The comparative energetics and growth strategies of sympatric Antarctic and subantarctic fur seal pups at Îles Crozet

• Published in: Journal of Experimental Biology
• Main Authors: Arnould, John P.Y., Luque, Sebastian P., Guinet, Christophe, Costa, D.P., Kingston, J., Shaffer, Scott A.
• Other Authors: Department of Zoology, University of Melbourne, Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Department of Biology, Memorial University of Newfoundland St. John's, Department of Ecology and Evolutionary Biology, University of California Santa Cruz (UCSC), University of California-University of California, School of Biological Sciences, Macquarie University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: Arctocephalus tropicalis; maternal provisioning; metabolic rate; growth strategy; resource partitioning; energetics; weaning; fur seal; Arctocephalus gazella; envir; socio; Antarctic; Antarc*; Antarctic Fur Seal; Antarctic Fur Seals; Îles Crozet
• Online Access: https://doi.org/10.1242/jeb.00703; https://hal.archives-ouvertes.fr/hal-00189199

International audience The period of maternal dependence is a time during which mammalian infants must optimise both their growth and the development of behavioural skills in order to successfully meet the demands of independent living. The rate and duration of maternal provisioning, postweaning food availability and climatic conditions are all factors likely to influence the growth strategies of infants. While numerous studies have documented differences in growth strategies at high taxonomic levels, few have investigated those of closely related species inhabiting similar environments. The present study examined the body composition, metabolism and indices of physiological development in pups of Antarctic fur seals (Arctocephalus gazella) and subantarctic fur seals (Arctocephalus tropicalis), congeneric species with different weaning ages (4·months and 10·months, respectively), during their overlap in lactation at a sympatric breeding site in the Iles Crozet. Body lipid reserves in pre-moult pups were significantly greater (t28=2.73, P0.4), although this is unlikely to reflect a greater ability for pre-moult pups of the latter species to thermoregulate in water. Pup daily energy expenditure was also significantly greater (t27=2.36, P<0.03) in Antarctic fur seals (638±33·kJ·kg–1·day–1) than in subantarctic fur seals (533±33·kJ·kg–1·day–1), which corroborates observations that pups of the former species spend considerably more time actively learning to swim and dive. Consistent with this observation is the finding that blood oxygen storage capacity was significantly greater (t9=2.81, P<0.03) in Antarctic (11.5%) than subantarctic fur seal (8.9%) pups. These results suggest that, compared with subantarctic fur seals, Antarctic fur seal pups adopt a strategy of faster lean growth and physiological development, coupled with greater amounts of metabolically expensive behavioural activity, in order to acquire the necessary foraging skills in time for their younger weaning age. 10 pages