Breeding Biology of the Northern Elephant Seal (Mirounga angustirostris) at the Isla San Benito del Oeste, Eastern Pacific, Mexico

Abstract: The reproduction of the northern elephant seal (Mirounga angustirostris) has been studied within the colonies of California, but little information exists for the colonies of the Pacific coast of Mexico. Here, I present information for two consecutive breeding seasons (2001-2002 and 2002-2003) collected at one of the San Benito Islands, close to the southern limit of the distribution of the species. The number of females that arrived at the island was higher in 2002-2003, but this did not indicate that the colony is increasing in population. The principle reproductive parameters (the length of stay on land and the duration of lactation), and the birth and death rates were similar for both years. The breeding season was estimated to begin in early December and end in early March, lasting for 100 days or more, and the peak of the season, with the greatest number of females, occurred on January 19 in both years. There were some differences between San Benito and information reported from other northern colonies: the duration of the breeding season is longer in San Benito, the peak of the season occurred earliest, and the preweaning pup mortality was less.

Key Words: Mexican Pacific, Mirounga angustirostris, reproductive biology, Rothery & McCann model

Document Type: Research article

DOI: 10.1578/AM.30.2.2004.289

Page Numbers: 289-295

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