Justification of Red List Category
The species is classified as Vulnerable because it has a very small range: it nests at just three known sites, with possibly over 95% of all known breeding birds concentrated at one cave. Overall population trends are unclear, but suspected to be stable in the absence of any clear increase or decline. If contraction of its breeding range continues, or populations are shown to be undergoing a continuous decline owing to a decrease in the number of nest-caves, perhaps compounded by continuing decline in extent and quality of marshy feeding areas, it should be uplisted to Endangered.
Studies in 1996-1997 estimated the total population at 2,500-3,000 individuals, roughly equivalent to 1,700-2,000 mature individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
This species is endemic to the Seychelles and ranges over the islands of Mahé, Praslin and La Digue, with one known breeding site on each island. A colony on Félicité has disappeared, as has one on Mahé (Watson 1984). The La Digue cave held 80 nests in 2009 (D. Jacques and S. Bibi, Dept. of Environment via A. Skerrett 2016), but as numbers have fluctuated in the past (45 in 1977 [MacDonald 1978], 80 in 1980s [Watson 1984], 35-45 in 1996-1997 [Rocamora 1997] and 56 in 2001 [Remie and Joubert 2001]) the population trend is unclear at this site. In the Praslin colony, 56 nests and 152 birds were estimated in 1977 (MacDonald 1978), with c.55-80 nests from 1980 (Rocamora 1997, Watson 1984, Remie and Joubert 2001). Studies in 1996-1997 estimated the total population at 2,500-3,000 individuals (Rocamora 1997).
It is an aerial, insectivorous species, and feeds over a variety of habitats including forest and wetlands. Flying ants form the majority of prey caught (MacDonald 1978). On Praslin and Mahé, it is most commonly seen flying over boulder-filled valleys or rocky slopes in the hills, usually in small flocks (MacDonald 1978), or in lowland areas (A. Skerrett in litt. 2016). It nests colonially on the roofs of deep caves, laying a single egg (MacDonald 1978). There is increasing evidence that it breeds year-round (G. Rocamora in litt. 1999).
The past decline of this species may have been due to the widespread use of insecticides such as DDT, perhaps the collection of nests for bird-nest soup, and the ongoing drainage of wetlands (Shah 1997) for housing and tourist developments in coastal and lowland areas, although this may not have a direct effect as the species feeds mainly elsewhere (G. Rocamora in litt. 2007). In the future, development encroachment could impact upon nest-caves and buffer areas (S. Parr in litt. 1999). Quarrying may be a threat, and led to the destruction of a Praslin nest-cave in the 1970s (G. Rocamora in litt. 1999, A. Skerrett in litt. 1999). Barn Owls Tyto alba are likely predators of this species (Rocamora 1997), and can limit the number of potential nest-sites by direct disturbance or occupation (A. Skerrett in litt. 1999). Cats may be a threat where nests are accessible to them (Rocamora 1997, A. Skerrett in litt. 1999). Marshes on La Digue have been invaded by introduced plant species and it has been suggested that this has affected invertebrates dependent on the marsh ecosystem (Rocamora 1997), reducing the food supply for the species (Gerlach 1996), although this is unproven. In 2015, there were incidents in which tourists paid locals on La Digue to take them to the nesting cave to harvest nests (A. Skerrett in litt. 2016).
Conservation Actions Underway
Cave sites on Praslin and La Digue are monitored by Ministry of Environment rangers (S. Parr in litt. 1999, G. Rocamora in litt. 2007). Programmes for the control of invasive wetland plants are ongoing (G. Rocamora in litt. 2007).
10-12 cm. Small, dark swift. Greyish-brown all over, but a little paler below. Similar spp. Vagrant Little Swift Apus affinis is dark brown with a white rump. Voice Soft twittering (flying groups), metallic clicking (within caves).
Text account compilers
Ekstrom, J., Khwaja, N., Pilgrim, J., Shutes, S., Symes, A., Taylor, J., Warren, B., Westrip, J.
Jacques, D., Bibi, S., Lucking, R., Rocamora, G., Parr, S., Skerrett, A.
BirdLife International (2019) Species factsheet: Aerodramus elaphrus. Downloaded from http://www.birdlife.org on 13/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/11/2019.