SOURCE: Washington Post
DATE: January 20, 2018
SNIP: Thanksgiving was right around the corner, and a sizable number of one of America’s most famous migrants could be seen still sputtering south. Not across the Texas-Mexico border, where most monarch butterflies should be by that time of year. These fluttered tardily through the migratory funnel that is Cape May, N.J., their iconic orange-and-black patterns splashing against the muted green of pines frosted by the season’s first chill.
This delayed migration is not normal, and it alarmed monarch researchers across the country. The Cape May stragglers were only a sliver of the record number of monarchs reported in the Northeast in November and December — news that sounded good initially to conservationists. But seeing butterflies so far north so late in the year suggested that few of these latecomers would reach their Mexican wintering grounds. Scientists fear that climate change is behind what they’re calling the latest monarch migration ever recorded in the eastern United States, and they worry that rising temperatures pose a new threat to a species that saw its population hit record lows in recent years.
Known for their complex, improbable migrations, most monarchs embark on 2,000-mile journeys each fall, from breeding grounds as far north as Canada’s maritime provinces to the Sierra Madre mountains in central Mexico. (A separate western population heads mostly to Southern California.) They mate in Mexico, then fly back north to lay their eggs (and die) in the spring.
Because they’re so delicate — each weighs less than a gram — monarchs are particular about the conditions they’ll fly in, and especially vulnerable to extreme weather systems. Major storms, high winds, early freezes — all pose large-scale dangers, and the butterflies faced all of those this year. But more pernicious than that, scientists believe, are the warmer temperatures, probably a sign of climate change, which manipulated the monarchs’ instincts and pushed their migration back.
“But nobody ever looks at the weather part of the system. Unless you understand the nuance created by the weather, your data will be completely full of noise,” Chip Taylor, who heads the University of Kansas’s Monarch Watch, said. And “if you look ahead to 2040 — oh my God, you don’t want to look ahead to 2040,” given the projections for future temperature rises.