Measuring the State of Canada's Birds
This report presents indicators of the status of Canadian bird populations and the ecosystems on which they depend.
Horned Grebe (Photo: May Haga)
The report presents indicators separately for eight major physiographic regions in Canada. These regions reflect major differences across the country in bird habitats, ecosystems and human activities that shape the landscape. For each of the regions, only species that were considered “characteristic” of the region were included, based on the species’ regional-density or the amount of the species’ range in the region, relative to the other regions. For the Oceans region, all seabird species that regularly occur in Canada were considered characteristic.
In each region, indicators for subsets of the characteristic species that reflect the most important bird groups or habitats within the region were calculated. Not all subgroups were displayed in any given region, so some species are only present in the main indicator (i.e., the black line labelled “All species”).
These indicators reflect the average population status of major groups of bird species. They were calculated using regional estimates of each species’ population status that reflect the percent change in the population since the first-year when population monitoring data existed for most regions—1970. The indicators are plotted based on the percentage change, with the scale adjusted so that negative changes are visually comparable to the corresponding positive change required to return the indicator to its original value; for example, an indicator that has decreased by 50% (i.e., reduced to ½ its original level) must then increase by 100% (i.e., double) to return to zero.
Bohemian Waxwing (Photo: Nick Saunders)
Averaging across species gives the best overall estimate of the group’s status, but does not necessarily reflect the trends for all species in a group equally well. For example, a stable indicator may reflect a group in which most or all species have stable trends, or it may reflect a group with an equal number of species with large increases and large decreases. For this reason, bar graphs are also presented to show the number of increasing and decreasing species in each indicator, with separate colours for species with population trends in each of five categories from strongly decreasing (> 50% decline) through strongly increasing (>100% increase).