By Melissa Segrest
Green Right Now
Up close they are such delicate creatures, their bright orange wings outlined in black and accented with white spots. But when they migrate by the millions each year — from Canada through the United States and most to a specific mountainous region of Mexico and back – monarch butterflies become one of nature’s most breathtaking spectacles.
Their tiny brains are hard-wired with biological clocks, and their eyes detect ultraviolet light variations to guide them. Every year, generations of the beautiful monarchs travel from 1,200 to 2,800 miles to their winter and summer habitats. Because most adults only live four weeks, they only travel part of the way. Then their offspring continue the trek, and on and on until they reach their habitats.
Their amazing migration has become a “threatened phenomenon,” according to the International Union for Conservation of Nature.
Forest clearing in Mexico, climate change from Canada to Mexico, diminishing habitats in the U.S. and a decline in the monarchs’ primary source of food – milkweed – are blamed for changes and disruptions that may forever alter the butterflies’ spectacular migrations.
The summer destination for butterflies who live east of the Rocky Mountains is a very specific spot in central Mexico: a 217-square-mile area of 12 mountaintops covered in oyamel fir trees. More than a billion butterflies spend winters there.
For years, that mountainous home has faced deforestation for agriculture, intentional forest fires and wood for heat. Losing the shelter of their trees exposes monarchs to wind and cold — millions of them have already died, according to a report in Science Daily. University of Kansas researchers who have created the Monarch Watch program to track the insects in their Mexican habitat (also known as the Monarch Biosphere Reserve) say the monarch populations have been decreasing yearly.
Other researchers say climate change is harming monarchs’ habitats in both the north and south. In the mountains of Mexico, the climate is predicted to get wetter and colder in the next half-century, according to the Environmental Defense Fund. Monarchs cannot survive rain followed by freezing temperatures.
In the eastern U.S. and Canada, monarchs may face global warming’s hotter, drier summers, which would push their migration farther north, making it longer. Hot, dry weather could impact their food supply – the monarch primarily eats and lays its eggs on the milkweed plant – as well as their ability to reproduce and survive. Urban sprawl in the U.S. – particularly in California, where monarchs from west of the Rockies spend their winters — is eating away at the insects’ habitat and food supply, scientists and environmental groups say.
The milkweed is considered a toxic and illegal weed in Canada, and in the U.S. many farmers kill it. There are about 115 species of milkweed in the U.S. and Caribbean, which allows the plant to grow in all climate zones monarchs pass through. Not all of those species are toxic to livestock.
In America, many fields planted with soybeans and corn are increasingly genetically modified in ways that diminish or eliminate milkweed.
Last year, the three nations where monarchs fly came together to create the North American Monarch Conservation Plan. They pinpointed threats to the monarch migrations, recommended steps to stop deforestation and habitat loss, and supported research of changes in breeding habits and monitoring migrations.
A key component of the study is to develop alternate ways for those who are clearing Mexico’s mountain forests to make a living. Also, Mexico’s government has issued three federal decrees to protect monarch habitats in their country.
There are many other programs in place to study and aid the monarchs’ migration. The Monarch Watch program supports “waystations” that provide nectar sources and plenty of breeding space. In 2007, the conservation plan says, there were more than 1,800 waystations.
Journey North, the Monarch Butterfly Sanctuary Foundation, the Michoacan Reforestation Fund, the Monarch Program, and Monarchs in the Classroom are other programs that raise money to support the insects and increase awareness of them.
There are also 13 monarch butterfly “sister-protected area networks” that stretch from Mexico to Long Point National Wildlife Area in Ontario, large spaces of land that provide all the monarch essentials.
You can help track the numbers of monarchs (and other butterflies) in your area by joining the North American Butterfly Association’s annual Fourth of July butterfly count (the count actually occurs over a period of days around July 4). Volunteers can join the association and then sign up online or use their site to locate the organizer in your area and join in the counting of beautiful butterflies.
Photo credits: (Photo from MonarchLab, University of Minnesota; Monarch on Bottlebrush flower, from North American Monarch Conservation Plan; dead monarches on a forest floor, from Ecolife Foundation; cluster of monarchs in winter habitat, photo from Texas Parks and Wildlife, Monarch Migration page
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