Local quality versus regional connectivity-habitat requirements of wintering woodpeckers in urban green spaces

Abstract

In urban landscapes, city parks represent strongholds of avian biodiversity. Hence, understanding which variables promote species richness of bird communities has major implications for urban planning in order to sustain high biodiversity in an increasingly urbanised environment. From a management perspective, three options are available: Increase park area, increase habitat quality within parks and increase connectivity between parks. We used two woodpecker species, a generalist species (Great Spotted Woodpecker) and a habitat specialist (Middle Spotted Woodpecker), as indicators to identify key variables promoting biodiversity in the city parks of Vienna. Bird surveys were carried out during winter time between 2005 and 2015 in 29 urban parks. An information theoretic approach based on generalised linear models identified park area as the most relevant local variable, positively affecting the occurrence of both species. The variable was included in all best ranked models of the two woodpecker species (based on Akaike's information criterion corrected for small-sample sizes). Other local scale variables as well as the position of city parks within the urban matrix and their connectivity were of minor importance. Our results also provide some evidence that city parks may act as refuges for birds during cold winters. The park occupancy of the Great Spotted Woodpecker increased significantly with decreasing mean winter temperatures. The management of existing parks and the planning of new parks represent opportunities to improve the ecological conditions for nature development in addition to their principal function to provide recreational, cultural and aesthetic values.