Mao 

Gymnomyza samoensis

Species Report 

May 2020

U.S. Fish and Wildlife Service

Pacific Islands Fish and Wildlife Office

Honolulu, HI
ii

Cover Photo Credits 

Mao, Gymnomyza samoensis photographs courtesy R. Stirnemann. 

Suggested Citation 

USFWS. 2020. Species Status Assessment for Mao (Gymnomyza samoensis). May 2020

(Version 1.1). U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office, 

Honolulu, HI. 46 pp. 

Primary Authors 

Version 1.1 of this document was prepared by Fred Amidon and James Kwon of the Pacific 

Islands Fish and Wildlife Office, Honolulu, Hawaii. Preparation and review was conducted by 

Gregory Koob, Megan Laut, and Stephen E. Miller of the Pacific Islands Fish and Wildlife 

Office.
iii

Executive Summary

The Mao or Ma‘oma‘o (Gymnomyza samoensis) is a large endangered honeyeater (Family

Meliphagidae) endemic to the Samoa archipelago. Historically, the species occurred on the 

islands of Savai‘i and ‘Upolu in the independent nation of Samoa, and on the island of Tutuila in 

American Samoa, an unincorporated territory of the United States. Historical population 

estimates are unknown but the species was considered widespread in forested habitats on Savai‘i 

and ‘Upolu. Currently the species is only known to occur on the islands of Savai‘i and ‘Upolu

and the total population is estimated to be around 500 individuals.

The range restriction and population declines are believed to be associated with the loss and 

degradation of Mao habitat and high rates of nest failure and fledgling depredations. Mao habitat 

loss and degradation is related to human development (.e.g, agriculture and logging), increase in 

the distribution and number of invasive plant species, increase in number of feral ungulates, and 

forest impacts from naturally occurring tropical cyclones (hurricanes). Increased nest failures and 

fledgling depredations are related to nest predation by introduced rats, depredation of juveniles 

by feral cats, and nest loss due to naturally occurring tropical cyclones (hurricanes).

This Species Report evaluates the viability of the Mao, defined as the likelihood that it will 

persist over time. Viability is assessed by the resiliency, representation, and redundancy of the 

Mao populations. Each of these terms, and the Mao’s resultant viability, under current conditions 

are described below. Currently, there are no known Mao in American Samoa.

Resiliency is the capacity of a population to withstand stochastic disturbance events. There are 

no historical population estimates, but the species was considered widespread in forested habitats 

on Savai‘i and ‘Upolu. Currently, the Savai‘i, ‘Upolu, and Tutuila populations have low to 

moderate, low, and no resiliency, respectively. The Tutuila population is believed extirpated and 

both the Savai‘i and ‘Upolu populations have experienced population restrictions and declines. 

These trends are expected to continue if the threats to the species continue at current levels or 

worsen.

Representation is having one or more populations of a species occupying the full range of habitat 

types used by the species. Currently, the species is considered to have low to moderate 

representation due to range restrictions on Savai‘i and ‘Upolu and the extirpation of the Tutuila 

population. These range restrictions are expected to continue if the threats to the species continue 

at current levels or worsen.

Redundancy is minimizing the risk of extinction of the species by establishing multiple 

populations across a landscape so some populations will always survive catastrophic events.

Currently, the species is considered to have moderate redundancy as the species still occurs in 

two of the three original populations. Redundancy is expected to decrease in the future if threats 

to the species continue at current levels or worsen, potentially resulting in the extirpation of one 

or both of the two remaining populations.
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Table of Contents

Cover Photo Credits........................................................................................................................ ii

Suggested Citation .......................................................................................................................... ii

Primary Authors.............................................................................................................................. ii

Executive Summary.......................................................................................................................iii

List of Figures................................................................................................................................. v

List of Tables ................................................................................................................................. vi

Introduction..................................................................................................................................... 1

Regulatory History.......................................................................................................................... 1

Methodology................................................................................................................................ 1

Part 1. Life History and Historical Status....................................................................................... 4

Geography ................................................................................................................................... 4

Species Description ................................................................................................................... 12

Life History................................................................................................................................ 14

Historical Range, Distribution, and Population Status.............................................................. 18

Part 2. Current Conditions and Species Status.............................................................................. 20

Current Range and Distribution................................................................................................. 20

Factors Affecting Viability........................................................................................................ 22

Resiliency, Representation, and Redundancy of the Species ....................................................... 30

Resiliency of Current Populations............................................................................................. 30

Current Representation and Redundancy of the Species........................................................... 30

Literature Cited ............................................................................................................................. 32
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List of Figures

Figure 1. The three conservation biology principles of resiliency, redundancy, and 

representation, or the “3Rs”............................................................................................................ 2

Figure 2. Islands of the Samoan archipelago.................................................................................. 5

Figure 3. Monthly mean precipitation for selected areas of the Samoan archipelago. All data 

from PCCSP (2019). ....................................................................................................................... 6

Figure 4. Monthly mean temperatures for selected areas of the Samoan archipelago. All data 

from PCCSP (2019). ....................................................................................................................... 7

Figure 5. Cyclone (hurricane) tracks for the central South Pacific from 1898 to 2019. All data 

from Knapp et al. (2010) and NOAA IBTrACS (2019). ................................................................ 7

Figure 6. Locations of roads in the Samoan archipelago................................................................ 9

Figure 7. Vegetation land cover on American Samoa (from data by Meyer et al., 2017)............ 10

Figure 8. Vegetation land cover for Samoa (from data by LINZ, 2015a-i).................................. 11

Figure 9. Photograph of an adult Mao by R. Stirnemann. ............................................................ 13

Figure 10. Beak, wing, tarsus, and tail measurements from Mao in Western Samoa (Stirnemann 

et al., 2015a, p. 381)...................................................................................................................... 13

Figure 11. Breeding cycle of the Mao (from data in Stirnemann et al., 2015b, pp.5-7)............... 15

Figure 12. Generalized life stages of the Mao. ............................................................................. 17

Figure 13. The estimated historical range of the Mao. ................................................................. 19

Figure 14. Sites where Mao where observed in Samoa from 1987 to 2000. (Land cover from 

MNRE, 2006, p. 3)........................................................................................................................ 20

Figure 15. Locations in 2005-2006 where Mao were detected (●) and not detected (+) (MNRE 

2006, p. 4; Tipamaa 2007, in litt., cited in Birdlife International 2012). Land cover from MNRE, 

2006, p. 4....................................................................................................................................... 21

Figure 16. Estimated forest cover in Samoa from 1954 to 1999 (MNRE 2014, in litt.; FAO 2005, 

in litt.) Maps from Figures 4-6 of MNRE (2006, p. 6-7).............................................................. 23
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List of Tables

Table 1. Census estimates of the American Samoa population on the islands of Tutuila, Ta’ū, 

Ofu, Olosega, and Swains............................................................................................................... 8

Table 2. Census estimates of the Samoa population by island and for the entire country.............. 8

Table 3. Major land cover types for the Samoan archipelago. Area estimates in acres (hectares).

....................................................................................................................................................... 11

Table 4. Estimated acreages of vegetation types for the main islands of American Samoa. Area in 

acres (hectares).............................................................................................................................. 12

Table 5. List of Gymnomyza species and their conservation status. All data obtained from 

Higgins et al. (2008, p. 670-671). ................................................................................................. 14

Table 6. Diet and foraging locations recorded for Gymnomyza species. All data obtained from 

Higgins et al. (2008, p. 670-671). ................................................................................................. 14

Table 7. Nest descriptions and nest location information for Gymnomyza species..................... 16

Table 8. Estimated lifespans, sizes, and weights of honeyeaters in Australia. Lifespan estimates 

are based on banded wild birds..................................................................................................... 17
1

Introduction

This document synthesizes the available information on the Mao and provides an assessment of 

the its current viability. The Mao or Ma‘oma‘o (Gymnomyza samoensis) is a large honeyeater

(Family Meliphagidae) endemic to the Samoa archipelago (Figure 1). Historically, the species 

occurred on the islands of Savai‘i and ‘Upolu in the independent nation of Samoa and the island 

of Tutuila in American Samoa, an unincorporated territory of the United States (Watling 2001, p. 

175). Currently the species is only known to occur on the islands of Savai‘i and ‘Upolu. 

Regulatory History

The U.S. Fish and Wildlife Service issued a final listing rule in 2016, in which the Service 

determine endangered status under the Endangered Species Act of 1973, as amended, for two 

endemic American Samoan land snails (Eua zebrina and Ostodes strigatus), the American 

Samoa distinct population segment of the Friendly Ground-dove, the Pacific Sheath-tailed Bat, 

(South Pacific subspecies) (Emballonura semicaudata semicaudata), and the Mao (Gymnomyza 

samoensis). The Mao was listed as endangered under the Endangered Species Act in 2016, and is 

also classified as endangered by the IUCN (USFWS 2016a, Birdlife International 2016). The 

effect of this regulation added these species to the List of Endangered and Threatened Wildlife. 

There are no additional regulatory documents for Mao, apart from a 2014 Candidate Notice of 

Review (CNOR) and a proposed rule for listing in 2016. (Links to the CNOR,and the proposed

and final listing rules are at https://www.fws.gov/endangered/, then do a species search for

Gymnomyza samoensis.

Methodology

This Species Report provides an assessment of the Mao’s current viability, based on the best 

information available at this time, including peer-reviewed literature, gray literature 

(government, academic, business, and industry reports), and expert elicitation. Viability is the 

ability or likelihood of the species to maintain populations over time, i.e., likelihood of avoiding 

extinction. The viability of federally listed species is currently being assessed using the three 

conservation biology principles of resiliency, redundancy, and representation, or the “3Rs” 

(Figure 1; USFWS 2016b, p 12-16). The viability of Mao was evaluated by describing what the 

bird needs to be resilient, redundant, and represented, followed by comparing this assessment of 

what is needed for viability to the status of the bird in its current condition or its condition based 

on the most recent information.

Our analysis follows the SSA Framework (Figure 1) developed by the USFWS (USFWS 

2016b), in which viability is defined as the likelihood that a species will persist over time and is 

a product of resiliency, representation, and redundancy, otherwise known as “the three Rs” 

(USFWS 2016b, p. 12-13). 
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Figure 1. The three conservation biology principles of resiliency, redundancy, and representation, 

or the “3Rs”.

The definitions of the “3Rs” are defined below, and are used to infer the status of the species.

• Resiliency is the capacity of a population or a species to withstand the more extreme 

limits of normal year-to-year variation in environmental conditions such as temperature 

and rainfall extremes, and unpredictable but seasonally frequent perturbations such as 

fire, flooding, and storms (i.e., environmental stochasticity). Quantitative information on 

the resiliency of a population or species is often unavailable. However, in the most 

general sense, a population or species that can be found within a known area over an 

extended period of time (e.g., seasons or years) is likely to be resilient to current 
3

environmental stochasticity. If quantitative information is available, a resilient population 

or species will show enough reproduction and recruitment to maintain or increase the 

numbers of individuals in the population or species, and possibly expand the range of 

occupancy. Thus, resiliency is positively related to population size and growth rate, and 

may also influence the connectivity among populations. 

• Redundancy is having more than one resilient population distributed across the 

landscape, thereby minimizing the risk of extinction of the species. To be effective at 

achieving redundancy, the distribution of redundant populations across the geographic 

range should exceed the area of impact of a catastrophic event that would otherwise 

overwhelm the resilient capacity of the populations of a species. In the report, 

catastrophic events are distinguished from environmental stochasticity in that they are 

relatively unpredictable and infrequent events that exceed the more extreme limits of 

normal year-to-year variation in environmental conditions (i.e., environmental 

stochasticity), and thus expose populations or species to an elevated extinction risk within 

the area of impact of the catastrophic event. Redundancy is conferred upon a species 

when the geographic range of the species exceeds the area of impact of any anticipated 

catastrophic event. In general, a wider range of habitat types, a greater geographic 

distribution, and connectivity across the geographic range will increase the redundancy of 

a species and its ability to survive a catastrophic event.

• Representation is having more than one population of a species occupying the full range 

of habitat types used by the species. Alternatively, representation can be viewed as 

maintaining the breadth of genetic diversity within and among populations, in order to 

allow the species to adapt to changing environmental conditions over time. The diversity 

of habitat types, or the breadth of the genetic diversity of a species, is strongly influenced 

by the current and historic biogeographical range of the species. Conserving this range 

should take into account historic latitudinal and longitudinal ranges, elevation gradients, 

climatic gradients, soil types, habitat types, seasonal condition, etc. Connectivity among 

populations and habitats is also an important consideration in evaluating representation.

The viability of a species is derived from the combined effects of the 3Rs. A species is 

considered viable when there are a sufficient number of self-sustaining populations (resiliency) 

distributed over a large enough area across the range of the species (redundancy) and occupying 

a range of habitats to maintain environmental and genetic diversity (redundancy) to allow the 

species to persist indefinitely when faced with annual environmental stochasticity and infrequent 

catastrophic events. Common ecological features are part of each of the 3Rs. This is especially 

true of connectivity among habitats across the range of the species. Connectivity sustains 

dispersal of individuals, which in turn greatly affects genetic diversity within and among 

populations. Connectivity also sustains access to the full range of habitats normally used by the 

species, and is essential for re-establishing occupancy of habitats following severe environmental 

stochasticity or catastrophic events (see Figure 1 for examples of overlap among the 3Rs). 

Another way the three principles are inter-related is through the foundation of population 
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resiliency. Resiliency is assessed at the population level, while redundancy and representation 

are assessed at the species level. Resiliency populations are the necessary foundation needed to 

attain sustained or increasing Representation and Redundancy within the species. 

The assessment of viability is not binary, in which a species is either viable or not, but rather on 

a continual scale of degrees of viability, from low to high. The health, number and distribution of 

populations were analyzed to determine the 3Rs and viability. In broad terms, the more resilient, 

represented, and redundant a species is, the more viable the species is. The current understanding 

of factors, including threats and conservation actions, will influence how the 3Rs and viability 

are interpreted for Mao.

Part 1. Life History and Historical Status

Geography

The Samoan archipelago is a chain of 13 islands and two atolls in the Pacific Ocean south of the 

equator (Figure 2), and is divided into the unincorporated United States Territory American 

Samoa to the southeast and the independent nation of Samoa to the northwest (Craig 2009, p. 5).

These islands extend northwest to southeast over 298 miles (mi) (480 kilometers (km)) between 

13o and 15o south latitude, and 168o to 172o west longitude (Goldin 2002, p. 4). They date to the 

early Pleistocene and were formed as hot-spot shield volcanoes, with the older islands located on 

the northwestern end of the chain (Thornberry-Ehrlich 2008, pp. 16, 28). 

American Samoa consists of five high islands and two atolls: Tutuila (the largest island; 54 

square (sq.) mi (140 sq. km)); Aunu‘u (1 sq. mi (2 sq. km)) off the southeast end of Tutuila; Ofu 

and Olosega (3.5 sq. mi (9 sq. km)) separated by a narrow channel now spanned by a bridge; 

Ta‘ū (15 sq. mi (39 sq. km)); Rose Atoll (1.5 sq. mi (4 sq. km)), a National Wildlife Refuge) 

with two small uninhabited islands, Rose and Sand; and Swains Island (0.6 sq. mi (1.5 sq. km)), 

which is politically part of American Samoa, but geologically and biologically part of the 

Tokelau archipelago , which is a territory of New Zealand (Goldin 2002, pp. 5–6). These islands 

and atolls range in elevation from 3,170 feet (ft) (966 meters (m)) at Mt. Lata on Ta‘ū to 4 to 6 ft 

(1 to 2 m) above sea level at Rose Atoll (Goldin 2002, pp. 5-6). 

Samoa is located less than 100 mi (160 km) northwest of Tutuila Island, American Samoa, and 

consists of two large inhabited islands, ‘Upolu (424 sq. mi (1,100 sq. km)) and Savai‘i (703 sq.

mi (1,820 sq. km)), and 8 small offshore islets, several of which are inhabited. Samoa lies 

between 13o to 14o south latitude and 170o to 173o west longitude and has a total land area of 

approximately 1,133 sq. mi (2,934 sq. km)) (Watling 2001, p. 26). The highest point in Samoa is 

Mt. Silisili on Savai‘i at 6,093 ft (1,857 m).
5

Figure 2. Islands of the Samoan archipelago.

Physical Environment

The Samoan archipelago lies within the tropics, where it is hot, humid, and rainy year-round. 

The wet season is from October to May, with a slightly cooler and drier season from June 

through September (Figures 3 and 4). Temperatures average about 81.5o Fahrenheit (F) (27o

Celsius (C)) at lower elevations. Rainfall averages 125 inches (in) (318 centimeters (cm)) 

annually at lower elevations, but can vary greatly depending upon topography, reaching 300 in 

(750 cm) or greater annually in the mountain areas. Tropical cyclones (called hurricanes north of 

the equator and east of 180o latitude, and typhoons north of the equator and west of 180o latitude) 

are a regular feature of natural disturbance in the Samoan Archipelago (Figure 5), and occur at 

intervals of between 1 to 13 years (Goldin 2002, p. 7).

Land-Use

In 2010/2011, the population of American Samoa and Samoa was 55,519 and 187,820, 

respectively (U.S. Census Bureau 2010; Samoa Bureau of Statistics (SBS) 2011, p. 14). Ninetyeight percent of the American Samoa population occurs on the island of Tutuila (Table 1).

Census data collected since 1920 for American Samoa shows initial increases in populations on 

the Manu‘a Islands (Ta‘ū, Ofu and Olosega) and then declines by 2010 (Table 1). Tutuila shows 

a steadily increasing population from 1920 to 1980 and then some fluctuation in subsequent 

years. 

In Samoa, 76% of the population occurs on ‘Upolu (which includes Manono and Apolima 

islands, Table 2). Samoa shows a steadily increasing population from 1951 to 2011, with the 

population on Savai‘i remaining stable from 1981 to 2016 while ‘Upolu shows a steady increase 

during that period (Table 2).
6

Figure 3. Monthly mean precipitation for selected areas of the Samoan archipelago. All data from

PCCSP (2019).
7

Figure 4. Monthly mean temperatures for selected areas of the Samoan archipelago. All data

from PCCSP (2019).

Figure 5. Cyclone (hurricane) tracks for the central South Pacific from 1898 to 2019. All data 

from Knapp et al. (2010) and NOAA IBTrACS (2019).
8

Table 1. Census estimates of the American Samoa population on the islands of Tutuila, Ta’ū, 

Ofu, Olosega, and Swains.

Year American 

Samoa

Island

Tutuila Ta‘ū Ofu Olosega Swains Island

19201 8,056 6,185 1,155 361 355 -

19301,2 10,055 7,809 1,243 466 438 99

19401,2 12,908 10,164 1,588 500 509 147

19501,2 18,937 15,954 1,698 576 545 164

19602 20,051 17,250 1,661 605 429 106

19703 27,159 24,973 1,320 412 380 74

19803 47,283 45,524 1,138 345 249 27

19904 46,773 45,043 1,136 353 225 16

20005 57,291 55,876 873 289 216 37

20105 55,519 54,359 790 176 177 17 1

Unkown (1956) , 2 Levin and Wright (1974), 3 U.S. Census Bureau (1982), 4 U.S. 

Census Bureau (1992), 5 U.S. Census Bureau (2010)

Table 2. Census estimates of the Samoa population by island and for the entire country.

Year1 Samoa Island

‘Upolu Savai‘i

1951 84,909 - -

1961 114,427 - -

1971 146,647 - -

1981 156,349 113,199 43,150

1991 161,298 116,248 45,050

2001 176,710 133,886 42,824

2011 187,820 143,418 44,402 1

All data from Samoa Bureau of Statistics (SBS) (2011 p. 14, 17).

Due to the steep topography of the islands, human habitation is primarily located along the 

coastlines (Figure 6). On American Samoa, small-scale agriculture occurs inland from villages in 

former lowland rainforest areas on slopes that sometimes exceed 45o (Atkinson and Medeiros 

2006, p. 4). Approximately 11% (5,456 acres (ac), 2,208 hectares (ha)) of American Samoa is 

classified as developed (i.e., urban areas, roads, infrastructure, and 6% (2,824 ac, 1,143 ha) of 

American Samoa is classified as agriculture (Table 3). The majority of the development and 

agriculture in American Samoa occurs on Tutuila where the largest human population resides 

(Table 1 and Table 3). 

In Samoa approximately 3 percent (21,869 ac, 8,850 ha) is classified as developed and 25 

percent (174,449 acres, 70,597 hectares) is agriculture. The majority of the development and 

agriculture occurs on ‘Upolu, where the majority of the human population resides (Table 2 and 

Table 3).
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Figure 6. Locations of roads in the Samoan archipelago.

Biological Environment

Mueller-Dombois and Fosberg (1998, p. 361) describes seven general categories of vegetation in 

the Samoan archipelago: 

• Littoral vegetation generally refers to vegetation that is directly exposed to salt spray and 

occurs along the coasts. It includes a variety of forest, scrub, and herbaceous 

communities (see Whistler (1992) and Mueller-Dombois and Fosberg (1998) for detailed 

descriptions). 

• Lowland rainforests occur below approximately 1,600-2,000 ft (500-600 m) elevation 

and include a variety of subtypes based on the dominate canopy species. 

• Montane rainforests occur above 1,600-2,000 ft (500-600 m) elevation and are generally 

cooler and rainier than lowland forests. 

• Cloud forest and cloud scrub is limited to Savai‘i, ‘Upolu, Ta‘ū and Olosega and are 

wetter than montane forests due to the persistence of clouds. 

• Wetland vegetation includes mangroves, swamp forest, coastal marsh, and montane 

marsh and bog areas. Montane marsh and bog areas are limited to Savai‘i and ‘Upolu. 

• Vegetation on recent volcanic surfaces includes scrubby woody vegetation, ferns, and 

grasses that may represent pioneer rainforest. 

• Modified vegetation includes all areas that were formerly dominated by native vegetation 

but were altered due to human activity (e.g., urban areas, agriculture areas, secondary 

forest, etc.). 

Approximately 70% of American Samoa is forested, with the majority classified as lowland 

tropical rainforest (Figure 7; Tables 3 and 4). Montane rainforest makes up a smaller percent of 
10

the forest areas and is primarily restricted to Ta‘u with a small amount on Tutuila (Figure 7, 

Table 4). 

Approximately 58% of Samoa is forested (Figure 8, Table 3). However, not all of this is native 

forest. It is estimated that only 360 ac (146 ha) of native lowland rainforests (below 2,000 ft or 

600 m) remain on Savai‘i and ‘Upolu as a result of forest clearing (MNRE 2013, p. 47). Savai‘i 

still has extensive upland forests that are for the most part undisturbed and composed of native 

species (MNRE 2013, p. 40). However, upland forest on ‘Upolu is largely dominated by 

introduced species today (MNRE 2013, p. 12). 

Figure 7. Vegetation land cover on American Samoa (from data by Meyer et al., 2017).
11

Figure 8. Vegetation land cover for Samoa (from data by LINZ, 2015a-i).

Table 3. Major land cover types for the Samoan archipelago. Area estimates in acres (hectares).

1 All data from Meyer et al. (2017) and MNRE (2014).

Land cover1

Samoa American Samoa

Savai‘i ‘Upolu Minor Islands Tutuila Ofu/ 

Olosega Ta‘ū

Developed 6,934 (2,806) 14,794 (5,987) 141 (57) 5,179 (2,096) 101 (41) 175 (71)

Agriculture 77,905 (31,527) 96,037 (38,865) 507 (205) 2,664 (1,078) 42 (17) 119 (48)

Forest 281,593 

(113,957)

124,830 

(50,517) 722 (292) 23,262 (9,414) 2,797 (1,132) 8,300 (3,359)

Scrub 29,734 (12,033) 17,957 (7,267) 171 (69) 1,564 (633) 52 (21) 1,873 (758)

Grassland/ 

Herbaceous 16,131 (6,528) 21,730 (8,794) 37 (15) 440 (178) 35 (14) 625 (253)

Mangrove 67 (27) 801 (324) 15 (6) 79 (32) 0 (0) 0 (0)

Wetland 306 (124) 726 (294) 67 (27) 72 (29) 7 (3) 17 (7)

Open Water 91 (37) 692 (280) 10 (4) 62 (25) 0 (0) 0 (0)

Barren 7,811 (3,161) 247 (100) 49 (20) 432 (175) 94 (38) 128 (52)
12

Table 4. Estimated acreages of vegetation types for the main islands of American Samoa. Area in 

acres (hectares).

Type1 Subtype Tutuila Aunu‘u Ofu/Olesega Ta‘ū

Littoral

Vegetation

Herbaceous 

Strand 26 (11) 22 (9) 1 (<1) 572 (231)

Littoral Forest 608 (246) 35 (14) 295 (119) 338 (137)

Littoral Scrub 117 (47) 4 (2) 9 (4) 17 (7)

Pandanus Scrub 18 (7) 0 (0) 0(0) 0 (0)

Wetland

Vegetation

Coastal Marsh 7 (3) 34 (14) 7 (3) 7 (3)

Mangrove Scrub 

& Forest 79 (32) 14 (6) 0 (0) 0 (0)

Swamp Forest 64 (26) 29 (12) 0 (0) 10 (4)

Lowland 

Rainforest - 20,507 (8,299) 0 (0) 480 (194) 761 (308)

Montane 

Rainforest - 95 (38) 0 (0) 92 (37) 2,809 (1,137)

Cloud Forest & 

Scrub - 0 (0) 0 (0) 0 (0) 546 (221)

Vegetation on 

Recent Volcanic 

Surfaces

- 223 (90) 0 (0) 0 (0) 0 (0)

Modified 

Vegetation

Fern lands 3 (1) 2 (1) 13 (5) 34 (14)

Managed Land 10,296 (4,167) 139 (56) 406 (164) 513 (208)

Secondary 

Forest 0 (0) 53 (22) 1,696 (686) 5,421 (2,194)

Secondary 

Scrub 1,214 (491) 14 (6) 37 (15) 78 (31)

Open Water - 62 (25) 11 (4) 0 (0) 0 (0)

Terrestrial

Non-vegetated - 431 (175) 18 (7) 93 (38) 129 (52)

1 Data from Meyer et al. (2017).

Species Description

Appearance

The Mao is a large honeyeater with dark plumage varying from blackish on the head and breast 

to olive- green on the wings, tail, and body (Stirnemann et al. 2015a, p. 1). It has an olive-green 

stripe under the eye (Figure 9). The bill is long, curved, and black in adults. Males have bluegrey and brown eyes, and females have brown eyes only (Stirnemann et al. 2015b, p. 383). 

Males are significantly larger than females with respect to wing, bill, tarsus, and tail length, 

although there is considerable overlap in size (Stirnemann et al. 2015b, pp. 380–381). Juveniles 

have a shorter bill than adults, and eye color changes 2 months post-fledging (Stirnemann et al.

2015b, p. 383). The Mao is a very vocal species and makes a variety of loud distinctive calls 

with bouts of calling lasting up to a minute (Watling 2001, p. 174). Calls differ between sexes 

(Stirnemann et al. 2015b, p. 382).
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Figure 9. Photograph of an adult Mao by R. Stirnemann.

Figure 10. Beak, wing, tarsus, and tail measurements from Mao in Western Samoa (Stirnemann 

et al., 2015a, p. 381). Length (mm) Length (mm)

Length (mm) Length (mm)
14

Measurements and Mass

The Mao is a large honeyeater approximately 11 to 12 in (28 to 31 cm) long (Higgins et al. 2008, 

p. 670). Morphometric data from the Samoa populations indicates that males are generally larger 

than females, with some overlap (Figure 10).

Systematics

The Mao is one of three species in the genus Gymnomyza in the honeyeater family, Meliphagidae 

(Table 5). The species was first described in 1841 by Hombron and Jacquinot from a specimen 

collected in ‘Upolu, Samoa (Higgins et al. 2008, p. 670)

Table 5. List of Gymnomyza species and their conservation status. All data obtained from 

Higgins et al. (2008, p. 670-671).

Species Common Name Status Distribution

Gymnomyza virdis Giant Honeyeater Not Globally Threatened Fiji

Gymnomyza samoensis Mao Endangered Samoa

Gymnomyza aubryana Crow Honeyater Endangered New Caledonia

Life History

Foraging Biology

Diet

The Mao forage on invertebrates, fruits and nectar and may also prey on small reptiles (Table 6; 

Higgins et al. 2008, p. 670-671; Butler and Stirnemann 2013, p. 30). Potential nectar sources 

include native and non-native species like Erythrina spp., Heliconia spp., etc. (Butler and 

Stirnemann 2013, p. 30).

Table 6. Diet and foraging locations recorded for Gymnomyza species. All data obtained from 

Higgins et al. (2008, p. 670-671).

Species Diet Foraging Location

Gymnomyza virdis Nectar, Fruit, Invertebrates, 

Reptiles

Canopy, Subcanopy, 

Occasionally on Ground

Gymnomyza samoensis Nectar, Arthropods, Fruit Canopy and Subcanopy

Gymnomyza aubryana Arthropods and Nectar Canopy, Mid-storey
15

Foraging Method and Location

Mao forage by gleaning invertebrates from leaves, probe dead material and moss for 

invertebrates, and probe flowers for nectar (Higgins et al. 2008, p. 671; Butler and Stirnemann 

2013, p. 30). They forage primarily in the canopy and subcanopy in forested areas, like other 

members of their genus (Table 6). Females will also forage for invertebrates under dead leaves 

on the forest floor to feed their fledglings (Butler and Stirnemann 2013, p. 30). Fledglings solicit 

food from the female by begging continually on the he forest floor (Butler and Stirnemann 2013, 

p. 28).

Breeding Biology

Figure 11 provides an overview of the breeding cycle of the Mao. The Mao’s breeding cycle is 

typical for passerines with most breeding activities centered on the nest site. Once a nest is 

constructed the female lays and incubates the egg for 19-21 days (Stirnemann et al. 2015b, p.4-

7). The egg hatches after incubation and the emerging chick or hatchling is fed and cared for by 

the female for 22-24 days until it leaves the nest (i.e., fledging). The immature or juvenile birds 

is dependent on its parents for 8-10 weeks post-fledging. Specific details on the breeding 

characteristics of the species are outline below.

Figure 11. Breeding cycle of the Mao (from data in Stirnemann et al., 2015b, pp.5-7)

Breeding Season

Based on observations of 10 nests, Mao breeding can occur over 9 to 10 months, although peak 

egg-laying appears to occur from late May to October, when rainfall levels are decreased

(Stirnemann et al. 2015b; p.4-5). The Mao will re-nest if the first nest fails, but not if the first 

nesting attempt produces a chick (Stirnemann et al. 2015b; pp. 4–7).

Nest Characteristics

The Mao’s nest consists of young branches of various trees and contains little lining (Butler and 

Stirnemann 2013, p. 25). Nests are oval, cup-shaped, approximately 5.5 in (14 cm, n = 10) by 3.1 

in (8 cm, n = 10), and are constructed in the junction of branches (Stirnemann et al. 2015b; p. 5).

Heights of 10 nests ranged from 8 to 20 m above the forest floor, and percent nest cover ranged 

from 0 to 80% (Stirnemann et al. 2015b, p. 6). Nest descriptions and nest heights were similar 

among the species in the same genus (Table 7). Stirnemman et al. (2015b, p. 6) reported nests in 

the following native and introduced tree species: Planchonella garberi (Alaa, n = 1), Loranthus 
16

samoensis (Native mistletoe, n = 1), Dysoxylum huntii (Maota, n = 1), Glochidion ramiflorum

(Masame, n = 1), Fagraea berteroana (Pua lulu, n = 1), Hevea brasiliensis (Rubber tree, n = 2), 

and Dendrocnide harveyi (Salato, n = 2). The duration of the nest building process is unknown.

Table 7. Nest descriptions and nest location information for Gymnomyza species.

Species Nest Description Nest Location

Gymnomyza virdisa Cup made of rootlets ~ 20m above ground, outer foliage

Gymnomyza samoensisb Cup 14.2 ± 1.9 m (range 8-20 m, n = 10)

Gymnomyza aubryanaa Cup ~ 20m above ground, branch fork

a

Higgins et al. 2008, p670-671; bStirnemann et al. 2015b, p. 5.

Egg Stage

One off-white egg is produced per clutch (Stirnemann et al. 2015b; p. 5; n = 10). Higgins et al.

(2008, p. 671) reports a clutch size of 2-3 eggs, however no information is reported on the 

number of nests observed or the original citation for this observation. The incubation period, 

based on two nest observations, is 19-21 days (Stirnemann et al. 2015b, p. 5) and only females 

incubate eggs. Males feed females during incubation, infrequently.

Hatchling Stage

Based on observations of six nests, nestling fledge 22-24 days after hatching (Stirnemann et al.

2015b, p. 6). The female is almost exclusively responsible for feeding the chick.

Fledgling Stage

Juveniles are dependent on adults for approximately 8 to 10 weeks post-fledging (Stirnemann et 

al. 2015b; pp. 4–7). The female is almost exclusively responsible for feeding the fledgling.

Survivorship and Lifespan

Figure 12 shows the main life stages of the Mao. The survival rates of the species at each of 

these life stages are important determinants of population viability. The sections below provide 

details on known survival rates for each of the stages and the overall lifespan of the species.
17

Figure 12. Generalized life stages of the Mao.

Breeding Success

Nest survival was estimated to be 2.8% (±4.1% SE, n = 12) for a 42-day nesting period (egg and 

nestling stage; Stirnemann et al. 2015c, p.74). However, based on observations of 19 females 

over two breeding seasons, overall reproductive productivity was 0.34 juveniles per female per 

breeding season (Stirnemann et al. 2015c, p. 74). The inconsistency between low nest survival 

and overall reproductive productivity is believed to be related to repeated nesting attempts by 

Mao, with failed nests, over the breeding season (Stirnemann et al. 2015c, p.76).

Juvenile and Adult Survival

Strinemman et al. (2015c, p. 74) estimated 0.95 ± 0.07 annual survival and 100% annual survival 

for 19 monitored adult females and 12 monitored adult males. Juvenile survival was estimated to 

be 100% during the 8-10 week post-fledging parental care period. Estimates of juvenile survival 

to adulthood are not available.

Lifespan

Estimates of lifespan have not been determined for the Mao. Estimates for other species in the 

Meliphagidae family range from 6.8 to 15.3 years (Table 8).

Table 8. Estimated lifespans, sizes, and weights of honeyeaters in Australia. Lifespan estimates 

are based on banded wild birds. 

Species Common Name

Lifespan 

(yrs)

Size5

(cm)

Weight5

(g)

Lichenostomus melanops Yellow-tufted Honeyeater 15.34 16.5-21 14.2-31

Phylidonyris novaehollandiae3 New Holland Honeyeater 14.54 16-20 10-15

Lichenostomus fuscus Fuscous Honeyeater 14.14 13.5-17 12-24
18

1

Editor 2014, p. 668; 2Lane and Lonnon 1967, p. 33; 3Leishman 2012, p. 14; 4Geering 2002; 5Higgins et al., 2008, 

pp. 589, 597, 604, 607, 622, 667, 668, 673, 675.

Habitat

Mao was thought to be primarily restricted to mature, well- developed, moist, mossy forests at 

upper elevations (Watling 2001, p. 175; Engbring and Ramsey 1989, p. 68), but has recently 

been observed at elevations ranging from 932 to 5,075 ft (284 to 1,547 m) and in ecosystems 

including lowland rainforest, disturbed secondary forest, and montane rainforest (MNRE 2006, 

pp. 9–10). The birds use the mid- to upper-canopy levels of the forest and will also forage along 

forest edges and brushy forest openings (Engbring and Ramsey 1989, p. 68). The Mao has also 

been recorded visiting coconut trees near the coast (Watling 2001, p. 175).

Butler and Stirnemann (2013, p. 30) provide the following information about the Mao’s habitat 

use. The birds occur only in forested areas with a canopy layer, including modified habitat such 

as plantations where large trees also are present. They do not occur in logged areas with no large 

trees or canopy. Mao are primarily found in the high canopy layer, but also spend considerable 

time foraging on the trunks of trees and feeding on nectar sources near the ground (such as 

ginger (family Zingiberaceae)) and in low bushes (such as Heliconia spp.). The Mao selects 

territories with high tree species diversity and with appropriate nectar sources and a large tree 

from which the male sings. Trees near a commonly used singing tree are selected for nesting.

Mao maintain a territory during breeding with both sexes defending the territory (Stirnemann et 

al. 2015b, p. 4-5). Territory sizes for the Mao are currently unknown. However, the crow 

honeyeater (Gymnomyza aubryana) has an estimated territory size of 0.5 to 0.75 km2 (Higgins et 

al. 2008, p. 671).

Historical Range, Distribution, and Population Status

Mao is endemic to the islands of Savai’i and ‘Upolu, Samoa, and Tutuila Island, American 

Samoa (Figure 13; Engbring and Ramsey 1989, p. 68; Watling 2001, p. 174). It was once found 

throughout Savai‘i and ‘Upolu in Samoa, likely in forests ranging from the coast to mountain 

tops (MNRE 2006, p. 2). Bellingham and Davis (1988, p.124-125) recorded the species in 

lowland and montane forests on both islands in 1984 but found them more abundant in montane 

forests on Savai‘i and unlogged forest on ‘Upolu. Reed (1980, p. 158) also recorded the species 

as more abundant in high elevation forests in 1979. No population estimates were provided. 

Meliphaga lewinii Lewins Honeyeater 134 19-21.5 27.3-49.5

Lichenostomus chrysops Yellow-faced Honeyeater 12.14 15-17.5 12-20.5

Phylidonyris niger White-cheeked Honeyeater 10.41 16-20 15.5-25

Anthochaera phrygia Regent Honeyeater 9.114 20.4-24 33-45

Melithreptus brevirostris Brown-headed Honeyeater 72 11.5-14 12-17

Melithreptus lunatus White-naped Honeyeater 6.83q A 11.5-25
19

Figure 14 summarizes the records of Mao from 1987 to 2000. These records show the species 

largely restricted to native forest on both islands. 

Little is known about the historical distribution and population status of the species on Tutuila. It 

was observed during U.S. Exploring Expedition in 1839 (Amerson et al. 1982a, p. 72) but 

apparently no specimens were collected (Banks 1984, p. 166). Three specimens were collected 

on Tutuila by the Whitney South Seas Expedition in February 1924 (two males with enlarged 

testes and a potential young female; Banks 1984, p. 166). The species was not recorded during 

surveys by Amerson et al. in 1975 and 1976 (1982a, p. 72). However, P. Bruner recorded an 

observation of the species on Tutuila in 1977 (Pratt et al. 1987, p. 280). Extensive surveys of 

Tutuila in 1986 and from 1992 to 1996 failed to detect the species (Engbring and Ramsey 1989, 

p 68; Freifeld et al 2004, p. 104). 

Figure 13. The estimated historical range of the Mao.
20

Figure 14. Sites where Mao where observed in Samoa from 1987 to 2000. (Land cover from 

MNRE, 2006, p. 3).

Part 2. Current Conditions and Species Status

Current Range and Distribution

Mao is currently found only on the islands of Savai‘i and ‘Upolu in Samoa (MNRE 2006, p. 2). 

Birdlife International (2016) reported that the population size is around 500 individuals, 

however, extensive surveys have not been conducted. The following sections provide 

information on population trends in each of the historical populations.

Savai‘i and ‘Upolu, Samoa

Historically the Mao was reported as common in undisturbed upland forests (foothill, montane, 

and cloud forests above 1,970 ft (600 m)) of ‘Upolu and Savai‘i (Bellingham and Davis 1988, p. 

124). A decline in distribution was observed in the 1990s following a period in which several 

powerful cyclones (hurricanes) hit Samoa: Tusi (1987), Ofa (1990), and Val (1991) (Lovegrove 

et al. 1992,p. 26; MNRE 2006, pp. 2, 4). Otherwise, no detailed surveys of the Mao were 

conducted before 2005, and little information exists regarding changes in abundance and 

distribution (MNRE 2006, p. 2). Surveys conducted in 2005– 2006 found Mao at seven sites on 

‘Upolu and Savai‘i in upland forested habitat (Figure 15), yielded a rough estimate of 500 

individuals and indicated that numbers are declining (MNRE 2006, p. 4; Tipamaa 2007, in litt., 
21

cited in Birdlife International 2012). The Rapid Biodiversity Assessment of Upland Savai‘i, 

Samoa, conducted in 2012, detected small numbers of the Mao at two sites on the island 

(Atherton and Jefferies 2012, p. 14). None of the recent surveys (Atherton and Jeffries 2012, p. 

110; MNRE 2013, p. 87) or studies (Stirnemann 2015a) has yielded an updated population 

estimate. However, researchers observed that the species is rarer than previously thought and 

recommended that comprehensive surveys be conducted to generate a new population estimate 

(Stirnemann 2015b, in litt).

Tutuila, American Samoa

The Mao is likely extirpated from Tutuila Island in American Samoa (Freifeld 1999, p. 1,208). 

Surveys conducted on Tutuila Island in 1986 and from 1992 to 1996 did not detect the Mao 

(Engbring and Ramsey 1989; p. 68; Freifeld et al 2004, p. 104). Given that the species is noisy 

and conspicuous, it is believed unlikely that a population on Tutuila was missed during those 

surveys (Engbring and Ramsey 1989; p. 68). More recent surveys conducted by DMWR, in 

forested habitats likely to support Mao, also failed to detect their presence, further indicating the 

likelihood that the species no longer occurs on Tutuila (MacDonald 2015, in litt.). 

Figure 15. Locations in 2005-2006 where Mao were detected (●) and not detected (+) (MNRE 

2006, p. 4; Tipamaa 2007, in litt., cited in Birdlife International 2012). Land cover from MNRE, 

2006, p. 4.
22

Factors Affecting Viability

This section describes the various factors that may be affecting the viability of the current Mao 

populations and may have led to the observed population and range declines from historical 

levels. 

Habitat Loss and Degradation

The following sections provide information on habitat loss and degradation due to development, 

introduced ungulates, and introduced plants. This section also provides information on efforts to 

restore and improve potential Mao habitat.

Development

Before the arrival of Polynesians, approximately 3,000 years ago, the Samoan archipelago was 

likely covered by forest, except for recent volcanic flows, marshes, and steep and windswept 

regions of the islands (Amerson et al. 1982b, p. 20; Mueller-Dombois and Fosberg 1998, p. 360). 

Thousands of year of subsistence agriculture and, more recent, commercial agriculture has 

resulted in the alteration and great reduction in area of forests at lower elevations in the Samoan 

archipelago (Whistler 1994, p. 40; Mueller-Dombois and Fosberg 1998, p. 361; Whistler 2002, 

pp. 130–131). 

On the island of Tutuila, American Samoa, agriculture and urban development covers 

approximately 24 percent of the island, and up to 60 percent of the island contains slopes of less 

than 30 percent where additional land clearing is feasible (ASCC 2010, p. 13; DWMR 2006, p. 

25). Farmers are increasingly encroaching into some of the steep forested areas as a result of 

suitable flat lands already being occupied with urban development and agriculture (ASCC 2010, 

p. 13). Consequently, agricultural plots have spread from low elevations up to middle and some 

high elevations on Tutuila.

In Samoa, the amount of forested area declined from 74 to 40 percent of total land area between 

1954 and 1990 (Figure 16; MNRE 2014, in litt.) and continued to decline by roughly 2 percent or 

7,400 ac (3,000 ha) per year from 1990 to 2000 (Figure 16, FAO 2005, in litt.). The clearing of 

land for commercial agriculture has been the leading cause of deforestation in Samoa (Whistler 

2002, p. 131). The transition from subsistence agriculture to cash crops for export (e.g., taro, 

bananas, cacao), coupled with rapid population growth and new technologies, led to increased 

forest clearing in Samoa (Paulson 1994, pp. 326–332; Whistler 2002, pp. 130–131). Shifting or 

slash- and-burn cultivation is also a concern in upland forest as farmers use forestry roads from 

heavily logged lowland forests to gain access to formerly inaccessible land (MNRE 2006, p. 5). 

For example, there is much concern about potential forest loss because of road that has been 

bulldozed into the cloud forest (above 3,280 ft (1,000 m)) on Savai‘i, apparently illegally 

(Atherton and Jeffries 2012, p. 16). 

Logging has also been a cause of forest loss in Samoa. Between 1978 and 1990, 20 percent of all 

forest losses in Samoa were attributable to logging, with 97 percent of the logging having 

occurred on Savai’i (Government of Samoa 1998 in Whistler 2002, p. 132). These logging 

activities have slowed down in recent years due to the reduction of forest accessible to logging, 
23

but is an ongoing problem on Savai’i despite years of effort to phase it out (MNRE 2006, p. 5; 

Atherton and Jeffries 2012, p. 17).

Today, only 360 ac (146 ha) of native lowland rainforests (below 2,000 ft or 600 m) remain on 

Savai‘i and ‘Upolu as a result of logging, agricultural clearing, residential clearing (including 

relocation due to tsunami), and natural causes such as rising sea level and cyclones (hurricanes)

(MNRE 2013, p. 47). On ‘Upolu, direct or indirect human influence has caused extensive 

damage to native forest habitat above 2,000 ft (600 m) elevation (MNRE 2013, p. 13). Although 

upland ‘Upolu is forested, almost all of the upland forests are largely dominated by introduced 

species today (MNRE 2013, p. 12). Savai‘i still has extensive upland forests that are for the most 

part undisturbed and composed of native species (Figure 16; MNRE 2013, p. 40). As a result, 

forest clearance as a result of development is considered an ongoing threat to the Mao (MNRE 

2006, p. 5). 

1954 1987 1999

Figure 16. Estimated forest cover in Samoa from 1954 to 1999 (MNRE 2014, in litt.; FAO 2005,

in litt.) Maps from Figures 4-6 of MNRE (2006, p. 6-7).

Invasive Plants

Nonnative plants are known to have invaded native ecosystems in American Samoa and Samoa, 

with documented adverse impacts to native forests (Space and Flynn 2000, pp. 5, 12; Space and 

Flynn 2002, pp. 4–5; Whistler 2002, p. 122; Atkinson and Medeiros 2006, pp. 17–18; Craig 

2009, pp. 94, 98; ASCC 2010, p. 22; NPSA 2012, in litt.; Atherton and Jeffries 2012, p. 103; 

Butler and Stirnemann 2013, p. 30; MNRE 2013, p. 29). The native flora of the Samoan 

archipelago (plant species that were present before humans arrived) consisted of approximately 

550 taxa, 30 percent of which were endemic (species that occur only in the American Samoa and 

Samoa) (Whistler 2002, p. 8). An additional 250 plant species have been introduced intentionally 

or accidentally and have become naturalized, with 20 or more of these considered invasive or 

potentially invasive in American Samoa (Whistler 2002, p. 8; Space and Flynn 2000, pp. 23–24). 

Of these approximately 20 or more nonnative pest plant species, at least 10 have altered or have 

the potential to alter the habitat of the Mao (Atkinson and Medeiros 2006, p. 18; Craig 2009, pp. 

94, 97–98; ASCC 2010, p. 15).

Nonnative plants have been documented to degrade native ecosystems in the Pacific island 

through the following means: (1) modifying the availability of light through alterations of the 
24

canopy structure; (2) altering soil–water regimes; (3) modifying nutrient cycling; (4) converting 

native- dominated plant communities to nonnative plant communities through competition with 

native species; and (5) increasing the frequency of landslides and erosion (Smith 1985, pp. 217–

218; Cuddihy and Stone, 1990, p. 74; Matson 1990, p. 245; D’Antonio and Vitousek 1992, p. 73; 

Vitousek et al. 1997, pp. 6–9; Atkinson and Medeiros 2006, p. 16). Nonnative plant species can 

also exploit the disturbance caused by other natural and human caused factors, such as cyclones

(hurricanes), agriculture and development, and feral ungulates, and thus, in combination 

reinforce or exacerbate their negative impacts to native habitats. 

The following list provides a brief description of the nonnative plants that may have the greatest 

negative impacts to the native forest habitat for the Mao in American Samoa (Space and Flynn 

2000, pp. 23–24; Craig 2009, pp. 94, 96–98; ASCC 2010, p. 15):

• Adenanthera pavonina (red bean tree, coral bean tree, lopa), native to India and Malaysia, 

is a medium-sized tree up to 50 ft (15 m) high that invades intact forests as well as 

disturbed sites, and can quickly form large stands (GISD 2006). In American Samoa, it is 

invasive in secondary forests, but also has the ability to become more widely established 

on Tutuila and the Manua Islands (Space and Flynn 2000, p. 4). It is considered to have 

negative impacts on the native forests in American Samoa because the trees produce 

large quantities of seed, grow on a variety of soils, and can overtop many native trees and 

eventually form monotypic stands (Space and Flynn 2002, p. 5).

• Castilla elastica (Mexican rubber tree, pulu mamoe), native to tropical America, is a 

medium-sized tree 15 to 30 ft (5 to 10 m) high that can invade intact forest where it 

reproduces prolifically and can crowd out native species (NPSA 2012, in litt.). It has 

displaced significant areas of lowland forest in Samoa, and is now considered to be an 

important threat to native forests in American Samoa (Atkinson and Medeiros 2006, p. 

18).

• Cinnamomum verum (cinnamon, tinamoni), native to south Asia, is a fast-growing, 

medium-sized tree up to 30 ft (9 m) high with aromatic bark and leaves. It forms dense 

root mats that inhibit establishment of other plants, and can shade out other tree species 

and thus create monotypic stands. On Tutuila, it is actively spreading in the ridge forests 

of Mt. Matafao, Matuu, and Maloata (Space and Flynn 2000, p. 4; NPSA 2012, in litt.).

• The shrub Clidemia hirta (Koster's curse), native to the New World from Mexico to 

Argentina, grows to be 6.6 ft (2 m) in height, forms a dense understory, shades out native 

plants, and prevents their regeneration (Wagner et al. 1985, p. 41; Smith 1989, p. 64). On 

Ta‘ū, it has become a serious problem in the unique summit scrub community (Whistler 

1992, p. 22).

• Falcataria moluccana (albizia, tamaligi), native to Moluccas, New Guinea, New Britain, 

and the Solomon Islands, is a tree that can reach 131 ft (40 m) in height and has a widespreading canopy. It grows rapidly and outcompetes slow-growing native trees by 

reducing light availability, and its abundant, high-nutrient litter alters soil chemistry 

(GISD 2008). Its shallow root system may lead to soil instability and landslides 

(Atkinson and Medeiros 2006, p. 17). 
25

• Funtumia elastica (African rubber tree, pulu vao), is a medium-sized tree up to 100 ft (30 

m) tall native to tropical Africa (USDA 2006). This tree is invasive because of its 

“parachute seeds” that can disperse long distances and germinate in sunny or shady 

conditions (Whistler 2002, p. 122). Funtumia has become a dominant subcanopy and 

understory tree in the western half of ‘Upolu where it can form monotypic forests 

(Pearsall and Whistler 1991, p. 30). It is also established and becoming dominant on 

eastern Savai‘i (Whistler 2002, p. 122). This species has the potential to become a major 

problem in American Samoa due to its proximity and the volume of traffic with Samoa 

(Space and Flynn 2000, p. 12).

• Leucaena leucocephala (wild tamarind, lusina, fua pepe), a shrub native to the 

neotropics, is a nitrogen-fixer and an aggressive competitor that often forms the dominant 

element of the vegetation (Geesink et al. 1999, pp. 679–680). It crowds out native 

species and resprouts vigorously after cutting, and seeds can remain viable for 10 to 20 

years (Craig 2009, p. 98).

• Merremia peltata (Merremia, fue lautetele), is an indigenous, sprawling, or high-climbing 

vine that can invade areas following disturbances such as land-clearing and cyclones 

(hurricanes). This fast-growing vine can smother plantation and forest trees (Craig 2009, 

p. 98).

• Mikania micrantha (mile-a-minute vine, fue saina), native to tropical America, is a 

scrambling or climbing herbaceous vine, that retards forest regeneration with its 

smothering growth (Whistler 1994, p. 42). This sun-loving, shade-intolerant vine is a 

major pest of plantations and forests on all major American Samoa islands (Space and 

Flynn 2000, p. 5; Craig 2009, p. 94).

• Psidium cattleianum (strawberry guava, kuava) is a tall shrub or small tree that forms 

dense stands in which few other plants can grow, displacing native vegetation through 

competition. The fruit is eaten by feral pigs and birds that disperse the seeds throughout 

the forest (Smith 1985, p. 200; Wagner et al. 1985, p. 24). It is thought to have been 

cultivated in American Samoa for more than 40 years and has become naturalized in 

lowland rainforest on western Tutuila.

• Spathodea campanulata (African tulip, faapasi), native to tropical Africa, is a large tree 

up to 80 ft (24 m) or more in height with showy red-orange tulip-like flowers and pods 

containing hundreds of wind-dispersed seeds (PIER 2013). It is particularly invasive in 

low-to mid-elevation forests, and can spread in open agricultural land, waste areas, and 

intact native forest, forming dense stands that shade out other vegetation (GISD 2010).

Mao forage and occasionally nest in modified habitat, such as plantation areas where nonnative 

trees provide nectar and nesting habitat (e.g., Falcataria moluccana). However, these habitats 

lack the high tree-species diversity, which Mao are believed to prefer, and may also place the 

species at a greater risk of predation by nonnative predators that may inhabit these forests (Butler 

and Stirnemann 2013, p. 30).
26

Introduced Ungulates

Feral pigs (Sus scrofa) and feral cattle (Bos taurus) are both factors in forest degradation in 

Samoa. Feral pigs are known to cause deleterious impacts to ecosystem processes and functions 

throughout their worldwide distribution (Aplet et al. 1991, p. 56; Anderson and Stone 1993, p. 

201; Campbell and Long 2009, p. 2,319). Feral pigs are extremely destructive and have both 

direct and indirect impacts on native plant communities. Pigs are a major vector for the 

establishment and spread of invasive, nonnative plant species by dispersing plant seeds on their 

hooves and fur, and in their feces (Diong 1982, pp. 169–170, 196–197), which also serve to 

fertilize disturbed soil (Siemann et al. 2009, p. 547). In addition, pig rooting and wallowing 

contributes to erosion by clearing vegetation and creating large areas of disturbed soil, especially 

on slopes (Smith 1985, pp. 190, 192, 196, 200, 204, 230–231; Stone 1985, pp. 254– 255, 262–

264; Tomich 1986, pp. 120– 126; Cuddihy and Stone 1990, pp. 64– 65; Aplet et al. 1991, p. 56; 

Loope et al. 1991, pp. 18–19; Gagne and Cuddihy 1999, p. 52; Nogueira-Filho et al. 2009, p. 

3,681; CNMI-SWARS 2010, p. 15; Dunkell et al. 2011, pp. 175–177; Kessler 2011, pp. 320, 

323). Erosion resulting from rooting and trampling by pigs impacts native plant communities by 

contributing to watershed degradation and alteration of plant nutrient status, and increasing the 

likelihood of landslides (Vitousek et al. 2009, pp. 3,074–3,086; Chan-Halbrendt et al. 2010, p. 

251; Kessler 2011, pp. 320–324). In the Hawaiian Islands, pigs have been described as the most 

pervasive and disruptive nonnative influence on the unique native forests, and are widely 

recognized as one of the greatest current threats to Hawai‘i’s forest ecosystems (Aplet et al.

1991, p. 56; Anderson and Stone 1993, p. 195).

In American Samoa, feral pigs negatively affect forested habitats. Feral pigs have been present in 

American Samoa since humans first settled the islands (American Samoa Historic Preservation 

Office 2015, in litt.). In the past, hunting pressure kept their numbers down, however, increasing 

urbanization and increasing availability of material goods has resulted in the decline in the 

practice of pig hunting to almost nothing (Whistler 1992, p. 21; 1994, p. 41). Feral pigs are 

moderately common to abundant in many forested areas, where they spread invasive plants, 

damage understory vegetation, and destroy riparian areas by their feeding and wallowing 

behavior (DMWR 2006, p. 23; ASCC 2010, p. 15).

Feral pigs are a serious problem in the National Park of American Samoa (NPSA) because of the 

damage they cause to native vegetation through their rooting and wallowing (Whistler 1992, p. 

21; 1994, p. 41; Hoshide 1996, p. 2; Cowie and Cook 1999, p. 48; Togia pers. comm. in Loope et 

al. 2013, p. 321). Such damage to understory vegetation is likely to reduce foraging opportunities 

for the Mao. Pig densities have been reduced in some areas by snaring and hunting, but remain 

high in other areas (ASCC 2010, p. 15).

In Samoa, feral pigs are present throughout lowland and upland areas on Savai‘i, and are 

considered to have a negative impact on the ecological integrity of upland forests of Savai‘i, an 

important conservation area for the Mao and other rare species (Atherton and Jeffries 2012, p. 

17). During recent surveys, feral pig activity was common at most sites in upland forests on 

Savai‘i, and was even detected at the upper range of the Mao at an elevation of 4,920 ft (1,500 

m) (Atherton and Jefferies 2012, pp. 103, 146).
27

Finally, significant numbers of feral cattle (Bos taurus) were present in an upland site on Savai‘i 

where their trampling had kept open grassy areas within forested flats, and where Mao had 

previously been observed (Atherton and Jeffries 2012, pp. 103– 105). Trampling in forested 

areas damages understory vegetation and is likely to reduce foraging opportunities for Mao as 

well as provide vectors for invasion by nonnative plants. In addition, feral cattle consume tree 

seedlings and browse saplings, and combined with undergrowth disturbance, prevent forest 

regeneration, subsequently opening the forest to invasion by nonnative species (Cuddihy 1984, p. 

16).

Conservation Efforts to Reduce Habitat Loss and Degradation

American Samoa – The National Park of American Samoa (NPSA) was established to preserve 

and protect the tropical forest and archaeological and cultural resources, to maintain the habitat 

of flying foxes, to preserve the ecological balance of the Samoan tropical forest, and, consistent 

with the preservation of these resources, to provide for the enjoyment of the unique resources of 

the Samoan tropical forest by visitors from around the world (Public Law 1988; Public Law

2006). Under a 50-year lease agreement between local villages, the American Samoa 

Government, and the Federal Government, approximately 8,000 ac (3,240 ha) of forested habitat 

on the islands of Tutuila, Ta‘ū, and Ofu are protected and managed (ASG-NPSA Lease 

Agreement 1993).

Several programs and partnerships to address the threat of nonnative plant species have been 

established and are ongoing in American Samoa. Since 2000, the NPSA has implemented an 

invasive plant management program that has focused on monitoring and removal of nonnative 

plant threats. The nonnative plant species prioritized for removal include the following: 

Adenanthera pavonina or lopa, Castilla elastica or pulu mamoe, Falcataria moluccana or 

tamaligi, Leucaena leucocephala or lusina, and Psidium cattleianum or strawberry guava (Togia 

2015, in litt.). In particular, efforts have been focused on the removal of the tamiligi from within 

the boundaries of the NPSA as well as in adjacent areas (Hughes et al. 2012).

The thrip Liothrips urichi is an insect that was introduced to American Samoa in the 1970s as a 

biocontrol for the weed Clidemia hirta (Tauiliili and Vargo 1993, p. 59). This thrip has been 

successful at controlling Clidemia on Tutuila. Though Clidemia is still common and widespread 

throughout Tutuila, thrips inhibit its growth and vigor, preventing it from achieving ecological 

dominance (Cook 2001, p. 143).

In 2004, the American Samoa Invasive Species Team (ASIST) was established as an interagency 

team of nine local government and Federal agencies. The mission of ASIST is to reduce the rate 

of invasion and impact of invasive species in American Samoa with the goals of promoting 

education and awareness on invasive species and preventing, controlling, and eradicating 

invasive species. In 2010, the U.S. Forest Service conducted an invasive plant management 

workshop for Territorial and Federal agencies, and local partners (Nagle 2010). More recently, 

the NPSA produced a field guide of 15 invasive plants that the park and its partners target for 

early detection and response (NPSA 2012, in litt.).
28

In 1996, the NPSA initiated a feral pig control program that includes fencing and removal of pigs 

using snares in the Tutuila Island and Ta‘ū Island Units. Two fences have been constructed and 

several hundred pigs have been removed since 2007 (Togia 2015, in litt.). The program is 

ongoing and includes monitoring feral pig activity twice per year and additional removal actions 

as needed (Togia 2015, in litt.).

Samoa – The Mt. Vaea Ecological Restoration Project surveyed and mapped the presence of 

native bird and plant species and invasive plant species within lowland forest habitat of the 454-

ac (183-ha) Mt. Vaea Scenic Reserve on ‘Upolu, Samoa (Bonin 2008, pp. 2–5). The project was 

envisioned as the first demonstration project of invasive species management and forest 

restoration in Samoa. Phase I of the project resulted in the development of a restoration plan 

recommending removal of five priority invasive plant species and planting of native tree species 

(Bonin 2008, pp. viii, 24). Phase 2 of the project resulted in identifying techniques for treatment 

of two problematic rubber tree species (Castilla elastica or pulu mamoe and Funtumia elastica 

or pulu vao) and replanting areas with native tree species (Bonin 2010, pp. 20–21).

Predation

The following sections provide information about predation by rats (Rattus spp.) and feral cats

(Felis catus) and existing efforts to address these stressors.

Rats

Nest predation by rats has negative impacts on many island birds, including the Mao (Atkinson 

1977, p. 129; 1985, pp. 55–70; Butler and Stirnemann 2013, p. 29; O’Donnell et al. 2015, pp. 

24–26). Three species of rats occur in American Samoa and are likely to be present on the 

islands of Ofu and Olosega: the Polynesian rat, Norway rat, and black rat (Atkinson 1977, p. 38; 

DMWR 2006, p. 22; Caruso 2015, in litt.). Rats have been identified as the main cause of decline 

in the closely related Gymnomyza aubryana in New Caledonia (MNRE 2006, p. 8). Butler and 

Stirnemann (2013, p. 29) captured footage of one nest depredation event on Mao by a black rat

(Rattus rattus), which took an egg. The rat gained access to the egg by jumping on the incubating 

female’s back from the branch above, driving the female off the nest. Combined with the 

disappearance of two females during the breeding season, this footage suggests that adult 

females are potentially vulnerable to predation on the nest at night, while they are incubating 

(Butler and Stirnemann 2013, p. 31), a phenomenon documented or suspected in other island 

bird species, which lack innate behavioral defenses against nonnative mammalian predators (see 

for example Robertson et al. 1994, p. 1,084; Armstrong et al. 2006, p. 1,034; VanderWerf 2009, 

p. 741). This potential bias toward predation of females has the potential to create a skewed sex 

ratio in Mao populations (Robertson et al. 1994, pp. 1,083–1,084).

The location of Mao nests affects their vulnerability to predation by rats. Nests in close 

proximity to plantation habitats, where rats are most abundant, are particularly susceptible and 

experience low reproductive success (Butler and Stirnemann 2013, p. 31). Nests within 160 ft 

(50 m) of a plantation are 40 percent more likely to be depredated than nests in forested areas 

farther from plantations (Butler and Stirnemann 2013, p. 31).

Cats
29

Predation by cats has been directly responsible for the extinction of numerous birds on oceanic 

islands (Medina et al. 2011, p. 6). Native mammalian carnivores are absent from oceanic islands 

because of their low dispersal ability, but once introduced by humans, they can become 

significant predators on native animals such as seabirds and land birds that are not adapted to 

predation by terrestrial carnivores (Nogales et al. 2013, p. 804; Scott et al. 1986, p. 363; Ainley 

et al. 1997, p. 24; Hess and Banko 2006, in litt.). The considerable amount of time spent on the 

ground (up to 7 days) and poor flight ability of Mao chicks post- fledging increases the risk of 

predation by feral cats (Butler and Stirnemann 2013, p. 28). Evidence of feral cat presence exists 

in montane forests and along an elevational gradient on Savai‘i (Atherton and Jeffries 2012, pp. 

76, 103). Predation by feral cats has been suggested as a contributing factor in the Mao’s 

extirpation from Tutuila (Stirnemann 2015b, in litt.). However, feral cats have not commonly 

been observed in native forest areas on Tutuila, though they have been observed in remote and 

forested areas on Ta‘ū (Badia 2014, in litt.; Arcilla 2015, in litt.). 

Conservation Efforts to Reduce Predation

Rats – A project to restore habitat for the Mao and other priority species by removing the threat 

of predation by the Polynesian rat (R. exulans) was attempted on the uninhabited islands of 

Nu‘utele (267 ac (108 ha)) and Nu‘ulua (62 ac (25 ha)) off the eastern end of ‘Upolu, Samoa 

(Tye 2012, in litt). The demonstration project aimed to eradicate the Polynesian rat from both 

islands through aerial delivery of poison baits. Post-project monitoring detected rats on Nu‘utele, 

suggesting that rats survived the initial eradication effort or were able to recolonize the island 

(Tye 2012, in litt.).

Cats – There are no known projects to reduce feral cat predation of Mao.

Disease

Avian malaria and pox have been important factors in the decline of Hawai‘i’s avifauna (Warner 

1968, Van Riper et al. 1986). Field and laboratory investigations suggest that avian malaria may 

be indigenous and non-pathogenic in American Samoa and, therefore, is unlikely to affect bird 

populations (Jarvi et al. 2003, p. 636; Seamon 2004, in litt.). The best available information does 

not indicate there are other diseases affecting the Mao populations in Samoa (MNRE 2006, p. 8).

Competition

No information is available on competition between other species and the Mao.

Natural Events

Tropical Cyclones (Hurricanes)

Tropical Cyclones (hurricanes) are a common natural disturbance in the tropical Pacific and have 

occurred in the Samoan archipelago with varying frequency and intensity (Figure 5). Although 

severe storms are a natural disturbance with which the Mao has coexisted for millennia, such 

storms can exacerbate the threats to its remaining small, isolated populations by, at least 

temporarily, damaging or redistributing habitat and food resources for the birds and causing 
30

direct mortality of individuals (Wiley and Wunderle 1993, pp. 340–341; Wunderle and Wiley 

1996, p. 261).

Two storms in the 1990s, Cyclones Ofa (1990) and Val (1991), severely damaged much of the 

remaining forested habitat in Samoa, reducing forest canopy cover by 73 percent (MNRE 2006, 

pp. 5, 7). In addition, Cyclone Evan struck Samoa in 2012 causing severe and widespread forest 

damage, including defoliation and downed trees in 80 to 90 percent of the Reserves and National 

Parks on ‘Upolu (Butler and Stirnemann 2013, p. 41). Secondary forests were also severely 

damaged by the storm, and most trees in the known Mao locations were stripped of their leaves, 

fruits, and flowers (Butler and Stirnemann 2013, p. 41). 

Resiliency, Representation, and Redundancy of the Species

Resiliency of Current Populations

Savai‘i, Samoa

The Mao was once found throughout Savai‘i likely in forests ranging from the coast to mountain 

tops (MNRE 2006, p. 2). Historical population estimates are not available but the species was 

considered common but patchily distributed in high elevation forests in 2005 (Pratt and 

Mittermeirer 2016, p. 226). Surveys conducted in 2012 detected small numbers at two sites 

(Atherton and Jefferies 2012, p. 14), indicating the population may have declined. In addition, 

reductions in the distribution of the population were noted in the 1990s and 2000s (Lovegrove et 

al. 1992, p. 26; MNRE 2006, pp. 2, 4). Based on the available information, we estimate the 

resiliency of the Savai‘i Mao population to be moderate due to an apparent decline in the 

population size and reduction in range.

‘Upolu, Samoa

The Mao was once found throughout ‘Upolu likely in forests ranging from the coast to mountain 

tops (MNRE 2006, p. 2). Historical population estimates are not available but the species was 

considered common in preferred habitat in 1984 (Bellingham and Davis 1988, p. 124). 

Subsequent surveys indicate the population may have declined (Lovegrove et al. 1992, p. 26). In 

addition, reductions in the distribution of the population were noted in the 1990s and 2000s 

(Lovegrove et al. 1992, p. 26; MNRE 2006, pp. 2, 4). Based on the available information, we 

estimate the resiliency of the ‘Upolu Mao population to be low to moderate due to an apparent 

decline in the population size and reduction in range.

Tutuila, American Samoa

The Mao is believed to be extirpated from Tutuila (Freifeld 1999, p. 1,208). Therefore, this 

population has no resiliency.

Current Representation and Redundancy of the Species

Species Representation
31

Historically the Mao was found on the islands of Savai‘i and ‘Upolu, Samoa, and Tutuila Island, 

American Samoa (Engbring and Ramsey 1989, p. 68; Watling 2001, p. 174). The Mao has not 

been observed on Tutuila since 1977 and is likely absent from that island (Freifeld 1999, p. 

1,208; MacDonald 2015, in litt.). In addition, the Mao was once found throughout Savai‘i and 

‘Upolu (Samoa) likely in forests ranging from the coast to mountain tops (MNRE 2006, p. 2). 

Distribution declines were noted in the 1990s and 2000s (Lovegrove et al. 1992, p. 26; MNRE 

2006, pp. 2, 4) and the species appears restricted to forested areas at higher elevations (Figure 

15). Based on the available information, we estimate the representation of the Mao to be low to 

moderate due to loss of the Tutuila population and restricted altitudinal ranges on the remaining 

islands.

Species Redundancy

Historically the Mao was found on the islands of Savai‘i and ‘Upolu, Samoa, and Tutuila Island, 

American Samoa (Engbring and Ramsey 1989, p. 68; Watling 2001, p. 174). The Mao has not 

been observed on Tutuila since 1977 and is likely absent from that island (Freifeld 1999, p. 

1,208; MacDonald 2015, in litt.). While there are multiple locations of Mao on Savai‘i and 

‘Upolu, each of these islands represents a single population. Historically, there were three 

populations of Mao. Currently there are only two populations, and those two populations are 

reduced in their area of occupancy and in number of individuals. Based on the available 

information, we estimate the redundancy of the Mao to be moderate due to loss of the Tutuila 

population.
32

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