Family Hemiprocnidae
crested swifts

Treeswifts are in the order Apodiformes. There are three families within this order: Hemiprocnidae (treeswifts), Apodidae (true swifts) and Trochilidae (hummingbirds). Treeswifts also belong to the suborder Apodi. There is one genus of treeswifts and 4 species. The four species are: grey-rumped treeswift (Hemiprocne longipennis), crested treeswift (Hemiprocne coronata), whiskered treeswift (Hemiprocne comata) and moustached treeswift (Hemiprocne mystacea).

Treeswifts are insectivores and catch the majority of their prey while flying. Unlike their close relatives, true swifts, treeswifts are able to perch, are not very social and have more ornate coloring (some species have bold white striping on their heads). Treeswifts also have crests on their heads and are easy to identify when perched because of their long crossed wing-tips and deeply forked tail.

They are monogamous and both males and females provide parental care. In-flight copulation has been recorded. Although they occur throughout much of the Oriental region, little is known about the Hemiprocnidae family. ()

Treeswifts are found throughout the Oriental Region (East to the Solomon Islands) and in some of the Australian region. ()

Treeswifts are tropical terrestrial forest birds and are found in evergreen forest, deciduous forest and mature mangrove stands. They require stretches of continuous forest, but can make use of areas with breaks in the canopy (for example, roads and rivers) and some edge habitat. They are found from lower elevations up to 2000 m. ()

When classified using anatomical and morphological characteristics, treeswifts are generally placed in the order Apodiformes along with true swifts (Apodidae) and hummingbirds (Trochilidae). Treeswifts are also related to nightjars (Caprimulgiformes). Although they are not related, due to similarities in appearance and behavior, treeswifts and swallows (Hirundinidae) were often grouped together. In fact, the family name Hemiprocne means “half-swallow.”

Characteristics shared with other Apodiformes include: tiny feet, long wings with long primaries, short humeri and short secondaries.

Distinguishing characteristics include: plumes or crest on head, a patch of downy or silky feathers on the flank, no claw on manus, non-reversible hind toe, general feathers soft, the anatomy of the tarsus and the shape of the cranium and skeletal palate. ()

Grey-rumped (Hemiprocne longipennis) and crested (Hemiprocne coronata) treeswifts have glossy, primarily grey plumage with a forehead crest that is 2.5 to 3 cm tall. Both males and females have crests that they raise when perched. Both whiskered treeswifts (Hemiprocne comata), the smallest member of the genus and moustached treeswifts (Hemiprocne mystacea), the largest treeswifts, have a slight crest and a bold face pattern with white stripes along the side of the head. Sexes of all species may differ in coloration on the head.

Treeswifts have a short bill and a broad gape and are typically 15 to 31 cm long. They have large eyes that may help them forage into late evening when the light is low. Unlike true swifts (Apodidae), treeswifts are able to perch, they are easy to identify when perched because of their long crossed wing-tips and deeply forked tail. Their long outer streamers allow for increased manoeuvrability while foraging. Like typical swifts, treeswifts have a long manus and primary feathers.

Juveniles have cryptic head and body plumage that they lose during the first moult after fledging. ()

The lifespan of treeswifts is unknown; however, most small birds live only two to five years. ()

Unlike true swifts (Apodidae), treeswifts are generally not social, although they will sometimes forage in small groups and they become more social at the end of the breeding season. Grey-rumped treeswifts (Hemiprocne longipennis) will roost communally (roosts of about 50 individuals have been seen) in winter and return to the same roost each year.

Adult swifts are territorial, but it is not known how they defend territories. Juveniles leave adult territories soon after fledging. Treeswifts are not migratory, although they will make local nomadic trips or shift seasonally.

Treeswifts have highly manoeuvrable, fast flight and often behave more like flycatchers than swifts when foraging; they will intermittently dart out from their perch to catch airborne insects. They nest in the open and choose high, exposed perches.

In general, very little is known about treeswift behavior beyond short anecdotes. ()

Calls are used for communication between pairs while flying or perched. Treeswifts calls have been described as a squeal, with a few syllables grouped together to form a disyllabic or trisyllabic call. Treeswifts can also raise the crest of feathers on their head, a gesture assumed to be a form of communication. Large eyes help treeswifts navigate while feeding at dusk and dawn. ()

Treeswifts are insectivores, they catch their prey while in-flight (hawking) or they glean insects from foliage. Treeswifts drink by flying near the surface of water with an open mouth. They are often crepuscular (feed at dawn or dusk). Treeswifts hunt opportunistically and frequently feed on Hymenoptera (bees, wasps and ants), Diptera (true flies), Hemiptera (true bugs), Isoptera (termites) and Coleoptera (beetles).

Treeswifts will not travel as far to feed as true swifts (Apodidae) and instead of doing all hunting on the wing, they will perch in an open place and dart from their perch to catch aerial insects. The birds’ large gape and manoeuvrable flight help them to catch their prey. They also have bristles around their mouths that may help them trap insects as they fly. ()

The only confirmed predators of treeswifts are Asian falconets (Microhierax), although there are almost certainly additional predators (snakes (Serpentes), for example, are likely predators). Nest placement on the end of a thin branch is thought to aid treeswifts in the detection of climbing predators. Nests and juvenile plumage are cryptic. Groups of treeswifts will mob predators as they approach. ()

As insectivores, treeswifts affect insect populations throughout their range.

There are no known adverse affects of treeswifts on humans.

Treeswifts are hunted as a food source for humans. Because they are insectivores, treeswifts are also important agents in pest control. ()

The IUCN lists no treeswifts as endangered or vulnerable and none are listed by CITES. Because treeswifts use forest edge they may benefit to some degree from disturbance and fragmentation. However, they do rely on large tracts of contiguous forest and could be adversely affected if too much of their habitat is lost. Grey-rumped treeswift (Hemiprocne longipennis) numbers are thought to be declining as a result of increases in hunting and pesticide use (that decreases the number of available prey). It is also important to note that little is known about the four species of treeswifts, so it may be difficult to accurately assess the status of their populations. ()