Contribution of woody habitat islands to the conservation of birds and their potential ecosystem services in an extensive Colombian rangeland

In agricultural landscapes, patches of natural or semi-natural habitat are crucial for the survival of plant and animal populations, which in turn are essential to maintain ecosystem functioning. Species composition and diversity of trees and birds among woody habitat islands were compared in a Colombian rangeland to assess how habitat characteristics influence bird community composition, bird species traits and their potential ecosystem services. Bird and tree diversity was higher in gallery forest fragments compared to hedgerows and isolated tree islands within rangelands. Forest fragments shared over 50% of their bird and tree species with tree islands and hedgerows, yet communities differed markedly. Tree islands and hedgerows had relatively more endozoochorous and small-seeded tree species and hosted birds of forest, savanna and shrubland, while forest fragments had more synzoochorous and large-seeded tree species and primarily hosted forest birds. Hedges and tree islands contribute to the conservation of forest bird and tree biodiversity in rangeland, but gallery forests are essential for the conservation of less tolerant forest species. The savanna rangeland acts as an ecological filter between the gallery forests and the hedges and tree islands, which in turn facilitate the spillover of tolerant forest birds and their ecological functions, including tree seed dispersal, into the rangeland, and thus support regional forest conservation and restoration.