Exotic tree plantations as alternative breeding habitat for an endemic avian predator

Abstract

Forest-dwelling raptors living on islands are more vulnerable than continental relatives due to their particular life history traits and habitat degradation. The Canary Islands' forests have suffered severe transformations because of intense human exploitation since its colonization by the Europeans. In recent decades, forest managers have initiated actions to restore the original ecosystems. Consequently, gathering knowledge on the relationships between habitat and reproduction output of forest species is essential to develop long-term conservation actions. Here, we explore the suitability of exotic tree plantations as breeding habitat for an island endemic raptor, the Macaronesian sparrowhawk Accipiter nisus granti. We monitored territories distributed in three main forest types, two native (laurel forest and Canarian pinewood) and one composed of exotic trees. We assessed breeding density, characterized nesting habitat at macro-, micro-habitat and nest tree levels, and estimated breeding parameters in the three forests. We evaluated habitat selection and its potential relationship with breeding parameters, as well as nest structure survival in native versus exotic tree species. Density was higher in exotic forests and habitat features differed among forests at three spatial scales. Sparrowhawks used areas with high cover of exotic trees, with high trees, far away from human settlements and at low altitudes. All models testing for differences in breeding success and productivity among the forest types were not significant, but the percentage of successful pairs was slightly higher in exotic tree plantations than in native forests. Nest structures located in exotic trees showed a higher annual survival than those placed in native trees. Our results indicate that exotic plantations are a secure nesting habitat and therefore forestry practices, including those aiming to eradicate exotic trees, must be carefully planned to avoid nest destruction or disturbance in occupied forest patches.

Nesting behaviour of Indian Giant Squirrel (Ratufa indica) in the exotic timber plantations of the Palani Hills, Western Ghats, India

“…Over the last two decades, however, there have been contrasting results from studies that examine the impact of plantations on native biodiversity. Tree plantations were found to retain and provide valuable habitat for a wide variety of species, including native plants, animals and fungi (Humphrey et al 2000;Pawson et al 2008;Rodríguez et al 2021). In exotic Eucalyptus plantations of Mexico, densities of black howler monkeys (Alouatta pigra) were higher than in adjoining rainforests (Bonilla-Sánchez et al 2012).…”