The ecological importance of wetlands for aerial insectivores (swifts, martins and swallows) along the Tyrrhenian coast.

Abstract

We studied phenology and density of migrant aerial insectivore birds (Riparia riparia, Hirundo rustica, Delichon urbicum, Apus sp.) from a coastal landscape mosaic of central Italy, in order to detect differences in habitat use and seasonal dynamics of each species. Two habitat types were surveyed: wetlands (a mosaic of reed beds and rush beds) and altered habitats, consisting of orchards and urban areas. We used the point count method from January to June, in a set of randomly selected sampling points. A comparison between all species showed that swifts reached the highest mean point density, while sand martin showed the lowest values, mainly in altered habitats. Initially, all the breeding species were numerous in wetlands; subsequently they shifted toward altered habitats (mainly used as breeding sites), where they were observed up to the end of the counts. Along the Tyrrhenian coast, wetlands are exploited as soon as these aerial foragers arrive in the study area and then shift to the surrounding altered (i.e., urbanized or land reclaimed) zones for nesting after some ten-days