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Tachycineta bicolortree swallow

By Kari Kirschbaum; Jennifer Roof; Marie S. Harris

Ge­o­graphic Range

Tree swal­lows breed through­out cen­tral and north­ern North Amer­ica. The north­ern­most limit of the tree swal­low breed­ing range co­in­cides ap­prox­i­mately with the tree line. Tree swal­lows win­ter in south­ern North Amer­ica, pri­mar­ily in Florida, and along the Caribbean coast of Cen­tral Amer­ica. (Robert­son, et al., 1992)

Habi­tat

Tree swal­lows live in open areas near water, such as fields, marshes, mead­ows, shore­lines, beaver ponds, and wooded swamps. Be­cause tree swal­lows are cav­ity nesters, an im­por­tant habi­tat re­quire­ment is cav­i­ties in which to nest. These can be pro­vided by stand­ing dead trees, sap­sucker-ex­ca­vated holes in live trees, under the eaves of build­ings,and in ar­ti­fi­cial nest boxes. (Robert­son, et al., 1992)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Phys­i­cal De­scrip­tion

Tree swal­lows are small birds (14 cm total length) with long wings and small legs and feet. They are ir­rides­cent green­ish-blue above and white below on the chin, breast and belly. Tree swal­lows have a short black beak and dark red­dish-brown or brown­ish-gray feet.

Ju­ve­nile tree swal­lows are sim­i­lar in ap­pear­ance to adults, but are brown­ish rather than green­ish blue. They also have a dusky wash across their white chests. One-year-old fe­males look very sim­i­lar to adults, but have a mix­ture of brown and ir­rides­cent green­ish-blue above. (Robert­son, et al., 1992)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    19 g
    0.67 oz
    AnAge
  • Average length
    14 cm
    5.51 in

Re­pro­duc­tion

Tree swal­lows are pri­mar­ily monog­a­mous. How­ever, polyg­yny has been doc­u­ments at low rates in some pop­u­la­tions. Breed­ing pairs form as soon as fe­males ar­rive at breed­ing sites in the spring. Ex­tra-pair cop­u­la­tions are com­mon in this species; as many as 50% of nests in a given pop­u­la­tion may con­tain young that were not fa­thered by the res­i­dent male. (Robert­son, et al., 1992)

Tree swal­lows breed be­tween May and Sep­tem­ber, and raise one brood per year. They usu­ally nest soli­tar­ily, though they will nest near each other if ex­ist­ing cav­i­ties are close to­gether. Nest build­ing takes place in late April or early May. Nests are typ­i­cally built in cav­i­ties in dead or live trees (ex­ca­vated ear­lier by wood­peck­ers or other species) or in hol­low stumps over water. How­ever, they can also be found under the eaves of build­ings, in steel drums, fire hy­drants, holes in the ground or nest boxes. Nests are built al­most en­tirely by the fe­male. They are made of grasses, mosses, rootlets, and aquatic plants, and are lined with feath­ers from other species of birds. Con­struc­tion takes from a few days to two weeks.

The fe­male lays 2 to 8 (usu­ally 4 to 7) eggs, at a rate of one per day. The fe­male then in­cu­bates the eggs for 11 to 19 (usu­ally 14 to 15) days. The fe­male broods the al­tri­cial chicks for the first three days after hatch­ing. Both par­ents share the re­spon­si­bil­ity of feed­ing and find­ing food for the chicks. Chicks fledge 15 to 25 days after hatch­ing (usu­ally 18 to 22 days), at which time they are good fliers. The par­ents con­tinue to feed the chicks for at least 3 days after they leave the nest. These chicks will be able to breed the next sum­mer if they are able to es­tab­lish a nest site. (Robert­son, et al., 1992)

  • Breeding interval
    Tree swallows breed once per year.
  • Breeding season
    Tree swallows breed between May and September.
  • Range eggs per season
    2 to 8
  • Average eggs per season
    5
    AnAge
  • Range time to hatching
    11 to 19 days
  • Average time to hatching
    14.5 days
  • Range fledging age
    15 to 25 days
  • Range time to independence
    3 (low) days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Fe­male tree swal­lows build the nest, in­cu­bate the eggs and brood the chicks. Both par­ents feed the chicks while they are in the nest and for at least three days after they fledge. (Robert­son, et al., 1992)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

Lifes­pan/Longevity

An­nual adult tree swal­low sur­vival is es­ti­mated at 40 to 60%. Es­ti­mated av­er­age life span of tree swal­lows is 2.7 years. How­ever, the old­est known tree swal­low lived at least 11 years. (Robert­son, et al., 1992)

  • Range lifespan
    Status: wild
    8 to 11 years
  • Average lifespan
    Status: wild
    2.7 years
  • Average lifespan
    Status: wild
    145 months
    Bird Banding Laboratory

Be­hav­ior

Tree swal­lows are highly so­cial and may form flocks of sev­eral thou­sand birds at night­time roosts out­side of the breed­ing sea­son. How­ever, they are strongly ter­ri­to­r­ial dur­ing the breed­ing sea­son. Both sexes de­fend an area around their nest, usu­ally a 10 to 15 m ra­dius, against con­specifics and other nest site com­peti­tors. Com­pe­ti­tion for nest sites is thought to be the un­der­ly­ing mo­tive be­hind much of tree swal­low be­hav­ior, in­clud­ing sex­u­ally se­lec­tive in­fan­ti­cide, fre­quent cop­u­la­tion, and strong ag­gres­sive re­sponses to nest site com­peti­tors.

Tree swal­lows are fully mi­gra­tory. They mi­grate dur­ing the day, often in loose flocks, and roost to­gether in large groups at night.

As their name sug­gests, tree swal­lows spend lit­tle time on the ground, pre­fer­ring in­stead to perch. They spend much of their time in flight and tend to glide more than any other species of swal­lows. In order to bathe, swal­lows swoop down over water. They lightly brush the water and then begin to fly up­wards, shak­ing the water off. They also bathe by preen­ing ex­ten­sively dur­ing rain­fall, using it as a shower. (Robert­son, et al., 1992)

  • Range territory size
    3 to 700 m^2

Home Range

The size of tree swal­low home ranges changes through­out the year. Be­fore eggs are laid, tree swal­lows may travel up to 60 km to for­age. How­ever, dur­ing the in­cu­ba­tion and nestling stages, tree swal­lows prob­a­bly stay within about 5 km of the nest site. (Robert­son, et al., 1992)

Com­mu­ni­ca­tion and Per­cep­tion

Tree swal­lows com­mu­ni­cate pri­mar­ily using sounds and phys­i­cal dis­plays. Only male tree swal­lows sing, ap­par­ently for the pur­pose of pro­claim­ing their ter­ri­tory. Both sexes use calls to com­mu­ni­cate. At least 14 dif­fer­ent tree swal­low calls have been iden­ti­fied. The ap­par­ent pur­poses of these calls range from sig­nal­ing dis­tress, anx­i­ety, plea­sure and sub­mis­sion to beg­ging for food and so­lic­it­ing cop­u­la­tion. Body sig­nals such as crouch­ing and wing-flut­ter­ing are used to com­mu­ni­cate a va­ri­ety of mes­sages, in­clud­ing ag­gres­sion and so­lic­i­ta­tion of cop­u­la­tion. (Robert­son, et al., 1992)

Food Habits

Tree swal­lows pri­mar­ily eat fly­ing in­sects, though they also eat plant ma­te­ri­als (about 20% of their diet). They for­age in flight, in open areas above water or ground. They some­times for­age in flocks when in­sects are abun­dant. They can also glean in­sects from the sur­face of water or ver­ti­cal sur­faces. Swal­lows feed from dawn until dusk, mainly on flies, bee­tles and ants, though stone­flies, mayflies, cad­dis­flies, spi­ders and grasshop­pers are also com­mon prey. When weather con­di­tions are bad, tree swal­lows feed on veg­e­ta­tion, in­clud­ing bul­rushes, bay­ber­ries, and other plants' seeds. (Robert­son, et al., 1992)

  • Animal Foods
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Pre­da­tion

Tree swal­low eggs and nestlings are vul­ner­a­ble to pre­da­tion by rat snakes, rac­coons, black bears, Amer­i­can kestrels, com­mon grack­les, Amer­i­can crows, north­ern flick­ers, chip­munks, weasels, deer mice and feral cats. Adults are taken in flight by black-billed mag­pies and rap­tors, in­clud­ing sharp-shinned hawks, Amer­i­can kestrels, mer­lins, pere­grine fal­cons and great horned owls.

Tree swal­lows re­spond to preda­tors by mob­bing them. Large num­bers of tree swal­lows swarm and dive-bomb the preda­tor while giv­ing alarm calls. (Robert­son, et al., 1992)

Ecosys­tem Roles

Tree swal­lows af­fect the pop­u­la­tions of the an­i­mals they eat. They also pro­vide food for their preda­tors. They host a num­ber of body par­a­sites, in­clud­ing blowfly lar­vae. (Robert­son, et al., 1992)

Com­men­sal/Par­a­sitic Species

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Tree swal­lows eat many kinds of in­sects that hu­mans may con­sider to be pests.

  • Positive Impacts
  • controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of tree swal­lows on hu­mans.

Con­ser­va­tion Sta­tus

Tree swal­lows are a rel­a­tively com­mon birds. Global pop­u­la­tions of tree swal­lows have in­creased over the last 25 years to an es­ti­mated 20,000,000. Tree swal­lows read­ily use nest­ing boxes, mak­ing them a good study species for stud­ies of the ef­fect of pol­lu­tant on birds. PCBs and DDE have been found to be pre­sent in high lev­els in adults, eggs, and nestlings. It has also been found that birds in more acidic wet­lands pro­duce fewer and smaller young. These ob­ser­va­tions may sug­gest a pos­si­ble long-term prob­lem for tree swal­lows. A more press­ing con­sid­er­a­tion, how­ever, is the main­te­nance of dead trees, which pro­vide nest sites for tree swal­lows and other cav­ity-dwellers. (Robert­son, et al., 1992)

Con­trib­u­tors

Kari Kirschbaum (au­thor, ed­i­tor), An­i­mal Di­ver­sity Web.

Jen­nifer Roof (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Marie S. Har­ris (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

Ref­er­ences

Har­ri­son, H. 1975. A field guide to the birds' nests: United States east of the Mis­sis­sippi River. New York: Houghton Mif­flin, Pe­ter­son Field Guide Se­ries.

Robert­son, R., B. Stutch­bury, R. Cohen. 1992. Tree Swal­low (Tachycineta bi­color). Pp. 1-28 in A Poole, P Stet­ten­heim, F Gill, eds. The Birds of North Amer­ica, Vol. 11. Philadel­phia, PA: The Acad­emy of Nat­ural Sci­ences; Wash­ing­ton, DC: The Amer­i­can Or­nithol­o­gists' Union.

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