Wildlife : Conservation

Adult Great Blue Herons have few natural enemies. eagles often attack young at the nest and even predate on adults. Crows, ravens, gulls, birds of prey, and raccoons also prey upon the eggs and young; mortality of the young is high, but often for reasons other than predation.

Heavy rains and cold weather at the time of hatching take a substantial toll. Also, when food is scarce, the weakest young birds often do without and waste away. Pesticides are suspected of causing reproductive failures and deaths, although data obtained up to this time suggest that toxic chemicals have not caused any decline in overall population levels. Nest productivity declines are mostly due to nest predation and disturbance are the cause for listing as Species of Special Concern and Vulnerable .

In the past, hunting caused many heron deaths. Today, a frequent reason for nesting failures is disturbance by eagles and humans; herons are particularly sensitive to disturbance while nesting. This threat has led the Committee on the Status of Endangered Wildlife in Canada to list the coastal “Pacific” subspecies of Great Blue Heron as a “Species of Concern” and has prompted the Government of British Columbia to name the subspecies in the interior of British Columbia a “blue” species. Both categories are reserved for populations that have characteristics that make them particularly sensitive to human activities or natural events. Scientists suggest that, as a general rule, there should be no development within 300 m of the edge of a heron colony and no disturbance in or near colonies from March to August.

Draining of marshes and destruction of other favourite haunts is a serious threat to the Great Blue Heron’s survival. The number of herons breeding in an area is directly related to the amount of feeding habitat available to them.

Overall, the Great Blue Heron population is healthy. Scientists estimate that there are tens of thousands of Great Blue Herons in Canada.