Mashomack Musings: Monarchs under threat

Though it is finally beginning to feeling like fall, a few monarchs still flutter by these days. 

The bright orange color makes the butterfly stand out. But birds and other predators know to avoid the unsavory beauty. The milkweed on which monarchs grow, hatch and feed — found in Mashomack’s meadows and throughout much of eastern and central North America — leaves the monarch tasting bitter.  

While more likely to be seen in summer, the monarchs and their fall migration are notable. In September, caterpillars here still munched on milkweed, emerged from their chrysalises and winged their way to the warm south to wait out the cold weather. The entire eastern population of this delicate insect, which constitutes 90% of the monarchs in North America, ends its journey in the oyamel fir forests on high-elevation mountaintops in central Mexico.

In spring, the over-wintering butterflies start back up the continent, laying their eggs. The next generation will continue north, with the pattern continuing until the third or fourth generation arrives back to us. 

Monarchs, once common, face many challenges, and have declined by more than 80% since 2000. Milkweed, the caterpillars’ only food source, is often found along the edges of roads and yards, areas many people consider messy and weedy, and “tidy up” with less beneficial plants. Swallow-wort, an invasive vine, will actually kill monarch caterpillars if eggs are laid on its leaves.

The use of pesticides can also harm the butterflies, which are highly sensitive to environmental degradation. Fewer feeding areas for both caterpillars and adults and fewer resting stops available during migration both stress the population.

Since the monarchs’ winter refuge in the mountains of Mexico is limited in range, illegal logging, storms or other natural disasters have the potential to severely impact the species. Likewise, the warming climate may bring to breeding areas more dangerous droughts and severe storms.

The charismatic monarch can be considered a “canary in the coal mine” for pollinators. Other, less noticeable pollinators are also declining. That, in turn, can impact the human food supply.

Those of us on Shelter Island are lucky enough to see this butterfly fairly often. But the monarchs’ decline is so severe that the U.S. Fish & Wildlife Service is considering placing them on the endangered species list, meaning they are at serious risk of extinction.

So keep your eyes open as the last vestiges of summer flutter by and consider how you might take action.

Mashomack is owned and operated by The Nature Conservancy, a global environmental nonprofit working to create a world where people and nature thrive. Our mission is to conserve the lands and waters on which all life depends. To learn more, visit nature.org.