Hello Bioacoustics-L,
The following article can be downloaded at
http://www.uvm.edu/~bmitchel/Bioacoustics.html:
Charrier, Isabelle, and Robert G. Harcourt. 2006. Individual vocal
identity in mother and pup Australian sea lions (Neophoca cinerea).
Journal of Mammalogy 87(5):929-938.
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.
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