Data Zone
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 previous population size is considered to have been an underestimate. 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 the species occurrence has been negatively impacted by the recent rate of forest loss (M. Halaouate in litt. 2022). This rate is ongoing, hence a continuing decline in the area, extent or quality of habitat is inferred. 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 Hooded Pitta is assessed as Near Threatened.
Population justification
A previous population estimate of between 2,500-10,000 mature individuals (BirdLife International 2016) is now considered to be an underestimate. The majority of the range of the species is now considered suitable and likely occupied, while the previous estimate assumed only a small occupied fraction. The species is closely related to P. sordida on the island of Sangihe, Indonesia, which has been estimated to occur at densities of 17.5-24.2 individuals/km2, derived from calling birds which are likely to be mature (Riley 2002). Using the global landcover 2 estimate of forest cover for the island (closed to open broadleaved evergreen or semi-deciduous forest) and excluding fragments smaller than 1 km2 results in an area classified as forest habitat of 1,572 km2. If the species occurred at equivalent densities to those reported for P. sordida from Sangihe, the population size would be between 27,510-38,042 mature individuals. It is plausible that this species occurs at a lower density than on Sangihe, hence a precautionary lower bound for the population is assumed by using 50% of the minimum density value, 8.75 per km2, which results in a population size inferred to fall between 13,255 and 38,042 mature individuals, rounded to 13,000-38,000 mature individuals. As such, it is assessed that the population most likely exceeds thresholds for listing as threatened under the small population size criterion, and there is no direct estimate of the population that indicates that it falls below this threshold.
Trend justification
This species is considered to be moderately forest dependent. There has been a slow rate of forest cover loss, up to 3.6% over the past three generations (data from Global Forest Watch 2021, using Hansen et al. [2013] data and methods disclosed therein), and the loss of forest has been noted to have caused a decline in the population (M. Halaouate in litt. 2022). No direct assessment of rate of population change has been made for the species.
Pitta rosenbergii is restricted to the twin islands of Biak and Supiori, in the Geelvink Bay in north West Papua, Indonesia. It is poorly known, but likely to be common in Biak's forests. On Supiori the forest is largely intact and is difficult to access, hence is considered to be generally secure. The extent of occurrence is small, at 3,600 km2, while the maximum area of a grid of 2x2 km squares overlain on the confirmed and probable occurrence polygons is 3,032 km2. The area of forest, as derived from the 'GlobCover 2' land classification GIS layer (Arino et al. 2012), is estimated at 1,572 km2, after the exclusion of fragments smaller than 1 km2. There are observations of the species from mixed tree crop and forest garden habitat, indicating a level of tolerance of forest cover loss and of forest degradation (eBird 2021).
It is thought to be present in a wide range of habitats, and tolerant of secondary forest. It feeds on insects, earthworms and snails foraged from the forest floor. Nests are usually built on the forest floor (del Hoyo et al. 2003).
Forest on Biak has come under heavy pressure from logging and subsistence farming, though large-scale logging has not been economically feasible for some time (Wikramanayake et al. 2002). The rate of forest cover loss recorded through satellite monitoring has been slow in the past two decades, and over the past three generations of the species the maximum rate is estimated at 3.6% (Global Forest Watch 2021, using Hansen et al. [2013] data and methods disclosed therein). The species has some tolerance of degraded forest but does require forest cover and recent rates of forest loss are associated with a reduction in the occurrence of the species (M. Halaouate in litt. 2022). It is unclear how this low rate of forest cover loss will be affecting the population, but it is inferred that the extent and quality of habitat is suffering an ongoing decline, hence it is suspected to be causing a slow population reduction. There is no information on trapping of this species (S. Brusland in litt. 2022), though the intensive use of snares close to settlements has been reported in the south of Biak and this may impact this ground-dwelling species.
Conservation Actions Underway
The species is assumed to be present in the 110 km2 Biak-Utara protected area and throughout the 420 km2 Pulau Supiori Nature Reserve (UNEP-WCMC 2021a,b), both of which comprise virtually impenetrable limestone areas (Wikramanayake et al. 2002).
Conservation Actions Proposed
Obtain a direct population estimate for the species. Survey to confirm its presence in the Biak-Utara protected area.
16-19 cm. Small pitta. Relatively dark. Dark green above with a black tail; blue rump; dark blue breast; blue-green sides; red lower breast to vent; dark, ultramarine blue lower flanks, and a little white in the wing.
Text account compilers
Martin, R.
Contributors
Halaouate, M. & Brusland, S.
Recommended citation
BirdLife International (2024) Species factsheet: Biak Hooded Pitta Pitta rosenbergii. Downloaded from
https://datazone.birdlife.org/species/factsheet/biak-hooded-pitta-pitta-rosenbergii on 22/12/2024.
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 22/12/2024.