Data Zone
Justification of Red List category
This species has a very small population numbering only 150-250 mature individuals, restricted to montane forest on Savai'i and 'Upolu where it is thought to be declining principally as a result of ongoing habitat loss and predation within its range. It is therefore classified as Endangered.
Population justification
This species is patchily distributed and difficult to find, seemingly absent from large tracts of suitable upland habitat (O'Brien and Masibalavu 2017, M. O'Brien in litt. 2022). It was found to be common but patchily distributed in Savai'i highland forests in 2005 (Pratt and Mittermeier 2016). The Rapid Biodiversity Assessment of Upland Savai'i, Samoa, conducted in 2012, detected small numbers at two sites on the island (Butler 2012). The ICCRIF study of 2014 found it at only one of five sites it surveyed (R. Stirnemann in litt. 2016), and during surveys of multiple sites in 2016 the species was recorded on point counts only at Aopo (O'Brien and Masibalavu 2017, M. O'Brien in litt. 2022). Based on point count data from 2016, there were crudely estimated to be 1 pair for every 16 to 22km2 overall, equating to c. 50 mature individuals on Savai'i (M. O'Brien in litt. 2022). However, although its call is far-reaching, the species' detectability is otherwise very low and this is likely to be an underestimate (though the subpopulation is not thought to exceed 250 mature individuals) (M. O'Brien in litt. 2022). As such, the population on Savai'i is tentatively placed in the band 100-200 mature individuals, with the global population placed at 125-250 mature individuals under the assumption that c.75% of the population occurs on Savai'i.
Trend justification
Although the species was considered common in preferred upland habitat on `Upolu and Savai'i in 1984 (Bellingham and Davis 1988), it has reportedly become rarer and appears to be absent from sites it was recorded at previously (e.g. Uafato) (M. O'Brien in litt. 2022). The species is mostly restricted to montane forest and declines are believed to be associated with habitat loss and degradation, as well as high rates of nest failure and predation (USFWS 2020). A decline in distribution in the 1990s it thought to have been driven by a series of cyclones (Lovegrove et al. 1992, Park et al. 1992), and surveys in 2005-2006 indicated that numbers were continuing to decline (MNRE 2006, USFWS 2020). Nest predation by Black rat Rattus rattus has been shown to impact reproductive success (Stirnemann et al. 2015a) and the species appears to have increased following rat control in Malololelei (M. O'Brien in litt. 2022). This threat acts parallel to that of habitat loss and fragmentation, with nests near plantations or on forest edge likely experiencing higher predation rates than those in interior forest (Stirnemann et al. 2015a). These threats are thought to be especially impactful for this species due to its slow life history traits. As the threats are ongoing, a continuing decline is inferred.
Gymnomyza samoensis occurs on Savai'i and 'Upolu, Samoa, and formerly occurred on Tutuila, American Samoa (it was collected there in the 1920s).
This large honeyeater occurs in foothill and montane forest, though was likely once found in forests ranging from the coast to mountain tops (MNRE 2006). It has also been observed in an area of cinder cone, heathland scrub, at forest edge, in the wet forest at 760 m (Reed 1980) and on steep slopes along rivers (Stirnemann in litt. 2016). Birds occasionally forage and nest in modified habitat such as plantation areas (USFWS 2020). It has been observed feeding on a wide range of flowers trees including the flowers of the coral trees Erythrina spp., mistletoe, heliconia, ginger, banana and some orchids species (R. Stirnemann in litt. 2012). Insects are also an important part of the diet and are the main food source in the dry season. During breeding, a simple nest is constructed in a tree, at varying heights above 5m, and a single egg is laid (Stirnemann et al. 2015b). In the nest, the chick is fed a mix of invertebrates and geckos. Incubation lasts 19 days, and chicks fledge 21-22 days after hatching (Stirneman et al. 2015b). Juveniles are dependent on adults for approximately 8 to 10 weeks post-fledging (Stirnemann et al. 2015b). The female is almost exclusively responsible for incubation and feeding the chick, and both adults defend the nest. Pairs are highly territorial with high site fidelity (Stirnemann et al. 2015b).
Forest clearance for commercial agriculture has been the primary cause of deforestation in Samoa, and although remote sensing data are not available to detect current rates of forest loss (Global Forest Watch 2023, using data from Hansen et al. [2013] and methods disclosed therein), it remains an ongoing threat to the species (MNRE 2006, USFWS 2020). Logging and clearing for residential development are also considered ongoing threats (MNRE 2006, USFWS 2020). In surveys in upland Savai'i, the species was not recorded in the disturbed forests above Asau and were only found in a limited altitudinal range on the A’opo trail (Butler 2012). Shifting or slash-and-burn cultivation threatens remaining areas of upland forest, as farmers use forestry roads from heavily logged lowland forests to gain access to formerly inaccessible land (Bellingham and Davis 1988, MNRE 2006, USFWS 2020).
The species is also likely to have suffered following cyclones Ofa and Val in 1990 and 1991, when canopy cover was significantly reduced (Elmqvist et al. 1994). Habitat quality is continually degraded by non-native invasive plants (USFWS 2020), with the loss of closed-canopy forest following cyclones increasing the emergence of invasive and weedy species (MNRE 2006, Butler and Stirnemann 2013). Forest quality has also declined because of the invasion of highly aggressive non-native trees, whose spread is also aided by cyclones (H. Freifeld in litt. 1999). Rubber plants are taking over the forest and resulting in 'empty bird forests' particularly in 'Upolu (H. Freifeld in litt. 1999, Stirnemann pers com. 2016). Feral pigs and cattle are also present within the range, causing damage to native vegetation, negatively impacting ecological integrity and faciliating the spread of invasive plants (USFWS 2020).
Nest predation by black rats Rattus rattus has been observed on camera; in these cases the rat jumped onto an incubating female, driving her off the nest (Stirnemann 2015). During the same study two adult females also disappeared during the breeding season, though no other predator species were identified (though other invasive rat species may pose a threat) (Stirnemann 2015). The behaviour of juveniles also places them at risk of predation; in the week post-fledging they spend a considerable time on the forest floor where they are at risk from predation by feral cats (Stirnemann 2015). Although the species may forage and occasionally nest in modified habitat such as plantations, predation risk is higher here (Stirneman 2015).
Local people reportedly shot this species when they saw it near villages in the past due to its consideration as a bird of ill omen (MNRE 2006), but it is unclear whether this is an ongoing threat.
Conservation Actions Underway
A species recovery plan has been published (MNRE 2006), and an updated plan is being finalised (USFWS 2021). There has been some rat control in some parts of the range (M. O'Brien in litt. 2022).
Conservation Actions Proposed
Conduct surveys to more accurately quantify the population size and trend. Establish a network of long-term monitoring stations. Protect remaining suitable habitat. Implement measures to control invasive species throughout the range. Increase local involvement and education on the species and conservation in general. Survey suitable habitat on Tutuila, American Samoa, to investigate if re-establishment is feasible.
31 cm. Large, dark honeyeater with long, slightly decurved bill. Sooty-black head, shading to dusky olive-green posteriorly and on wings, slightly tawny on undertail-coverts. Olive streak under eye. Eyes are blue in adults and brown in chicks. Similar spp. Samoan Starling Aplonis atrifusca has heavier, less pointed and curved bill, is brownish-black with no green tones. Voice Calls include mechanical-sounding chips and short squeaks. Song a composite of cat-like squeaky wails and cries and hoarse low notes.
Text account compilers
Vine, J.
Contributors
Freifeld, H., Stirnemann, R. & O'Brien, M.
Recommended citation
BirdLife International (2024) Species factsheet: Mao Gymnomyza samoensis. Downloaded from
https://datazone.birdlife.org/species/factsheet/mao-gymnomyza-samoensis on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.