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But do crows count?
The crows of Burnaby are revered for their intelligence, feared for the role they could play in the spread of disease, and abused for their messy habits. We report from B.C.'s biggest roost
Peter Clough, The Province
Published: Sunday, April 29, 2007
At the BCAA's head office on Canada Way in Burnaby, they call it Crow Hour.
Meetings in the fifth-floor office of president Bill Bullis have been known to grind to a halt, discussions about membership fees and travel packages put on hold as swivel-chairs are turned to the windows.
It's one of the Lower Mainland's most incredible natural spectacles.
Dr. Michael Jackson is studying the behaviour of crows because of the role they might play in the spread of West Nile virus.View Larger Image View Larger Image
Dr. Michael Jackson is studying the behaviour of crows because of the role they might play in the spread of West Nile virus.
Les Bazso, the Province
Day after day, in the hour before dusk, office workers in the Willingdon and Lougheed area witness the phenomenon of black undulating clouds approaching from all directions.
Before long, every tree, building and power line in the area is alive with crows. The residents of the biggest roost in B.C. -- it's been called the Vancouver International Airport of the bird world -- are returning home for a good night's sleep.
But first: Happy Hour.
"It's fascinating," observes Bullis.
"They gaggle and it's loud and they're just kind of boisterous and having a great old time.
"It seems to me there are some trees that are full of boy crows and other trees that are full of girl crows -- not unlike a bar.
"There's a lot of banter back and forth and the occasional fly-over and that sort of thing."
The BCAA boss is amazed to be told that he's describing classic pre-roosting behaviour.
Researchers, you see, have been learning quite a lot lately about the the crows of Burnaby.
The ancestral habitat, once pristine forest and now prime commercial real estate, has become ground zero in the battle to prevent an outbreak of West Nile virus in B.C. The crows are being studied for the role they could play in the spread of the disease.
Their roost, home to an estimated 35,000 crows in peak non-breeding season, is also the focus of a messy showdown between man and nature.
And all in all, it doesn't look good for the crows.
THE BIG FLAP
If Willingdon and Lougheed sounds like a less than ideal spot for a crow roost, you can't blame it on the birds.
Barbara Watt, an inspector with the Canadian Food Inspection Agency on Still Creek Drive, says she understands and sympathizes: The crows were there first.
It does not, however, stop her from wishing they would take the hint and find new digs.
Watt says it's not unusual for her colleagues to be seen walking to their cars or the bus stop after work with their umbrellas up -- when it's not raining.
"The owners of these buildings are spending a fortune on pressure washing," she says. "They pressure wash on a Friday and by Monday you can't tell they were here."
As a food inspector, she is also concerned about the health hazards associated with working in the heart of B.C.'s biggest crow roost.
"Quite frankly, we're tracking bird crap right on the bottom of our shoes all over the carpeting in the building," says Watt. She wonders whether food inspectors are carrying bacteria from the droppings into food plants all over town.
People who work in the area have learned to put up with the endless squawking. What makes it worse is that they're forced to listen to the artificial calls of crow predators and other noxious noises, amplified from roof-top speakers.
Fake owls have been even less effective in scaring the crows away. When the trees are full, they make pretty good perches. Some building owners are now threatening to install electric wires to cut down on their cleaning expenses.
"It's quite hilarious," says birder and naturalist Jude Grass. "The birds sit up on top of the building and go, 'Ha ha ha. You want to scare me? Try something better.'"
Grass, who co-ordinates the bird section of the Vancouver Natural History Society, became a fierce defender of the Burnaby roost when she was asked to organize a crow count across the Lower Mainland.
The request came from Dr. Michael Jackson, a UBC research associate and expert on West Nile virus. Jackson needed important data about crow behaviour because experts suspect that if the mosquito-borne disease arrives in B.C., as predicted, it will be spread by the birds of the corvid family -- mainly crows.
"He needed people to go out first thing in the mornings or in the afternoon and watch where the crows were coming from and how many and what they were doing," explains Grass.
Jude and her husband Al are among dozens of crow enthusiasts who participated in the count and who have developed a flocking pattern of their own. Binoculars and rubber boots are said to be a common site on the patio of the McDonald's that has sprung up at the heart of the roost.
Grass says she has learned to respect the crows for their high level of intelligence, their ability to look after one another and the complexity of their social order.
The Grasses have observed how the crows fan out in every direction at dawn, splitting into "clans" along the way and finally into small family groups.
Every day, they fly farther than most people drive to work. Richmond, the North Shore and other areas close to the water are favourite spots for foraging and nesting. At this time of year, mating pairs begin to stay away from the roost, even at night, in order to protect their eggs.
Grass says she's impressed by evidence that juvenile crows are taught parenting skills before being introduced to crow society back at the roost.
But the real entertainment starts just before dusk when the crows gather in pre-roosting areas on the edge of the main habitat around Still Creek near Willingdon and Lougheed.
"There's a lot of socializing that goes on when they come in," says Grass. "I guess they're finding each other and they seem to be talking to each other."
Nico Verbeek, a retired SFU ornithologist who has studied crows extensively, says it's still not clear why the crows have used that site for their roost for at least three decades.
He points out that the site offers a central location from which the crows can radiate out to feed around the Lower Mainland.
And he says it appears that the daily comings and goings follow a familiar pattern.
"They seem to follow a more or less similar pathway every day and stop along the route at fixed places where they do some more feeding," says Verbeek. "They fly a little further and do some feeding there and gradually head for the roost. As they do so, of course, the groups get bigger because they all have to eventually end up in the same place."
He says he believes the crows are inclined to return to the same tree night after night -- and possibly even the same branch.
And he says studies by other researchers have shown that crows who occupy superior positions in the hierarchy are more likely to take sleeping spots in the higher branches.
The theory as to why does not need to be spelled out.
While the birds are programmed to return to their ancestral habitat, Verbeek fears that if the pace of development continues, the crows will have no choice but to find somewhere else.
"As we keep reducing the number of places where they can spend the night, obviously they are going to have to vacate that area if it gets completely paved over," he says.
"There are other places available, you would think, but so far they seem to prefer sleeping in places that to me would look somewhat sub-standard."
THE BIRDS AND THE BUGS
Human cases of West Nile virus have been reported in most areas of North America. Researchers fear it is just a matter of time before we see an outbreak in B.C.
In 2006, there were 127 human cases of the disease between Ontario and Alberta. West Nile causes a range of illnesses from mild to severe and can be fatal.
In 2003, for example, there were 1,494 outbreaks in Canada, leading to an estimated 14 deaths.
If an outbreak does occur here, the first sign is likely to come in the form of dead crows. The worry is that after being infected by mosquitoes, the crows -- and other birds in the corvid family -- will spread the disease further afield, transmitting the virus back to mosquitoes, who in turn pass it on to humans.
It's why UBC researcher Michael Jackson describes the Burnaby crow roost as a blessing in disguise.
His company, Culex Environmental, has been contracted to keep the area's mosquito population under control.
"The great thing about the roost is that you know exactly where the birds are and you can control the mosquitoes relatively easily," he says
Jackson's squad of mosquito assassins has concentrated its efforts on larvae that accumulates in drainage ditches around the roost and in the hundreds of puddles that are formed by construction activity.
As heavy equipment releases nutrients from the ground, algae forms in the shallow water. That makes the pools attractive to female mosquitoes.
"We looked at just one pool where there was something like 5,000 egg rafts on top of the pool -- which amounts to almost a million mosquito hatchings," says Jackson.
He and other researchers are concerned that the crows are beginning to display signs of confusion and disoriented behaviour as they try to find roosting spots on buildings and in small, crowded trees.
Observers have noted that crows can sometimes be seen flying around the roost after dark in an almost drunken manner. The theory is that late-night noise and bright lights are disturbing their sleeping patterns.
Jackson says the crow displacement caused by development could have serious consequences.
"Now it's become a moving target," he says.
Just this week, Jackson was back at the roost to count the incoming crows. He reports some disturbing news.
On April 22 last year, he counted some 20,000 birds. The numbers are always lower at this time of year because mating pairs are beginning to stay at their nests. But this week Jackson counted just 6,000 crows.
He says it's possible that nesting season has started early this year -- but believes there's a more likely explanation for the big drop in numbers.
"They could be forming other roosts," he says.
"Something fairly dramatic is happening."
SO WHAT IS IT ABOUT CROWS?
You can't blame all the bad press on Alfred Hitchcock.
I'm as guilty as anyone.
Years ago, I wrote about the bizarre events that followed my efforts to rescue an injured baby crow that my kids had found in the backyard.
We put it a shoebox in the shed and tried to nurse it back to health with soggy bread.
Not a good idea.
All week long, as I headed out to work, hundreds of crows lined the power lines on our street. They would hop from one section to the next, following me all the way to my car.
I had no way of telling them that the little bird had died.
Michael Jackson says he's heard lots of stories about crows protecting their young and going to great lengths to look after one another.
"The other day someone told me about an injured crow that somehow got its wing snagged on a branch in a tree," says Jackson.
"All these other birds came around and helped to get the wings free from the branch. There is something definitely very communal about the way they work."
Nico Verbeek says our mistrust of crows has deep cultural roots. "The colour black doesn't help because we tend to think of black as the colour of mourning," he says.
The word "crow" is almost always used in a negative context. The pro-crow lobby argues that we're spooked by the crow's high level of intelligence. It doesn't help that they're often seen hanging out together in large groups.
Experts say crows are smart enough to use twigs and other tools for digging bugs out of holes, or to play tricks on one another -- or, for that matter, on humans.
Verbeek says crows aren't quite as smart as parrots "but they're certainly up there."
He's impressed by the way crows form pair bonds that appear to last a lifetime. "It's a meaningful marriage," he says.
Jude Grass, meanwhile, says she doesn't understand why so many people think of crows as being aggressive.
"You'll see them chasing each other for a chip or something but they're not really fighting," she says.
"They've got this sad reputation as the bullies of the bird world -- but they're not.
"They're beautiful birds."
WHO'S A BIRD BRAIN?
Five signs that crows are a lot smarter than you might think:
1. They make tools: Studies have shown that crows are not only capable of using twigs to dig grubs out of holes but will actually shape the tool for more effective use. They can even fashion a hook.
"Once they've got a tool that works they'll put it in their back pocket (i.e., beak) and take it with them," says Dr. Rob Butler, a biologist with the Pacific Wildlife Foundation and one of Canada's leading crow experts.
Don't believe it? Type "crow" and "tool" into youtube.com and see for yourself.
2. They teach their children: In the crow world, yearlings who have yet to find a mate don't waste time hanging around the roost. They can often be seen flying off with their parents to the nesting area.
"They're helping their parents raise the kids from this year," says Butler.
3. Meaningful conversations: You might think crows do nothing but squawk, but scientists say these misunderstood birds have complex ways of exchanging information through body language and calls.
"I think we're barely scratching the surface on this one," says Butler. "They have a very complex repertoire of calls and their social interactions are very convoluted."
4. They're good at math: The jury is still out on whether crows can calculate the change in garbage day after a long weekend. However, says Butler, experiments involving boxes containing food have shown that crows and their cousins, jays and ravens, are able to count -- and remember.
5: They can manipulate the outcome of a situation: Butler says researchers are learning that ravens are capable of leading wolves to their prey -- presumably so they can share in the spoils.
He says that's another indication of crow intelligence. Like ravens, crows have brains that are well-developed in the area that affects logic and rational thinking.