Are We Watching the End of the Monarch Butterfly?
Citizen scientists recently gathered in a coastal Northern California town to count the butterfly during its winter migration. The results were alarming.
By Mary Ellen Hannibal
Ms. Hannibal writes about science and the environment from San Francisco.
Jan. 25, 2019
For almost 30 years, hundreds of volunteers have helped document monarch butterfly numbers at more than 200 sites across California, from Mendocino to San Diego. A small group of these citizen scientists recently descended on the sleepy coastal town of Bolinas, near Stinson Beach, north of San Francisco, to conduct the latest tally in a place where thousands of these butterflies were once counted during their winter migration.
The group was met by Mia Monroe, a ranger for the National Park Service for 40 years. She was representing the Xerces Society, a nonprofit devoted to invertebrate conservation.
“We aren’t expecting many butterflies today,” Ms. Monroe warned. Monarch numbers have been plummeting for decades, and recent surveys of their breeding habitats had reported low numbers. Making matters worse, only weeks before, wildfires had swept through the region, engulfing the Bay Area with smoke for two weeks.
“Maybe the monarchs have taken a different route, around the fire and smoke?” someone asked. “That’s a dream,” Ms. Monroe said. “But we are here to honor the survivors, and to be together in a difficult moment.”
Directing us to move with stealth into a lot overgrown with poison oak vines and blackberry brambles, she pointed to a ring of eucalyptus trees. The morning had begun cold but the temperature had inched past 54 degrees, when monarchs begin to emerge from their slumber. The brown and green branches of one tree were stirring, as if a slight breeze was ruffling the dun-colored leaves. But then a distinctive orange color revealed itself. Butterflies peeled off from the branches, each one opening like a warm kiss before fluttering into the air.
Increasingly, people without formal backgrounds in science are collaborating with scientists to collect data on a scale that scientists alone would be unable to compile. The work of these people in recording the exact time, place and conditions of their butterfly observations is vital to monitoring the health of monarch populations. Tracking these butterflies is one of the longest-standing examples of this kind of teamwork.
Over the period of a year, monarchs produce four to five generations. The last and longest-lasting of them is born between August and October. Unlike their predecessors, which live as butterflies for a mere two to four weeks, these monarchs survive for six to eight months. After staying put over the winter in Mexico or California, they disperse in March or April, spreading far and wide in search of milkweed upon which to lay their eggs. Larvae then morph into caterpillars that become the next generation of butterflies. The final generation in this yearlong cycle will return to the same California coast as their ancestors did. How these butterflies find their place of origin remains a mystery.
Last year’s count in Bolinas had been very low; still, the trees had been festooned with scores of butterfly clumps, in which hundreds of monarchs hung together for warmth and protection. This time, there was just one clump. Later we would learn that the total count of this site in Bolinas, which the previous year tallied 12,360 butterflies, plummeted this winter to just 1,256 monarchs. “This animal story that has been going on for centuries and perhaps thousands of years is disappearing and may be gone” soon, Ms. Monroe told us, her eyes tearing.
The total number of West Coast monarchs was estimated at approximately 4.5 million in the 1980s. In the latest count, that number fell to 28,429, dipping below the number scientists estimate is needed to keep the population going. This drastic decline indicates the migration is collapsing. The United States Fish and Wildlife Service is expected to announce in June whether its scientists think the monarch qualifies for protection under the Endangered Species Act.
We love butterflies but tally them in transactional and utilitarian terms. We say that losing so many is dangerous because in their life stages from pupa to imago they provide food for creatures higher up the food chain. Fewer butterflies means fewer birds, and we need birds, in part, to help control other insects, like mosquitoes, that carry dangerous diseases. We acknowledge that the biotic world only works by way of the networks that connect each species in a web of life. We must take account of our role in the demise of this species, a consequence of habitat loss, climate change, and pesticides and herbicides, if only to help us understand how to rebuild the population.
We can still muster hope for these butterflies. We can rally against the chemicals we use to kill insects not only in big agricultural operations but also in local backyards. We can create more habitats by gardening with native plants. We can stay keenly attuned to development plans in our communities and insist that they include sustaining habitat for other living things. In partnership with their Ph.D. brethren, citizen scientists can measure efforts against results and amend strategies accordingly. We would not know the extent of the monarch decline without citizen science, and we will continue to need these volunteers if we hope to make a difference for butterflies and other species in trouble.
We ended our day in the yard of one Bolinas resident who relishes the yearly return of monarchs to his tall trees. He was happy to share the love. He explained how mowing his grass at specific times of the year supported the growth of native grasses and flowers, food sources for the overwintering butterflies. “This is a spiritual place,” he told us, “so I have to take care of it.” We sat down on his lawn to watch the sky around us fluttering with wings. The orange cloud shifted this way and that in the sunlight, the very soul of nature, still present.
Mary Ellen Hannibal is the author of “Citizen Scientist: Searching for Heroes and Hope in an Age of Extinction.”
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