Habitat Associations

One approach we are using to understand habitat selection by birds is the graphing of their habitat associations.
 These plots 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.

The bars show the density of birds in each habitat, scaled to their maximum density.  Our estimates for each area across the country (i.e. boreal Bird Conservation Regions in each province/territory) were averaged to obtain the mean density of a species per habitat type.  We then divided the average density per habitat by the maximum average density for all habitats.  This scales all species to the same standard, such that the “optimal habitat” is shown as 1 on the x-axis, and all other habitats are relative to that class.  The bars depict the proportion of the species’ entire boreal population that is found in each type of habitat.

The criteria or method 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 about 30 different categories.  To facilitate comparisons, we collapsed those into 17 the habitat types shown on the graph.