Monarch Butterflies in the Bay Area
When one hears the word “pollinator,” an image of a bee usually pops into their head. Pollinators provide a niche service to ecosystems across the globe, helping plants reproduce the next generation and increasing genetic diversity. While bees are undoubtedly impactful actors in the process of plant reproduction and the dispersion of pollen grains, there are a countless number of other species that are not as recognized for their contribution to pollination sequences.
We see monarch butterflies fly throughout the UC Botanical Gardens and in the green crevices of campus life. Their vibrant orange and black wings grace students with their four-inch wingspan and benefit neighboring plant life as crucial pollinators in the Bay Area. This species of butterfly is one of the most recognizable in California, yet their population is well at-risk of extinction.
Monarchs are found in North and South America, splitting off into two separate populations: one west of the Rocky Mountains and the other just east of it. These butterflies are one of the very few migratory insects; their geographic location ranges from the high mountains of Mexico to southern Canada. These patterns rely heavily on where their peerless host grows: milkweed.
Monarch caterpillars only eat milkweed, which makes it difficult for them to acclimate to changing conditions in our environment. Both species evolved with one another. Milkweeds are toxic, making them indigestible to all but monarch butterflies, who have manifested themselves as poisonous as a result. This has functioned as evolutionary protection, and it displays the mere length of time both the monarchs and milkweed plants have collaborated in nature. This partnership is dwindling, however. Due to habitat loss in the Bay Area and throughout California, as well as destructive herbicides widely used to exterminate unwanted plants, milkweeds have been on a rapid decline over the past few decades. Since both species are so dependent on one another, monarch butterflies have been following their lead. Their downward trend can be traced back to the 1980s and continues to do so today. Considering the fact that all components in an environment fit together like puzzle pieces, other plants and animals like bees and insect-eating birds are predicted to be negatively affected as well.
Climate change has increased average global temperatures by roughly two degrees Fahrenheit since 1880, the dawn of the Second Industrial Revolution. It has caused more severe droughts, hurricanes, floods, and heat waves. Although this rapidly emerging threat is not the sole evil, more extreme weather occurrences have crippled monarchs’ ability to migrate. Since they relocate primarily to find regions where milkweeds flourish, their food source has grown less accessible. On top of that, higher atmospheric carbon levels have reduced the natural toxin levels in milkweed. Consequently, monarch caterpillars are slowly losing their form of defense to fight off parasites.
The California population has been fading away at an average of about 7% a year, according to a 2017 study by the U.S. Fish and Wildlife Service. After learning about the extremity of their decline, I realized how much less I’ve seen wild monarch butterflies in comparison to just a decade ago.
From the 1980s to 2010s, western Monarch butterfly populations have plummeted about 97% from their average historical count. So how much hope exactly is there for these brilliantly pigmented critters? According to Emma Pelton, a conservation biologist for the Xerces Society for Invertebrate Conservation, their halt in decline and fast reproduction rate provides a glimmer of hope.
There are certainly ways we can assist local monarch butterflies in the Bay Area and help revitalize their communities. First off, since herbicides have proved to be a lethal method to clear up home gardens, the avoidance of using such chemicals on milkweeds would allow more room for them to thrive and offer monarch butterflies the sustenance necessary to mature. We can make an effort to conserve already existing milkweeds as well as plant new seeds. An abundance of its host will improve the strength of butterfly populations, though it will take time to see subsequent nationwide results. As pollinators, monarchs act as an imperative element in a biosphere of complex interactions. In order to protect the stability of the natural realm in the Bay Area, we must do all we can to shield them from extinction.
