Editing Animal echolocation (section)

=== Oilbirds and swiftlets ===

[[File:Palawan swiftlet (Aerodramus palawanensis) hunting by echolocation.JPG|thumb|A Palawan swiftlet (''Aerodramus palawanensis'') flies in complete darkness inside the Puerto Princesa subterranean river cave.]]

[[Oilbird]]s and some species of [[swiftlet]] are known to use a relatively crude form of echolocation compared to that of bats and dolphins. These nocturnal birds emit calls while flying and use the calls to navigate through trees and caves where they live.<ref>{{cite book |title=Birds of the High Andes: a manual to the birds of the temperate zone of the Andes and Patagonia, South America |first1=Jon |last1=Fjeldså |first2=Niels |last2=Krabbe |publisher=Apollo Books |year=1990 |isbn=978-87-88757-16-3 |page=232 |url=https://books.google.com/books?id=NmXSeVrmlgIC&q=oilbird+echo+trees+caves+nocturnal&pg=PA232 }}</ref><ref>{{cite book |title=Exploring Life Biology |author=Marshall Cavendish |publisher=Marshall Cavendish |year=2000 |isbn=978-0-7614-7142-4 |page=547 |url=https://books.google.com/books?id=vC4cwlhjGxsC&q=swiftlet+echo+trees+caves+nocturnal&pg=PA547 }}</ref>