Data Zone
Justification of Red List category
This species has a very small range, in which the extent and quality of its habitat are suspected to decline. The population is small and thought to form just one subpopulation. Nevertheless, the species cannot be considered severely fragmented or occurring at a limited number of locations, and there is insufficient data to infer a continuing decline in population size and habitat availability. Therefore, the species is listed as Near Threatened.
Population justification
The population size of this species has not been quantified. However, a preliminary population estimate can be derived from a congener, the Island Leaf-warbler (Phylloscopus poliocephalus), which occurs from the Indonesian Archipelago through Papua New Guinea to the Solomon Islands. This species occurs at a density of c. 180 individuals/km2 in intact forest (Marsden 1998). Only an area of 244 km2 offer suitable forested habitat for Rote Leaf-warbler throughout its range (Ng et al. 2018). Assuming that Rote Leaf-warbler occurs at a similar density throughout suitable habitat, and that only about 20% of suitable habitat is occupied, the population may number c. 8,800 individuals, which roughly equates to 5,900 mature individuals. As this estimate is highly preliminary and requires confirmation, the species is tentatively placed in the band 2,500-9,999 mature individuals.
Trend justification
The population trend has not been quantified, but the species is threatened by habitat loss and deforestation. Although the species is currently predominantly found on the Tapuafu Peninsula, where large areas of intact forest persist (Ng et al. 2018, eBird 2019), the species's restricted range and specific habitat requirements make it vulnerable to habitat degradation and loss. As a result, and given the degree of disturbance and fragmentation already within its range, the species is precautionarily suggested to be undergoing a slow decline (Ng et al. 2018).
The species is endemic to the island of Rote, part of the East Nusa Tenggara province in the Lesser Sunda Islands of Indonesia (Ng et al. 2018). Rote Island is one of Timor's largest satellites and is arid and low-lying, rising to a maximum elevation of 420 m (Ng et al. 2018). The majority of the island has been subjected to severe deforestation, and the species is primarily confined to the remaining forested areas of Seda and the Tapuafu Peninsula (Ng et al. 2018).
The habitat, behaviour and ecological requirements of the species are not yet well understood (Ng et al. 2018). The species is known to inhabit both intact primary deciduous forest as well as secondary forest, being found most frequently in arid woodlands and tropical dry forest in the northwest of Rote Island (Ng et al. 2018). The species tends to occupy the highest strata of the canopy in which it resides. It is also a bark-gleaner, actively taking prey from tree branches and trunks (Ng et al. 2018).
The most severe threat to the species is habitat loss due to deforestation. Forests on Rote are severely fragmented and patchily distributed due to agriculture and it is estimated that only 19% of the island offers suitable habitat for the species (Ng et al. 2018). As the human population continues to grow rapidly on Rote (Ng et al. 2018), it is expected that the forest will be further depleted for conversion into agricultural land and road developments.
Conservation Actions Underway
No targeted conservation actions are known for this species.
Conservation Actions Proposed
Assess the population size. Monitor the population trend. Assess the threats to the species and their impact on the population size. Protect remaining habitat.
The Rote Leaf-warbler weighs approximately 7.5 g and is approximately 10 cm in length. Its crown is a dark olive-grey, with a pale lemon yellow median crown stripe stretching from the base of the culmen to the nape. The lores is also a dark olive grey and forms an eye stripe from the base of the bill, through the eye, along the sides of the head above the pale lemon yellow ear coverts. The supercilium, chin, throat, breast, belly and flanks are a slightly more saturated lemon yellow, with the mid-breast and mid-belly a brighter lemon yellow. The nape, mantle, scapulars, rump and upper tail coverts are olive-grey, slightly paler than on the rectrices and remiges. The outermost tail feathers on each side have white inner vanes and dark olive grey outer vanes. Pale cream margins on the greater coverts form a single narrow wingbar. White underwing coverts, grade to cream and then pale lemon yellow along the leading edge of the underwing between the bend of the wing and the alula. The primaries have a dark olive-grey underside with a whitish inner edge. The lower mandible is yellow-orange. Iris dark brown (Ng et al. 2018).
Text account compilers
Everest, J.
Recommended citation
BirdLife International (2024) Species factsheet: Rote Leaf-warbler Phylloscopus rotiensis. Downloaded from
https://datazone.birdlife.org/species/factsheet/rote-leaf-warbler-phylloscopus-rotiensis on 26/12/2024.
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 26/12/2024.