- Category: Tech & Science
- Published Friday, February 26, 2016
- CTV News
MEXICO CITY - Monarch butterflies have made a big comeback in their wintering grounds in Mexico, after suffering serious declines, investigators said Friday.
The area covered by the orange-and-black insects in the mountains west of Mexico City this season was more than three and a half times greater than last winter. The butterflies clump so densely in the pine and fir forests they are counted by the area they cover rather than by individuals.
The number of monarchs making the 3,400-mile (5,500-kilometre) migration from the United States and Canada declined steadily in recent years before recovering in 2014. This winter was even better.
This December, the butterflies covered a total of 10 acres (about 4 hectares), compared to 2.8 acres (1.13 hectares) in 2014 and a record low of 1.66 acres (0.67 hectares) in 2013.
While the news was good, the monarchs still face problems: The butterflies covered as much as 44 acres (18 hectares) 20 years ago.
The United States is working to reintroduce milkweed, a plant key to the butterflies' migration, on about 1,160 square miles (3 million hectares) within five years, both by planting and by designating pesticide-free areas.