Miami Herald (Sunday)
Monarch butterflies down 26% in Mexico wintering grounds
The number of monarch butterflies that showed up at their winter resting grounds in central Mexico decreased by about 26% this year, and four times as many trees were lost to illegal logging, drought and other causes, making 2020 a bad year for the butterflies.
The government commission for natural protected areas said the butterflies’ population covered only 5.2 acres in 2020, compared to 6.9 acres the previous year and about one-third of the 14.95 acres detected in 2018.
Because the monarchs cluster so densely in pine and fir trees, it is easier to count them by area rather than by individuals.
Gloria Tavera, the regional director of Mexico’s Commission for National Protected Areas, blamed the drop on “extreme climate conditions,” the loss of milkweed habitat in the
United States and Canada on which butterflies depend, and deforestation in the butterflies’ wintering grounds in Mexico.
Illegal logging in the monarchs wintering rounds rose to almost 33 acres, a huge increase from the 1 acre lost to logging last year.
Jorge Rickards of the WWF environmental group acknowledged the lost trees were a blow, but said “the logging is very localized” in three or four of the mountain communities that make up the butterfly reserve.
In addition, wind storms, drought and the felling of trees that had fallen victim to pine beetles or disease, caused the loss of another 17 acres in the reserve, bringing the total forest loss in 2020 to 51 acres. That compares to an overall loss of about 12.3 acres from all causes the previous year.
Tavera said the drought was affecting the butterflies themselves, as well as the pine and fir trees where the clump together for warmth.
“The severe drought we are experiencing is having effects,” Tavera said. “The butterflies are looking for water on the lower slopes, near the houses.”
Millions of monarchs migrate from the U.S. and Canada each year to forests west of Mexico’s capital. The butterflies hit a low of just 1.66 acres in 2013-14.
Loss of habitat, especially the milkweed where the monarchs lay eggs, pesticide and herbicide use, and climate change pose threats to the species’ migration.
While there was plenty of bad news for the butterflies — very few showed up to some historic wintering sites like Sierra Chincua — there was the welcome news that a new wintering site was discovered nearby, in a mountaintop near the Lagunas de Zempoala protected area, near Mexico City.