Dear All,
The following paper has been recently published in Journal of
Mammalogy.
Charrier, I & Harcourt, R.G. 2006. Individual vocal identity in
mother and pup Australian sea lions (Neophoca cinerea). J. Mammal. 87(5),
929-939.
Individual vocal recognition between
mothers and pups has been widely observed in pinnipeds, especially
otariids. Otariids are colonial breeders; mothers suckle only their own
offspring, aggressively attacking
nonrelated young. Mothers alternate foraging trips with periods ashore,
and at each return to the colony, mothers
and pups must find each other among all the individuals of the colony. In
the Australian sea lion
(Neophoca
cinerea), the need for a finely
tuned mechanism of recognition is exacerbated by their habit of changing
the
nursing location over the course of lactation. We investigated potential
acoustic parameters used in mother–pup
recognition in Australian sea lions. We measured 11 acoustic parameters
on calls of mothers and pups and found
that several parameters (fundamental frequency, energy spectrum,
amplitude, and frequency modulation) were
highly individually specific. Discriminant analysis correctly assigned
calls to individual mothers or pups with an
average classification rate of 65% and 77%, respectively. Spectral
features and frequency modulation were the
most important features distinguishing individuals. Lastly, principal
component analysis showed that calls of
pups and mothers were easily distinguishable using energy spectrum and
frequency modulation. Comparison
with other pinniped species suggests that individual vocal identity is
likely to be selected through ecological
constraints such as density of the colony, degree of polygyny, likelihood
of allosuckling or fostering, and degree
of maternal absence during lactation.
A pdf file is available and can be sent on request
(isabelle.charrier@ibaic.u-psud.fr)
All the best,
Isabelle Charrier
Isabelle CHARRIER
Équipe Communications Acoustiques.
NAMC-CNRS UMR 8620,
Université Paris Sud, Bat.446
F-91405, Orsay, FRANCE.
Tel:(33-1).69.15.68.26
Fax:(33-1).69.15.77.26
Email: isabelle.charrier@ibaic.u-psud.fr
http://perso.wanadoo.fr/isa-seal/
http://www.cb.u-psud.fr/