Responses of Polylepis birds to patch and landscape attributes in the High Andes

Habitat loss and fragmentation can devastate biodiversity, especially at regional and global scales. However, generalizing to individual species is challenging given the wide variety of intrinsic and extrinsic factors that shape species-specific responses – particularly among species that are specialists, generalists, or adapted to naturally patchy landscapes. In this study, we examined how patch and landscape attributes affected bird communities within Polylepis forest ecosystems, which are patchily distributed within landscapes of Puna grasslands and shrublands in the High Andes of Peru (3,300–4,700 m). We surveyed birds in 59 Polylepis patches and 47 sites in the Puna matrix, resulting in 13,210 observations of 88 bird species, including 15 species of conservation concern specialized on Polylepis. Data were analysed using Multi-Species Occupancy-Models (MSOM) and cumulative species-area curves. Species richness was generally greatest at mid-to-low elevations, within small fragments, and in landscapes with comparatively little forest cover; this was especially true for birds associated with the Puna matrix. Consistent with the hypothesis that Polylepis specialists are adapted to naturally patchy landscapes, we found no evidence that Polylepis specialists were sensitive to patch size, though two of nine species were positively related to forest cover within 200 m. Our work shows that small patches of Polylepis have high ecological value and that conservation of species of concern may depend more on retaining at least 10% forest cover within landscapes than on the presence of large patches of Polylepis.