26 April 2019

Watch great blue herons defend nests from eagle attacks with Vancouver park board's Heron Cam

by Martin Dunphy on April 25th, 2019 The Georgia Straight

For the fifth year, the Vancouver park board has made a high-definition camera feed available to the public to peek into the nests of one of North America's largest urban great blue heron colonies.

The great blue heron is our continent's largest (up to more than one metre tall) wading bird, and our local subspecies, the Pacific great blue heron, has been returning to the large breeding colony behind the park board offices in Stanley Park (2099 Beach Avenue) for 19 years.

The local variant has been deemed a species at risk in Canada.

Records show that the herons have been nesting in the park for about a century, at least since the early 1920s, and an earlier colony's large twig-and-branch nests, now abandoned, once occupied trees near the Vancouver Aquarium and the former park zoo. Theories for abandonment range from construction noise to bald-eagle predation of eggs and chicks.

The herons also constructed nests near Brockton Point and Beaver Lake, according to a City of Vancouver online history of the park colony.

In its 2018 Stanley Park Heronry Report, the Stanley Park Ecology Society reported that volunteers counted 104 tree nests in the colony area (which stretches from behind the park-board headqurters to the tennis-courts surroundings), with 85 of those nests deemed active. (Go here to download a PDF of the report at the bottom of the page, as well as to access instructions on how to manipulate the Heron Cam remotely.)

Society observers reported "daily eagle attacks" early in the 2018 nesting season, which starts at about the middle of March. The raids stopped after about a month, only to resume when the chicks had hatched. Only two active eagle nests were observed in the park last year.
A March 20 park-board release noted that more than 180,000 people have used the Heron Cam since its launch in 2015. "It’s amazing to be able to get a birds eye view of  the nesting, courtship, mating, nest-building, and egg-laying of these magnificent birds,” Stuart Mackinnon, park-board chair, said in the release. “Heron Cam supports engagement by residents with nature in the city as part of our Biodiversity Strategy and Vancouver Bird Strategy and enables our partner the Stanley Park Ecology Society to better monitor and protect the health of the colony.”

This year, according to the release, herons returned to the nesting area on March 11. As well, it notes: "One-third of Great Blue Herons worldwide live around the Salish Sea and the Stanley Park colony is a vital part of the [B.C.] south coast heron population."

Stanley Park Ecology Society representatives will answer questions during a live Facebook Q&A hosted by the board (date to come), and society volunteers will host on-the-ground weekly interpretive sessions in the park for visitors. The society also conducts an "adopt a nest" fundraiser to support its work with the herons.

The annual nesting season ends in August, when most chicks will have left the nests. About 100 fledglings were counted in 2018, which was an increase in numbers from the previous year.
You can view a detailed society timeline of the herons' arrival, breeding, and nesting here.

(c) 2019 Straight.com

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