Bird guilds need different features on city squares

Abstract

Urban green spaces provide habitats for animals. However, animals differ in habitat requirements depending on their traits. Consequently, it remains unclear how animal guilds differ in their response to characteristics of urban green spaces like shrubs, trees or grass. Using birds inhabiting city squares in Munich as a model system, we ask: Do trait-based bird guilds respond differently to characteristics of small green spaces? What is the difference between an urban-adapted bird community and an exploiter like the Feral Pigeon (Columba livia f. domestica)? Do the responses of guilds and the Feral Pigeon differ between spring and winter?

We show that all guilds profited from green structures, and most guilds benefited from trees and grass cover on city squares. Additional green characteristics influenced some guilds. Cavity-breeding birds needed old trees, and ground-nesting birds decreased with the presence of domestic animals but increased with the shrub volume on a square. Also, insectivorous birds increased with an increasing number of old trees on a square. In contrast to these guilds, the Feral Pigeon did not react to any green characteristic but increased with the abundance of people. Only a few guilds showed differing responses for single variables between seasons. A community analysis revealed that squares differed in the abundance of guilds and the Feral Pigeon. We, therefore, confirm the positive effects of creating urban vegetation for many bird guilds but suggest to plan urban green spaces diversely considering the particular needs of different guilds to promote urban biodiversity.