REPRODUCTIVE SYNCHRONY AND THE ESTIMATION OF MEAN DATE OF BIRTH FROM DAILY COUNTS OF NORTHERN FUR SEAL PUPS

Authors

  • Andrew W. Trites

    1. Resource Ecology and Department of Zoology, University of British Columbia, 2204 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4
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  • 1

    Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, B.C., Canada V9R 5K6.

Abstract

Two methods for estimating the mean date of birth from daily counts of northern fur seal pups (Callorhinus ursinus) are presented and applied to data collected on the Pribilof Islands in 1951, 1962, 1963 and 1983. The mean date of birth over the four years was July 9. Reproduction is highly synchronized and consistent from one year to the next. Pupping occurs over a five week period with over 50% of the pups being born during the first two weeks of July.

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