Atiu Swiftlet Aerodramus sawtelli


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. If the population were shown to be in decline it may warrant uplisting to a higher threat category.

Population justification
McCormack (1997).

Trend justification
Populations were formerly thought to be stable. Owing to a lack of new data this is still suspected to be the case.

Distribution and population

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). When it was collected in 1973 from the Anatakitaki Cave there were c. 60 nests and the local inhabitants reported that there were a few smaller colonies elsewhere on the island (Holyoak 1974). Local knowledge suggests the species was higher in numbers decades ago, with the species reported as resembling swarms of butterflies (Rongo and Dyer 2014). In 1987-1988, a detailed survey recorded 190 active nests in two caves (Tarburton 1990). 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 and 175 (McCormack 1997).


The species favours forests, fernlands, agriculturally developed areas such as croplands, and mixed horticultural areas, but avoids the dry, uparised coral ring (makatea) of Atiu (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). The species nests colonially in caves in makatea limestone (Pratt et al. 1987).


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 Cardisoma longipes (Tarburton 1990). The fledging period is prolonged, perhaps because of lack of food. 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). Polynesian rats Rattus exulans are present on the island and may be a threat (J. Pilgrim in litt. 2002).

Conservation actions

Conservation Actions Underway
Surveys have been conducted and a standardised method for monitoring has been designed (McCormack 1997). Baiting to prevent the arrival of rats is underway by the airport and dock (J. Pilgrim in litt. 2002), and a new programme based on increased community vigilance, reporting any rat or sign of rats in cargo, and a response with traps and toxic bait has been initiated (G. McCormack in litt. 2007).

Conservation Actions Proposed
Resurvey the population including a detailed study of the breeding biology over a full season so that further actions can be identified/justified (SPREP 1999). Exclude crabs from breeding caves (SPREP 1999). Investigate the possibility of translocation to another suitable island (SPREP 1999). Monitor and regulate tourism. Control Polynesian Rats Rattus exulans close to breeding caves. Take measures to ensure that alien species, especially black rat Rattus rattus, are not accidentally introduced to the island.


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


Text account compilers
Derhé, M., Harding, M., Mahood, S., Shutes, S., Stattersfield, A., North, A.

McCormack, G., Pilgrim, J.

Recommended citation
BirdLife International (2020) Species factsheet: Aerodramus sawtelli. Downloaded from on 30/05/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from on 30/05/2020.