Lactation and suckling in relation to early growth of the southern elephant seal, Mirounga leonina (L.)

Abstract

The growth rate of elephant seal pups during the suckling period is shown to be lower at Macquarie I. than at the Falkland Is. Dependencies. Earlier initiation of suckling and lower suckling frequency occurs in the more rapidly growing Falkland Is. seal pups. The analyses of the milk samples collected from Macquarie I. elephant seal cows at different stages of lactation are reported, and a striking difference in milk composition at the different stages is noted. An attempt to determine quantitatively the milk production of the elephant seal is described, and the inaccuracies of the methods used are discussed, with comments on how a better estimate could be obtained. It is concluded that the principal cause of depressed growth rate of elephant seal pups at Macquarie I. is disturbance within the harems. This disturbance has been alleviated to some extent at the Falkland Is. due to alteration in the structure of the population by long-term sealing operations. Indicative of disturbance within the harems at Macquarie I. were the high incidence of injury noted during dissection of 54 seal pups, the delayed initiation of sucking in new-born pups, and the higher frequency of sucking by pups.