimidae (Mockingbirds), 45, 69

Mimus saturninus, 45, 69

Mionectes rufiventris, 32, 57, 

59, 69

Misiones, Argentina, 21

Mockingbird, Chalk-browed 

(Mimus saturninus), 45, 69

Mockingbirds (Mimidae), 45, 

69

Molothrus

bonariensis, 56–57, 70

rufoaxillaris, 56, 70

molt, 61

annual cycle, 60, 63

breeding overlap, 11, 31, 41

methods, 5

Momotidae (Motmots), 17, 68

Monjita, White (Xolmis 

irupero), 64, 72

monkey, brown capuchin 

(Sapajus cay), 3

Moraceae, 61

Motmot, Rufous-capped 

(Baryphthengus 

ruficapillus), 17, 59, 61, 68

Motmots (Momotidae), 17, 68

Myers, J. P., 9

Myers, L. P., 9

Myiarchus

ferox, 72

swainsoni, 38, 69

Myiodynastes maculatus, 36, 

61, 69

Myiopagis

caniceps, 29, 59, 61, 69

viridicata, 29, 61, 69

Myiophobus fasciatus, 72

Myiopsitta monachus, 20–21, 

68

Myiornis auricularis, 33, 59, 69

Myiothlypis leucoblephara, 

54–55, 70

Myiozetetes similis, 36, 69

Myrtaceae, 21, 39

Near Threatened species 

(IUCN), 32, 43, 45, 53, 64

Nemosia pileata, 45, 49, 50, 70

Neothraupis fasciata, 45, 64, 69

Nephelea setosa, 3

nestlings, 52, 55

nests

Basileuterus culicivorus, 55

Cacicus haemorrhous, 56

Chiroxiphia caudata, 39

Coryphospingus cucullatus, 

51–52

Patagioenas picazuro, 9

Trogon surrucura, 16

Turdus leucomelas, 43

Turdus rufiventris, 44

Veniliornis spilogaster, 19

New World and African Parrots 

(Psittacidae), 20–21, 

58–59, 64, 68, 70

New World Quails 

(Odontophoridae), 7, 67

New World Vultures 

(Cathartidae), 7–8, 64, 67

Nighthawk, Short-tailed 

(Lurocalis semitorquatus), 

72

Night-heron, Black-crowned 

(Nycticorax nycticorax), 71

Nightjar

Little (Setopagis parvula), 

14, 68

Rufus (Antrostomus rufus), 

14, 68

Scissor-tailed (Hydropsalis 

torquata), 14, 68

Silky-tailed (Antrostomus 

sericocaudatus), 72

Nightjars (Caprimulgidae), 14, 

64, 68, 72

nine-banded armadillo 

(Dasypus novemcinctus), 3

Nonnula rubecula, 17, 68

Nothura, Spotted (Nothura 

maculosa), 58, 63, 70, 71

Nothura maculosa, 58, 63, 70, 

71

Nunlet, Rusty-breasted 

(Nonnula rubecula), 17, 68

Nyctibiidae (Potoos), 13–14, 

64, 68

Nyctibius griseus, 13–14, 61, 68

Nycticorax nycticorax, 71

Nyctidromus albicollis, 14, 68

Nystalus chacuru, 17, 68

Ocotea puberula, 61

Elaenia, 30

Empidonomus varius, 37
NUMBER 648 • 8 1

Myiarchus swainsoni, 38

Myiodynastes maculatus, 36

Pitangus sulphuratus, 36

Tersina viridis, 48

Thraupis sayaca, 48

Tityra cayana, 40

Turdus amaurochalinus, 44

Tyrannus melancholicus, 37

Tyrannus savana, 38

Vireo olivaceus, 41

Odontophoridae (New World 

Quails), 7, 67

Odontophorus capueira, 7, 67

Onagraceae, 15

opossum, white-eared 

(Didelphis albiventris), 3

Oriole, Epaulet (Icterus 

cayanensis), 56, 70

ovaries, 60

Ovenbirds (Furnariidae), 24–29, 

59, 64, 69, 72

Owl

Buff-fronted (Aegolius 

harrisii), 13, 61, 64, 68

Burrowing (Athene 

cunicularia), 13, 61, 68

Ferruginous Pygmy- 

(Glaucidium brasilianum), 

13, 24, 61, 68

Tawny-browed (Pulsatrix 

koeniswaldiana), 58, 63, 

64, 70, 71

Tropical Screech- (Megascops 

choliba), 13, 68

Owls (Strigidae), 13, 58, 61, 64, 

68, 70

Oxyruncidae, 72

Oxyruncus cristatus, 72

Pachyramphus

polychopterus, 40, 69

validus, 72

Paraguay, map, 2

Parakeet

Maroon-bellied (Pyrrhura 

frontalis), 21, 68

Monk (Myiopsitta 

monachus), 20–21, 68

Nanday (Aratinga nenday), 

58, 70

White-eyed (Psittacara 

leucophthalmus), 59, 70

Paroaria capitata, 64, 72

Parrot

Pileated (Pionopsitta pileata), 

58, 70

Scaly-headed (Pionus 

maximiliani), 21, 61, 68

Turquoise-fronted (Amazona 

aestiva), 58, 70

Parrotlet, Blue-winged (Forpus 

xanthopterygius), 58, 70

Parrots (Psittacidae), 20–21, 61, 

64, 68, 70

Parula, Tropical (Setophaga 

pitiayumi), 47, 54, 70

Parulidae (Wood-warblers), 

54–55, 70

Patagioenas

cayennensis, 71

picazuro, 4, 9, 59, 61, 62, 68

Pauraque, Common 

(Nyctidromus albicollis), 

14, 68

Penelope superciliaris, 7, 64, 67

Pentatomidae, 34

Peppershrike, Rufous-browed 

(Cyclarhis gujanensis), 

41, 69

Petrochelidon pyrrhonota, 42, 

62, 69

Pewee

Tropical (Contopus cinereus), 

35, 69

Western Wood (Contopus 

sordidulus), 30

Phacellodromus rufifrons, 64, 72

Phaethornis eurynome, 15, 68

Phasmatodea, 8

Philydor

atricapillus, 26, 59, 69

rufum, 27, 59, 69

Philydorinae, 59

Phimosus infuscatus, 71

Phoradendron piperoides, 32, 

57, 58

Phyllomyias burmeisteri, 29, 69

Phylloscartes

eximius, 22, 32, 59, 64, 69

ventralis, 32, 59, 69

Piaya cayana, 12, 62, 68

Picidae (Woodpeckers), 18–20, 

61, 64, 68

Piculet, Ochre-collared 

(Picumnus temminckii), 18, 

59, 61, 68

Picumnus temminckii, 18, 59, 

61, 68

Pigeon

Pale-vented (Patagioenas 

cayennensis), 71

Piacazuro (Patagioenas 

picazuro), 4, 9, 59, 61, 

62, 68

Rock (Columba livia), 9, 60, 

61, 63, 68

Pigeons (Columbidae)

annual cycle, 63

diet, 61

reproduction, 59–60

species list, 9–11, 68, 71

Pinaceae, 7

Pinus sp., 7

Pionopsitta pileata, 58, 70

Pionus maximiliani, 21, 58, 

61, 68

Pipraeidea melanonota, 47, 

54, 70

Pipra fasciicauda, 39, 60–61, 69

Pipridae (Manakins), 39, 69

Piprites, Wing-barred (Piprites 

chloris), 40–41, 59, 61, 

63, 69

Piprites chloris, 40–41, 59, 61, 

63, 69

Pipromorphidae, 59

Piranga flava, 64, 72

Pitangus sulphuratus, 8, 36, 69

Pizo, M. A., 15

Platyrinchus mystaceus, 34, 

59, 69

Plegadis chihi, 71

Plovercrest, Green-crowned 

(Stephanoxis lalandi), 15, 

63, 68

Plovers (Charadriidae), 9, 68

plumage, 5, 6, 11, 60–61

pneumatization, skull, 5, 6, 59, 

60–61

Poaceae bamboo, 3

Poecilotriccus plumbeiceps, 34, 

59, 69

Polioptila lactea, 43, 64, 69

Polioptilidae (Gnatcatchers), 

43, 69

Potoo, Common (Nyctibius 

griseus), 13–14, 61, 68

Potoos (Nyctibiidae), 13–14, 

64, 68

Progne

chalybea, 14, 42, 69

tapera, 72

Psittacara leucophthalmus, 59, 

70

Psittacidae (New World and 

African Parrots), 20–21, 

58–59, 61, 64, 68, 70

Psychotria carthagenensis, 39, 

43, 44, 45

Pteroglossus castanotis, 17–18, 

64, 68

Puffbird, White-eared (Nystalus 

chacuru), 17, 68

Puffbirds (Bucconidae), 17, 68

Pulsatrix koeniswaldiana, 58, 

63, 64, 70, 71

Pygmy-owl, Ferruginous 

(Glaucidium brasilianum), 

13, 24, 61, 68

Pygmy-tyrant

Drab-breasted (Hemitriccus 

diops), 33, 59, 69

Eared (Myiornis auricularis), 

33, 59, 69

Tawny-crowned 

(Euscarthmus meloryphus), 

32, 69

Pygochelidon cyanoleuca, 72

Pyriglena leucoptera, 23–24, 61, 

62, 63, 68

Pyroderus scutatus, 38, 56, 

64, 69

Pyrrhocoma ruficeps, 45–46, 

59, 60, 61, 70

Pyrrhura frontalis, 21, 68

Quail, Spot-winged Wood- 

(Odontophorus capueira), 

7, 67

Quail-dove

Ruddy (Geotrygon montana), 

71

Violaceous (Geotrygon 

violacea), 9, 68

Quails, New World 

(Odontophoridae), 7, 67

Rail, Slaty-breasted Wood- 

(Aramides saracura), 8–9, 67

Rails (Rallidae), 8–9, 67

rainfall patterns, 3–4, 5

Rallidae (Rails), 8–9, 67

Ramphastidae (Toucans), 

17–18, 68, 72

Ramphastos

dicolorus, 17, 64, 68

toco, 17, 64, 68

Recurvirostridae (Avocets and 

Stilts), 58, 70

Relbunium hypocarpium, 51

Remsen, J. V., Jr., 71

reproduction, 59–60, 60

annual cycle, 63

methods, 5

molt-breeding overlap, 11, 

31, 41

terminology and aging, 6

Reynaerts, Armando, 4

Rhipsalis

cereuscula, 57

shaferi, 57

Rhynchocyclidae, 59

Ricinus communis, 3

Ridgely, R. S.

Batara cinerea, 21

Contopus cinereus, 35

Dacnis cayana, 49

Neothraupis fasciata, 45

Pachyramphus polychopterus, 

40

Sicalis flaveola, 50

Tersina viridis, 48–49, 62

Tolmomyias sulphurescens, 34

Turdus albicollis, 45

Turdus nigriceps, 44

Rohwer, S., 13

Rostrhamus sociabilis, 71

Rubiaceae, 15, 39, 51

Ruellia angustifolia, 15, 16

Rupornis magnirostris, 8, 67

Rutaceae, 11

Salicaceae, 39

Saltator

Grayish (Saltator 

coerulescens), 72
8 2 • SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Saltator (continued)

Green-winged (Saltator 

similis), 52, 70

Saltator

coerulescens, 72

similis, 52, 70

Sandpiper, Buff-breasted 

(Calidris subruficollis), 9, 

62, 64, 68

Sandpipers (Scolopacidae), 9, 68

San Rafael National Park

comparisons with other sites, 

64, 65

Dromococcyx phasianellus, 

12

Euscarthmus meloryphus, 32

hypotheticals, 58

map, 2

Petrochelidon pyrrhonota, 42

Pipra fasciicauda, 39

Polioptila lactea, 43

Sapajus cay, 3

Sapindaceae, 30, 36, 38, 57

Sapucái, Paraguay

breeding season, 60

Colaptes campestris, 19

Crypturellus tataupa, 7

Dryocopus lineatus, 19

Elaenia flavogaster, 30

map, 2

Megascops choliba, 13

Pitangus sulphuratus, 36

Troglodytes aedon, 43

Schiffornis, Greenish 

(Schiffornis virescens), 40, 

61, 62, 69

Schiffornis virescens, 40, 61, 

62, 69

Schoeniophylax

phryganophilus, 64, 72

Sclerurus scansor, 24, 69

Scolopacidae (Sandpipers), 9, 68

Screech-owl, Tropical 

(Megascops choliba), 13, 68

Scythebill, Black-billed 

(Campylorhamphus 

falcularius), 25–26, 69

Seedeater

Blackish-blue (Amaurospiza 

moesta), 53, 64, 70

Double-collared (Sporophila 

caerulescens), 51, 61, 62, 

63, 70

Seed-finch, Chestnut-bellied 

(Sporophila angolensis), 

50–51, 70

Selenidera maculirostris, 72

Serpophaga

munda, 31, 62, 64, 69

subcristata, 31, 62, 69

Setopagis parvula, 14, 68

Setophaga pitiayumi, 47, 54, 70

Sharpbill (Oxyruncus cristatus), 

72

Sicalis flaveola, 4, 50, 60, 61, 70

Sick, H., 62, 63

Sirystes, Sibilant (Sirystes 

sibilator), 38, 69

Sirystes sibilator, 38, 69

Siskin, Hooded (Spinus 

magellanicus), 57, 70

Sittasomus griseicapillus, 24–25, 

63, 69

skull pneumatization, 5, 6, 59, 

60–61

Smith, P., 40, 47, 58, 63–64, 71

Solanaceae, 30, 37

Solanum sp., 37, 43

Sorocea bonplandii, 61

Spadebill, White-throated 

(Platyrinchus mystaceus), 

34, 59, 69

Sparrow, Rufous-collared 

(Zonotrichia capensis), 52, 

61, 70

Sparrows (Emberizidae), 52, 70

Spinetail

Chotoy (Schoeniophylax 

phryganophilus), 72

Gray-bellied (Synallaxis 

cinerascens), 28, 69

Olive (Cranioleuca obsoleta), 

28, 59, 69

Pale-breasted (Synallaxis 

albescens), 71

Rufous-capped (Synallaxis 

ruficapilla), 28, 59, 62, 69

Sooty-fronted (Synallaxis 

frontalis), 29, 59, 69

Spix’s (Synallaxis spixi), 

28–29, 59, 69

Spinus magellanicus, 57, 70

Sporophila

angolensis, 50–51, 70

caerulescens, 51, 61, 62, 63, 70

Starthroat, Blue-tufted 

(Heliomaster furcifer), 64, 

72

Stephanophorus diadematus, 

47, 62, 70

Stephanoxis lalandi, 15, 63, 68

Stilt, Black-necked (Himantopus 

mexicanus), 58, 70

Stilts and Avocets 

(Recurvirostridae), 58, 70

Streamcreeper, Sharp-tailed 

(Lochmias nematura), 26, 

69

Strigidae (Owls), 13, 58, 61, 64, 

68, 70

Suiriri suiriri, 31, 69

Swallow

Blue-and-white (Pygochelidon 

cyanoleuca), 72

Chilean (Tachycineta 

leucopyga), 72

Cliff (Petrochelidon 

pyrrhonota), 42, 62, 69

Swallows (Hirundinidae), 42, 

69, 72

Swift

Gray-rumped (Chaetura 

cinereiventris), 14–15, 42, 

68

Sick’s (Chaetura 

meridionalis), 72

Swifts (Apodidae), 14–15, 68, 

72

Synallaxis

albescens, 71

cinerascens, 28, 69

cinereus, 59

frontalis, 29, 59, 69

ruficapilla, 28, 59, 62, 69

spixi, 28–29, 59, 69

Syndactyla rufosuperciliata, 27, 

59, 62, 69

Syrigma sibilatrix, 7, 67

Tachycineta leucopyga, 72

Tachyphonus coronatus, 47, 59, 

60, 61, 70

Tanager

Black-goggled (Trichothraupis 

melanops), 46–47, 70

Chestnut-headed 

(Pyrrhocoma ruficeps), 

45–46, 59, 60, 61, 70

Diademed (Stephanophorus 

diadematus), 47, 62, 70

Fawn-breasted (Pipraeidea 

melanonota), 47, 54, 70

Green-headed (Tangara 

seledon), 48, 70

Guira (Hemithraupis guira), 

39, 45, 47, 49, 50, 70

Hepatic (Piranga flava), 64, 

72

Hooded (Nemosia pileata), 

45, 49, 50, 70

Magpie (Cissopis leverianus), 

45, 69

Ruby-crowned (Tachyphonus 

coronatus), 47, 59, 60, 

61, 70

Sayaca (Thraupis sayaca), 48, 

59, 61, 62, 70

Swallow (Tersina viridis), 

48–49, 60, 61, 62, 70

White-banded (Neothraupis 

fasciata), 45, 64, 69

Tanagers (Thraupidae), 45–52, 

61, 64, 69–70, 72

Tangara seledon, 48, 70

Tapera naevia, 11, 68

Tersina viridis, 48–49, 60, 61, 

62, 70

testes, 60, 63

Thalurania furcata, 15–16, 

62–63, 64, 68

Thamnophilidae (Antbirds), 

21–24, 68

Thamnophilus

caerulescens, 22, 59, 61, 62, 68

ruficapillus, 22, 64, 68

Thornbird, Rufous-fronted 

(Phacellodromus rufifrons), 

64, 72

Thraupidae (Tanagers), 45–52, 

61, 64, 69–70, 72

Thraupis sayaca, 48, 59, 61, 

62, 70

Threskiornithidae (Ibises), 58, 

70, 71

Thrush

Creamy-bellied (Turdus 

amaurochalinus), 44, 69

Pale-breasted (Turdus 

leucomelas), 43, 69

Rufous-bellied (Turdus 

rufiventris), 43–44, 69

Slaty (Turdus nigriceps), 44, 

67, 69

White-necked (Turdus 

albicollis), 44–45, 69

Thrushes (Turdidae), 43–45, 

61, 69

Tillandsia

stricta, 15

usneoides, 3

Tinamidae (Tinamous), 7, 58, 

64, 67, 70, 71

Tinamou

Brown (Crypturellus 

obsoletus), 71

Tataupa (Crypturellus 

tataupa), 7, 64, 67

Tinamous (Tinamidae), 7, 58, 

64, 67, 70, 71

Tityra

Black-crowned (Tityra 

inquisitor), 39–40, 69

Black-tailed (Tityra cayana), 

40, 69

Tityra

cayana, 40, 69

inquisitor, 39–40, 69

semifasciata, 40

Tityras (Tityridae), 39–41, 61, 

69, 72

Tityridae (Tityras), 39–41, 61, 

69, 72

Tody-flycatcher, Ochrefaced (Poecilotriccus 

plumbeiceps), 34, 59, 69

Tody-tyrant, Pearlyvented (Hemitriccus 

margaritaceiventer), 33, 

59, 69

Tolmomyias sulphurescens, 34, 

59, 69

Toucan

Red-breasted (Ramphastos 

dicolorus), 17, 64, 68

Toco (Ramphastos toco), 17, 

64, 68
NUMBER 648 • 8 3

Toucanet, Spot-billed 

(Selenidera maculirostris), 

72

Toucans (Ramphastidae), 

17–18, 68, 72

tree ferns, 3

Trema micrantha

Chiroxiphia caudata, 39

Cyanoloxia glaucocaerulea, 

53

Dacnis cayana, 49

Elaenia, 30

Icterus cayanensis, 56

Pitangus sulphuratus, 36

Trichothraupis melanops, 

47

Turdus, 43, 45

Trichilia catigua, 39, 49, 61

Trichothraupis melanops, 

46–47, 70

diet, 62

mixed-species flocks, 22, 39, 

49, 54, 55

plumage, 60, 61

predators, 13, 24

Trochilidae (Hummingbirds), 

15–16, 62–63, 68, 72

Troglodytes aedoni, 4, 42–43, 

69

Troglodytidae (Wrens), 42–43, 

69

Trogon

Black-throated (Trogon 

rufus), 16, 68

Surucua (Trogon surrucura), 

16, 68

Trogon

rufus, 16, 68

surrucura, 16, 68

Trogonidae (Trogons), 16, 68

Trogons (Trogonidae), 16, 68

Tudor, G.

Batara cinerea, 21

Contopus cinereus, 35

Dacnis cayana, 49

Neothraupis fasciata, 45

Pachyramphus polychopterus, 

40

Sicalis flaveola, 50

Tersina viridis, 48–49, 62

Tolmomyias sulphurescens, 

34

Turdus albicollis, 45

Turdus nigriceps, 44

tung trees (Vernicia fordii), 3, 4

Turdidae (Thrushes), 43–45, 

61, 69

Turdus

albicollis, 44–45, 69

amaurochalinus, 44, 69

leucomelas, 43, 69

nigriceps, 44, 67, 69

nigriceps sublaris, 44, 67

rufiventris, 43–44, 69

Tyrannidae (Tyrant Flycatchers), 

29–38, 59, 61, 64, 69, 72

Tyrannulet

Mottle-cheeked (Phylloscartes 

ventralis), 32, 59, 69

Rough-legged (Phyllomyias 

burmeisteri), 29, 69

White-bellied (Serpophaga 

munda), 31, 62, 64, 69

White-crested (Serpophaga 

subcristata), 31, 62, 69

Yellow (Capsiempis flaveola), 

31, 61, 63, 69

Tyrannus

melancholicus, 37, 69

savana, 37–38, 69

Tyrant

Cattle (Machetornis rixosa), 

35–36, 69

Drab-breasted Pygmy- 

(Hemitriccus diops), 33, 

59, 69

Eared Pygmy- (Myiornis 

auricularis), 33, 59, 69

Long-tailed (Colonia 

colonus), 35, 69

Pearly-vented Tody- 

(Hemitriccus 

margaritaceiventer), 33, 

59, 69

Southern Bristle- 

(Phylloscartes eximius), 22, 

32, 59, 64, 69

Tawny-crowned Pygmy- 

(Euscarthmus meloryphus), 

32, 69

Tyrant Flycatchers (Tyrannidae), 

29–38, 59, 61, 64, 69, 72

Tytonidae, 64

Urticaceae, 61

Vanellus chilensis, 9, 68

Veniliornis spilogaster, 19, 68

Vernicia fordii, 3, 4

Villarrica, Paraguay, 58

Vireo, Red-eyed (Vireo 

olivaceus), 41–42, 57, 69

Vireonidae (Vireos), 41–42, 69

Vireo olivaceus, 41–42, 57, 69

Vireos (Vireonidae), 41–42, 69

Volatinia jacarina, 50, 70

Vulture

Black (Coragyps atratus), 

7–8, 67

Turkey (Cathartes aura), 7, 67

Vultures, New World 

(Cathartidae), 7–8, 64

Warbler

Golden-crowned (Basileuterus 

culicivorus), 22, 47, 49, 54, 

55, 70

White-browed (Myiothlypis 

leucoblephara), 54–55, 70

white-eared opossum (Didelphis 

albiventris), 3

Willis, E. O., 43

Woodcreeper

Lesser (Xiphorhynchus 

fuscus), 25, 69

Narrow-billed 

(Lepidocolaptes 

angustirostris), 26, 69

Olivaceous (Sittasomus 

griseicapillus), 24–25, 

63, 69

Plain-winged (Dendrocincla 

turdina), 25, 64, 69

Planalto (Dendrocolaptes 

platyrostris), 25, 69

Scalloped (Lepidocolaptes 

falcinellus), 63, 72

Woodnymph, Fork-tailed 

(Thalurania furcata), 

15–16, 62–63, 64, 68

Woodpecker

Green-barred (Colaptes 

melanochloros), 19, 61, 

68

Lineated (Dryocopus 

lineatus), 19, 61, 64, 68

Robust (Campephilus 

robustus), 19–20, 64, 68

White (Melanerpes candidus), 

18, 61, 68

White-spotted (Veniliornis 

spilogaster), 19, 68

Woodpeckers (Picidae), 18–20, 

61, 64, 68

Wood-quail, Spot-winged 

(Odontophorus capueira), 

7, 67

Wood-rail, Slaty-breasted 

(Aramides saracura), 

8–9, 67

Wood-warblers (Parulidae), 

54–55, 70

Wren, House (Troglodytes 

aedoni), 4, 42–43, 69

Wrens (Troglodytidae), 42–43, 

69

Xenopinae, 59

Xenops

Plain (Xenops minutus), 26, 

69

Streaked (Xenops rutilans), 

26, 69

Xenops, 59

minutus, 26, 69

rutilans, 26, 69

Xiphorhynchus fuscus, 25, 69

Xolmis irupero, 64, 72

Ybycuí National Park, 2, 39

Yellowthroat, Masked 

(Geothlypis aequinoctialis), 

54, 70

yuca (Manihot esculenta), 3

Zelaya, P., 35

Zenaida auriculata, 71

Zink, Robert M., 42

Zonotrichia capensis, 52, 61, 

70
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