Mass changes during their annual cycle in females of southern elephant seals at King George Island

A.R. CARLINI; M.E.I. MARQUEZ; G.A. DANERI; S. POLJAK

POLAR BIOLOGY

Springer

Lugar: Verlag; Año: 1999 vol. 21 p. 234 - 239

0722-4060

Abstract  Mass changes in female southern elephant seals, sampled sequentially at diferent points through their annual cycle, were measured at King George Is- land, South Shetland Islands, during the 1995/1996 and 1996/1997 field seasons. Females weighed after they had given birth showed an increase of 37 ± 36 kg (mean ± SD), which represented 6.2 ± 6.4% in rela- tion to their mass in the ®rst breeding season. During the ®rst aquatic phase, between the end of lactation and the beginning of moult, females gained a mean of 128 ± 35 kg, (n = 18) (2.19 ± 0.65 kg day)1), which represented between 27 and 83% of the mass they had lost during lactation. Nine females followed during moulting showed a mass loss rate of 5.0 ± 0.4 kg day)1, which was half the rate during lactation. Total mass loss during moulting (129 ± 22 kg) was not significantly diferent from mass gain for the same females between lactation and moult (135 ± 37 kg). Furthermore, at the end of moulting, female mass was not significantly diferent from the mass at the end of lactation. These masses represented 65±  5% and 64 ± 5%, respectively, of their initial mass after par- turition. During the second period at sea, from the end of the moult until females hauled out to give birth in the following breeding season, the estimated mass gain was 1.45 ± 0.24 kg day)1 (n = 5), which was not sig- nificantly diferent to the rate of mass gain shown by the same females during the first period at sea (2.26 ± 0.70 kg day)1). Total mass gain during the second aquatic phase (364 ± 63 kg) was not correlated with the mass at the end of moulting, but it was posi- tively related to the mass loss experienced by females from parturition until the end of the moulting period in the first breeding season.