Recruitment is an important aspect of life history that is difficult to estimate without long-term data. We used 28 years of data to create multistate capture—mark—recapture models with maturity status as state to provide estimates of age-dependent probabilistic recruitment (transition from juvenile to breeder state) of Cassin's Auklets (Ptychoramphus aleuticus) breeding at Southeast Farallon Island, California. We found strong evidence for age effects in recruitment and survival, but not in breeding propensity. We also examined parental-age effects on return rate of offspring. Although an average of 70% of a cohort begins breeding by age 4, fledglings from 2- to 4-year-old mothers were less likely to become breeders than fledglings produced by older mothers. This may be attributable to age-related differences in egg production and maternal offspring-rearing abilities that could contribute to differences in fledgling recruitment rates. Eggs of younger mothers had lower volume and their fledglings had lower mass than those of older mothers. We suggest that researchers, managers, and population modelers consider the possibility that young breeding birds that successfully fledge young do not always produce viable offspring that will become breeders.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.