Butterflies Make Partial Comeback in Mexico

Year after year, generations of monarch butterflies migrate the stretch of North America from Mexico to Canada and back again. No single animal makes the entire trip, but descendents follow the trail. Every year, hundreds of volunteers create way stations, report sightings and even tag the vivid copper and black insects. Butterflies east of the Rockies head to Mexico, and “This winter, there are four hectares of colonies, more than double the 1.9 hectares last year, the lowest level since comparable recordkeeping began in 1993,” reports Mark Stevenson for the Associated Press. Yet some winter reserves saw no colonies return this year, he reports. Researchers suspect the monarch population fluctuates and struggles due to generational lags, climate change along the route, pesticides that kill milkweed and deforestation in the monarchs’ winter destination of Mexico. – YaleGlobal