• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

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 Monarch is assessed as Near Threatened.

Population justification
Previously, the population was suspected to number 2,500-9,999 (BirdLife International 2016) although this is now considered an underestimate. This species is typically described as rare (Pratt and Beehler 2015), but eBird (2022) data suggest that it may at least locally be more common, with eight individuals encountered on one 2.5-km checklist, although generally only 2-3 are encountered on such transects. Most habitat surveyed appears to host this species (eBird 2022). Other Symposiachrus typically occur at a high density, numbering 100-200 birds/km² (e.g. Marsden et al. 1997, Poulsen 1998). 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. Even precautionarily assuming that S. brehmii occurs at a density 20-40% of congeners, the population is here inferred to number 30,000-120,000 birds, or c.20,000-80,000 mature individuals, with a best estimate (20,000-40,000) at the lower end of this.

Trend justification
No direct assessment of the rate of population change has been made. This species is considered to be highly forest dependent. There has been a slow rate of forest cover loss, up to 4% over the past three generations (data from Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein), and this is suspected to be causing broadly equivalent reductions in population size of this species, set here to 1-9% over three generations (11.1 years; Bird et al. 2020).

This species is endemic to the twin-islands of Biak-Supiori in Geelvink Bay, West Papua, Indonesia (Beehler et al. 1986).

It occurs mostly in primary forest, to 600 m.

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 in the three generations to 2022, the maximum rate is estimated at 4.0% (Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein). Much of Supiori comprises virtually impenetrable, forested limestone mountains, which are likely to be safe from habitat degradation.

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
Conduct surveys on both islands to establish its current distribution, population status and assess its habitat requirements. Afford formal protection to further key sites where appropriate.

17 cm. Striking black, white and pale yellow monarch. Black or dark brown head, throat, mantle, wings and central tail feathers, with white wing-patch, lower breast and belly, rump and outer tail feathers. Variable yellowish-white on head and breast may be sex- or age-related. Similar spp. Male Golden Monarch Carterornis chrysomela is bright golden-yellow with black throat, mantle, tail and flight feathers. Northern Fantail Rhipidura hyperythra has white throat and lacks extensive white on wings, rump and tail. Voice Short rasps. Hints Rarely seen at Warafri, perhaps best to trek into forested hills inland.

Text account compilers
Berryman, A.

Contributors
Bishop, K.D., Burrows, R., Gregory, P., Holmes, D. & van Balen, B.S.

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Recommended citation
BirdLife International (2024) Species factsheet: Biak Monarch Symposiachrus brehmii. Downloaded from https://datazone.birdlife.org/species/factsheet/biak-monarch-symposiachrus-brehmii 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.