Echolocation behavior of big brown bats, Eptesicus fuscus, in the field and the laboratory

Annemarie Surlykke, Cynthia F. Moss

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Echolocation signals were recorded from big brown bats, Eptesicus fuscus, flying in the field and the
laboratory. In open field areas the interpulse intervals ~IPI! of search signals were either around 134
ms or twice that value, 270 ms. At long IPI’s the signals were of long duration ~14 to 18–20 ms!,
narrow bandwidth, and low frequency, sweeping down to a minimum frequency (Fmin) of 22–25
kHz. At short IPI’s the signals were shorter ~6–13 ms!, of higher frequency, and broader bandwidth.
In wooded areas only short ~6–11 ms! relatively broadband search signals were emitted at a higher
rate ~avg. IPI5122 ms) with higher Fmin ~27–30 kHz!. In the laboratory the IPI was even shorter ~88
ms!, the duration was 3–5 ms, and the Fmin 30– 35 kHz, resembling approach phase signals of field
recordings. Excluding terminal phase signals, all signals from all areas showed a negative
correlation between signal duration and Fmin , i.e., the shorter the signal, the higher was Fmin . This
correlation was reversed in the terminal phase of insect capture sequences, where Fmin decreased
with decreasing signal duration. Overall, the signals recorded in the field were longer, with longer
IPI’s and greater variability in bandwidth than signals recorded in the laboratory.
TidsskriftJournal of the Acoustical Society of America
Udgave nummer5
Sider (fra-til)2419-2429
Antal sider11
StatusUdgivet - 2000