Avian diversity, assemblages and use of vegetation in an urban
ecosystem



         

         Urbanization is known to have a negative impact on biodiversity (3).  However, it is possible to increase bird species richness in cities through local action such as increasing density and diversity of vegetation (2).  My first objective was to compare bird density and diversity on the island of Montreal among four urban habitat types: low and medium density residential sectors, and residential and natural parks.  A second objective was to determine the presence of bird species assemblages within each urban habitat. A third objective was to explore associative relationships among six bird species and vegetation.  Point counts were conducted in each of 103 locations (1).  Environmental variables measured consisted of the type (coniferous versus deciduous), density and height of vegetation within each 1ha sector.  The results demonstrate a decrease in bird density 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 assemblage was determined through correspondance analysis.  Most bird species appeared to be associated with at least one type of urban
habitat.  Correlation between bird species and vegetation was measured through
canonical correspondance analysis.  The six focal species demonstrate different levels of association with different habitat variables.

Literature cited

1. Bibby, C. J., N. D. Burgess and D. A. Hill. 1992. Bird Census Techniques.
Academic Press, London, UK.

2. Clergeau, P., J. Jokimki and J-P. L. Savard. 2001. Are urban bird
communities influenced by the bird diversity of adjacent landscapes ? Journal
of Applied Ecology. 38: 1122-1134.

3. Savard, J-P. L., P. Clergeau and G. Mennechez. 2000. Biodiversity concepts
and urban ecosystems. Landscape and Urban Planning. 48: 131-142.

 Josée Rousseau

 

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