Journal of Comparative Physiology A

, Volume 197, Issue 5, pp 413–423

Frequency alternation and an offbeat rhythm indicate foraging behavior in the echolocating bat, Saccopteryx bilineata

  • John M. Ratcliffe
  • Lasse Jakobsen
  • Elisabeth K. V. Kalko
  • Annemarie Surlykke
Original Paper

Abstract

The greater sac-winged bat, Saccopteryx bilineata (Emballonuridae), uses two distinct echolocation call sequences: a ‘monotonous’ sequence, where bats emit ~48 kHz calls at a relatively stable rate, and a frequency-alternating sequence, where bats emit calls at ~45 kHz (low-note call) and ~48 kHz (high-note call). The frequencies of these low–high-note pairs remain stable within sequences. In Panama, we recorded echolocation calls from S. bilineata with a multi-microphone array at two sites: one a known roosting site, the other a known foraging site. Our results indicate that this species (1) only produces monotonous sequences in non-foraging contexts and, at times, directly after emitting a feeding buzz and (2) produces frequency-alternating sequences when actively foraging. These latter sequences are also characterized by an unusual, offbeat emission rhythm. We found significant positive relationships between (1) call intensity and call duration and (2) call intensity and distance from clutter. However, these relationships were weaker than those reported for bats from other families. We speculate on how call frequency alternation and an offbeat emission rhythm might reflect a novel strategy for prey detection at the edge of complex habitat in this ancient family of bats.

Keywords

Sensory ecology Foraging Behavioral flexibility Source level Detection distance 

Abbreviations

dB SPL RMS

Decibel sound pressure level re. 20 μPa root mean square

PF

Peak frequency

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • John M. Ratcliffe
    • 1
  • Lasse Jakobsen
    • 1
  • Elisabeth K. V. Kalko
    • 2
    • 3
  • Annemarie Surlykke
    • 1
  1. 1.Institute of BiologyUniversity of Southern DenmarkOdense MDenmark
  2. 2.Institute of Experimental EcologyUniversity of UlmUlmGermany
  3. 3.Smithsonian Tropical Research InstituteBalboaRepublic of Panama

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