Hauling out behaviour of harbour seals : (Phoca vitulina richardsi), with particular attention to thermal constraints ...

• Main Author: Watts, Peter
• Format: Text
• Language: English
• Published: University of British Columbia 2011
• Subjects: harbour seal; Phoca vitulina
• Online Access: https://dx.doi.org/10.14288/1.0302424; https://doi.library.ubc.ca/10.14288/1.0302424

Harbour seals throughout their range are known to "haul out" onto land according to a daily cycle, which has never been fully investigated. This cycle may represent a tradeoff between the need to forage and the need to avoid aquatic predators; if so, seals should forage when prey availability is greatest and remain hauled at other times. A model based upon these premises accounted for approximately two thirds of the variation in observed hauling behaviour at a harbour seal colony in the Strait of Georgia, once other environmental effects had been filtered from the data. Some such effects could not be corrected for; since air temperature and solar radiation follow the same general pattern as that predicted by the hauling model, the possibility that hauling occurs in response to thermal conditions could not be excluded. This issue was addressed by correlating hauling activity at three seal colonies with "flux" Fs, an index of heat exchange between a seal and its environment. Once time of day and tidal effects ...