genus small dark cave nesting birds tribe swift family members confined tropical subtropical regions southern asia oceania northeastern australia members classified placed separate genus american difficult group similar species dna parasitic establish relationships problems placement fully resolved pose major identification problems species occur distinguishes birds ability use simple effective form enables navigate breeding caves nests constructed major component species material nests collected famous chinese bird nest soup collection puts pressure populations distribution range confined tropical southern asia oceania northeastern australia indian_ocean greatest diversity southeast_asia indonesia species restricted small islands limited range vulnerable like guam recently extinct species known fossils description respects typical having narrow wings fast flight wide small reduced surrounded catching insects flight dull plumage mainly shades black brown grey members genus typically dark brown upper wings upper body paler light brown paler throat brownish white wings dark brown males female similar appearance juvenile species described species juvenile shows pale fringes flight feathers legs short preventing birds allowing vertical surfaces flight mainly long primary feathers small breast muscles depending species weigh centimetres long similar species occur borneo new_guinea philippines field behaviour aerial prey like flies wing breed caves day leave caves forage food return night partners caring males perform aerial displays attract females mating occurs nest breeding season overlaps wet season corresponds increased insect population clutch size depends location food source generally lay eggs eggs dull white laid day species colonial build nests high dark corners cave walls live tropical region migrate birds usually remain cave nesting site examples cave sites include located characteristics behaviour materials apart nests contain differentiate certain species genus special interest use use technique navigate darkness shafts caves breed night apart species use unrelated double normal human hearing range apart interval shorter darker locations unlike rest genus species studied black nest single species uses outside caves use separate non cave genera virtually known recently discovered making similar noises inside outside cave recently determined agree evolutionary relationship species suggested dna sequence comparison suggests bats sounds present adapt rapidly independently particular species acoustic environment study suggested mainly located central nervous system vocal apparatus present capable use evolved study supports hypothesis independent evolution subsequent evolution complex behaviour needed complement physical system possibly vocal apparatus parts system inherited prehistoric nocturnal ancestor suggested giant descended ancestor nests constructed nests genus species contain material collected bird nest soup command extremely high prices authentic bird nest soup nests edible nest white nest black nest instead incorporating twigs feathers straw like genus nest strands exposed air nests harvested cleaned sold restaurants past years high demand nests species adverse effect populations caves population black nest million pairs pairs early 1990s harvesting early authors doubts material nest whale fish sperm sea foam proposed basis construction 1830s use fairly established believed cement sea plant provided bulk gelatinous material nest difficult groups information relationships study parasites northern borneo involved transferring closely related species survival transfers significantly reduced proportion mean difference feather size donor recipient species hosts adaptation particular resource body host appears govern transfers survived moved different areas body host mean diameter feathers occurred required value toes instead usual group ability previously studied species use primarily flying caves appears nocturnal uses active outside night uses single double dna sequence data provides strong support basal relationship taxa suggest species swift sister taxa relationship indicate genus species taxonomic order indian philippine group mountain white australian included volcano bare legged nest included uniform island prehistoric extinction black nest edible nest brown
Aerodramus