Tens of thousands of monarch butterflies that should be in Texas by now, en route to their wintering grounds in Mexico, are still in the northern U.S. and Canada, their migrations delayed due to above-average temperatures and strong winds this fall.
Swarms of the butterflies have been seen from Ontario to Cape May, New Jersey at levels more normal for late September, the Associated Press reported. Monarchs typically reach Mexico by November 1. The large number of stragglers is “definitely new territory for us,” University of Kansas biologist Chip Taylor, director of Monarch Watch, told the AP.
After weeks of warmer-than-usual weather, temperatures from the Great Lakes to New England are beginning to fall. Monarchs’ muscles stop functioning correctly when temperatures are in the 50s, so scientists warn that unless the butterflies start their 3,000-mile journey south soon, many of them may end up stuck up north and die. Even if they do leave now, many of the plants they eat along the way will be gone by the time they reach them, making starvation a real threat, biologists said.
Monarch populations have been in decline for years, plummeting from 1 billion to 33 million in just two decades. Conservation groups and scientists are petitioning to make them a threatened species. One project is aiming to transform an interstate highway into a sort-of monarch highway that would help shepherd the species south.