Editing Chimney swift (section)

===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"/>