Tree Martin

Identification

The tree martin is a compact swallow, averaging 13 cm in length with a distinctive shallowly forked tail. Adults display striking iridescent blue on the back and crown, contrasting with brown wings and tail, a rufous forehead, and a whitish rump. The underparts are pure white. While the sexes are similar in appearance, young birds are considerably duller and browner, with a paler forehead and pale fringes to their back and wing feathers. The bird is vocal and communicative, with a distinctive call of a tsweet and a high-pitched twitter song.

Among Australian swallows, the tree martin is readily identified by its distinctive tail shape and pale rump. The most similar species, the fairy martin, can be distinguished by its rufous head and nape, features absent in the tree martin.

Range & Habitat

The tree martin breeds in Australia, predominantly south of latitude 20°S, and on Timor island. Three subspecies are recognised, with the largest form breeding in eastern Australia (except northern Queensland and Tasmania), a slightly smaller subspecies in western and northern Australia, and the smallest subspecies across the Lesser Sunda Islands. The species is migratory, wintering across most of Australia, New Guinea, Indonesia east of the Wallace Line, and the Solomon Islands, with occasional records as a vagrant to New Zealand (where it has bred) and New Caledonia.

Tree martins favour open woodland with large trees that provide suitable nesting holes, and have become increasingly common in urban and suburban areas. They are particularly abundant in large cities like Adelaide and Perth in western Australia.

Behaviour & Diet

Breeding occurs from July through January depending on region, with pairs or semi-colonial groups nesting in natural holes in dead trees, rock crevices, or increasingly in artificial sites on bridges and buildings. Nests are constructed from grass and leaves, sometimes reinforced with mud, and may feature a mud and plant fibre cement to reduce entrance width. Clutches typically comprise 3–5 brown and mauve-spotted white eggs, with this species often producing two broods per season. Tree martins occasionally appropriate nests from welcome swallows, sometimes displacing the original owners.

These birds are aerial insectivores with a fast, twisting flight pattern, typically feeding higher than welcome swallows at heights exceeding 6 m above the ground. They frequently hunt above tall eucalyptus canopies but will also feed on insect swarms over water. Outside the breeding season, they are highly gregarious and form mixed flocks with fairy martins.

Best Time & Places to See It

The breeding season from July to January offers the best opportunity to observe tree martins, particularly in open woodland areas with large trees and in urban and suburban settings, especially in western Australian cities. During winter months, look for them throughout their range in Australia, New Guinea, Indonesia, and the Solomon Islands, where they gather in mixed flocks with other swallow species.

Photography Tips

Capture tree martins in flight above woodland canopies and over water, where their fast, twisting flight and iridescent blue plumage are most visible. The pale rump and distinctive tail shape are key identifying features to emphasise. Early morning and late afternoon often provide the best light for photographing these active birds, particularly when they gather in larger flocks during non-breeding periods. Urban and suburban sites with nesting colonies on buildings and bridges offer excellent opportunities for close-range photography of breeding birds and behaviour.