Australian Swiftlet Aerodramus terraereginae Scientific name definitions

11 cm; mean 9·4 g (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ). Medium-sized swiftlet with shallowly forked tail ; dark brown upperparts with typically paler rump, though some birds uniform across upperparts; pale grey-brown underparts  ; tarsi heavily feathered and tail proportionately long for A. spodiopygius group. Race chillagoensis is smaller (mean wing 107 mm, versus 114·5 mm in nominate) (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ) and paler. The only swiftlet in Australia and therefore unlikely to be confused. Species capable of echolocation.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Recorded to 1000 m, generally below 500 m. Much foraging over dry savanna-type terrain, though also seen feeding at rainforest margin. Breeds in both island (caves) and mainland sites (gorges) (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ).

Resident. Birds enter their breeding caves at remarkable speeds of up to 111 km/h, but are able to control their wings asynchronously in order to compensate for tight turns inside the caves (2 Tarburton, M. (2012). Swift manoeuvres: how nesting Australian Swiflets beat La Niña floodings. Australian Birdlife. 1(3): 26-29. Close ).

Habits of race chilla­goensis compared with those of A. spodiopygius assimilis of Fiji: present species takes larger prey in larger boluses, containing fewer individuals; 32 boluses contained 303 invertebrate species, averaging ten species more per bolus than in A. spodiopygius; 32 boluses of latter contained only 167 species. Large numbers of present species leave nest cave at regular intervals during day to feed locally; after c. 30 minutes they return to cave for ten minutes of lesser activity. Feeds less than 30 km from breeding sites.

Flight call a high-pitched “cheep” (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ). Echolocating calls consist of incessant metallic clicks (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ); the two subclicks have minimum and maximum frequencies of 2·74–5·58 kHz, for the first, and 2·17–7·40 kHz, for the second, respectively, with a mean 1·83- second silent interval between them. It has recently been hypothesized that these clicks serve in social interaction as well as echolocation (3 Thomassen, H.A. and Povel, G.D.E. (2006). Comparative and phylogenetic analysis of the echo clicks and social vocalizations of swiftlets (Aves: Apodidae). Biological Journal of the Linnean Society. 88(4):631–643. Close ).

At Tully Gorge, North Queensland, 95% of nests contained eggs or nestlings at various stages of development, early Oct to mid-Jan; breeds at Chillagoe, Oct–Mar. However, species is adaptable and during periods of unusually heavy rainfall (e.g. in La Niña years), which may flood nests and temporarily destroy colonies, breeds earlier, i.e. before water-levels become too high inside their caves, yet still capitalizing on insect availability (2 Tarburton, M. (2012). Swift manoeuvres: how nesting Australian Swiflets beat La Niña floodings. Australian Birdlife. 1(3): 26-29. Close ). Colonial, averaging 77 nests Chillagoe. Nesting caves totally dark or with little twilight; nests 2–20 m above cave floor on smoothly concave walls, though extrusions or cracks readily utilized; at one large colony average distance between nests 8 cm. At Chillagoe kangaroo grass (Themeda australis) and black spear grass (Heteropogon contortus) commonest nesting materials; one nest made of Casuarina twigs agglutinated with laminae of firm translucent saliva. Shallower nests than those of A. spodiopygius: nest of nominate race 56 × 45·5 × 3 mm, mean volume index 7·5 cm³; chillagoensis 49 × 42·5 × 12 mm, mean 25 cm³. One egg  , laying apparently stimulated by rain; mean incubation 26·5 days, both sexes incubating; lost clutches and broods < 10 days old replaced within 6–18 days. Nestling period 46 days in good season, 51 in poor season. Second clutch also of one egg laid 50 days after first: to aid incubation uses heat from first nestling, which usually fledges just before second egg hatches (2 Tarburton, M. (2012). Swift manoeuvres: how nesting Australian Swiflets beat La Niña floodings. Australian Birdlife. 1(3): 26-29. Close ); this strategy is unique almost all birds (1 Chantler, P., and G. Driessens (2000). Swifts: A Guide to the Swifts and Treeswifts of the World. 2nd edition. Pica Press, Robertsbridge, UK. Close ). Feeding rates five per day in good season, two per day in bad season.

Not globally threatened. Common in lowlands. Survey of 34 active colonies during 1985–1987 showed peak count of 500 pairs for a single colony. Range appears stable but diminished numbers of breeding birds recorded at several colonies. It has been suggested that frequency of sightings away from areas with colonies implies new colonies will be found.