| Summary: | The elephant seal (Mirounga angustirostris) breeding colony at Año Nuevo, California, was founded in 1961, and since monitored closely until the present. Since 1968 a research group at the University of California, Santa Cruz, has studied it in detail. Individually identified females were monitored during the breeding season, and pupping records of many throughout their lifetimes were assembled. We address here the maximum reproductive success of females using the lifetime breeding histories. Females lived to a maximum of 23 years and were observed breeding in as many as 17 seasons. One female was observed with a pup nearby in 16 consecutive seasons, from age 4 through age 19. We compared females that gave birth to 10 or more pups (Supermoms) with females that bred at least once but produced fewer than 10 pups (Generic moms). Less than 17% of female weanlings bred at least once. Only 0.87% of females in the sample became Supermoms. We conclude that exceptional reproductive success in elephant seals is associated with giving birth annually, living long and weaning pups successfully. Once female elephant seals begin reproducing they are pregnant or nursing throughout life until they die. The dataset includes a single table with a single row for every breeding event of tagged females at the Año Nuevo colony. All breeding observations of a single female appear consecutively in the table in the default sorting. Full descriptions of the data can be found in the accompanying paper, cited below. Users interested in publishing results with these data should consult the principal investigators to best understand details of the methods. Those PIs might request co-authorship on publications based largely on the data. Column headings and definitions animalID: an arbitrary number identifying individuals year: the breeding season, including December of the previous year plus December-March of the designated year age: the female's age in years, blank for animals tagged as adults and thus of unknown age firstday: the first ...
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