Reproductive Energetics of Phocids

Abstract

Phocid seals have a highly derived reproductive strategy characterized by the separation of feeding and reproduction, oftentimes across considerable spatial and temporal scales. Seals spend an extended period of time foraging far from the breeding colony, building up their energy reserves for a relatively brief pupping season onshore where access to food is limited. During lactation, enormous amounts of energy are quickly transferred from mother to pup before an abrupt weaning. This unusual reproductive strategy enables phocids to utilize habitats unavailable to most other mammals that must feed during lactation, from the unproductive waters of the tropics to the unstable pack ice of the world’s polar seas. In this chapter, we examine: the physiological, ecological, and behavioral adaptations behind the phocid breeding system; the ways in which resources are acquired and allocated to understand the importance of body size, lactation interval, milk energy content, and lipid stores in support of phocid reproduction; the connections between phocid mating systems and pupping substrate; and, finally, the origins and evolutionary implications of this extraordinary life history pattern.

Topics & Concepts