We all know the Monarch butterflies. Typically, they are the type we first picture whenever someone mentions a butterfly, black and orange with white fringing on the edges of the wings, fluttering around gardens, landing on flowers and plants alike to their hearts’ content.
These butterflies live in Southern Canada and various parts of the U.S., generally the north and center. They migrate to warmer regions such as Mexico during the winter to hibernate, usually mountain forest areas in Central Mexico.
Some Monarchs will fly over 2,000 miles for this journey.
Unfortunately, in recent years, Mexico has seen a decline in the number of butterflies that survive this migration.
What could be causing this decline in migration?
Mexican tradition attributes the butterflies’ migration to a more spiritual cause rather than scientific. Some Mexicans believe the Monarchs are the souls of the dead coming back to Earth. This belief comes from the fact that the butterflies migrate in September and October, right around the Day of the Dead on October 31st.
El Rosario is home to one of the world’s biggest butterfly reserves. The reserve stretches 33,482 acres or 13,550-hectare. In a report by PBS, journalist Ross Veltona speaks with various individuals studying in the Monarch migration dilemma. According to Eduardo Rendon-Salinas, a spokesperson for the World Wildlife Fund, within the last decade or two, butterfly colonies have gone from occupying three hectares or 7.4 acres to 1.9 hectares or 4.5 acres. This is the lowest number of butterflies seen in the last 20 years and is close to a 60 percent decline from a year ago.
Scientists point out that Monarch butterflies as a population are not necessarily in danger but rather their migration patterns and paths. When they fly to Mexico from the north, something in the beginning of their journey is interfering.
Herbicides are one plausible theory. Crops like soybeans and corn are sprayed with herbicides to protect them from the elements and this process in turn destroys the butterflies food source, a plant known as milkweed.
Land development is also threatening milkweed’s ability to grow. When natural areas give way to buildings, milkweed has less places to grow and less resources to draw on.
Female butterflies lay an egg on this plant and once the caterpillar is born, it eats the leaf until it is ready to move. So not only are these plants important for consumption, they are the birthing grounds for females to leave their offspring.
Herbicides and the loss of milkweed aren’t the only problems butterflies have endured during their migrations. Nectar is another one of their main food sources and they consume it regularly on their trip south.
Extreme droughts cause a decline in nectar-producing plants thereby destroying a large portion of the butterflies’ main source of nutrition. This is one reason the country has also seen a decline in bees and other pollinating insects in the past few years.
Illegal logging is yet another threat to the Monarchs. The Oyamel or fir forest that the butterflies reside in has been severely degraded over the past few years and while efforts are being made to plant thousands of new trees, it may not be enough to make up for years of unrestrained logging.
Illegal tree-cutting destroyed about 3.7 acres (1.5 hectares) in 2010, fortunately a decrease of 97 percent from 2009. The peak was in 2005, when logging destroyed close to 1,140 acres (461 hectares) annually in the reserve.
Saving the Monarch migration
Scientists and citizens alike are concerned about the Monarchs and the danger to their population. Some children have begun planting milkweed gardens in hopes of providing the butterflies with more food.
Research about the genetics and body clocks of butterflies is being conducted in hopes of finding a clear explanation or cause of the odd migration patterns.
El Rosario locals have taken it upon themselves to do what they can to protect these magnificent creatures. Whether it’s making sure tourists don’t get too close or that illegal logging remains a thing of the past, people are determined to help these insects survive.