Unintentional habitats: Value of a city for the wheatear (Oenanthe oenanthe)

Abstract

Humans are rapidly reducing and isolating the habitats of native species such as the wheatear (Oenanthe oenanthe) through urbanisation and agricultural intensification. The wheatear, a small songbird, has declined dramatically throughout Europe. It is known to live in alpine meadows, in tundra, and rural landscapes as well as in urban areas, but it is unknown if these urban populations reproduce sufficiently. This study aimed to investigate reproductive success and habitat requirements of the wheatear in the city of Berlin, Germany. We analysed occurrence and breeding success in relation to vegetation and surface structure of the settled sites, intensity of direct disturbance by humans and dogs, as well as degree of sealing and residential population density in the surrounding urban matrix. Finally, we compared early-settled to late-settled territories to appraise habitat preferences of wheatears.The proportion of successful nests was high (73%) compared to other regions and habitats. Area size of a site greatly affected the probability of wheatear occurrence; it was much higher on sites larger than five hectare. Factors affecting breeding success differed completely from those explaining variation in occurrence, indicating that breeding success seems not to be related to habitat preferences. There was no influence of the urban matrix at a landscape level (200m and 2000m zone) on occurrence or breeding success. To maintain and create habitat for endangered open-land species as the wheatear, we recommend minimum area size of five hectare, sparse vegetation, open soils, short grass, and very few trees and shrubs.