Echolocation call intensity and directionality in flying short-tailed fruit bats, Carollia perspicillata (Phyllostomidae)

Signe Brinkløv, Lasse Jakobsen, John M Ratcliffe, Elisabeth K V Kalko, Annemarie Surlykke

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Abstrakt

The directionality of bat echolocation calls defines the width of bats' sonar "view," while call intensity directly influences detection range since adequate sound energy must impinge upon objects to return audible echoes. Both are thus crucial parameters for understanding biosonar signal design. Phyllostomid bats have been classified as low intensity or "whispering bats," but recent data indicate that this designation may be inaccurate. Echolocation beam directionality in phyllostomids has only been measured through electrode brain-stimulation of restrained bats, presumably excluding active beam control via the noseleaf. Here, a 12-microphone array was used to measure echolocation call intensity and beam directionality in the frugivorous phyllostomid, Carollia perspicillata, echolocating in flight. The results showed a considerably narrower beam shape (half-amplitude beam angles of approximately 16° horizontally and 14° vertically) and louder echolocation calls [source levels averaging 99 dB sound pressure level (SPL) root mean square] for C. perspicillata than was found for this species when stationary. This suggests that naturally behaving phyllostomids shape their sound beam to achieve a longer and narrower sonar range than previously thought. C. perspicillata orient and forage in the forest interior and the narrow beam might be adaptive in clutter, by reducing the number and intensity of off-axis echoes.

OriginalsprogEngelsk
TidsskriftAcoustical Society of America. Journal
Vol/bind129
Udgave nummer1
Sider (fra-til)427-435
Antal sider9
ISSN0001-4966
DOI
StatusUdgivet - jan. 2011

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