Data Zone
Justification of Red List category
This poorly known swift qualifies as Near Threatened under D1 due to a potentially small population size that, while not directly estimated, is precautionarily suspected to be between 900-10,000.
Population justification
This species has been described as very local and scarce (Rasmussen and Anderton 2012). The number of individuals recorded in each eBird (2024) observation indicates that the population size is unlikely to be less than 250. However, it is possible that the population size could be fewer than 1,000 mature individuals. Given the significant lack of understanding surrounding the population, a precautionary estimate ranges from 900 to 10,000 individuals. This estimate considers both the apparent small population size and the substantial uncertainty, leaving room for the possibility of a larger population that has yet to be discovered.
Trend justification
The species has a broad range and there are no known threats that are thought to be causing significant global declines in the population. An analysis conducted via Global Forest Watch indicates a notable decline of 6.4% in forest cover spanning the period from 2010 to 2023 (3 generations) (Global Forest Watch (2024), based on data from Hansen et al. (2013) and methods therein). Primarily concentrated within the recognised resident range of the species, this reduction in forest cover could pose a concern for the species, however it is not thought to be heavily dependent on forest. The species has an expansive breeding range, with regions in Bhutan where the species is present, experiencing minimal forest cover loss. Furthermore, regions characterised by robust forest ecosystems, like Phawngpui National Park, are known for hosting healthy populations of A. acuticauda (Kasambe et al. 2014). The species also exhibits a high elevational tolerance, having been documented between 200 and 2,470 meters within India (Chantler and Kirwan 2020). Consequently, owing to potential accessibility constraints, suitable habitat extends beyond areas with higher rates of forest loss. Records at its known sites have remained stable for many years, for example at Cherrapunji (J. Eaton in litt. 2013), and it continues to be regularly reported at well-known sites (eBird 2024). Given the limited understanding of this species' ecology, assessing the extent to which forest cover loss poses a threat remains challenging, but it does not seem likely to have caused any significant population declines yet. Due to these factors the population is suspected to be stable in the absence of evidence for any declines or substantial threats.
Apus acuticauda is known from just a few breeding colonies in the Himalayan foothills of Bhutan and north-east India (BirdLife International 2001, Chantler 2005, Ahmed et al. 2007, K. D. Bishop in litt. 2013, J. Eaton in litt. 2013, M. Sharma in litt. 2013, Choudhury 2013). There are year-round records from various parts of India and Myanmar, along with previous records from north-western Thailand where may be vagrant, though status here is unclear (Chantler and Kirwan 2020, eBird 2024). Its seasonal movements and wintering areas are virtually unknown.
It breeds colonially in the crevices of rocky cliffs and deep gorges, at 200-2,470 m, generally in the vicinity of forest. Breeding is from March to May usually at the same site each year (Chantler and Kirwan 2020). Birds apparently remain in close proximity to the nesting colonies while breeding, normally disappearing soon afterwards and reappearing the following year. Away from breeding sites, it has been recorded up to at least 1,500 m. It has been suggested that it may only undertake local movements, but this requires further investigation.
There are no known substantial threats to the species. While there is some deforestation within its range, this hasn't yet thought to have caused population declines. However, due to limited population data and ecological knowledge, assessing this is challenging.
Conservation Actions Underway
A presumed breeding site is located within the Blue Mountain National Park, Mizoram, north-eastern India. Strict forest policy and wildlife protection laws in Bhutan suggest that its future there is secure.
17-18 cm. Slim, all-dark swift with scaly underside and deeply forked tail. Tends to have dark throat. Similar spp. Fork-tailed Swift A. pacificus has white rump-band, less sharply forked tail and paler throat. Common Swift A. apus lacks scaling to underparts and has shorter, less deeply forked tail. Voice High-pitched, rapid, quavering tsrr'i'i'i'i and tsrr'i'i'i'i'is'it at nest-sites.
Text account compilers
Peet, N., Tobias, J., Taylor, J., Westrip, J.R.S., Allinson, T, Davidson, P., Bird, J., Chad, E.
Contributors
Ahmed, F, Bishop, K.D., Duckworth, J.W., Eaton, J., Hornskov, J., Mahood, S., Robson, C. & Sharma, M.
Recommended citation
BirdLife International (2024) Species factsheet: Dark-rumped Swift Apus acuticauda. Downloaded from
https://datazone.birdlife.org/species/factsheet/dark-rumped-swift-apus-acuticauda 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.