Largest butterfly migration recorded in Canada

Community and Forum → Blog → Largest butterfly migration recorded in Canada

Lev Bely, 16.05.2012 21:56

Approximately 300 million red admiral (Vanessa atalanta) butterflies moved from Windsor (Canada, Ontario) to New Brunswick. Such a massive butterfly migration through Eastern Canada was caused by the unusually warm winter in North America. This will surely have some further consequences for other species too.

“It's probably the most exciting year for butterflies that Canada has ever seen,” said Jeremy Kerr, a professor of biology at the University of Ottawa.

Field observation results estimate about 300 million red admiral butterflies migrated from Windsor to New Brunswick what's 10 times more than in previous years. Kerr said that other species also arrived or appeared in greater numbers.

The “butterfly boom” is likely to have happened due to the abnormal warm weather last winter throughout North America. Higher temperatures made overwintering butterflies emerge sooner in some places like Texas and Florida. It also improved their survival rates as they went forward north at once.

First Canadian butterflies of those that overwinter here were noticed in March that is “damned peculiar” as Kerr said. In the mid-April southern Ontario was hit by a big wave of migrant butterflies that in part were brought with strong winds. Red admiral butterflies moved north so early that they flew even into the snowy areas what usually doesn't happen. Red admirals were also joined by the Painted lady butterflies that belong to Vanessa genus as well.

A second butterfly wave arrived at the beginning of May and diversified southern Ontario, especially from Windsor to Toronto, with other species. Kerr said one enthusiast recorded 22 different species in a single Windsor park. The blog of the Royal Ontario Museum in Toronto reports about few species appeared there such as the American Painted Lady (Vanessa virginiensis), the Question Mark (Polygonia interrogationis), the Mourning Cloak (Nymphalis antiopa), the Cloudless Sulphur (Phoebis sennae), the Gray Hairstreak (Strymon melinus), the Variegated Fritillary (Euptoieta claudia) and the American snout (Libytheana carinenta).

Felix Sperling, a biologist at the University of Alberta, said the early and large migration has been a strictly eastern phenomenon, save for some red admirals approaching the southern border of Manitoba. He said the red admiral is known to have surges — and years where they're no-shows — but in Western Canada they tend to have their own ebbs and flows in numbers.

Kerr said the butterflies won't have any immediate effect on their environment — the bigger question is what it might mean for other animals. Butterflies are excellent indicators of environmental changes. “Is it a really beautiful sign of something really worrying to come?”

Sperling and Kerr both admit that it's barely possible to find out exact causes of these changes. “We don't know yet which species are going to be winners and which are going to be losers in this time of rapid environmental change,” Kerr said.

Yet there are two questions to be bothered with. How will the monarch butterflies (Danaus plexippus) migration come about as it's expected in early to mid-June and what will be the second red admiral generation that is to be started this summer.

CBC/Radio-Canada, http://www.cbc.ca

Photo: the Red Admiral butterfly

Vanessa atalanta