Age-specific birth rates of California sea lions (Zalophus californianus) in the Gulf of California, Mexico

摘要: Estimates of demographic parameters are essential for assessing the status populations and assigning conservation priority. In light difficulties associated with obtaining such estimates, vital rates rarely available even well-studied species. We present first estimates age-specific birth female California sea lions (Zalophus californianus) >10 yr age. These were estimated from reproductive histories five cohorts animals branded as pups between 1980 1984 at Los Islotes colony in Gulf California, Mexico. Age-specific varied among age classes ranged 0.06 0.80. The highest observed females 10 15 age, decreased older females. effect year, resighting effort explored using logistic regression analysis. Based on Akaike Information Criteria, best explained by while year did not have a significant effect. odds ratio producing pup but change significantly middle-aged Our consistent general patterns other large vertebrates.