Massachusetts Butterflies Move North as Climate Warms

http://www.sciencedaily.com/releases/2012/08/120819153741.htm

ScienceDaily (Aug. 19, 2012) — The authors of a Harvard study published August 19 in Nature Climate Change gathered their data from an unlikely source -- the trip accounts of the Massachusetts Butterfly Club. During the past 19 years, the amateur naturalist group has logged species counts on nearly 20,000 expeditions throughout Massachusetts. Their records fill a crucial gap in the scientific record.

Once analyzed, the data show a clear trend. "Over the past 19 years, a warming climate has been reshaping Massachusetts butterfly communities," notes Greg Breed, lead author on the study and a postdoctoral fellow at the Harvard Forest in Petersham.

Subtropical and warm-climate species such as the giant swallowtail and zabulon skipper -- many of which were rare or absent in Massachusetts as recently as the late 1980s -- show the sharpest increases. At the same time, more than three-quarters of northerly species (species with a range centered north of Boston) are now declining in Massachusetts, many of them rapidly. Most impacted are the species that overwinter as eggs or small larvae, indicating that these overwintering stages may be much more sensitive to drought or lack of snow cover.

The study creates new questions for managing threatened species. "For most butterfly species, climate change seems to be a stronger change-agent than habitat loss," says Breed. "Protecting habitat remains a key management strategy, and that may help some butterfly species. However, for many others, habitat protection will not mitigate the impacts of warming."