Why the monarch butterfly migration may be endangered
The latest survey of monarch butterflies in Mexico shows numbers are way down from last year, and the lowest since measurements began 20 years ago.
Every year, the butterflies leave eastern Canada and the U.S. in late summer for a spectacular, 4,000-kilometre migration to overwinter in a small area northwest of Mexico City. The return trip, now underway, will take four generations for the monarchs to reach Canada.
In 1996-97, the monarch survey – which is now a joint project of Mexico’s National Commission of Protected Areas, the World Wildlife Fund (WWF) and Telcel, a Mexican company – reported 18.19 hectares occupied by monarch butterfly colonies, the largest ever recorded. The current survey in the Oyamel forest found the area was now only 1.19 hectares.
For Lincoln Brower, who teaches biology at Sweet Briar College in Virginia and is arguably the leading expert on the monarch butterfly, the insect’s plight “is symbolic of what’s going on in terms of environmental degradation everywhere.”
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