Justification of Red List Category
Given the small range and relative mobility of this species, it is judged to comprise a single small population which is likely to be decreasing as a result of continuing habitat loss and degradation creeping up hill-slopes into its altitudinal range. For these reasons it qualifies as Vulnerable.
The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.
A population decline is suspected on the basis of rates of logging and land clearance from lower altitudes up into the montane habitat of this species. The likely rate of population decline, however, has not been estimated.
Spilornis kinabaluensis is confined to the mountains of central and northern Borneo in Brunei, Sabah and Sarawak, Malaysia, and Kalimantan, Indonesia (BirdLife International 2001). From observations in the 1980s and 1990s, it appears to be a genuinely scarce species, with a small total population. However, much of its range is infrequently visited and it may prove to be more widespread than current indications suggest. It is likely to occur more or less continuously along the Crocker Range from Mount Kinabalu to Ulu Padas, G. Mulu and the border mountains of Brunei, and Gunung Murud (Pulong Tau National Park) (G. Davison in litt. 2007). Five individuals were seen in the Menyapa Mountains during surveys in 2007, which represents a southerly range extension for the species (Brickle et al. 2010), though the southern and western limits of its distribution are poorly known and need to be investigated, e.g., its occurrence in the Kelabit Highlands and Usun Apau, Kayan Mentarang and central montane parts of Kalimantan (G. Davison in litt. 2007).
It is apparently sedentary in submontane and montane evergreen rainforest where it tends to prefer ridge-top forest at 750-2,900 m. In areas where it occurs alongside S. cheela it is separated vertically by a few hundred metres.
Habitat loss, degradation and fragmentation are the primary threats to the species, particularly towards the lower altitudinal limits of its distribution, where the extent of forest is diminishing fairly rapidly in the face of agricultural expansion and intensification, although forest at higher altitudes is also threatened, for example by small-holder agriculture (G. Davison in litt. 2007, 2012).
Conservation Actions Underway
CITES Appendix II. It occurs within Kinabalu and Mulu National Parks and Temburong/Kuala Belalong (Brunei) (G. Davison in litt. 2007).
51-56 cm. Small, dark, forest-dwelling eagle. Plumage dark brown, speckled paler on underparts, wings and hindneck. Rich umber-brown patch on nape. Black throat. Fairly long, blackish tail with broad white band. Long wings with black tips and white bases to flight feathers. Similar spp. Its widespread relative, Crested Serpent-eagle S. cheela, is paler with shorter wings and narrower, less distinct greyish-white band on tail. Hints Frequently soars over ridge-tops and occurs at higher altitudes than S. cheela. Voice High repeated whistling notes similar to S. cheela.
Text account compilers
Martin, R, Taylor, J., Benstead, P., Westrip, J., Davidson, P., Tobias, J., Bird, J.
Eaton, J., Mann, C., Davison, G., van Balen, B.
BirdLife International (2022) Species factsheet: Spilornis kinabaluensis. Downloaded from http://www.birdlife.org on 06/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/07/2022.