Family: Acanthizidae (Thornbills)

Authority: Salvadori, 1878

Red List Category

Criteria: B1b(iii)

Click here for more information about the Red List categories and criteria

Justification of Red List category
This species is restricted to the twin islands of Biak-Supiori but despite the very small distribution the population size is not suspected to approach thresholds for listing as threatened under Criterion C. The population is suspected to be declining due to an ongoing slow rate of forest cover loss. The extent of occurrence, only 3,600 km², indicates that the species may be at risk, although the population is not severely fragmented and there are parts of the range where the main threat is not believed to apply. But forest loss is ongoing, hence a continuing decline in the area, extent or quality of habitat is estimated. In conjunction with the very small extent of occurrence, the species is considered to approach the thresholds for listing as threatened, meeting Criterion B1b(iii) but not a second subcriterion. Accordingly, Biak Gerygone is assessed as Near Threatened.

Population size: 15000-45000 mature individuals

Population trend: decreasing

Extent of occurrence (breeding/resident): 3,600 km²

Country endemic: yes

Attributes
Land-mass type - oceanic island
Realm - Oceanian
IUCN System - Terrestrial