Birth timing after the long feeding migration in northern elephant seals|动物迁徙数据集|繁殖行为数据集

A prominent phase of the annual cyle in migratory animals is the transition between migration and reproduction. The transition is a small part of the annual cycle, but details of its timing deserve attention. From a distant location, animals must initiate a long migration so that they arrive at the breeding ground on a precise schedule. Here we take advantage of a sample of female northern elephant seals that were tracked by satellite during their migration prior to parturition. In these animals, we could estimate the time interval between arrival and birth, allowing tests of the following hypotheses: 1) More experienced mothers could time arrival more precisely and thus reduce the pre-parturition interval. 2) Mothers in poor body condition were forced to forage longer and thus shorten the interval. 3) Late-arriving mothers had a shorter interval because they foraged longer. We also calculated the distance traveled in the last two weeks of the migration to examine females' ability to control arrival time, hypothesizing that animals further from the colony traveled back at a higher speed.