Grasslands provide diverse opportunities for bird species along an urban-rural gradient

Abstract

Urbanisation is a major cause of biodiversity loss but careful habitat management and provision of green space within cities can help to mitigate its negative effects. Grasslands occupy large surface areas and have many functions but only a few studies have begun to explore how birds exploit these habitats in urban contexts. We hypothesized that the value of grasslands for nesting and feeding birds is likely to depend both on landscape context, and on local characteristics (grassland size, use and vegetation structure). We surveyed local habitat characteristics, breeding bird presence, abundance and foraging activity in 47 grassland sites, distributed along an urban-rural gradient in two French cities, and varying in the proportions of grassland, built-up land and residential gardens in the neighbouring landscape. Species richness was influenced by local rather than landscape variables; larger sites with scrub within the grassland and taller hedgerow vegetation were more species rich. Total bird abundance, however, depended on landscape context, and increased in suburban grasslands with a higher proportion of gardens in the landscape. Foraging in grass was more frequently observed in shorter, regularly mown, recreational grasslands. These were more common in urban contexts and favoured by species requiring easily accessible and visible invertebrate prey. Less intensively managed wastelands were species rich despite being in urban contexts and favoured by seedeaters and one farmland specialist. A diversity of use and management of grasslands along the urban-rural gradient could allow birds with various requirements to co-exist at landscape scale.