Editing Swift (bird) (section)

==Distribution and habitat==
Swifts occur on all the continents except Antarctica, but not in the far north, in large deserts, or on many oceanic islands.<ref name = H&C>{{Cite book | last = Martins | first = Thais | author2 = Mead, Christopher J. | year = 2003 | chapter = Swifts | editor = Perrins, Christopher | editor-link = Chris Perrins | title = The Firefly Encyclopedia of Birds | publisher = Firefly Books | pages = [https://archive.org/details/fireflyencyclope0000unse/page/346 346–350] | isbn = 1-55297-777-3 | chapter-url-access = registration | chapter-url = https://archive.org/details/fireflyencyclope0000unse/page/346 }}</ref> The swifts of temperate regions are strongly [[bird migration|migratory]] and winter in the tropics. Some species can survive short periods of cold weather by entering [[torpor]], a state similar to hibernation.<ref name=EoB>{{Cite book|editor=Forshaw, Joseph|author= Collins, Charles T.|year=1991|title=Encyclopaedia of Animals: Birds|publisher= Merehurst Press|location=London|pages= 134–136|isbn= 1-85391-186-0}}</ref>

Many have a characteristic shape, with a short forked tail and very long swept-back wings that resemble a crescent or a [[boomerang]]. The flight of some species is characterised by a distinctive "flicking" action quite different from swallows. Swifts range in size from the pygmy swiftlet (''Collocalia troglodytes''), which weighs 5.4 g and measures {{convert|9|cm|in|abbr=on}} long, to the [[purple needletail]] (''Hirundapus celebensis''), which weighs {{convert|184|g|oz|abbr=on}} and measures {{convert|25|cm|in|abbr=on}} long.<ref name=EoB/>