We are now at week #12 of the heron breeding season in Stanley Park, and the chicks continue to grow at an incredible rate since hatching began on April 28. Around two months after hatching, they will reach 40 times their weight and will be ready to fledge!
Nest time for hatchlings can be a dangerous time not only from predators like eagles, but also from the nestlings’ own kin: siblicide is not uncommon, as a stronger nestling pushes its sibling from the nest to reduce competition for food. We have encountered a few heron chick fatalities on the ground below the colony this month. There have been minimal eagle visits, though, since April, although it’s likely that the colony will continue to experience some pressure with at least two mating eagle pairs raising young in the Park this year.
Here’s an update on the heronry activities since the herons returned to breed this past February:
Consistent with the last two years, February left us cold with
biting, wintry weather and a lack of herons returning to the nests.
Historically, the Stanley Park heronry would expect to receive the herons by
mid-February (the earliest record was January 15).
Winter’s overnight frosts persisted and kept the herons at bay until the
second week of March, when the neighbourhood began to report seeing them
perched on nearby rooftops. Finally, the male herons—convinced of the
safety and suitability of these nesting trees for another year—began to move in
and roost overnight on March 11th.
This marks the 19th consecutive year of the
Great Blue Herons’ return to this location since 2001.
Courtship and nest maintenance quickly followed, even as we began our weekly heron outreach table underneath the nests by the Vancouver Park Board office. Males would do their languid stretch, shaking their plume feathers at watching females. Bonded pairs engaged in bill duels, the hollow clacking easily mistaken for the ambient sound of tennis balls being hit in the nearby courts!
Our rooftop survey on April 2nd found the first eggs of the season, counting 6 among the 55 nests we could observe. 15 other nests had incubating adults. The community observed eagle attacks on the heronry within this first week of egg-laying, and it is likely that their success at feeding in some of the nests necessitated double-clutching (laying a new clutch of eggs) for some of the parents. Nevertheless, the first hatchlings arrived on schedule: April 28, the weekend of our Stanley Park Earth Day Celebration.
Watch the chicks grow on
the Vancouver
Park Board’s Heron Cam,
which is now live. Be part of our community of heron monitors by e-mailing nests@stanleyparkecology.ca when you
observe things of note, and engage us on social media with the #HeronTalk hashtag.
You can also find us under the nests at our heron outreach table every week
(usually on Wednesdays, 1:30-3:30 p.m., but check
our calendar first!).
The Pacific Great Blue Heron (Ardea herodias fannini) is a species-at-risk due to habitat loss and population decline. SPES monitors and gathers data on the number of birds, nests, eggs, and chicks to determine the colony’s productivity and population size. We install and maintain metal bands on the trees to protect the herons from ground predators like raccoons. We also work alongside the Vancouver Park Board to bring awareness to this beautiful and vulnerable bird through education and the Stanley Park Heron Cam.
Please help support these efforts by adopting a heron nest for the 2019 season!
By Dannie Piezas, Environmental Educator