Relation between bird nests and insects: an evidence that breeding activities of birds create a habitat for insects

Abstract

Many insects have been identified in bird nests, and the birds have been considered as serving as ecosystem engineers creating habitats for insects. However, few ecological studies have demonstrated this link between birds and insects. We investigated whether avian breeding activities provide habitats for insects, and whether insects positively utilize bird nests, by investigating Japanese Tits Parus minor using nest boxes over three years. We found that the occurrence of keratin-feeding insects was positively correlated with the length of the periods the birds used the nests (i.e. from the day of first egg laying to fledging, predation or desertion day). Detritivores insects showed the same tendency. These results suggest that avian breeding activities provide new habitat not only for keratin feeders, which are thought to depend on feather sheath debris, but also insects that feed on humus. When nest materials collected immediately after birds had finished using their nests were compared with those material collected three weeks later, there was no difference in the frequency of the generation of insects regardless of their food habits. This result indicates that insects invade nests before birds finish breeding.