Signs are good that the western monarch butterfly is again flourishing in the Golden State after fluttering near the brink of extinction. The Xerces Society for Invertebrate Conservation has announced that its most recent yearly monarch count registered more than 330,000 of the distinctive orange-and-black beauties in California—a massive increase since 2020, when just 2,000 were tallied.
To be exact, the 26th annual Western Monarch Count—conducted over Thanksgiving 2022 with the help of 250 volunteers—logged 335,479 of the butterflies, the Xerces Society said in a press press release Tuesday. These counts are conducted in late November because that’s when the migratory metamorphic creatures reach their overwintering peak along California’s coast after a long journey from central Mexico.
Isis Howard, an Endangered Species Conservation Biologist with Xerces, who helps manage the count, believes that this year’s numbers are a sign of continued growth toward returning to the millions of monarchs that once overwintered in California.
“Two years of increasing Thanksgiving counts is definitely exciting and hopeful—it means that we have more time to act to help support this western migration,” she told LAMag. “But we definitely have a long way to go to reach population recovery.”
The monarchs, which can travel up to 4,000 miles as they cross through Mexico and into the U.S. and were declared endangered last summer, saw a decrease of 22 to 72 percent in their population over the past decade, the International Union for Conservation of Nature reported. Habitat destruction, the use of pesticides and herbicides, and climate change have all contributed to their decline.
Aside from the Thanksgiving count, there is usually a followup study conducted on New Year’s Eve for a better grasp on the population’s numbers, but those totals tend to be lower. “We typically see a 30 to 50 percent decline between the Thanksgiving and the New Year’s count… due to factors such as winter storm mortality, mortality from predation, and monarchs dispersing from their overwintering sites,” Howard said.
Howard warned that the results of the 2023 New Year’s count, due in February, could show a greater decrease than usual due to the series of atmospheric rivers that relentlessly pummeled California, making it difficult for volunteers to access monarch population sites.
“We do expect the mortality to be a bit greater this year,” Howard said, but clarified that it’ll really be dependent on how impacted the sites are. She noted that Pacific Grove near Monterey didn’t see as great of a decrease than previous years.
One might wonder how 250 volunteers can count over 330,000 of these tiny, airborne invertebrates. First, they’re recorded as they perch in clusters on branches, eerily resembling dead leaves, and not when they’re flapping through the air in the thousands.
Occasionally, Howard says, if they aren’t numbering in the hundreds, volunteers will literally count every monarch. For larger clusters, which can be in the tens of thousands, they’ll take them on, binoculars and clipboards in hand, section by section, estimating and comparing numbers. So long as volunteers aren’t off by a margin of 20, they’ll take the average.
“If they’re pretty off, we’ll ask volunteers to count again,” Howard says. Despite what would appear to be a large margin of error she that the group has “found it’s actually pretty accurate. In the old days, they would actually bring the monarchs down and individually count them,” she said. That practice is no longer allowed.
Most of the butterflies were found along California’s Central Coast near Santa Barbara and San Luis Obispo counties, where 130,000 were counted—25,710 of them were on a lucky landowner’s private property. The Bay Area, which has seen extremely low numbers in recent, years also saw a substantial increase with over 8,000 counted.
Through the years, habitat destruction has fueled the monarchs’ decline and the recent atmospheric rivers only fueled further losses. Returning to healthy populations will require restoring monarch habitats and focusing on specific sites where they are known to overwinter by replacing “dead and dying trees, landscape sites to prevent or mitigate flooding, and plant native nectar sources,” the release said.
“The plain fact is that if we lose overwintering sites in California, we could lose migratory western monarchs. Development, eucalyptus removal, and tree trimming all need to be managed thoughtfully if we are to leave space for these animals to survive.”
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