Reversed sexual size dimorphism in raptors: evaluation of the hypotheses in kestrels breeding in a temporally changing environment

摘要: Reversed sexual size dimorphism (RSD, females larger than males) is commonly found in birds of prey. We used kestrels (Falco tinnunculus), breeding western Finland a temporally varying environment 3-year vole cycles, to assess current hypotheses for the evolution and maintenance RSD. Our 12-year data showed only weak correlations between parental parameters (laying date, clutch number fledglings produced). The degree RSD per se was unrelated success, contrary prediction female dominance hypothesis. Females with small males produced clutches low-vole years, independently laying which supports male (or its equivalent inter-sexual selection) Small tended have more fledglings, particularly inconsistent an advantage large (the starvation, intra-sexual selection, reproductive effort, supplementary feeding hypotheses). As males, smaller may be efficient hunters, importance should most pronounced under harsh conditions. results suggest that directional selection on particular contrasting pressures by environment, and, at least females, advantages can actually counterbalanced during environmental