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Variation in the Sonar of an Aerial‐hawking Bat ( Eptesicus nilssonii )
Author(s) -
Rydell Jens
Publication year - 1993
Publication title -
ethology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.739
H-Index - 74
eISSN - 1439-0310
pISSN - 0179-1613
DOI - 10.1111/j.1439-0310.1993.tb01209.x
Subject(s) - human echolocation , foraging , eptesicus fuscus , variation (astronomy) , biology , zoology , geography , ecology , physics , neuroscience , astrophysics
Echolocation calls from 10 individually marked female northern bats ( Eptesicus nilssonii ) were recorded as the bats foraged at three distinct feeding sites (territories) near their maternity roost in southern Sweden (57° N). In addition, recordings of unmarked bats were made in northern Sweden (65° N). The frequency at maximum amplitude of “search phase” echolocation pulses was bimodally distributed, with peaks around 29–30 kHz and 31–32 kHz and was negatively correlated with pulse duration. The frequency at maximum amplitude was related to flight altitude (bats used higher frequencies when they flew near the ground) and also differed among the feeding sites. Hence, much of the variation, probably including regional differences, was behavioural and is interpreted as short term (in the order of s or min) adaptation to current foraging situations. Variation among individual bats, caused by age and size, seemed to be of less importance. Individuals did not use exclusive frequency bands.