干旱区生态环境知识资源中心

In polyandrous species females produce successive clutches with several males. Female barn owls (Tyto alba) often desert their offspring and mate to produce a 2nd annual brood with a second male. We tested whether copulating during chick rearing at the 1st annual brood increases the male’s likelihood to obtain paternity at the 2nd annual breeding attempt of his female mate in case she deserts their brood to produce a second brood with a different male. Using molecular paternity analyses we found that 2 out of 26 (8%) second annual broods of deserting females contained in total 6 extra-pair young out of 15 nestlings. These young were all sired by the male with whom the female had produced the 1st annual brood. In contrast, none of the 49 1st annual breeding attempts (219 offspring) and of the 20 2nd annual breeding attempts (93 offspring) of non-deserting females contained extra-pair young. We suggest that female desertion can select male counter-strategies to increase paternity and hence individual fitness. Alternatively, females may copulate with the 1st male to derive genetic benefits, since he is usually of higher quality than the 2nd male which is commonly a yearling individual.