Two adult birds with 33 goslings grab attention at Burnaby Lake
BY LARRY PYNN, VANCOUVER SUN MAY 22, 2015
A family of Canada Geese with 33 goslings at Burnaby Lake May 21 2015.
METRO VANCOUVER -- A new gang has claimed Burnaby Lake as its ‘hood.
Although a pair of Canada geese normally give birth to five or six young, Burnaby streamkeeper John Preissl documented two adults with no fewer than 33 goslings in tow. “As I walked down the trail near Piper Spit Pier, I noticed the large brood ... following the pair,” he explained Friday. “About 45 minutes later they swam right by me and across the lake to spend the night. It was good to see most of the rowers stopped for the family.”
The explanation is that Canada geese often form “gang broods” — defined as two or more broods amalgamated into a single cohesive unit and shepherded by four or more parents — according a 2009 study in the journal, Condor.
Gang brooding is more typical among older, experienced geese, and among geese that change mates from the previous year, the study found.
Gang broods, or crèches, can reportedly range to 100 goslings following just a few adults and are more common in areas of high nest density, in urban and suburban areas.
Rob Butler, a retired bird scientist with the Canadian Wildlife Service, said he spotted the same gang brood at Burnaby Lake. While he’s heard and read about such large numbers, this is the first time he’s actually seen it. “I said, ‘Holy smokes, look at that pair, they have a lot of young.’ ”
Butler said gang broods may be a case of safety in numbers — more eyes to watch for predators such as bald eagles, and reduced odds of being targeted should they attack.
“It’s mutual protection, lots of eyes and adults around,” he said.
It’s not clear why Preissl photographed just one pair of adults with the 33 goslings, but it’s possible the other parents are nearby, are dead, or are younger adults with less experience at raising young. “Anything’s possible,” Butler said. “At Burnaby Lake, they all get together to mooch food off people. They get all these broods together. It’s pretty easy to band together into one big group.”
lpynn@vancouversun.com
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PLEASE NOTE: there's a really cool short video with this that I couldn't embed. Here's a link to the whole story.
http://www.vancouversun.com/technology/Canada+geese+form+gang+broods+Burnaby/11075978/story.html
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