To understand the ecological consequences of climate change we need knowledge about environmental influence on individual performance. Individuals can vary in their response to environmental variation, due to differences in resources, quality and demographic attributes. Lasting environmental effects on individual lifetime reproductive performance can generate population structure, influencing long-time population growth rate. We evaluated reproductive performance in goshawks in relation to environmental variation. We especially asked whether response was most prominent between breeding locations, between females, or if it was shaped by variation within individual females, e.g. from age or breeding experience. Moreover, we investigated long-term consequences of environmental conditions at first breeding attempt. Of particular importance in raptors is the ability to hunt and kill preferred prey species, which makes the diet an important quality measure. Accordingly, diet was included as a performance-measure at the breeding location level, between-individual level, and within-individual level.
Results/Conclusions
Environmental conditions had a strong influence on the performance at the between-individual level, but little importance at breeding location level and within-individual level. This suggests that variation in reproductive performance is related to individual differences, rather than spatial differences due to nest quality, or changes occurring over time within each individual. Moreover, the initiation of the reproductive lifespan was found to depend on climate and female quality. At certain given environmental conditions the first-time breeders had a better diet, longer breeding lifespan, and evidently a higher lifetime reproductive success. Such lasting effects of environmental conditions on individuals generate individual heterogeneity that influences the long-term growth rate of populations. This should be accounted for when predicting climatic effects on populations' extinction risk.