|Male Monarch- Patrick Coin|
Monarchs migrating to Mexico are impossible to count as they clump together for warmth in the forests outside Mexico City. They are measured in their dense collections by the number of acres they pack into. This year the butterflies cover only 1.65 acres (0.67 hectares) in the pine and fir forests west of Mexico City, compared to 2.93 acres (1.19 hectares) last year. and 44.5 acres at their recorded peak in 1995. Let me repeat: 44.5 acres down to 1.65 acres!
|Monarch Migration in Mexico- Wikimedia|
|Monarch Butterfly Migration- Learner.org|
There is certainly more to the story. There has been logging the forest refuges they use in Mexico, reducing their winter opportunities. Severe weather and drought in the US has also been a factor.
The monarch isn't headed toward extinction as they can survive in southern climes. However, there is a strong likelyhood that the dramatic migration that we celebrate is likely to end. The miraculous multi-generational trip where the great grandchildren find their way back from the northern US to the same area in Mexico, never having been there, is one of the greatest unexplained mysteries of nature.
We continue to urge people to plant milkweed to expand their migratory food resources, even if we eventually fail to save their centuries of instinctive migration. If nothing else, it helps remind more people of what we can lose if we don't take better care of the planet.
There is a lot more detail in the Washington Post Interview.