The Nonannual, Nonseasonal Breeding Cycle of the Australian Sea Lion, Neophoca cinerea

Abstract

A population of Australian sea lions, Neophoca cinerea, had a breeding cycle of ca. 17.6 months, with a pupping period of 5 months. Data were collected by using the birth dates of 22 individually recognizable females that were re-identified during 2 or more breeding periods, and by the temporal documentation of the births of 56–85 females during each of 4 breeding periods. Comparison of these data to census data collected since 1973 shows that breeding events shift forward in time to 13.8 days earlier every 18 months.