"Butterflies from the southern US that used to be rare in the northeast are now appearing there on a regular basis. The trend correlates to a warming climate report the authors of a paper in Nature Climate Change."
"Subtropical and warm-climate butterflies—including the giant swallowtail and the zabulon skipper -- showed the sharpest population shift to the north. As recently as the late 1980s these species were rare or absent in Massachusetts.
At the same time southern butterflies are moving north, more than 75 percent of northern species—with a range centered north of Boston—are rapidly declining in Massachusetts now. Disappearing fastest are the species that overwinter as eggs or larvae. Which suggests that changes in the winter climate (like more drought or less snow cover) may be harming nonadult butterflies."