Monarch butterflies may be making a comeback after years of habitat loss and dwindling populations.
Monarchs are known for their annual migration, or seasonal movement, from Canada and the U.S. to Mexico. But over the past two decades, the number of monarchs sighted in Mexico declined by 95 percent. Last winter, however, scientists observed three times as many butterflies as the year before.
“Monarch numbers can change greatly from year to year, depending on things like weather and food availability,” says biologist Brice Semmens of the University of California, San Diego. So while the recent increase is good news, the insects might not be out of the woods just yet.