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Great Blue Heron coming in for a landing
Special thanks to Mike Yip at http://www.vancouverislandbirds.com

Great Blue Heron
Great Blue Heron
Great Blue Heron on a nest
Great Blue Heron - close up
Great Blue Herons - neting
Great Blue Herons -nesting

Great Blue Heron

Ardea herodias fannini

The great blue heron is a common wading bird found all over North America, with the fannini subspecies only present along the coast from southern Alaska to northern Washington. They are a fishing bird, preferring shallow intertidal zones, swamps, lake edges, and occasionally, backyard ponds. The heron is not considered threatened worldwide, but is considered a species of “special concern” in BC due to its shrinking habitat and unwillingness to nest near human activity.


Description


Standing between one and one and a half meters high, the great blue heron is the largest heron in Canada. They are grey-blue in colour, with distinctive plume feathers on their head and breast. They hunt by wading slowly through shallow waters, remaining immobile until a fish swims close enough, and then striking quickly with their neck outstretched to pluck the fish out of the water. They will eat small crustaceans, baby turtles, and even small rodents given a shortage of fish. The fannini subspecies is one of four subspecies found in North America.


Vancouver Island Range


Preferring to live in large nesting colonies, the distribution of herons on Vancouver Island is very specific. Two colonies of 50+ breeding pairs exist on the island, one on the northern portion of Saltspring Island, and one just west of Duncan, BC. Several smaller sites, with an average of ten breeding pairs exist and are located in Downtown Victoria, Esquimalt, Sooke, Bamberton, Nanaimo, Parksville, Hornby Island, Courtenay, Merville, and Quadra Island. They prefer low-lying wetlands, and long, shallow, nearshore habitats where wading is an efficient method of fishing. Unfortunately, these are attractive areas in which to build cities and as such, many of the urban centers on Vancouver Island are also heron nesting sites. Overall, the island likely supports 200-300 herons in total.


Major Threats


Living in such close proximity with humans means that habitat loss is the biggest threat facing the great blue heron. Not only do they require good, relatively undisturbed foraging territory, but the herons are picky nesters, and have been known to abandon their eggs if the nesting site is disturbed or becomes too noisy. They require high trees in which to nest, and these trees must be within three kilometers of the prime foraging ground. Once one of those conditions is affected by human activity, the others become useless, compounding the effect of habitat loss and leaving seemingly perfect land unutilized by the birds. Bald eagles are the only major predator to the great blue heron, and will eat their eggs and chicks. The opening up of the canopy cover by humans greatly increases the risk of eagle predation as the nests become easier to spot, and harder to defend. There is also some evidence that as nesting sites become more populated and utilized by humans, the herons are accumulating some toxins, including pesticides, in their tissues, though the effect of this is not yet known.


Why they are Important on Vancouver Island


The great blue heron is not a particularly vital species in Vancouver Island’s ecosystem, but the population here is part of only 1500 breeding pairs of the fannini subspecies in the world. Also, the pairs on Vancouver Island (and on the lower mainland) have the lowest breeding success of any population of heron in North America, and investigation into why this is should be considered a priority.

 

Web site ©: The Institute for Coastal and Oceans Research (ICOR) at the University of Victoria, British Columbia Canada.