Animal Diversity Web

Di­ver­sity

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. (Chantler and Driessens, 2000; Wells, 1999)

Ge­o­graphic Range

Treeswifts are found through­out the Ori­en­tal Re­gion (East to the Solomon Is­lands) and in some of the Aus­tralian re­gion. (Chantler and Driessens, 2000; ; Wells, 1999)

• Biogeographic Regions
• oriental
  • native
• australian
  • native

Habi­tat

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. (Chantler and Driessens, 2000; ; Smythies, 2001; Wells, 1999)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest

Phys­i­cal De­scrip­tion

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. (Chantler and Driessens, 2000; Smythies, 1999; Smythies, 2001; Wells, 1999)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• ornamentation

Re­pro­duc­tion

Treeswifts are monog­a­mous; both males and fe­males pro­vide parental care. Breed­ing pairs will de­fend nest sites against in­trud­ers. No male dis­play flights have been recorded. (Chantler and Driessens, 2000; ; Wells, 1999)

• Mating System
• monogamous

Treeswifts have a long breed­ing sea­son that oc­curs dur­ing the spring and sum­mer. Both males and fe­males take part in nest build­ing; nests are made of bark, feath­ers and bryophyte held to­gether with saliva. Nests are half-saucer shaped and from 25 to 40 mm in di­am­e­ter (just big enough to hold one egg) they are usu­ally placed on ex­posed branches in the for­est canopy (4 to 30 m in height). Be­cause nests are so small adults must perch on a branch and strad­dle the nest while in­cu­bat­ing; nestlings out­grow the nest rapidly and will move out of the nest and perch on a nearby branch while wait­ing to be fed.

Both in-flight cop­u­la­tion and cop­u­la­tion on a perch have been recorded in treeswifts. Clutch size is one and eggs are plain white or pale grey. Crested treeswift (Hemiprocne coro­nata) eggs are 23 to 26 by 15.5 to 19 mm, grey-rumped treeswift (Hemiprocne longipen­nis) eggs are 23 to 24.5 by 17 to 18 mm, whiskered treeswift (Hemiprocne co­mata) eggs are 12 by 15 mm and mous­tached treeswift (Hemiprocne mys­tacea) eggs are 30 by 20mm. Fe­males spend two to three times more time in­cu­bat­ing than males. There are no exact mea­sure­ments of in­cu­ba­tion and nestling pe­ri­ods. How­ever, dur­ing one ob­ser­va­tion of whiskered swifts chicks hatched on or be­fore day 21, fledged on day 28 and con­tin­ued to be fed by adults for an­other three weeks. Es­ti­mates for mous­tached swifts sug­gest that in­cu­ba­tion and nest­ing pe­ri­ods to­gether last more than 60 days. Young chicks are brooded for an un­known pe­riod of time after hatch­ing.

Chicks are al­tri­cial with grey skin and some grey down. Ju­ve­nile plumage is cryp­tic and is lost dur­ing moult after fledg­ing. (Chantler and Driessens, 2000; ; Mead, 1985; Smythies, 2001; Wells, 1999)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

Both male and fe­male treeswifts are in­volved in parental care, al­though fe­males in­cu­bate two to three times more than males. Treeswift chicks are al­tri­cial. The length of the nestling pe­riod is not known, but chicks may be fed for three weeks after fledg­ing. Adults brood chicks for an un­known amount of time after hatch­ing. Chicks are fed “food balls” con­tain­ing in­sects. (Chantler and Driessens, 2000; ; Mead, 1985; Smythies, 2001; Wells, 1999)

• Parental Investment
• altricial
• male parental care
• female parental care

Lifes­pan/Longevity

The lifes­pan of treeswifts is un­known; how­ever, most small birds live only two to five years. (Gill, 1995)

Be­hav­ior

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. (Chantler and Driessens, 2000; ; Smythies, 1999; Wells, 1999)

• Key Behaviors
• arboreal
• flies
• crepuscular
• motile
• nomadic
• territorial

Com­mu­ni­ca­tion and Per­cep­tion

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. (; Wells, 1999)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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. (Chantler and Driessens, 2000; ; Smythies, 1999; Smythies, 2001; Wells, 1999)

• Primary Diet
• carnivore
  • insectivore

Pre­da­tion

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. (; Wells, 1999)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • Asian falconets (Microhierax)

Ecosys­tem Roles

As in­sec­ti­vores, treeswifts af­fect in­sect pop­u­la­tions through­out their range.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Treeswifts are hunted as a food source for hu­mans. Be­cause they are in­sec­ti­vores, treeswifts are also im­por­tant agents in pest con­trol. (; Wells, 1999)

• Positive Impacts
• food
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse af­fects of treeswifts on hu­mans.

Con­ser­va­tion Sta­tus

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. ("UNEP-WCMC Species Data­base: CITES-Listed Species", 2003; ; IUCN, 2002; Wells, 1999)

• IUCN Red List [Link]

  Not Evaluated

Con­trib­u­tors

Alaine Cam­field (au­thor), An­i­mal Di­ver­sity Web.

Kari Kirschbaum (ed­i­tor), An­i­mal Di­ver­sity Web.

Ref­er­ences

2003. "UNEP-WCMC Species Data­base: CITES-Listed Species" (On-line). Ac­cessed No­vem­ber 14, 2003 at http://​www.​cites.​org/​eng/​resources/​species.​html.

Chantler, P., G. Driessens. 2000. Swifts: A guide to the swifts and treeswifts of the world, Sec­ond Edi­tion. Sus­sex: Pica Press.

Gill, F. 1995. Or­nithol­ogy, Sec­ond Edi­tion. New York: W.H. Free­man and Com­pany.

IUCN, 2002. "The IUCN Red List of Threat­ened Species" (On-line). Ac­cessed Oc­to­ber 10, 2003 at http://​www.​redlist.​org/​.

Mead, C. 1985. Swifts. Pp. 254-257 in C Per­rins, A Mid­dle­ton, eds. The En­cy­clo­pe­dia of Birds. New York: Facts on File, Inc.

Payne, R. 2003. "Bird Fam­i­lies of the World" (On-line). Ac­cessed Oc­to­ber 10, 2003 at http://​www.​ummz.​lsa.​umich.​edu/​birds/​Bird_​Families_​of_​the_​World.​html.

Sib­ley, C., J. Ahlquist. 1990. Phy­logeny and Clas­si­fi­ca­tion of Birds, A study in Mol­e­c­u­lar Evo­lu­tion. New Haven: Yale Uni­ver­sity Press.

Smythies, B. 1999. The Birds of Bor­neo, Fourth Edi­tion. Kota Kin­a­balu: Nat­ural His­tory Pub­li­ca­tions (Bor­neo).

Smythies, B. 2001. The Birds of Burma, Fourth Edi­tion. Kota Kin­a­balu: Nat­ural His­tory Pub­li­ca­tions (Bor­neo).

Wells, D. 1999. Fam­ily Hemiproc­nidae. J del Hoyo, A El­liott, S Jordi, eds. Hand­book of the Birds of the World, Vol. 5. Barcelona: Lynx Edi­cions.