Marine Mammal Science
Volume 27, Issue 1 Page 1 - 253
<http://onlinelibrary.wiley.com/doi/10.1111/mms.2011.27.issue-1/issuetoc>
http://onlinelibrary.wiley.com/doi/10.1111/mms.2011.27.issue-1/issuetoc
Behavioral response of manatees to variations in environmental sound
levels (pages 130–148)
Jennifer L. Miksis-Olds and Tyler Wagner
Abstract
Florida manatees (/Trichechus manatus latirostris/) inhabit coastal
regions because they feed on the aquatic vegetation that grows in
shallow waters, which are the same areas where human activities are
greatest. Noise produced from anthropogenic and natural sources has the
potential to affect these animals by eliciting responses ranging from
mild behavioral changes to extreme aversion. Sound levels were
calculated from recordings made throughout behavioral observation
periods. An information theoretic approach was used to investigate the
relationship between behavior patterns and sound level. Results
indicated that elevated sound levels affect manatee activity and are a
function of behavioral state. The proportion of time manatees spent
feeding and milling changed in response to sound level. When ambient
sound levels were highest, more time was spent in the directed,
goal-oriented behavior of feeding, whereas less time was spent engaged
in undirected behavior such as milling. This work illustrates how shifts
in activity of individual manatees may be useful parameters for
identifying impacts of noise on manatees and might inform population
level effects.
Individual vocal production in a sperm whale (Physeter macrocephalus)
social unit (pages 149–166)
Tyler M. Schulz, Hal Whitehead, Shane Gero and Luke Rendell
Abstract
The vocal repertoires of group-living animals may communicate individual
or group identity. Female and juvenile sperm whales live in long-term
social units that can be assigned to vocal clans based on the pattern of
clicks in coda vocalizations. An unusual set of circumstances allowed us
to record the vocalizations of photo-identified individuals within a
single social unit over a 41 d period. Using click interpulse intervals,
we were able to assign codas to individuals and investigate coda
production at the individual level within a social unit for the first
time. Adult females in the unit vocalized at approximately equal rates.
A calf and juvenile, both male, vocalized less often than the adult
females. Repertoires were indistinguishable for all unit members apart
from a mother and her calf, which possessed significantly different
repertoires—even from one another. We suggest that similarity among the
coda repertoires of most unit members indicates a function in
advertising unit identity. In contrast, the distinctive repertoires of
the calf and its mother may facilitate reunions between these whales. We
hypothesize that sperm whales may be able to vary their vocal
repertoires as their reproductive status alters the trade-off between
the benefits of individual and group identification.
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