Juvenile Survivorship of Northern Elephant Seals

Survivorship and fertility schedules shape life history tactics (Stearns 1976, 1980) and provide vital demographic data for estimating population growth (Wilson and Bossert 1971). This chapter addresses juvenile survivorship in northern elephant seals, the percentage of individuals born that survive to each of the first four years of life. Our aim is to describe age-specific survival rates and age-specific mortality rates of seals born at Año Nuevo, California, over the last two decades when colony size was increasing and to examine the role of year, cohort, and condition at weaning—as reflected by weight, length, or an index of the