This blog post was submitted by Susan Olcott, District 1 Wildlife Diversity Biologist for the West Virginia Division of Natural Resources.
Where are the monarchs?
This is a question I’ve gotten over the last several years here in West Virginia. This once common backyard butterfly has declined significantly across its North American range, and few are seen taking nectar from flowers in backyard gardens or roadsides. Although 2017 has been a good year for the species, its numbers are still 90 percent below what they were 20 years ago. In fact, the population is so low that this species’ unique migration to and from central Mexico is imperiled.
Currently, the US Fish and Wildlife Service is performing a species status assessment to determine if listing the monarch under the Endangered Species Act (ESA) is warranted. Their decision is due in June 2019. What has caused these declines, and what can people do to help?
Monarchs face multiple threats
Loss of habitat in the central Mexico over-wintering sites
Monarchs over-winter in oyamel fir forest stands averaging 10,000 feet in elevation in central Mexico. Like West Virginia’s high elevation red spruce, these fir forests are relics from a cooler environment that predominated thousands of years ago. These large coniferous trees, with dense canopies, provide a thermal shelter to dormant monarchs clustered on the trunks and boughs, and protects them from extreme temperature and moisture.
Monarchs need cool temperatures so they can remain mostly dormant, living off fat they stored during their fall southward migration. They cannot, however, survive temperatures below freezing for more than a few hours, and the bulk of these large trees helps moderate temperatures so they can survive the months of cool, and sometimes freezing, temperatures. Fragmentation of the fir stands opens the canopy and erodes this buffering capacity, making monarchs more vulnerable to death from freezing. The trees also shelter the butterflies from rain and snow. A wet butterfly succumbs more quickly than a dry one.
This area has a long history of timber harvests and, until recent years, ineffective and unsustainable management practices. Although large scale harvests have ceased, illegal poaching of a few to several acres continues.
Climate change is also a concern. Will these fir forests that need cool temperatures to survive be able to persist where they are, or will areas further north or higher in elevation be needed?
Systemic insecticide use in North American core breeding areas
After they leave their Mexican over-wintering areas in February, monarchs mate and journey north into Texas and Oklahoma and beyond. This is their breeding season, when females seek out species of milkweeds (genus Asclepias) to lay eggs on. Milkweed is the only type of plant that monarch caterpillars can eat. They die if they eat anything else, and starve without milkweed.
Although United States farmers and backyard gardeners no longer use unselective and persistent organo-chloride pesticides like DDT, some pesticides formerly thought to be safe are proving to be dangerous to pollinators, including monarchs. A primary class of these chemicals is neonicotinoids. These are systemic insecticides, meaning they are absorbed into plant tissues and persist there, delivering a death blow to any insect that eats it. They are applied on seeds planted as granules, and again as liquids on the plant or soil around it.
Although monarchs aren’t eating vegetable crops, they do depend on nectar sunflower or alfalfa blooms produce, just as bees need the pollen that they distribute. Neonicotinoids are found in these substances.
Drift from poorly applied spray can also impact caterpillars in areas near crop fields or gardens. Neonicotinoids exposure can be fatal, or they can have sub-lethal effects such as lower reproduction (laying fewer eggs, shorter life spans), difficulty foraging and difficulty in navigation, all of which leads to fewer monarchs. Increasingly, researchers are also finding that these chemicals are impacting beneficial insects, such as predatory beetles like ladybugs, that consume pest species, and earthworms that maintain the health of soils.
Loss of milkweed in North American core breeding areas
The Midwest contains North America’s corn and soybean belt — America’s agricultural heartland. This area also contains much of the core monarch summer breeding area — the breadbasket of monarch production.
Until the mid-2000’s, corn and soybean farmers had to put up with milkweeds and other plants growing in their crop fields. These perceived weeds used nutrients meant for crops, and the milky latex sap produced by milkweeds fouled harvesting machines, leading to repairs and increased harvesting times.
In the late 1990’s many farmers started adopting herbicide resistant corn and soybean strains — plants that were immune to glyphosate (RoundUp®) herbicide — in order to produce larger yields and make maintenance and harvest easier and more cost effective. As a bonus, farmers could also plant their crops using no-till methods and decrease soil run-off into nearby streams and improve water quality. They believed this was a win-win situation for them and the environment.
What they, and really no one, didn’t realize was that monarchs actually preferred using milkweeds in agricultural fields. Milkweeds in corn and soybean fields averaged almost four times more monarch eggs than milkweeds in natural areas. Today, because of the almost total adoption of herbicide resistant corn and soybeans, the milkweed population in this core breeding area has declined roughly 64 percent, and because of the monarch’s preference for these plants, a resulting 88 percent decline in monarch numbers.
What is being done?
In Mexico, international conservation organizations have partnered with Mexican agencies and organizations to enforce logging bans and provide protection for the over-wintering sites. The area is now a United Nations Biosphere Reserve, which provides both conservation for the Oyamel fir stands (planting trees and maintenance of the stands) and opportunities for economic development for the local people.
Increasing pressure in the U.S. is being applied to improve the use of systemic insecticides including halting application to seeds. Consumers are increasingly insisting that nursery stock, vegetable seeds and other plants are neonicotinoid free. West Virginians can join this effort by refusing to purchase plants and seeds that aren’t neonicotinoid (neonic) free. If it isn’t labeled, then ask!
Because roughly 92 percent of the corn and soybeans now grown in the U.S. is herbicide resistant, in the short term at least, it is unlikely that agricultural producers will stop using these strains because of their benefits. However, the 16 or so states in the core spring and summer monarch breeding area have banded together to develop the Mid-American Monarch Conservation Strategy. Although West Virginia isn’t one of the Mid-America plan states, the state is participating in developing the plan due to its place within the monarch’s core breeding area.
Adoption of the Mid-America plan will be voluntary. Its primary goal is to stabilize and reverse monarch declines in the heartland to a point where the species is sustainable. Its key focus is and will be planting and maintaining milkweed and nectar plants for monarchs on both private and public lands by an army of partners, from farmers to corporate executives.
Numerous research papers, and on-the-ground observations by homeowners and citizen scientists, all demonstrate that if you plant milkweed, provide nectar and a pesticide free environment, monarchs will come and happily reproduce. The plan will also include strategies to engage and educate citizens at all levels, from backyard gardeners to ranchers and farmers who work thousands of acres.
The plan will be adaptive and will respond to new science and feedback from the monitoring of habitat creation and enhancement projects. And, best of all, the US Fish and Wildlife Service will consider it, and other monarch conservation plans, during the species status assessment. If enough committed and effective conservation is started or planned, they could defer listing the monarch under ESA. This means that everyone from farmers to landscapers to homeowners will be less burdened by daily activities on their land from regulations required by an endangered or threatened listing. Transparent and voluntary conservation will already be planned or in place, so uncertainty will be minimized.
In West Virginia, because we have a fraction of the corn and soybean production of the Midwest, we have healthy populations of milkweed, although probably less than the mid-1900’s when we had more family farms. However, we could certainly manage it better. Not only is it vital for monarchs, it is also a magnet for all pollinators, and a native group of plants that belong in the state. West Virginia, with the planned partnership of numerous stakeholders, has started the process to develop a monarch conservation plan. Strategies will be explored and focused over the coming months.
Monarchs are an iconic North American wildlife species. With commitment and an open mind, we can all participate in bringing it back to its former abundant glory.