Pulsed resources affect the timing of first breeding and lifetime reproductive success of tawny owls.

摘要: Summary 1. According to life-history theory, environmental variability and costs of reproduction account for the prevalence delayed in many taxa. Empirical estimates fitness consequences different ages at first breeding a variable environment are few however such that contributions individual remains poorly known. 2. Our objectives were elucidate processes underpin variation assess lifetime age site-faithful predator, tawny owl Strix aluco L. subjected fluctuating selection linked cyclical vole density (typically 3-year cycles with low, increasing decreasing densities successive years). 3. A multistate capture–recapture model revealed cohorts had strikingly juvenile survival prospects, ranging from 0·08 0·33 respectively birds born Decrease Increase phases cycle. This resulted highly skewed population structure >75% local recruits being reared during years. In contrast, adult remained constant throughout The probability commencing was lower 1 than older ages, especially so females. From 2 onwards, pre-breeders high probabilities entering population. 4. Variation reproductive success driven by phase cycle which female owls started their career (26–47% variance explained, whether based on number or fledglings), more conditions experienced birth. Females who postponed breed time 3 an phase, produced recruits, even when accounting may have died before reproduction. No effects detected males. 5. Sex-specific early accounted females prone delay Contrary expectations best-of-a-bad job strategy, early-hatched, hence potentially higher-quality likely 1, but then rapidly declining food resources seemed caught trap set multiannual