Food availability and predation risk, rather than intrinsic attributes, are the main factors shaping the reproductive decisions of a long‐lived predator

摘要: Deciphering the causes of variation in reproductive success is a fundamental issue ecology, as number offspring produced an important driver individual fitness and population dynamics. Little known, however, about how different factors interact to drive reproduction, such whether individual's response extrinsic conditions (e.g. food availability or predation) varies according its intrinsic attributes age, previous allocation resources towards reproduction). We used 29 years data from marked female tawny owls natural (field vole) predator abundance (northern goshawk) quantify extent which influence owl traits (breeding propensity, clutch size nest abandonment). Extrinsic appeared affect breeding propensity (which accounted for 83% success). Breeding increased with vole density, although increasing goshawk reduced strength this relationship. Owls became slightly more likely breed they aged, was only apparent individuals who had fledged chicks year before. laid larger clutches when abundant. When were territories less exposed predation, 99·5% all attempts reached fledging stage. In contrast, probability reaching stage predation depended on amount already allocated reproduction (averaging 87·7% 1-2 eggs compared 97·5% 4-6 eggs). Overall, our results suggested that changes (predominantly food availability, but also abundance) greatest reproduction. deteriorating (fewer voles goshawks), frequently, fewer per attempt. However, have relatively small responded conditions, indicates decisions shaped by complex series trade-offs.