by Dan Straker, SPES Urban Wildlife Programs Coordinator
The Stanley Park great blue heron colony nesting season is complete as most of the young birds fledged the nest by August and can now be seen congregating at nearby feeding grounds such as Iona Beach and Boundary Bay.
The colony has seen a benefit from a productive year and an early spring, and the trees were quiet by August, earlier than usual. In years with many eagle attacks, second and third nesting attempts have been common, but this season, with little pressure from the eagles, the herons finished nesting earlier on.
This year, thanks to the Vancouver Park Board’s heron cam, Stanley Park Ecology Society heron monitors were able to get a closer look at several nests and monitor them on a more regular basis. This also helped to test some of the assumptions we have made using our traditional method of monitoring the herons from a nearby rooftop in past years. The two methods proved to have very similar results which helped to validate our rooftop method used since 2004.
Ultimately, the colony had a high nest success rate (% of active nests with a young heron leaving the nest) at 92%. As a comparison we haven’t seen a nest success rate this high since 2007, the most successful year for the colony to date. The productivity – number of fledglings produced per successful nest – was an average of 2.3 chicks per successful nest. By multiplying our nest success rate by our average chicks as a ratio of the total of active nests (83 active nests), we estimate that the entire colony would have produced about 175 fledgling herons this year.
SPES’s heron monitoring program relies on generous contributions to our Heron Adopt a nest program. Your contribution goes towards monitoring this blue listed species at risk, which ultimately helps in their conservation. For more information please visit: the Adopt a Heron page
To see the entire full annual report and to look back at the story of the colony as it unfolds please visit: