Data Zone
Justification of Red List category
This unique species is suspected to be declining rapidly throughout much of its range as a result of ongoing forest loss and degradation. These losses are projected to exceed 30% over three generations; the species is therefore considered Vulnerable.
Population justification
Attempts to assess the population size of this species are confounded by its nomadic behaviour. Although it is described as uncommon (e.g. Smythies and Davison 1999, Eaton et al. 2016) it is widespread across Borneo's lowlands (Witt and Sheldon 1994, Mann 2008) and is not considered likely to approach population size thresholds (<10,000 mature individuals) for listing as threatened.
Trend justification
Pityriasis gymnocephala is tied to lowland forests, which are being lost rapidly on Borneo. Global Forest Watch (2021, using data from Hansen et al. [2013] and methods disclosed therein) indicate forest cover loss within the range of the species was at a rate of 1.95% per year (13.2 years; Bird et al. 2020) in the period 2007-2020, equivalent to c.25% over three generations. Between 2015-2020, the rate increased to 2.3-2.5% per annum, equivalent when projected forward to a rate of 30-33% over three generations. Although it can be found in mature secondary and selectively logged forests, it is most abundant in tall, primary forests, and almost never in plantations (Witt & Sheldon 1994, Mann 2008). Given most forest loss on Borneo has amounted to total clearance or conversion to plantations, it is suspected that this species will decline at a rate near-equal to that of forest loss. There is no reason to suspect that these rates of forest loss will slow or cease in the near-future.
Pityriasis gymnocephala is confined to Borneo, where it occurs patchily in lowland forests of Sabah and Sarawak, East Malaysia, Brunei and Kalimantan, Indonesia.
The species is often said to favour peatswamp-forest, but it is probably most commonly associated with primary dipterocarp forest. It is also occasionally found in various other forest types, including disturbed dipterocarp forest, upland heath forest (kerangas forest), coastal swamp-forest, and mangroves (Sheldon and Moyle 2020). Although recorded exceptionally to 1,200 m, it principally occurs below 600 m (Mann 2008, Eaton et al. 2016). It is a noisy and social species, moving in small groups through the canopy and feeding on invertebrates, small reptiles and amphibians.
Rates of forest loss in the lowlands of Borneo continue to be rapid, suffering from recent illegal logging and land conversion, with deliberate targeting of all remaining stands of valuable timber including those inside protected areas. Peatswamp-forests are additionally affected by fires. This species is principally tied to forests below 600 m, which are among the most threatened. Between 2015-2020, remnant lowland forest (<600 m) was lost a rate of 2.5% per annum (Global Forest Watch [2021], based on Hansen et al. [2013]) and this rate is not expected to slow in the near-future.
Conservation Actions Underway
No targeted conservation actions are known for this species, although it occurs in a number of protected areas.
Conservation Actions Proposed
Conduct repeated surveys to measure rates of population decline or range contraction. Conduct ecological studies to improve understanding of its precise habitat requirements, tolerance of secondary habitats and response to fragmentation. Continue to monitor rates of forest loss using remote sensing data. Campaign for the protection of remaining tracts of peatswamp forest on Borneo.
Text account compilers
Berryman, A.
Contributors
Benstead, P., Gilroy, J. & Taylor, J.
Recommended citation
BirdLife International (2024) Species factsheet: Bornean Bristlehead Pityriasis gymnocephala. Downloaded from
https://datazone.birdlife.org/species/factsheet/bornean-bristlehead-pityriasis-gymnocephala 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.