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Like most owl species, the Great Gray Owl is not well monitored in Canada; the species' periodic irruptions in response to prey populations further complicate the situation. The best available data are from Christmas Bird Count in Canada, which suggests a large increase in numbers since 1970, although precision of the trend estimate is poor due to highly variable annual totals. Furthermore, methods for Christmas Bird Counts are not standardized and targeted efforts to record owls may have increased over time. More recently, the Ontario and Manitoba (Duncan 2010) Nocturnal Owl surveys have both detected small numbers of this species since 1995, though neither covers a majority of the species' range in Canada. Data from the Ontario Nocturnal Owl survey suggest a stable or moderately increasing population since 1995, whereas results from the Manitoba survey show a stable or moderately decreasing population since 1991 (Duncan 2010). Considering all these results, the population status of the Great Gray Owl in Canada is best assessed as having shown little overall change since 1970, but that assessment has low reliability.
Additional information on: Ontario Nocturnal Owl Monitoring Program
Additional information on: Christmas Bird Count (CBC)
