The effect of plant richness and urban garden structure on bird species richness, diversity and community structure

Urban green areas improve the standard of living in cities and affect people's attitude to nature and conservation. Zoological knowledge may provide data that will help designers to enhance bird diversity in gardens. We studied the effect of plant species richness and structure on bird species richness, diversity and community structure in 25 public gardens in Tel-Aviv city and, neighboring suburbs, Israel. A total of 65 bird species were observed, of which nine were urban, exploiters or alien species. These latter species composed 54% of all individuals seen. Additional 13 bird species, mostly migrants, were observed in gardens further from the observation fixed radius. We found that shrubs species richness positively affected bird species diversity. Most bird species were found where trees and shrubs species richness was high, and trees and lawn cover were medium or low. High trees or high lawn cover attracted only a few bird species, mostly aliens and urban exploiters. Native birds preferred to forage on native trees and alien birds preferred to feed on alien trees. Bird species diversity was higher during spring and fall because of the presence of migrating bird species. Dogs and people had a negative effect on bird presence. Accordingly, we recommend that when planning new gardens, designers will avoid large lawns, prefer diverse and dense shrubberies, native trees, and will create some areas that will not be accessible to dogs and people. Finally, we emphasize the importance of multidisciplinary studies conducted in collaboration between landscape designers and zoologists.