ISSN:
1748-7692
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The hypothesis that haul-out space is a contested resource among harbor seals (Phoca vitulina) was tested by comparing the number of agonistic interactions and the time devoted to them, at a haul-out with unlimited space and a haul-out with limited space, in Humboldt County, California. 798 agonistic interactions were recorded in 160 h of observation. The average number of agonistic interactions per seal per hour and the time spent on these interactions were significantly higher at the site with limited haul-our space (P 〈 0.05, n= 20). At this restricted site, the frequency of agonistic interactions was positively correlated with seal density (r= 0.61, P 〈 0.05, n= 20), as was time spent on agonistic interactions (r= 0.84, P 〈 0.05, n= 20). Size, sex, and age-class of individuals all influenced agonistic interactions. In 72.5% of displacements, smaller seals were displaced by larger ones. This may support claims that some harbor seal populations maintain a size-based dominance hierarchy. The results of this study support the hypothesis that there is competition among harbor seals for suitable haul-out space where this resource is limited. The outcome of these interactions may be predicted, at least in part, by theoretical models on pay-off asymmetries, resource holding power, and the prior residency effect.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1748-7692.1999.tb00816.x
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