Life history and ecology of pinnipeds

The long-term objective of my research is to understand the evolutionary and ecological factors that have shaped the foraging and reproductive strategies of seals. During the next five years, my students and I to plan build upon our long-term studies of life history and foraging ecology of seals. Variability in reproductive performance within and among individuals over their reproductive life has been documented for relatively few large long-lived vertebrates. Mean population estimates of traits obscure potentially important variability in the response of individuals to environmental variation. We plan to use long-term data from >1450 individually marked, known-age females to investigate sources of individual variability (e.g., local breeding density, habitat, body condition, age, birth date, offspring size at weaning) in reproductive performance. We will also use resighting data of branded males and females to test sex-specific hypotheses about variation in age at recruitment and age-specific survival and how patterns of survival vary with changes in population abundance and environmental variability. Although offspring size is often used as a proxy for female and offspring fitness, this hypothesis has rarely been tested in large mammals. Size and other offspring traits were measured for about 1200 permanent-marked female grey seals pups that were born from 1998 to 2002. We have measured size and age at recruitment of the survivors of those pups to test the relationship between offspring size, survival and size and age at recruitment. We will also investigate the extent to which females exhibit personality with respect to the protection of their offspring during lactation and the consequences of differences in personality on reproductive success. Finally, we will use a large database of grey seals satellite tracks and individual estimates of diet and mass gain to better understand the relationship between foraging behaviour and reproductive performance.