Senescence and individual variation drive egg size and fertility of captive Gymnogyps californianus (California Condor)

作者：Carolina Granthon, Christopher J. W. McClure, Stephanie J. Galla, Todd E. Katzner, Julie A. Heath · 发表于：Ornithological Applications · 年份：2026 · DOI：10.1093/ornithapp/duag021 · 被引用次数：1 · 研究领域：Avian ecology and behavior、Animal Behavior and Reproduction、Wildlife Ecology and Conservation

Abstract Conservation breeding programs support biodiversity by supplementing wild populations with captive-bred individuals to bolster population size and genetic diversity. Successful reproduction and long-term viability of offspring, which may depend on early-life traits such as egg size and fertility, are fundamental components of conservation breeding programs but are rarely systematically assessed. We analyzed data from 499 Gymnogyps californianus (California Condor) eggs laid at The World Center for Birds of Prey in Boise, Idaho, USA in 1995–2024 to test the effects of individual-specific traits (age, rearing, inbreeding coefficient, seasonal laying order, and prior-year double laying), pair-specific traits (relatedness and length of pairing), and year effects on fertility and egg weight (a proxy for egg size). Bayesian mixed models suggested that egg weight varied strongly among but not within individual females. Egg weight decreased with seasonal laying order, was independent of prior-year reproductive output, and peaked when females were middle-aged (∼10–25 yr). Egg fertility was high (78%) and showed a similar female age quadratic effect. Egg weight had a positive effect on fertility. We found no effect of any other variables on egg weight or fertility. Our findings highlight senescence and individual variation as factors shaping early-life traits in a captive-bred species. Individuals breeding in captivity have access to unlimited resources, suggesting that variat...