(AP) – 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 2.1 hectares (5.2 acres) in 2020, compared to 2.8 hectares (6.9 acres) the previous year and about one-third of the 6.05 hectares (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 13.4 hectares (33 acres), a huge increase from the 0.43 hectare (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 6.9 hectares (17 acres) in the reserve, bringing the total forest loss in 2020 to 20.65 hectares (51 acres). That compares to an overall loss of about 5 hectares (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.