Monarch butterfly numbers are down by 27% this year, a decline that experts say was caused by late winter storms last year that damaged more than 40 hectares of forests where the butterflies overwinter.
Millions of the butterflies migrate annually from Canada and the United States to the forests of Michoacán and the State of México, where cold weather last March was estimated to have killed 11 million.
The Natural Protected Areas Commission now believes the number was closer to 6 million, but it was enough to contribute to a severe drop in numbers this season.
The butterflies are counted by how much area of forest they occupy. This year that coverage has been estimated at 2.91 hectares, down from last year’s figure of four, which itself was a sharp improvement from the 1.13 hectares in 2014-2015.
However, coverage was as much as 20 hectares 20 years ago.
“The reduction in the area of forest they occupied this year is most probably due to the high mortality caused by storms and cold weather last year,” said Omar Vidal, the head of the Mexico office of the World Wildlife Fund. “It is a clear reminder for the three countries that they must step up actions to protect breeding, feeding and migratory habitat.”
Yesterday, an umbrella group of organizations dedicated to the preservation of the monarchs said its efforts have improved the lives of more than 15,000 people living in the Monarch Butterfly Biosphere Reserve.
But the Red Monarca, or Monarch Network, told a press conference that more needs to be done to reduce poverty in the area in order to stop illegal logging, one of the reasons why the butterfly’s numbers have declined.
The organization also announced the launch of a monarch butterfly documentation center containing more than 30 years’ worth of information about the butterflies and the region in the form of an archive of 180 publications.
Much has been done to stop illegal logging in the butterfly reserve in Mexico and slow the loss
of milkweed plants — on which the monarchs feed — in the U.S. and Canada, but a new threat is emerging in Mexico, says a federal forestry and agriculture agency.
Víctor Manuel Coria Ávalos of the National Forestry, Agriculture and Livestock Research Institute (Inifap) observed that the boom in the consumption of Mexican avocados by U.S. consumers has led to the destruction of thousands of hectares of temperature forests in Michoacán, which are being replaced by avocado orchards.
He warned that further growth in demand for the fruit could put monarch butterfly habitat at risk as more forests are cleared.
Avocado consumption in the U.S. peaks during Super Bowl week which has become associated with eating guacamole. An estimated 35,000 tonnes of Mexican avocados were consumed in the U.S. during Sunday’s Super Bowl game.