Editing Chimney swift (section)

==Behavior==
The chimney swift is a [[wikt:gregarious|gregarious]] species, and is seldom seen alone. It generally hunts in groups of two or three, migrates in loose flocks of 6–20, and (once the breeding season is over) sleeps in huge communal roosts of hundreds or thousands of birds.<ref name = "Dunne2"/> Like all swifts, it is a superb aerialist, and only rarely seen at rest. It drinks on the wing, skimming the surface of the water with its beak.<ref name = "Wauer"/> It also bathes on the wing, gliding above the surface of a body of water, briefly smacking its breast into the water, then flying off again, shaking its feathers as it goes.<ref name = "Cornell"/> It has been recorded by pilots flying more than a mile above the surface of the earth, including one seen at {{convert|7300|ft|m|abbr=on}}.<ref name = "Williams"/> It is incapable of perching upright like most birds do; instead, it clings to vertical surfaces.<ref name="Sibley"/> If it is disturbed while at rest, the chimney swift will clap its wings loudly once or twice against its body; it does this either in place, or while dropping down several feet to a lower location. This behavior can result in a loud "thundering" sound if large roosts of the birds are disturbed. The sound is thought to be the bird's way of scaring away potential predators.<ref name = "Dexter3"/>

===Feeding===
Like all swifts, the chimney swift forages on the wing.<ref name = "Cornell"/> Studies have shown that {{nowrap|95 percent}} of its food items are flying insects, including various species of [[flies]], [[ant]]s, [[wasp]]s, [[bee]]s, [[whitefly|whiteflies]], [[aphid]]s, [[scale insect]]s, [[stonefly|stoneflies]] and [[mayfly|mayflies]]. It also eats [[ballooning (spider)|airborne spider]]s drifting on their threads.<ref name = "Wauer"/> It is an important predator of pest species such as the [[red imported fire ant]]<ref name = "Whitcomb"/> and the [[Sitona hispidulus|clover root curculio]].<ref name = "Webster"/> Researchers estimate that a pair of adults provisioning a nest with three youngsters consume the weight equivalent of at least {{nowrap|5000–6000 [[housefly]]-sized}} insects per day.<ref name = "Woods"/> Like many bird species, the chimney swift periodically coughs up pellets composed of indigestible bits of prey items.<ref name = "Duke"/>

During the breeding season, at least half of the chimney swift's forays occur within {{convert|0.5|km|mi|abbr=on|sigfig=1}} of its nest; however, it ranges up to {{convert|6|km|mi|abbr=on}} away.<ref name = "ON"/> While most of its food is seized following aerial pursuit, some is [[gleaning (birds)|gleaned]] from the [[foliage]] of trees; the bird hovers near the ends of branches or drops through upper canopy levels.<ref name = "George"/> The chimney swift generally flies quite high, though it descends during cold or rainy weather.<ref name = "Crossley"/> When feeding, it regularly occurs in small groups, and sometimes hunts with [[swallow]]s, particularly [[barn swallow]]s and [[purple martin]]s;<ref name = "Dunne2"/> in [[mixed-species flock]]s, it is typically among the lower fliers.<ref name = "Chantler187"/> There is at least one record of a chimney swift attempting to [[kleptoparasitism|steal]] a [[dragonfly]] from a purple martin, and it has been observed chasing other purple martins.<ref name = "Brown"/> In general, it is a [[diurnality|diurnal]] feeder which remains active into early evening. However, there are records, particularly during migration periods, of chimney swifts feeding well after dark over brightly lit buildings.<ref name = "Cottam"/>

The species shows two-weight peaks each year: one at the start of the breeding season, and a higher one shortly before it begins its migration south in the autumn. Its lowest weights are typically recorded during the breeding season, when it also begins a complete [[molt]] of its plumage. The chimney swift's weight gain before [[bird migration|migration]] is smaller than that of some passerines, suggesting that it must refuel en route at various stopover points.<ref name = "Collins"/>

===Breeding===
[[File:Chaetura pelagica MWNH 1241.JPG|thumb|Egg, Collection [[Museum Wiesbaden]]]]
[[File:ChimneySwift23.jpg|thumb|left|The nest is made of small, short twigs glued together with saliva.]]
The chimney swift is a [[Monogamy in animals|monogamous]] breeder which normally mates for life, though a small percentage of birds change partners.<ref name = "Dexter"/> Pairs perform display flights together, gliding with their wings upraised in a steep "V", and sometimes rocking from side to side. Breeding birds arrive as early as mid-March in the southern U.S., and late-April to mid-May in the Canadian provinces.<ref name = "NatWeb"/>

Before the arrival of European colonists into North America, the chimney swift nested in hollow trees; now, it uses human-built structures almost exclusively.<ref name = "Encyclopedia"/> While the occasional nest is still built in a hollow tree (or, exceptionally, in an abandoned woodpecker nest),<ref name = "WP"/> most are now found inside [[chimney]]s, with smaller numbers in [[ventilation shaft|airshaft]]s, the dark corners of lightly used buildings, [[cistern]]s,<ref name = "Cistern"/> or [[water well|wells]].<ref name = "Rogers"/> The [[bird nest|nest]] is a shallow bracket made of sticks, which the birds gather in flight, breaking them off trees. The sticks are glued together (and the nest to a vertical surface) with copious amounts of the bird's [[saliva]].<ref name = "Baicich"/> During the breeding season, each adult's [[salivary gland]]s more than double in size, from {{convert|7|x|2|mm|in|abbr=on}} in the non-breeding season to {{convert|14|x|5|mm|abbr=on}} during the breeding season.<ref name = "Johnston"/>

Unlike some swift species, which [[mating|mate]] in flight, chimney swifts mate while clinging to a vertical surface near their nest.<ref name="Kyle38"/> They [[wikt:copulate|copulate]] daily, until the [[clutch (eggs)|clutch]] is complete.<ref name = "Kyle39"/> The female typically lays {{nowrap|4–5 eggs}},<ref name = "Baicich"/> though clutch sizes range from {{nowrap|2 to 7}}.<ref name = "Kyle39"/> The eggs, which are long and elliptical in shape, are moderately glossy, smooth and white, and measure {{convert|20|x|13|mm|in|abbr=on}}.<ref name = "Baicich"/> Each weighs nearly {{nowrap|10 percent}} of the female's body weight.<ref name = "Kyle39"/> [[avian incubation|Incubated]] by both parents, the eggs hatch after {{nowrap|19 days}}. Baby chimney swifts are [[altricial]]—naked, blind and helpless when they hatch. [[Fledgling (birds)|Fledgling]]s leave the nest after a month.<ref name = "Baicich"/>

The average chimney swift's life span is {{nowrap|4.6 years}},<ref name = "Dexter2"/> but one is known to have lived more than {{nowrap|14 years}}. It was originally banded as an adult, and was recaptured in another banding operation some {{nowrap|12.5 years}} later.<ref name = "BandingLab"/>

===Predators and parasites===
[[Mississippi kite]]s, [[peregrine falcon]]s and [[Merlin (bird)|merlin]]s are [[birds of prey|raptors]] that are known to take adult chimney swifts in flight, being among the select few avian hunters fast enough to overtake the appropriately named swift on the wing.<ref name = "Steeves"/> [[Eastern screech-owl]]s have been seen attacking colonies, as have non-avian predators including [[Pantherophis alleghaniensis|eastern rat snake]]s, [[northern raccoon]]s and [[tree squirrel]]s. These are most likely to take nestlings but may take some nesting adults as well.<ref name = "Cink"/><ref>Laskey, A. R. 1946. ''Snake depredation at birds' nests''. Wilson Bull. 58:217-218.</ref> When disturbed by potential predators (including humans) at the colony, adult chimney swifts slap their wings together after arching back and taking flight, making a very loud noise known either as "booming" or "thunder noises". When disturbed, nestlings make a loud, raspy ''raah, raah, raah'' sound. Both sounds seem designed to startle potential predators.<ref>Dexter, R. W. 1946. ''More concerning the thundering and clapping sounds of the Chimney Swift''. Auk 63:439-440.</ref><ref>Fischer, R. B. 1958. The breeding biology of the Chimney Swift, Chaetura pelagica (Linnaeus). N.Y. State Mus. Sci. Serv. Bull. 368:1-139.</ref>

The chimney swift carries a number of internal and external parasites. It is the [[type (biology)|type]] [[host (biology)|host]] for the [[nematode]] species ''Aproctella nuda'',<ref name = "Hamann"/> the [[feather mite]] species ''Euchineustathia tricapitosetosa'',<ref name = "Mite"/> and the [[bird louse|biting lice]] species '' Dennyus dubius'',<ref name = "Ewing"/> and is also known to carry the [[tapeworm]] species ''Pseudochoanotaenia collocaliae''.<ref name = "Manter"/> Its nest is known to host the [[Hemiptera]] species ''[[Cimexopsis nyctali]]'', which is similar to the [[bed bug]] and can (on rare occasions) become a pest species in houses.<ref name = "Boyd"/><ref name = "UM"/>

===Voice===
{{listen |filename=Chaetura pelagica - Chimney Swift - XC105129.ogg |title=Chimney swift vocalizations |description=Calls of multiple birds in Iowa }}
The chimney swift has a twittering call, consisting of a rapid series of hard, high-pitched chirps. It sometimes gives single chirps.<ref name = "Sibley"/>