Battle for Butterflies The fight to bring back North America’s dwindling migratory monarchs
AFTER PASSING THE WINTER hunkered down on evergreens in central Mexico or coastal California, monarch butterflies are on the move again this spring. Fluttering 25 to 30 miles a day, the insects are headed north and east toward breeding grounds that by mid-summer will stretch from coast to coast across the United States and as far north as southern Canada.
Conservationists hope gardeners will spot more of the beloved orange-and-black butterflies in their yards this year than last. As this issue went to press in February, Mexican researchers had just announced results of their annual survey of monarchs roosting in the country’s high-elevation, oyamel fir forests—the winter home to 99 percent of North America’s monarch population. The scientists estimate that in the winter of 2014 to 2015, these forests housed 56.6 million monarchs—up 69 percent from the previous year’s survey, when the insects’ numbers fell to historic lows. In California, where the remainder of the continent’s monarchs overwinter, volunteers counted 234,732 butterflies at 185 sites, about the same number as last year.
While the news from Mexico was welcome, the increase “does not mean the monarch butterfly has recovered,” says Chip Taylor, director of the nonprofit Monarch Watch and a biologist at the University of Kansas. The latest count remains one of the lowest ever recorded, he notes, “and even if its numbers doubled or tripled, North America’s monarch population remains very small and very vulnerable.”
According to scientists, the continent’s monarch population has declined by more than 80 percent from its average during the past two decades—and by more than 90 percent from its peak of nearly one billion butterflies in the mid-1990s. With modest numbers of non-migratory monarchs ranging south to Peru, and small, introduced populations established in locations around the world, the species Danaus plexippus most likely will survive. But “we very well may lose the spectacular phenomena of monarch migration and overwintering,” says Lincoln Brower, a Sweet Briar College biologist who has studied the butterflies since the 1950s. ...
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