Monarchs are the only butterfly known to make an annual two-way migration, and it can be awesome.
I remember going to my parents' home at Possum Kingdom Lake (northwest of Fort Worth, Texas) during the migration one year and seeing them in the pecans. It looked like leaves on the trees until something disturbed them and suddenly there was a huge cloud of butterflies everywhere you could look.
October usually brings several of the iconic butterflies to my yard, but this year I only saw two.
Okay. So what?
Well, this area of Texas is typically part of the annual migration route and the monarch population has plummeted. When you consider only two the entire month compared to six or more a day, it seemed to be evidence of how bad things have gotten.
Numbers Declined Drastically
The monarch population has decreased approximately 90% in the last 20 years.
Although there are people who count every egg in certain parts of the breeding grounds, this is a fraction of the equation. Since they all migrate to the same fir forests in Mexico for the winter, that is where the official population numbers are derived. No one is counting each insect; that would be very difficult since they cluster by the thousands in the trees. Instead, their population is estimated by the amount of acreage they cover.
From a peak in 1996 of an estimated 910 million over 44.5 acres, they were at an all-time low of only 34 million over 1.65 acres in December of 2013.
|Graphic by Journey North.|
Experts say that the health of the monarch population is an indicator of our overall ecological health as well as the health of all pollinators.
"According to a recent White House report, pollinators such as monarchs contribute more than 24 billion dollars to the US economy, by promoting fruits and vegetables as well as agricultural crops like alfalfa. Pollinators also keep forests healthy by pollinating many species of trees." (vtdigger.org)
The US Fish and Wildlife Service (FWS) has even changed their land management because of the monarchs. According to AnnaMarie Krmpotich, Monarch coordinator for the FWS Midwest Region, "by helping save this one monarch butterfly, we could help save hundreds of other species". That list includes a dozen species of butterflies, including the endangered Poweshiek skipperling and the threatened Dakota skipper. From there, it goes up the food chain to several species of grassland birds, deer, even humans. (sctimes.com Ann Wessel 9/4/15)
|Clark Gardens October 2014|
Causes of Decline
The decline now marks a statistical long-term trend, and can no longer be seen as a combination of yearly or seasonal events. And the smaller population leads to trouble recovering from such events.
Weather extremes, especially drought and excessive heat in the breeding grounds and cold spring temperatures that delayed migration north, are definitely factors. And this year’s strong El Nino could cause problems if it brings its typical drought to the fir forests where the monarchs spend their winter.
Illegal logging of the oyamel fir forests in their overwintering grounds means less area for them. And numerous sites have been replaced with housing developments. Concentration of the entire population in even smaller areas makes them more vulnerable to a single storm, drought or fire.
Large-scale use of systemic insecticides, such as neonicotinoids, within the breeding range kills pests and beneficial insects, such as bees and butterflies. And there are always natural enemies such as disease, predators and parasites.
But experts agree that the main culprit is the wholesale killing of milkweed.
Although there are many plants the butterflies can use for nectar, common milkweed is the key to their survival. It is the only plant on which the eggs are laid, the only plant the larvae eat, and the source of the chemical that makes them bitter to predators – their defense mechanism.
The development of genetically modified herbicide-resistant corn and soybean has led to more crops being sprayed with total herbicides (think RoundupTM) to kill other plants, such as the milkweed. In 2013, 83% of all corn and 93% of soybeans in the United States were herbicide tolerant. That’s nearly 155 million acres.
|Taken at Butterfly Island in Clark Gardens|
What Is Being Done
In 2014, the Center for Biological Diversity and Center for Food Safety, the Xerces Society, and monarch scientist Lincoln Brower filed a petition with the US FWS seeking endangered species protection for monarch butterflies. Although they do not technically qualify for this protection yet, they are considered threatened.
The FWS has plans to promote wildflowers that are nectar plants (such as goldenrod and aster) along pipelines and electricity lines. And they are working with the National Wildlife Federation to grow milkweed along the main migration routes. The aim is to restore more than 200,000 acres of habitat through the spring breeding grounds of Texas and Oklahoma, and the summer breeding areas in the corn belt.
Also in 2014, The Natural Resources Defense Council petitioned the Environmental Protection Agency to review its rules regarding glyphosate use, the type of herbicide in question.
Monsanto, the makers of RoundupTM, are also getting involved. Per their website, they are collaborating with non-profits, universities, researchers and others to find ways to improve and protect the monarch habitats across North America. (Monsanto monarch page)
There was even a proposal by some groups that biotech companies could engineer a glyphosate-resistant milkweed variety. But personally, I prefer less engineering and more natural methods of conservation.
Hope and What You Can Do
Gail Manning, an entomologist at Fort Worth Botanic Gardens told The Fort Worth Star Telegram, “The numbers I’m seeing are definitely down this year”, confirming what I saw in my own yard.
But the numbers were up slightly in Mexico in December of 2014. And Chip Taylor, founder and director of Monarch Watch at the University of Kansas, said this is shaping up to be the best fall migration since 2011.
So why the lower numbers here?
That is probably due to unusually warm weather here. Folks watching the migration on the far western side of the typical route may have also noted lower numbers as the monarchs had to avoid hurricane Patricia. So the path narrowed a little this year.
That narrower path is probably the reason friends still in the Possum Kingdom area said they saw thousands of monarchs this year. One commented that they even had to pull over to the side of the road to avoid hitting them at one point because of the number of butterflies.
I hope that sighting is due not only to the narrower path, but also to an increase in population again this year. I will be watching for the numbers to come out of Mexico, hopefully confirming that.
Even if population numbers are up some, it’s still a far cry from their peak, and they’re still threatened.
But you can help.
- Avoid using insecticides and herbicides.
- Support conservation efforts for all pollinators either in your local area or through national organizations.
- Become a citizen scientist and contribute to research efforts to track the monarch population in both breeding and overwintering ranges. (For more information on this, visit xerces.org ).
- Check with local botanical gardens for educational and conservation programs through them.
- And of course, plant native milkweed. There are several varieties, including some that are more easily contained. A local botanic gardens or nursery that specializes in native plants can help you choose an appropriate variety for your yard in your area.
Small things make a difference.
Other resources will be added to a separate page on the blog soon.
|At first I thought there were only 2 butterflies in this picture. Look again and you'll see 3.|
Do you have stories about the monarch migration? I'd love to hear them. Or feel free to add comments about conservation efforts.