[MARMAM] New paper: Can harbor seals (Phoca vitulina) discriminate familiar conspecific calls after long periods of separation?

2021-11-15 Thread Andrea 
Dear colleagues,

Our paper on long-term memory in harbour seals has just been published in PeerJ.

Varola M, Verga L, Sroka MGU, Villanueva S, Charrier I, Ravignani A. 2021. Can 
harbor seals (Phoca vitulina) discriminate familiar conspecific calls after 
long periods of separation? PeerJ 9:e12431

The ability to discriminate between familiar and unfamiliar calls may play a 
key role in pinnipeds’ communication and survival, as in the case of mother-pup 
interactions. Vocal discrimination abilities have been suggested to be more 
developed in pinniped species with the highest selective pressure such as the 
otariids; yet, in some group-living phocids, such as harbor seals (Phoca 
vitulina), mothers are also able to recognize their pup’s voice. Conspecifics’ 
vocal recognition in pups has never been investigated; however, the repeated 
interaction occurring between pups within the breeding season suggests that 
long-term vocal discrimination may occur. Here we explored this hypothesis by 
presenting three rehabilitated seal pups with playbacks of vocalizations from 
unfamiliar or familiar pups. It is uncommon for seals to come into 
rehabilitation for a second time in their lifespan, and this study took 
advantage of these rare cases. A simple visual inspection of the data plots 
seemed to show more reactions, and of longer duration, in response to familiar 
as compared to unfamiliar playbacks in two out of three pups. However, 
statistical analyses revealed no significant difference between the 
experimental conditions. We also found no significant asymmetry in orientation 
(left vs. right) towards familiar and unfamiliar sounds. While statistics do 
not support the hypothesis of an established ability to discriminate familiar 
vocalizations from unfamiliar ones in harbor seal pups, further investigations 
with a larger sample size are needed to confirm or refute this hypothesis.

The paper is available here: https://doi.org/10.7717/peerj.12431 .

If the link above does not work and you would like to obtain a PDF, do not 
hesitate to contact me at: andrea.ravign...@mpi.nl .

Kind regards,
Andrea

Andrea Ravignani
Group Leader, Comparative Bioacoustics, 
Max Planck Institute for Psycholinguistics


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[MARMAM] New paper on harbor seals

2021-06-23 Thread Thomas Jefferson 
Dear MARMAM,  My co-authors and I are pleased to announce the publication of 
our new paper on harbor seals in Washington State, USA:
Estimating the stock size of harbor seals (Phoca vitulina richardii) in the 
inland waters of Washington State using line-transect methods
Thomas A. Jefferson, Mari A. Smultea, Eric J. Ward, and Barry Berejikian

Abstract
Harbor seals (Phoca vitulina richardii) in the inland waters of Washington were 
reduced by
predator control programs in the twentieth century, but stocks have rebounded 
since being
protected in the 1970s. Three management stocks are recognized, but there is 
little information
on their current abundance. We conducted 38,431 km of aerial line-transect 
surveys
throughout the range of these stocks in 2013–2016, sighting a total of 4,678 
groups of harbor
seals. Line-transect analysis with Beaufort sea state as a covariate provided 
estimates
of the number of seals in the water. We then incorporated tagging data from 15 
instrumented
seals to develop correction factors, both for seals missed in the water while 
diving, and
those that were on shore. Tagging data were modeled with generalized linear 
mixed models
to provide estimates of the proportions diving and hauled out. After applying 
these correction
factors, we estimated that the Hood Canal stock contained 1,368 seals (CV = 
16.8%), the
Southern Puget Sound stock contained 1,976 seals (CV = 20.5%), and the 
Washington
Northern Inland Waters stock contained 7,513 seals (CV = 11.5%). This study 
presents a
non-traditional approach to estimating the size of Washington inland waters 
harbor seal
stocks, which may also be applicable to other species for which survey and 
tagging data are available.
The paper is open-acces and can be downloaded from this link:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241254
Best wishes,Tom jeffersonsclym...@aol.com
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