Dear Colleagues,
A new article is available online.
Holt, M.M., Southall, B.L., Insley, S.J., and Schusterman, R.J. Call
directionality and its behavioural significance in male northern
elephant seals (/Mirounga angustirostris/). /Animal Behaviour/. 80:
351-361.
Abstract :
Animals often produce sounds that are focused in a particular direction
relative to the caller’s orientation. Although many studies have
suggested ways in which directional signal design might have behavioural
significance among vocally interacting individuals, there are few direct
tests using experimental approaches. During the breeding season and
while fasting on land, male northern elephant seals produce airborne
threat calls during dyadic interactions when competing for mating
opportunities. In this study, we investigated the directional cues of
these calls and tested hypotheses regarding directional signalling with
respect to the behaviour of receivers during vocally mediated male
agonistic interactions. We then determined effects of vocal
directionality on receiver responses using an acoustic playback
approach. We found that male calls had substantial directionality,
particularly at higher frequencies (>1000 Hz). Subordinate males
responded more strongly by retreating when the caller faced the receiver
compared to when the caller was at a right angle or faced away. We also
found a significant difference in responses to playback sequences with
different call directivity patterns. Males displayed significantly more
negative phonotaxis (i.e. moved away) in response to playbacks that
simulated a caller oriented towards them compared to when playbacks
simulated a caller oriented away from them. These results suggest that
the directionality of threat calls provides important information about
the auditory scene and spatial orientation of conspecifics and that this
trait, along with the receiver’s ability to extract this information,
may have evolved as a consequence of its effect on the breeding success
and fitness of the individual.
Published by Animal Behaviour,
doi:10.1016/j.anbehav.2010.06.013
<http://dx.doi.org/10.1016/j.anbehav.2010.06.013>
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__________________________________
Marla M. Holt, Ph.D.
Research Wildlife Biologist
Marine Mammal Ecology
NOAA/NMFS Northwest Fisheries Science Center
2725 Montlake Blvd East
Seattle, WA 98112
Phone: 206.860.3261
Fax: 206.860.3475
www.nwfsc.noaa.gov/research/divisions/cbd/marine_mammal/marinemammal.cfm
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