Female choice in the kestrel under different availability of mating options

Abstract

Mate choice in relation to its fitness consequences on females was studied in kestrels, Falco tinnunculus, in western Finland. The breeding season is short with rapidly declining prospects of successful breeding, suggesting that females should make their mating decision quickly. On average, males arrived a few days before females, but late males arrived much later than early females. Pairs were usually formed within 2 days of male arrival, and only early males were available to early females. Options for female choice differed considerably in years of different kestrel density. In a good vole year, 1988, females had many males to choose from, but in poor vole years, 1989 and 1990, they had few options. When females had many mating options, they preferred long-tailed males. Female choice was not significantly correlated with rate of courtship feeding by males. However, males with high provisioning rates had larger clutches. Tail length of the male did not affect the number of fledglings produced per pair. Females mainly appear to rely on male morphological characteristics when choosing a mate, but since the mating decision has to be made quickly, it is difficult for them to predict the future feeding ability of males. Searching costs may explain why females may not be effective in getting the very best mating opportunities, and it seems that females cannot be choosy at all in years of low kestrel density.