Mystery bird: Pacific swallow, Hirundo tahitica

This southeast Asian mystery bird closely resembles two other species, one of which may be its sister taxon (includes video)

Pacific swallow, Hirundo tahitica JF Gmelin, 1789, also known as the hill swallow, photographed in the Republic of Singapore, a southeast Asian city-state off the southern tip of the Malay Peninsula.

Image: Marie-Louise Ng, 12 January 2011 (with permission) [velociraptorize].
Nikon D3S, 500mm/F4

Question: This southeast Asian mystery bird closely resembles two other species, one of which may be its sister taxon and the other of which may be a conspecific. However, these species have a behaviour that sets them apart. What is that behaviour? Can you identify this bird's taxonomic family and species?

Response: This is an adult Pacific swallow, Hirundo tahitica. This passerine is placed into the taxonomic family, Hirundinidae, the swallows and martins. These birds are adapted to catching insects in flight, making them similar to another group of aerial insectivores, the swifts. However, unlike swifts, swallows often perch and wait for individual insects to pursue and capture instead of flying around with their mouths wide open. Further, swallows feed very low in the air column, often engage in aerial acrobatics, and they also can perch -- all behaviours that the swifts lack.

Interestingly, even though Pacific swallows hunt alongside barn swallows, H. rustica, but they don't associate with them otherwise. These two species can be distinguished by the barn swallow's blue breast band and by its much longer outer tail "streamers", which the Pacific swallow lacks.

The Pacific swallow is even more similar to the welcome swallow, H. neoxena, which is found in Australia. These two species are sometimes considered to be conspecific (or sister species). These two taxa are distinguished by the Pacific swallow's white underparts and by its longer outer tail "streamers" which the welcome swallow lacks. (For more information regarding how to distinguish these three species, refer to Collins Field Guide to the Birds of New Zealand, Hawaii, Central and West Pacific by Ber van Perlo [Amazon UK; Amazon US]).

Unlike their migratory relatives, Pacific swallows are resident. They are fairly common within their range, but favour open country with lots of water, and are also found in coastal areas and in mangroves.

Here's a slow-motion video of an individual Pacific swallow landing on a branch and then preening (filmed at Caliraya Lake, Laguna, Philippines on 10 April 2010):





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