Contribution of informal greenspace to bird conservation in cities: a comparative study on the diversity of bird communities in vacant lands, urban parks, and residential areas

Abstract

Vacant lands are part of the informal greenspace and could maintain native fauna in urban ecosystems. To provide scientific evidence that promotes bird conservation in cities, we compared different bird community attributes among vacant lands, urban parks, and residential areas in the city of Santiago de Chile. For this, we estimated taxonomic diversity in the three land-use types, calculated the species richness and abundance (of total and native species, including three trophic guilds: granivores, insectivores, and omnivores) among land-use types, and evaluated the influence of habitat variables on bird species richness and abundance recorded. We found that vacant lands supported a diverse community, with low species dominance, and high species richness and abundance, comprised mainly by native granivorous and insectivorous birds. In contrast, birds with generalist diet (omnivores) reached high abundances in urban parks and residential areas. While parks and residential areas were dominated by a single omnivore species (Turdus falcklandii in parks and the exotic Passer domesticus in residential areas), a set of native species reached high abundances in vacant lands. These included granivorous birds (Sicalis luteola, Zenaida auriculata, and Zonotrichia capensis) and insectivorous birds (Tachycineta meyeni and Anthus correndera). Sites with a larger cover of herbaceous plants exhibited greater richness and abundance of native birds. In addition, sites with larger proportion of their area covered by bare ground exhibited greater abundance of native birds. Our results demonstrate that vacant lands maintain high bird diversity, as well as a high species richness and abundance of native birds with specialized diets (granivores and insectivores), offering new opportunities to conserve biodiversity in cities.