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One approach BAM uses to understand habitat selection by birds is to plot their habitat associations. The plots of relative density by habitat included for each species were created using BAM's density estimates, and they illustrate the relative use by a species of the diverse array of habitats that comprise the boreal forest.

example graph of habitat association

The results are summarised by species under RESULTS. The bars show the density of birds in each habitat, scaled to their maximum density, for each area across the country (i.e. boreal Bird Conservation Regions in each jurisdiction).

The criteria or methods for defining and classifying habitat categories across broad spatial scales will influence resulting habitat associations, and there is no universal standard at this time. We evaluated a variety of classification schemes and chose to define habitat according to the 2005 Land Cover Classification (LCC05) from Natural Resources Canada. These data are obtained using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery via satellite. It classifies habitat into 39 different categories. To facilitate comparisons, we collapsed those into the 14 habitat types shown on the graph.

In some combinations of BCR and jurisdiction, less common habitats may not have been represented by a sufficient number of surveys to permit density estimation. In those cases we pooled data among adjacent jurisdictions to obtain an adequate sample of surveys (n=50). The bar charts with pooled habitats are marked with an asterisk, to indicate that the data were pooled across potentially-different ecological conditions, which may reduce the reliability of those specific estimates.