Imagine a state of laws where murder is illegal if the victim is clad in a blue shirt, but legal if the victim is not wearing blue. A system where robbery is illegal if the victim has white skin but legal if the victim has dark skin. Such a system would be an outrage in human society. But this is the system of laws we have created for others.
Other species, that is. For hundreds of years we have had treaties protecting migratory birds who traverse countries, but no similar protections for non-feathered fliers who also cross borders, such as butterflies. Butterflies are not protected under any treaty, and consequently their populations are in danger. Unlike birds, butterflies are a member of the class Insecta, along with bees and other pollinators.
When a German study reported last year a more than 75 percent insect decline in protected areas over 27 years, the news was particularly disturbing because insects are prodigious pollinators. Perhaps even more concerning, scientists have determined that the Sixth Mass Extinction is underway.
On the American continent, we have the sad declining numbers of the beautiful monarch butterfly (Danaus plexippus). Striking in appearance, these orange-and-black-winged beauties are also a biological phenomenon: their migration covers a journey of 3,000 miles, three countries and multiple generations, from their winter home in Mexico to as far north as Canada . . . and then another 3,000 miles on the return trip. A recent article in Science analyzes their plight and the complexity of threats against survival. A population declining for decades, it is threatened by habitat loss, pesticides, extreme weather, disease, and much variation in migratory success. Reproduction along the migratory route is particularly vulnerable as monarch caterpillars rely on milkweed for survival, and it has diminished.
In March this year counts by Mexican officials revealed a population decline for the second consecutive year. Only nine colonies were found, reduced from 13 last year. A declining population since 1994 has now made their migration an endangered biological phenomenon according to scientists.
A longitudinal study conducted over 38 years and recently published in Global Change Biology, has traced the birthplace of monarch butterflies in North America by examining chemical compositions of wing tissue samples. Focused exclusively on the generation of monarchs born in North America that continue their migration to overwinter in Mexico, it established regional climate as the greatest predictor of change in natal origin. Monarch caterpillars rely on milkweed, and the most important implication of this study is that planting milkweed hosts solely in the Midwest is not sufficient. Climate change forces the butterflies to breed in other regions.
Thus, to sustain monarch populations, abundant milkweed is needed not only in the Midwest but throughout the United States. In fact, the U.S. Geological Survey has concluded that as many as 1.8 billion additional milkweed stems are needed to return these butterflies to a sustainable population.
Unfortunately, despite these needs, international law promises little aid for the monarch. The Convention on Migratory Species (CMS), backed by the U.N. Environment Program, aims to “conserve terrestrial, aquatic and avian migratory species throughout their range.” While the monarch butterfly has been added to the list of species for conservation, neither the U.S. nor Mexico nor Canada is a party to the convention.
In 2007, the Commission for Environmental Cooperation held a conference in Morelia, Mexico, leading to the creation of the North American Monarch Conservation Plan (NAMCP), which proposes multilateral action between Mexico, Canada, and the U.S. The NAMCP is certainly a step in the right direction, outlining objectives for butterfly conservation, yet it does not have the ability to wield the power of enforcement mechanisms in a treaty, nor does it set forth specific mechanisms or measures to achieve its ends. The need for an enforceable treaty thus remains.
There is also the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), entered into force on July 1, 1973. It is designed to “ensure that international trade in specimens of wild animals and plants does not threaten their survival.” The United States, Mexico, and Canada are all parties. Monarch butterflies are not currently listed under CITES for protection. As CITES regulates trade, and monarch butterflies are generally not hunted in quantity, it is unlikely that CITES could ever help monarchs.