[MARMAM] New article

Marla Holt Marla.Holt at noaa.gov
Mon Aug 23 10:07:24 PDT 2010

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: 
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,

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

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