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Weird weather bugging up mosquito population

The mosquitoes were so bad in Edmonton that the Eskimos had to move their football practice indoors. Meanwhile in Winnipeg, so famous for its problem with blood-suckers that shops sell plush toys of them, the bugs have been virtually absent.

The nation's mosquito population is one of the most tangible metrics by which to gauge a year of strange weather that delivered an unusually cold winter on the West Coast, a scorching summer in Central Canada and a prolonged spring nearly everywhere.

Anecdotally, at least, years of such bizarre weather seem to be the new normal in Canada, affecting animals from marmots to songbirds. And research published this week in the journal Science shows that climate change, which sparks unusual weather patterns, is altering the ranges of various fauna more quickly than expected, pushing them closer to the poles and to higher altitudes.

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The results of the weather, however, aren't always what you would expect.

Take the mosquitoes. Manitoba seemed primed for a summer of swarms after torrential floods left behind pools, where the insects breed. But a cold spring followed by a sharp turn into a hot, rainless summer handed the province's capital its lowest mosquito count in three decades. The past few weeks have brought locals outside in droves.

"It's been bone dry here, and our summer nuisance mosquitoes are tied to storms," said Terry Galloway, an entomologist at the University of Manitoba. "At all the various events and at outdoor cafes – everybody's just loving it."

It's a different story in most other parts of the country. A snowy winter in Alberta snapped a years-long dry streak and left stagnant water on the ground. The potential for trouble was apparent to Mike Jenkins at the City of Edmonton's pest management department during the spring thaw.

"We were seeing water in places where we hadn't seen water in years," he said. "We also had heavy winds to the south that blew mosquitoes into the city."

The pests, which usually feed overnight, started biting people at all times of day. The surge in water also made the city's trees healthier, which spawned a population boom among aphids – with their propensity to drip their waste, known as honeydew, onto patios and passersby, they can be almost as annoying as their blood-feasting brethren. The high insect populations, meanwhile, have triggered a rise in ladybugs and warblers.

For other animals, such as the endangered Vancouver Island marmot, the wild weather was a problem. Fewer than 10 of the 60 captive-born marmots released into the wild last year survived the unseasonably cold winter. Don Doyle, who heads the program to reintroduce the rodents into the wild, said they often start hibernating too late in their first season, staying active when food sources are dwindling and using up nutrients that are supposed to support them until spring.

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"It's been really discouraging these past two years. You want enough to survive that they can reproduce," he said.

Throughout the ecosystem, the effect of a weather system is complicated and varied, said Peter Arcese, a biologist at the University of British Columbia. A wet spring could reduce the numbers of some birds by shortening their breeding season, for instance, but bump up the numbers of others through a plentiful crop of berries.

Water levels reached 20-year highs in Lake Ontario this spring, which washed out the nests of common terns and Canada geese; but the same waters led to spikes in insect numbers, a boon to flycatchers. A hot summer gives some avian creatures the time to build two nests and raise a second set of offspring, said Ralph Toninger an ecologist with the Toronto and Region Conservation Authority.

The longer-term effects are even harder to assess. While mosquitoes, true to their transient nature, will come back after a bad year or die off after a good one, some fear the advent of global warming will bring more disease-carrying insects.

It's not clear how much of this year's weirdness was related to climate change, but global warming can lead to unpredictable weather patterns.

Veteran Environment Canada climatologist David Phillips said that over his 40 years watching weather, a normal season seems to have become less common, while variability has spiked. The small town of North Battleford, Sask., for instance, bucked the national trend this year and experienced its driest spring on record. Its wettest was last year.

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"You used to have one season that was interesting. Now, almost every season has something unusual, has some wonkiness," he said. "You do everything based on normal – you build houses, you go on vacation – now what you're seeing is it's almost as if anything can happen. How do you deal with that variability?"

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About the Author
Washington correspondent

Adrian Morrow covers U.S. politics from Washington, D.C. Previously he was The Globe's Ontario politics reporter. He's covered news, crime and sports for The Globe since 2010. He won the National Newspaper Award for politics reporting in 2016. More

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