GoKawiilButterflies Are in Dramatic Decline Across North America. A Close Look at the Western Monarch Shows Why Pesticides, habitat loss and climate change have taken their toll on the beloved insects. But the experts working with them still find hope for their future Darren Orf Share Copy link Email SMS Facebook X Reddit LinkedIn Bluesky Print Add as preferred source
On a misty Friday morning in November, with dawn’s last warm hues clinging to the gloomy clouds above, the Pacific Grove Monarch Sanctuary is whisper quiet. Even the persistent roar of the ocean, only a few minutes’ walk from this small copse among single-family homes, is deadened by walls of eucalyptus and Monterey cypress. The tires of approaching cars crunch on a gravel road that slips between two buildings, each adorned with murals of the brilliant monarch butterfly.
In one of those cars is Natalie Johnston, the interpretive programs manager at the Pacific Grove Museum of Natural History. With a pair of binoculars and a clipboard in hand, Johnston, along with a small cadre of volunteers, is canvassing this two-acre sanctuary in search of monarchs.
Every year, the monarch butterfly makes one of the animal kingdom’s most wondrous migrations as millions flutter across the United States to warmer climates. In the east, their destination is the cozy comfort of central Mexico’s oyamel fir forests, but the much smaller western monarch population—mostly separated from its eastern counterparts by the Rocky Mountains—instead makes its way to Pacific Grove and hundreds of similar sites along the California coast.
Because monarchs require the sun’s warmth to fly, cool mornings like this one provide the perfect opportunity to count them before they begin stirring. Peering into the canopy, the volunteers categorize the insects by their behavior, counting “sunners,” “grounders,” “loners” and even a “flier” or two. On her clipboard, Johnston notes the individual trees containing butterflies. Today, a few “loners” are scattered throughout the grove, and only one small collection of 72 is nestled together. The day’s final count: 99.
In the past few years, Johnston has experienced some emotional highs during these weekly counts, as in 2021, when a single tree hosted thousands of monarchs among its broad branches. But nothing prepared her for what she witnessed one Friday morning in early 2024.
“‘Oh my God, there are so many grounders,’” Johnston remembers saying after spotting some 200 dead or dying monarchs on private property near the grove. “We started counting—one, two, three, four, five—but they’re in these dense piles … spasming, their abdomens curled. … For so many of them to be wiped out in a single event in a place that was supposed to be safe was just horrible.”
Johnston describes that day as one of the worst experiences of her life. Over the next two weeks, staff and volunteers continued to see dying monarchs with the same symptoms, though in smaller numbers. A toxicology report published a year later revealed a cocktail of pesticides in the dead insects’ bodies, including some toxins typically found in residential sprays.
This mass casualty is just one highly visible event among many invertebrate dramas that play out every day. Monarchs, as well as hundreds of other butterfly species across the U.S., are struggling to survive against toxic pesticides, habitat loss and a rapidly changing planet. Eastern monarchs face a 56 to 74 percent chance of extinction by 2080, according to the U.S. Fish and Wildlife Service. And western monarchs, during that same period, have a 99 percent chance of vanishing.
Quick fact: A spot of hope While western monarch counts recently revealed low numbers, the eastern monarch population had some good news in 2026. The amount of habitat occupied by overwintering eastern monarchs increased by 64 percent compared with last year.
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