Subject: Abstract: humpback whale's behaviors

Michael Williamson (whe_william)
Mon, 29 Jul 1995 21:57:49

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From: Michael Williamson <WHE_WILLIAM@FLO.ORG>
Subject: Abstract: humpback whale's behaviors
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Subj:	Abstract - humpback whales
Date:         Wed, 26 Jul 1995 11:56:00 EST
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From:         Phil Clapham <CLAPHAM.PHIL@SIMNH.SI.EDU>
Subject:      Abstract - humpback whales
To:           Multiple recipients of list MARMAM <MARMAM@UVVM.BITNET>
Clapham, P.J., Leimkuhler, E., Gray, B.K. & Mattila, D.K.  1995.  Do
humpback whales exhibit lateralized behaviour?  Anim. Behav. 50: 73-82.
Abstract.  Lateralized behaviour has been documented in non-human species,
although many observers believe that it occurs at the individual rather
than the population level.  Its occurrence in humpback whales in
Massachusetts Bay was investigated by examining active behaviour types in
which preference could be given to one direction or side.  These
included head breaching (direction of spin), flippering (right or left),
and tail breaching (direction of movement).  In addition, persistent
abrasions on the right or left jaw resulting from turns to one side during
bottom feeding were noted.  Of 75 individuals with jaw abrasions, 60
(80%) showed abrasions on only the right jaw, while 15 (20%) had abrasions
on only the left.  No whales had abrasions on both jaws.  Location of
abrasions was consistent in all resighted individuals for up to 12 years.
Two of the the active behaviour types were not strongly lateralized:
directional bias was seen in only five of 21 bouts (23.8%) of breaching,
and in three of 11 bouts (27.3%) of tail breaching.  However, 22 of 34
bouts (64.7%) of flippering showed a bias towards one direction (generally
the right).  Furthermore, direction of bias in all behaviour types was
individually consistent between bouts and was strongly correlated with
abrasions on the corresponding jaw (P = 0.0032).  The sex ratio of
individuals with jaw abrasions, and of those showing directional bias
in active behaviour, did not differ significantly from that of the
overall population.  Overall, these data suggest that humpback whales
exhibit some behavioural asymmetries, at least one of which is at the
population level.  this result suggests asymmetry of function in motor
or somatosensory representations, although too little is known about the
brain of this species to permit definitive conclusions.