Biak Gerygone Gerygone hypoxantha


Justification of Red List Category
This newly-split species is listed as Vulnerable on the basis that it is likely to have a single, small population that is inferred to be declining owing to ongoing loss of habitat.

Population justification
A population estimate of 2,500-9,999 mature individuals has been made based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied.

Trend justification
This population is suspected to be in slow decline owing to ongoing habitat destruction (Gregory 2016).

Distribution and population

G. hypoxantha is endemic to the twin-islands of Biak-Supiori in Geelvink Bay, Papua (formerly Irian Jaya), Indonesia.


The species inhabits old-growth and secondary forest habitats, mangroves and other riparian or littoral habitats in the lowlands and is not as rare or specialised in its occurrence as previously thought (G. Dutson in litt. 2016).


Forest on Biak has come under heavy pressure from logging and subsistence farming, though there have been suggestions that large-scale logging may no longer be economically feasible, and rates of deforestation and degradation are currently lower than in the 1980s and 1990s (Wikramanayake et al. 2002).

Conservation actions

Conservation Actions Proposed
The following actions have been recommended in order to conserve remaining populations of G. m. hypoxantha: Conduct surveys on both islands to establish its current distribution, population status and assess its habitat requirements. Afford formal protection to further key sites, particularly mangrove habitats. Control logging on Supiori.


10 cm. A small, discrete species, pale yellow underneath and mousy grey-brown above with white lores and broken eye ring. Bill is relatively long, but not as bulky as that of G. magnirostris. Tends to be generally quiet, making it difficult to locate.


Text account compilers
Benstead, P., Bird, J., Butchart, S., Gilroy, J., Martin, R

Dutson, G.

Recommended citation
BirdLife International (2021) Species factsheet: Gerygone hypoxantha. Downloaded from on 20/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 20/10/2021.