Age-Specific Natality of Northern Elephant Seals at the South Farallon Islands, California

摘要: We monitored 233 tagged, known-age female northern elephant seals ( Mirounga angustirostris ), age 3–16 years, that gave birth on the South Farallon Islands, 1975–1986. Females were from 1970–1982 cohorts born Farallon, Ano Nuevo, San Nicolas, and Miguel islands, California. Age-specific natality was significantly lower for 3- 4-year olds (0.13 0.75, respectively), then stabilized at about 0.80 females 5–10 years. Natality in 1984 1985 than other For 1971–1980 cohorts, mean first reproduction ranged 3.9 to 4.6 During this study, structure of giving Islands changed; rose 4 years 1975 7 1986. At least 20% Farallon-born survived reproduce, ≥17% returned ≥ 3% emigrated rookeries. Miguel, Nicolas islands immigrated give (≥3, ≥2, >1% respectively). Mature, nonpregnant seen during breeding season (6%), autumn haul out (15%), spring molt or a later (79%).