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Monarch Conservation

Research Projects

While the monarch butterfly is not endangered, the North American migration is considered an endangered biological phenomenon. The monarchs’ habitat and overwintering sites span the continent. Because of this, conservation efforts need to be addressed on a trinational level. (Canada, Mexico, as well as the U.S.)

During the breeding phase of the monarch annual life cycle, habitat loss and degradation are a conservation concern. Expanding suburbanization and other activities are leading to the loss of 2400 or more hectares of land per day in the United States, according to the American Farmland Trust. In agriculture, plant pests reduce yield, costing farmers. To eliminate insects like European corn borers, pesticides are applied. Unfortunately, these pesticides have non-target effects on monarchs that can be lethal. Another pesticide concern is the use of herbicide tolerant crops like soybeans, which allow herbicide applications after the crop has emerged. Increased use of these crops has reduced the amount of weeds, including milkweed, in agricultural fields. While the crops can withstand multiple herbicide applications, the milkweed cannot.

Mowing roadsides is another contributor of monarch habitat loss, reducing the number of plant species. It’s unfortunate that the monarch host plant has the word ‘weed’ in its name, as there are some cities and counties that consider it a noxious weed, and actively remove the plant.

Illegal logging in the overwintering sites of Mexico is also a concern. Removing trees from protected areas breaks up the forest, resulting in more edges, which make roosting monarchs more vulnerable to the elements. One study from Mexico published in 2006 used satellite imagery from 1986 to 2006 to determine the amount of forest that has been lost or disturbed. The analysis of the images concluded that 10,500 hectares of Monarch Butterfly Biosphere Reserve land have been affected, equivalent to one fifth of the total protected land.

An obstacle facing the preservation of the overwintering sites is that they are privately owned, even though they are federally protected. One way to encourage land owners to protect the trees the monarchs need is to pay them to relinquish their logging rights and/or for their conservation efforts. This approach allows the land owners to earn a living while at the same time protecting the monarchs.

For a detailed summary of monarch needs, threats to these needs, and actions that are being taken to address these threats, see the North American Monarch Conservation Plan. Development of this plan was supported by government agencies from Canada, Mexico and the US, as well as the trinational Commission on Environmental Cooperation. Its primary author is Karen Oberhauser.