The monarch butterfly population is in freefall, according to a new census of the wintering grounds in northern Mexico. The number of the charismatic insects dropped 59 percent this year, bringing their numbers to the lowest level in 20 years when the census first began. There are only one-fifteenth as many overwintering monarchs as there were in 1997. That’s the grim news from World Wildlife Fund (WWF) officials who spoke on Wednesday.
Dr. Lincoln Brower, a leading entomologist who specializes in monarch butterflies, recently published a report from a February visit to the northern Mexico wintering grounds. In addition to examining several logged areas, he met with former President Jimmy Carter to view the migration and discuss some of the problems of the population collapse.
Although many bird species migrate each winter to warmer climates, monarch butterflies are the only known butterflies to make a journey of up to 3,000 miles from their breeding grounds in the United States and Canada to northern Mexico and southern California. A single monarch can’t live long enough to make the journey, and, in fact, it takes several generations to complete the cycle.
According to National Geographic, the butterflies that return to Mexico are the great-grandchildren of the previous year’s visitors. No older monarchs make the journey twice, much less survives to show the youngsters the way. Instead, the whole process is programmed into their DNA, sometimes accurately enough that they can return to the same tree used by their great-grandparents.
However, the dramatic spectacle, which attracts 150,000 tourists a year to Mexico, is at serious risk. The director of the WWF in Mexico, Omar Vidal, said that Mexico has made substantial progress in protecting the wintering grounds from illegal logging. Although illegal logging was destroying more than 1,100 acres in the reserve in 2005, an aerial survey found virtually no detectable logging in 2012.
However, Brower said that he personally observed some illegal logging during his February visit. He also acknowledged that Canada and the United States must do their part to stop the abuse of herbicides in farming. Like all butterflies, monarch butterflies start their lives as caterpillars, but, in their case, they feed on a once-widespread weed called milkweed, which is now threatened by overspraying of crops.
For a better look at what we lose if we lose the monarch butterflies, check out this You Tube video taken of a previous year’s migration:
Each year, I plant a small patch of milkweed and allow them to be eaten by any caterpillars left behind by migrating monarch butterflies. To help the butterflies, ask your county extension agent or local butterfly plant seller if you should do the same.
[close-up monarch butterfly photo courtesy Kenneth Dwain Harrelson and en.wikipedia]
[overwintering monarch butterfly clump photo courtesy Brocken Inaglory]