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The makeup of butterfly populations in the Northeast has changed dramatically in the last two decades, according to a new study. That's because global warming is driving butterflies to cooler climates farther north.
The study by Harvard University's Harvard Forest is published in the latest issue of Nature Climate. It finds that butterflies that historically populated Massachusetts have moved farther north. Likewise, butterfly species from farther south have moved into the Northeast in the last 20 years.
"We've had a really fantastic year for this butterfly called the Giant Swallowtail, which is typically more common in the South. They showed up in absolutely astounding numbers this year," said the lead author of the study, Dr. Greg Breed. "Then there's perhaps six or seven other smaller species that moved into the state in the last 10 or 15 years that really weren't here before."
Breed says the study benefited from an avalanche of information from Butterfly enthusiasts.
"We got in touch with the Massachusetts Butterfly Club and they had been compiling all of their observations since 1992 and that amounted to nearly 20,000 individual observation trips," Breed said.
According to the report not all butterfly species have made the slow migration to cooler temperatures. Greg Breed suspects these butterflies are unable find a suitable food source farther north.
