Notes From the Naturalist: Where are the Monarchs?

It’s early October on the Rhode Island shoreline, and Seaside Goldenrod is blooming on the beach. Lovely stalks of golden yellow punctuate dune grass and the last of the remaining beach roses. Soft autumn breezes and light jackets reemerge following several months characterized by heat and humidity. Although it’s not summer anymore, the sun is warm, and the bright blue sky and sea are expansive. It’s a spectacular day, and yet something is missing – something profound and beautiful that has been a part of this picture for eons. The Monarch Butterfly.

Ten years ago at this time, a beachgoer standing near the sandy dunes might become dizzy watching the sheer amount of brightly colored orange butterflies dance by. Hundreds, perhaps thousands per hour. Bursts of orange confetti swirling like a sudden snow squall. The butterflies, like a river of fluttering wings, flow south through the mid-Atlantic states and then around the western arc of the Gulf of Mexico to a handful of mountains in central Mexico. Here, at their final destination, a kaleidoscope of Papilionoidea color and form settle in multitudes upon their winter roost.

Today, we still see an occasional butterfly here and there – sometimes in the air, sometimes alight stalks of Goldenrod. A mere trickle where there was once a river. What has happened to this amazing migration? Most studies point to habitat loss as the main factor for the decline, and with Monarchs, that means a huge loss of Milkweed plants. Monarchs lay their eggs on Milkweed leaves, and those same leaves are the only thing Monarch caterpillars eat. Fewer Milkweed plants equate to fewer butterflies. And because it takes three or more generations to complete the yearly travels from Mexico to our region and back, reproductive failure at any stage can lead to a population crash.

Several factors seem to be driving the loss of Milkweed in North America. One is the conversion of fallow land into cultivated fields. This has been driven – to a large extent, it seems – by the Federal ethanol mandate. Making fuel out of crops has produced powerful incentive for farmers to plant as much corn and soybean on their land as possible. Millions of acres of hedgerows and fallow land that once supported Milkweed and butterflies have been plowed and planted. Another factor is the widespread adoption of herbicide resistant crops. With traditional farming, Milkweed grows around the outside edges of row crops, sometimes even interspersing between the plants. However, with the wholesale application of herbicides, the Milkweed doesn’t stand a chance and, if changes aren’t soon made, neither will the butterflies.

Walking the autumn beaches is still a sublime experience, but it’s downright magical when the Monarchs migrate in healthy numbers. I hope you will join me for a beach walk this fall, as we look for Monarchs that are passing through, as well as other migrating animals. In the meantime, if you would like to help restore the great Monarch migration, please click here to find pointers on the U.S. Fish and Wildlife’s website.