Species-specific breeding habitat association of declining farmland birds within urban environments: conservation implications

Abstract

Human settlements represent important year-round habitats for many declining farmland birds; however, detailed knowledge of species-specific habitat associations is crucial for effective conservation of individual species. In this study, we examined the effect of environmental factors on the occurrence, population density, and habitat associations of three sedentary granivorous farmland bird species (house sparrow Passer domesticus, tree sparrow Passer montanus, and Eurasian collared dove Streptopelia decaocto) during the breeding season within an urban environment and compared the results with a previously published study carried out during winter. To fulfil our aims, we used a comprehensive dataset from a nation-wide monitoring program focused on the studied species in the Czech Republic covering the period 2010–2016 and including a total of 162 human settlements (330.3-km length of transect). House sparrow was the most numerous and common species recorded on the studied transects, followed by tree sparrow and Eurasian collared dove. The population density of house sparrows and Eurasian collared doves was positively correlated with the proportion of farmsteads, and the population density of tree sparrows was positively correlated with proportion of grasslands. The occurrence of house sparrows and Eurasian collared doves increased with higher proportion of buildings and small-scale farms, whereas occurrence of tree sparrows increased with higher proportion of small-scale farms and woody plants. Habitat preference analyses demonstrated that house sparrow and Eurasian collared dove primarily preferred buildings, and tree sparrows preferred small-scale farms. Arable habitats were generally avoided by all studied species. Based on species-specific occurrence and habitat associations, several management measures may be adopted to support declining populations of the studied species, as well as whole bird communities inhabiting urban environments.