LIVE FENCES HAVE GREATER DIVERSITY OF BIRD ASSEMBLAGES THAN GALLERY FORESTS IN HUMAN-MODIFIED ECOSYSTEMS

Abstract

Anthropogenic activities have led to changes in land use resulting in fragmented areas with a reduction of biodiversity and ecosystem services. Gallery forests and live fences are common elements in Neotropical agricultural landscapes that could contribute to the conservation of bird species and the services they provide. However, we need to better understand how different tree cover types influence bird assemblages in order to conserve biodiversity. I analysed the diversity of bird assemblages in space and time across two cover types in three agricultural-livestock farms in Guanacaste, Costa Rica. Bird assemblages were sampled during 2019 using transects, covering both the dry and rainy season. I estimated richness and relative abundance of bird assemblages at each tree cover type and site. To characterize vegetation structure, I calculated plant richness, diameter at breast height and tree height. Patterns in bird diversity changed at a spatial scale, whereas remained similar in time. Bird assemblages had consistently higher richness and abundance in live fence than in gallery forest in the three study sites. In addition, live fences resulted in a less structural complexity compared to gallery forest, as indicated by decreased plant richness and tree height. My results show that live fences play an important role for birds, allowing for more diverse avian assemblages in human-modified ecosystems. Although live fences are less structurally complex and may offer less suitable habitats for birds than gallery forests, they might provide complementary food resources and act as stepping-stones for both resident and migratory bird species. Thus, live fences may perform as corridors for birds increasing connectivity in rural landscapes, which make them an essential tool for bird conservation.