The Pacific great blue herons returned to their colony by the Park Board offices for the season on March 11th. This is about 3 weeks later than they returned last year. Once they returned, these majestic birds got straight to work on courtship, nest building, and mating.
Ten days after copulation, female herons start to lay their first eggs. This year, that was around late March. Unfortunately for the herons, many of these first eggs were preyed upon by bald eagles. As attached as we get to the herons in Stanley Park, it is important to remember that the eagles are just trying to survive and raise their own chicks, too. Not so long ago, bald eagles were listed as a species at risk themselves, and we are glad to see their recovery and return to the Park.
Herons lay between 2-5 eggs over the course of a week. Even if all five eggs were to hatch, the parents would have a hard time feeding and raising five chicks. Typically, parents can only provide enough food for 1-3 chicks to survive to fledging. Because of this, losing a couple of eggs early on–while certainly not beneficial–is not that detrimental to the population as a whole.
Our monitoring team is happy to report, that as of April 25th, 85% of the nests surveyed contained herons incubating eggs. That’s over 70 nests! More of the herons will continue to lay eggs as the season progresses. We expect to see the first chicks hatch in early May. Be sure to check out all the continuing excitement of the heron colony on the Vancouver Park Board’s Heron Cam. If you are interested in supporting the SPES’s efforts to monitor and protect the Stanley Park heron colony and would like to contribute to our efforts, you can Adopt a Nest!
By Greg Hart, Urban Wildlife Coordinator