Canada's butterfly migration is largest on record

Butterflies have migrated across Eastern Canada this spring in unprecedented numbers, reflecting the warm winter throughout North America and raising alarm bells about what it might mean for other species.

"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.

http://www.cbc.ca/news/technology/st...gest-ever.html