Meeting Abstract
44.2 Tuesday, Jan. 5 Maternal investment in the Antarctic fur seal: Impacts of maternal traits, pup traits, and provisioning strategy MCDONALD, B.I.*; GOEBEL, M.E.; CROCKER, D.E.; COSTA, D.P.; Univ. of California, Santa Cruz; Antarctic Ecology Research Division, NOAA; Sonoma State University; Univ. of California, Santa Cruz mcdonald@biology.ucsc.edu
Life history theory predicts that reproductive effort should increase with age in long lived animals. More recent studies indicate state variables such as individual quality and physiological state play an equally, if not more important role, in reproductive decisions. Reproductive effort was investigated in Antarctic fur seals (Arctocephalus gazella) at Cape Shirreff, Livingston Island. Prenatal effort was determined by catching and weighing 49 known-aged females and their pups. Milk intake was measured in the same pups during the perinatal period and at one and two months of age using the doubly labeled water technique. Total reproductive effort during the perinatal period was measured in 10 females. Reproductive effort did not increase with age, but mass and condition were important in determining maternal investment. Heavier females gave birth to larger pups and invested more during the perinatal period and at two months of age. Females in better condition gave birth to heavier pups and only invested more during the perinatal period. Pup mass and sex were important in determining maternal investment. Male pups were heavier at birth and at one month of age larger pups ingested more milk. Maternal investment during a nursing bout increased significantly with increasing foraging trip/visit cycle duration. However, when investment was controlled for trip/visit cycle duration, the overall rate of parental investment was similar across trip durations. The data suggest strong impacts of maternal traits, pup traits and provisioning strategy on investment that vary across the period of reproductive effort, emphasizing the importance of considering state variables in life history studies.
