MASS-TRANSFER FROM MOTHERS TO PUPS AND MASS RECOVERY BY MOTHERS DURING THE POSTBREEDING FORAGING PERIOD IN SOUTHERN ELEPHANT SEALS (MIROUNGA-LEONINA) AT KING-GEORGE ISLAND

Mass transfer from mother to pup during the lactation period, and mass recovery for the same females during the foraging period were measure d in the southern elephant seal at King George Island, Antarctica. Dur ing the 19.2 +/- 0.9-day lactation period measured (which represented 87% of the entire nursing), females lost a mean mass of 10.56 +/- 1.76 kg/day (n = 27), while their pups gained a mean mass of 5.27 +/- 1.1 kg/day. There was a correlation between daily body weight gain in pups and daily weight loss by their mothers. Pup weaning mass was positive ly related to maternal post-partum mass. Serial samples showed that we ight losses by females and gains by their pups were not linear over la ctation, but showed lower values at the beginning and at the end of la ctation. During the 60.5 +/- 6.2-day foraging phase between the end of lactation and molt, females gained 2.21 +/- 0.65 kg/day (n = 12), or 54% of the mass lost during nursing. Growth rates reported here are hi gher than those reported in other-breeding sites. However, the ratio o f body mass loss by females to gain by their pups was similar, suggest ing that higher growth rates and greater weaning mass at South Shetlan d are due to a higher mean weight of females on arrival at this breedi ng site. The foraging period was shorter and the mass gained greater t han those measured at South Georgia; this could be related to relative ly shorter distances to foraging areas.