Bird communities in two oceanic island forests fragmented by roads on Tenerife, Canary Islands

Abstract

Although most studies on road effects on birds have been conducted on continental grounds, road fragmentation on oceanic islands is often heavier. We assessed variation in bird communities near (≤25 m) and far (>100 m) from forest roads dividing laurel and pine forests on Tenerife, Canary Islands. Line transects were used as the census technique. We compared community structure and species responses between both forests, and among forest interior and edges of paved and unpaved roads. We analysed richness and diversity of species in these different situations, and tested for significance in bird community descriptors and species abundance responses to road proximity. The bird community of the laurel forest showed significantly higher average population density, richness, diversity and evenness than that of the pine forest. None of the two forests showed significant differences in community descriptors between edge and interior, except for a higher evenness along unpaved roads in the laurel forest. However, the bird community showed more overall abundances, richness and diversity on unpaved than on asphalt road edges in laurel forest. Excepting two passerines (Turdus merula in laurel forest and Phylloscopus canariensis in pine forest), all species had similar abundances on road edges and forest interior regardless of forest type. Most species might be regarded as forest generalists. Changes detected between edge and interior on road-fragmented forests were, overall, small at the bird community level. Managers should consider the effects of road edge and road type on the more sensitive species in present and future road planning.