Butterfly Still at Risk of Extinction
Favorable Weather Boosts Population But Pesticides Still Threaten Butterfly’s Chance of Survival

The annual overwintering count of monarch butterflies released today shows a modest population rebound from last year’s lowest-ever count of 34 million butterflies, but is still the second lowest population count since surveys began in 1993. The population was expected to be up this winter due to favorable spring and summer weather conditions in the monarch’s U.S. and Canadian breeding areas, as butterfly populations fluctuate widely with changing weather. But the 56.5 million monarchs currently gathered in Mexico for the winter still represents a population decline of 82 percent from the 20-year average — and a decline of 95 percent from the population highs in the mid-1990s. This year’s population was expected to be much larger due to nearly perfect climate conditions during the breeding season.

“The population increase is welcome news, but the monarch must reach a much larger population size to be able to bounce back from ups and downs, so this much-loved butterfly still needs Endangered Species Act protection to ensure that it’s around for future generations,” said Tierra Curry, a senior scientist at the Center for Biological Diversity.

Found throughout the United States during summer months, most monarchs from east of the Rockies winter in the mountains of central Mexico, where they form tight clusters on trees. Scientists from World Wildlife Fund Mexico estimate the population size by counting the number of hectares of trees covered by monarchs. Monarchs need a very large population size to be resilient to threats from severe weather events, pesticides, climate change, disease and predation. A single winter storm in 2002 killed an estimated 500 million monarchs, more than eight times the size of the current population even with this year’s boost.  ƸӜƷ 

Full press release — The Xerces Society