Avian diversity, assemblages and use of vegetation, mainly by shrub-nesters, in an urban ecosystem

Urbanization is known to have a negative impact on biodiversity. However, it is possible to increase bird species richness in cities through local actions such as increasing vegetation density and diversity. My first objective was to compare bird density and diversity on the island of Montreal among four urban habitat types: low-density and medium-density residential sectors, and residential and natural parks. A second objective was to determine the presence of bird species assemblages within these four urban habitats and a third was to explore associative relationships among six mainly shrub-nesting bird species and the vegetation they use. Point counts were conducted in each of 103 locations. Environmental variables measured consisted of the type (coniferous versus deciduous), density and height of vegetation within each 1 ha sector. Results revealed a decrease in bird abundance from medium-density residential habitats, residential park, low density residential habitats to natural parks and an increase in diversity from medium density residential habitats, low density residential habitats, residential parks to natural parks. Bird assemblages were determined through correspondence analysis. Most bird species were associated with at least one type of urban habitat. Associations between bird species and vegetation were measured through canonical correspondence analysis. The six focal species associated with shrubs demonstrated different levels of association with different habitat variables