The aim of this study was to examine the variation in body surface temperature of grey seal (Halichoerus grypus) pups throughout lactation in response to different environmental conditions. Radiative surface temperatures (Tr, °C) of pups were measured on the Isle of May (56°11′N, 02°33′W), southeast Scotland from 29 October to 25 November 2003. Records were obtained from a total of 60 pups (32 female and 28 male) from three different pupping sites during early and late lactation. Pups were sheltered from high wind speeds but air temperature, humidity and solar radiation at pupping sites were similar to general meteorological conditions. The mean Tr of all pups was 15.8°C (range 7.7–29.7°C) at an average air temperature of 10.2°C (range 6.5–13.8°C). There was no difference in the mean Tr of pups between early and late lactation. However, the Tr varied between different regions of the body with hind flippers on average 2–6°C warmer than all other areas measured. There was no difference in mean Tr of male and female pups and pup body mass did not account for the variation in Tr during early or late lactation. Throughout the day there was an increase in the Tr of pups and this explained 20–28% of the variation in Tr depending on stage of lactation. There was no difference in the mean Tr of pups between pupping sites or associated with different substrate types. Wind speed and substrate temperature had no effect on the Tr of pups. However, solar radiation, air temperature and relative humidity accounted for 48% of the variation in mean Tr of pups during early lactation. During late lactation air temperature and solar radiation alone accounted for 43% of the variation in Tr. These results indicate that environmental conditions explain only some of the variation in Tr of grey seal pups in natural conditions. Differences in Tr however indicate that the cost of thermoregulation for pups will vary throughout lactation. Further studies examining intrinsic factors such as blubber thickness and activity levels are necessary before developing reliable biophysical models for grey seals.
|Number of pages||9|
|Journal||Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology|
|Publication status||Published - 5 Jul 2005|