The simplicity of a butterfly in flight is something all of us have witnessed at one time or another. Watching this delicate insect flutter by is a sure sign of summer, and most of us take for granted that there will always be butterflies. However, if you key in on one specific species of butterfly, the monarch, it may be harder and harder to find one to watch.
What’s going on?
First, let’s take a quick look at the biology of a monarch. It’s a little different than all other butterflies. There are 2 definite populations of monarchs- western monarchs and eastern monarchs.
- Western monarchs (located west of the Rockies) travel as far north as Canada, and then overwinter in southwest California on eucalyptus trees.
- Eastern monarchs (located east of the Rockies) migrate about 3,000 miles to overwinter in Mexico. How do they do this when it looks like they can hardly make it across town with their erratic flight? When it comes time to migrate, they glide long distances using the air currents just like hawks and eagles that soar. In fact, one monarch was tagged and the very next day found 284 miles away!
Is it the same monarch that travels back and forth to Mexico?
No, and that is the baffling part about monarchs. Let’s start in Mexico. Here, they gather in large numbers from December to March where they roost in oyamel fir trees (also known as the sacred fir) for the winter. As spring approaches, these monarchs will start on their journey north to northern Mexico or the southern United States. Along the way, they will mate. The female will lay her eggs and then die.
These eggs will hatch and about one month later become a butterfly (1st generation) that flies further north and east where it will mate and start the process over again. (They usually reach northwest Ohio sometime in July.) This will happen about four times over the course of the summer until the last, or 4th generation butterfly, hatches in September or early October. These are the butterflies that will make the incredible journey back to Mexico.
How do they know where they are going if they have never been there?
That is a question that still mystifies scientists. Here is one theory:
Some scientific research has been done to suggest that the monarch uses the earth’s magnetic fields and the sun as a guide to send them in a general southwesterly direction. Then, the monarchs reach the Rocky Mountains, which are nearly impassible for this tiny insect. This funnels them down towards Mexico. How they are able to gather into very large numbers at very specific sites in Mexico is still and will most likely always be a mystery. Mother nature is fascinating, isn’t it?
The location of where monarchs roosted in Mexico was not discovered until 1975. This fascinating discovery was chronicled in an August 1976 National Geographic magazine. Scientists started counting monarchs in Mexico in the winter of ’94-’95.
So if the monarchs have been doing this for centuries, why are they declining in numbers now?
In regards to the cause of the monarch butterfly population decline, we can not just point to one reason. The decline is in fact several factors that each play a huge influence. Here are the top factors:
- Loss in milkweed plants
- Deforestation in Mexico
- Severe weather
Loss in Milkweed Plants
Your first instinct might be to say, “Well, it’s the herbicides!” Yes, this is true but it is not the only cause.
Milkweed grows in grasslands and disturbed areas. Grasslands have declined dramatically in the 20th century. However, the monarch was still thriving until the 21st century because plenty of milkweed was still found in our rural areas and agricultural fields. Then, in the 80’s and 90’s our small farm fields became larger and larger, as our need for more food and better farming technology increased. Many of the fence rows and odd areas where we would find milkweed started to disappear. Then round-up ready crops were introduced and milkweed has slowly been eliminated from our corn and soybean fields as well.
However, there are several other causes for the lack of milkweed. More land is being converted to establishment areas, cause what used to be primary pollinator habitats to disappear. The mowing and spraying of these pollinator habitats is also occurring along roads and ditches. If managed properly, these areas could be a great source of pollinator habitat for not only monarchs, but for other important pollinators as well.
MoarchWatch.org stated in the article “Bring Back the Monarchs,”
“We are losing 6,000 acres of potential monarch/pollinator habitat a day in the United Stated due to development (2.2 million acres per year). The losses of habitat due the adoption of glyphosate tolerant corn and soybeans in the last 10 years amount to at least 100 million acres. The conversion of 7 million acres of Conservation Reserve Program (CRP) land to crops for the production of biofuels adds to the total. In all, we estimate the loss of habitat to be 147 million acres since Monarch Watch was started in 1992– an area 4 times the state of Illinois.”
Deforestation in Mexico
As you can tell by the chart at the beginning of this post, monarchs roost in two areas- southern California and further south in Mexico. If the monarchs are overwintering in California, they roost in eucalyptus trees. If they are overwintering in Mexico, they will roost in oyamel fir trees (“Migration of the Monarch Butterfly,” Monarch-Butterfly.com).
The oyamel fir forests are very restricted throughout Mexico. They only grow at high altitudes of 7,800 to 12,000 feet. According to Journey North, The oyamel forest is the most endangered type of forest in Mexico which only 2% of the original forest remaining.
The reason for this decline in oyamel fir trees in Mexico is largely due to deforestation. This deforestation is a result of the illegal harvesting of trees for making furniture and building houses. In 1986, the Mexican government sectioned off an area of about 140,000 acres of the oyamel fir tree forest and declared it as a protected reserve, called the Monarch Biosphere Reserve. However, illegal logging in this area still occurs. In 2015, nearly 20 hectares (1 hectare= almost 2.5 acres) of habitat was lost.
According to DW.com, In March of 2016, extreme storms killed about 6.2 million butterflies, about 7.4% of the estimated population of butterflies that wintered in Mexico that year (about 84 million butterflies). This extreme weather continues to hurt the monarch populations while they overwinter in Mexico, destroying the habitat as well as taking out large number of the population in itself.
What is being done?
At the local level- The Seneca Conservation District is educating teachers, children, and Seneca County residents about the decline in monarchs and the loss of milkweed. Watch our website for information on upcoming educational programs, the milkweed pod collection, or other posts related to monarchs!
At the federal level- In 2015, the White House came out with a plan to help not only monarchs but all pollinators. Since then, many federal programs have been put in place to help the monarchs. Numerous organizations have offered grants to establish pollinator plots. The Ohio Pollinator Habitat Initiative has also been doing an annual Annual Milkweed Pod Collection in September and October.
What can you do?
While we can’t prevent severe storms from occurring or stop the deforestation in Mexico, we can do something about the decline in milkweed!
Designate a part of your yard/field or around your house as a milkweed garden for the monarch! Many organizations, such as MonarchWatch.org, give out free milkweed seeds! Seeds can be bought online or in some gardening stores. You can even harvest your own milkweed seeds once the pods begin to dry up in the fall. In fact, you can sell the seeds, just make sure they are native to the region in which you live/are selling them. For more information about maintaining milkweed plants and selling seeds, click here..
Follow us on social media and our website for more information and updates about the monarch!
Educate others on the monarch butterfly! The easiest way to help the butterflies is to simply spread awareness. For more information about other butterflies in danger, check out this article- The Ultimate Guide to Butterflies & How to Prevent Their Decline.
For ideas on teaching kids about monarchs, check out our Pinterest board!
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