Describes the annual haulout pattern of adult southern elephant seal cows. Analyses data collected during nine breeding seasons from 1973 to 1982.

The largest of all seals, elephant seals rank among the most impressive of marine mammals. They are renowned for their spectacular recovery from near-extinction at the end of the nineteenth century when seal hunters nearly eliminated the entire northern species. No other vertebrate has come so close to extinction and made such a complete recovery. The physiological extremes that elephant seals can tolerate are also remarkable: females fast for a month while lactating, and the largest breeding males fast for over one hundred days during the breeding seasons, at which times both sexes lose forty percent of their body weight. Elephant seals dive constantly during their long foraging migrations, spending more time under water than most whales and diving deeper and longer than any other marine mammal. This first book-length discussion of elephant seals brings together worldwide expertise from scientists who describe and debate recent research, including the history and status of various populations, their life-history tactics, and other findings obtained with the help of modern microcomputer diving instruments attached to free-ranging seals. Essential for all marine mammalogists for its information and its methodological innovations, Elephant Seals will also illuminate current debates about species extinctions and possible means of preventing them. This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1994.

Holistic studies of mammalian life history factors and their consequences on population demography require an intensive, multifaceted field methodology and effort over long temporal scales. A 25-year longitudinal mark-recapture experiment on southern elephant seals, Mirounga leonina, at Subantarctic Marion Island provide such a foundation for demographic analyses and relevant methodology advancement. Two gaps in the methodology related to life history and population demographic research are, the absence of large samples of known mass individuals, and an inability to identify mother-pup relatedness. A novel three-dimensional photogrammetric technique is designed here that allows for mass estimation of large samples of southern elephant seals in the field. An effective temporary marking technique for unweaned pups is implemented that allows for identification of large samples of pups with known mothers prior to the maternal bond being severed at weaning. These known pups can then be marked with more robust tags and relatedness information is preserved long-term. Thus, mass estimates can now be applied as covariates in modelling analyses to address questions of, for example, maternal investment, kinship associated behaviour, and the consequences thereof on survival and reproductive parameters. The state change in the Marion Island southern elephant seal population from decrease to stabilisation/increase is shown to have resulted from improved survivorship in both juvenile and adult female age classes. Male seals of all ages did not indicate improved survivorship following the period of decline. The inflexion in survivorship is identified as 1994, whence improved survivorship of juvenile seals preceded that of young adult females. This inflexion in survivorship is postulated to have resulted in a population trend inflexion around 1998. Female southern elephant seals do not show evidence of actuarial senescence, but reproductive senescence is apparent after 12 years of age. A longterm reproductive cost (reduced breeding effort) is associated with early primiparity (age three) as compared with later primiparity (4- 5- or 6-year-old). The mean proportion of 3-year-old breeders has not increased after 1994 as has been hypothesized in previous studies. Contrary to previous assumptions, females do not as a rule breed every year. Annually interrupted breeding efforts are more common than consecutive breeding efforts. No difference in the proportions of interrupted versus uninterrupted breeding efforts was identified between periods of population decline and stabilisation/increase. Longevity as predicted by survival estimates exceeds the observed frequencies. This study provides unique longevity and fertility schedules for the species. The improved survivorship, reproductive senescence and breeding schedules of female southern elephant seals in this population provide groundwork for reevaluation of previous studies and their conclusions. The addition of relatedness and body condition information will allow for sophisticated multistate modelling of population demography in future studies. However, analytical procedures and techniques employed need to be meticulously designed and thoroughly thought through to avoid mis-interpretation of biological data. In addition to a multistate single species analytical approach, the importance of an ecosystem approach to species population demographic studies is highlighted through the augmenting of data on relevant potential drivers of population change, such as killer whales, Orcinus orca.

The largest of all seals, elephant seals rank among the most impressive of marine mammals. They are renowned for their spectacular recovery from near-extinction at the end of the nineteenth century when seal hunters nearly eliminated the entire northern species. No other vertebrate has come so close to extinction and made such a complete recovery. The physiological extremes that elephant seals can tolerate are also remarkable: females fast for a month while lactating, and the largest breeding males fast for over one hundred days during the breeding seasons, at which times both sexes lose forty percent of their body weight. Elephant seals dive constantly during their long foraging migrations, spending more time under water than most whales and diving deeper and longer than any other marine mammal. This first book-length discussion of elephant seals brings together worldwide expertise from scientists who describe and debate recent research, including the history and status of various populations, their life-history tactics, and other findings obtained with the help of modern microcomputer diving instruments attached to free-ranging seals. Essential for all marine mammalogists for its information and its methodological innovations, Elephant Seals will also illuminate current debates about species extinctions and possible means of preventing them. This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1994.

It is a pleasure and a distinct honour for me to greet the participants, guests and ob servers of this Fourth International Symposium on Antarctic Biology which has adopted nutrient cycles and food webs as its central theme. On behalf of the Scientific Committee on Antarctic Research (SCAR) and other bodies of the International Council of Scientific Unions (ICSU), I bid you welcome. SCAR is pleased to acknowledge the role of the co-sponsors for this Symposium which include the Scientific Committee on Oceanic Research (SCOR), the Interna tional Association of Biological Oceanography (IABO), and the International Union of Biological Sciences (IUBS). In addition, SCAR and its co-sponsors wish to acknowledge the financial support of the Council for Scientific and Industrial Re search (CSIR) and the Department of Transport (DOT) of the South African govern ment. Nor should we forget to acknowledge also the role of the South African Scientific Committee on Antarctic Research (SASCAR) and one of its leaders and Vice President of SCAR, Mr. Jan de Wit, in arranging this charming venue for this Symposium.