• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
This species qualifies as Vulnerable because it has a small population on one island and is confined, when breeding, to just two caves, and hence is susceptible to stochastic events and human activities.

Population justification
In 1987-1988, a detailed survey recorded 190 active nests in two caves (74 in Anatakitaki and 116 in Vaitupurangi), leading to an estimated population size of 380 mature individuals (148 adults in Anatakitaki cave and 232 individuals in Vaitupurangi; Tarburton 1990). In 1989 the population in Anatakitaki cave was estimated at 163-241 individuals (Fullard et al. 2010). In 1994 and 1995, further surveys were conducted and, although the numbers of active nests in each cave varied from year to year, the totals were stable at 172 (82 in Anatakitaki and 90 in Vaitupurangi) and 175 (69 and 106 respectively; McCormack 1997, R. Dobbs and G. McCormack unpubl. data in Fullard et al. 2010). The number of mature individuals is therefore estimated to number 340-400.

Trend justification
Local knowledge suggests the species was higher in numbers decades ago, with the species reported as resembling swarms of butterflies (Rongo and Dyer 2014). When it was collected in 1973 from the Anatakitaki Cave there were c.60 nests and local inhabitants reported that there were a few smaller colonies elsewhere on the island (Holyoak 1974). In 1987-1988, a detailed survey recorded 380 mature individuals (148 adults in Anatakitaki cave and 232 individuals in Vaitupurangi; Tarburton 1990). In 1989 the population in Anatakitaki cave was estimated at 163-241 individuals (Fullard et al. 2010). In 1994 and 1995, further surveys were conducted and, although the numbers of active nests in each cave varied from year to year, the totals were stable at 172 (82 in Anatakitaki and 90 in Vaitupurangi) and 175 (69 and 106 respectively; McCormack 1997, R. Dobbs and G. McCormack unpubl. data in Fullard et al. 2010). In the absence of further evidence, the population is assumed to remain stable.

This species is restricted to Atiu, Cook Islands, although there is a possible early historic record from Mitiaro (Steadman 1989) and an unconfirmed report of swiftlet bones found on Mangaia (J. Pilgrim in litt. 2002). It breeds in two caves: Ana Takitaki in the east of the island, and Ana Tupurangi in the south (Tarburton 1990, McCormack 2007, Fullard et al. 2010). When it was collected in 1973 from the Anatakitaki cave, local inhabitants reported that there were a few smaller colonies elsewhere on the island (Holyoak 1974).

The species nests colonially in caves in makatea limestone (Pratt et al. 1987). When foraging, the species favours forests, fernlands, agriculturally developed areas such as croplands, and mixed horticultural areas, but avoids the makatea limestone (Fullard et al. 2010). Birds are most often seen foraging 3-5 m above the ground although occasionally descend to the edges of trees or bushes (Fullard et al. 2010). Nests are made from plant matter and saliva. Feeds on aerial invertebrates including Hymenoptera, Lepidoptera and Blattodea (Tarburton 2017).

The major causes of chick mortality have been identified as starvation after falling out of the nest and predation by coconut crab Birgus latro and land crab Discoplax longipes (Tarburton 1990). One of the caves has become a popular ecotourism destination (McCormack 1997) and thus disturbance could be a problem, as there do not appear to be any restrictions on noise and the use of torches (J. Pilgrim in litt. 2002).

Conservation Actions Underway
Surveys have been conducted and a standardised method for monitoring has been designed (McCormack 1997).

Conservation Actions Proposed
Resurvey the population to monitor trends. Conduct a detailed study of the breeding biology over a full season (SPREP 1999). Exclude crabs from breeding caves (SPREP 1999). Investigate the possibility of translocation to another suitable island (SPREP 1999). Regulate tourism to minimise disturbance in the species's nesting caves. Raise awareness of the importance of avoiding disturbance.

Identification

10 cm. Small, dark swift. All sooty-brown, slightly lighter below. Square tail. Voice Sharp chirps while foraging, echo-locating clicks in caves.

Acknowledgements

Text account compilers
Wheatley, H.

Contributors
Derhé, M., Harding, M., Mahood, S., McCormack, G., North, A., Pilgrim, J., Shutes, S., Stattersfield, A. & Tarburton, M.

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Recommended citation
BirdLife International (2024) Species factsheet: Atiu Swiftlet Aerodramus sawtelli. Downloaded from https://datazone.birdlife.org/species/factsheet/atiu-swiftlet-aerodramus-sawtelli on 23/11/2024.
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 23/11/2024.