Great tits nesting in apple orchards preferentially forage in organic but not conventional orchards and in hedgerows
Résumé
Great tits are insectivorous birds that feed mainly on caterpillars during the breeding season. Their high pest control potential in apple orchards has been documented. Nestbox provisioning is an increasingly suggested tool for ecological pest control, but the underlying assumption that birds forage in intensively managed orchards has never been formally tested. We conducted a fine-scale study of the great tit feeding microhabitat in different orchard management contexts as pesticide use affects the behaviour and physiology of birds through direct intoxication and reduced prey abundance. Using radiotracking techniques, we assessed foraging areas and foraging habitat selection of female great tits breeding in conventional and organic commercial apple orchards. We also tested whether different orchard-driven foraging strategies could be linked to differences in reproductive success. We collected 392 foraging locations from seven female great tits nesting in organic orchards and 375 locations from seven females nesting in conventional orchards. Females from organic orchards mostly searched for food inside the orchard where they bred. This contrasted strongly with females from conventional orchards (54 +/- 10.4 % and 7.1 +/- 3.0 % of foraging points inside the orchard, respectively). Further, females from organic orchards travelled shorter distances. Overall, organic orchards and hedgerows were the most preferred foraging habitats. Conventional orchard management was also associated with lower nestling survival and lower fledgling number than organic management. There were indications that the mean number of fledglings decreased with increasing mean foraging distance of the female. Our novel insights on the foraging behaviour of great tits in orchards support the benefits of installing nestboxes in organic but not in conventional orchards. We posit that nestboxes may encourage feeding activity of insectivorous birds within organic orchards where they may then contribute to the control of insect pest populations.
Domaines
Ecologie, EnvironnementOrigine | Fichiers produits par l'(les) auteur(s) |
---|