The flash of a red admiral’s tangerine wings, the shadow of a black swallowtail, or the beautiful bright orange hue of monarch butterflies: Each year, a network of volunteers fan out across Colorado to see how many of these and other butterfly species they can find.
But last year, many had a sad experience: They saw far fewer or even zero butterflies in their usual flitting grounds.
“It can be tough,” said Shiran Hershkovich, an entomologist at the Butterfly Pavilion in Westminster, Colorado. Hershkovich manages the volunteer network and other conservation projects for the invertebrate-only zoo. “They will say, ‘A route that had butterflies before, I’m now seeing nothing.’”
Those observations played a role in a study published earlier this year in the journal Science that found butterfly populations on the decline across the country. Butterflies are sensitive to changes in climate and habitat and face a hard time at the moment. Erin O’Toole, a host and producer with High Country News partner KUNC, talked with Hershkovich about the butterfly observation network and what its findings can tell us.
This interview was produced by Brad Turner and Ariel Lavery and originally appeared on KUNC’s podcast In the NoCo; it appears here with edits for clarity and length.
Erin O’Toole: Let’s talk about this network of volunteers. You’ve trained about 300 people to be part of the network over the past 13 years. Some of them are seeing noticeable drops in their butterfly counts. I would have to think that seeing butterflies is a huge part of what makes this an enjoyable experience, so how hard is it to keep them engaged when counts are plummeting?
Shiran Hershkovich: I think one of the most rewarding things about working with butterflies is that they are not abstract animals hiding deep in the forest somewhere out there, far away from us. They’re in our backyards and our open spaces. So anybody can be a participant in working with butterflies and working in their conservation. We are lucky to have such dedicated community scientists working with us to answer these pressing questions about what is happening to butterflies now.
2024 was a tough year for butterfly monitoring. We saw drops in our counts, and it’s hard when you’re so geared up, ready to see butterflies out in your fields, and you’re not seeing the numbers you’re used to seeing. That can be disheartening, especially because it is a labor of love. Our volunteers are doing this out of true passion. But it is important to also remind our volunteers — and I tell them this all the time — zeros are valid data, and zeros are important. Those gaps, those voids that we see, are a call for action. This is a space that needs addressing. A zero is a starting point in our conversation to say butterflies need our help.
EO: Your group’s study found that butterflies are declining about 1% per year over the past two decades or so. Why do those numbers worry you?
SH: Well, 1% per year might sound low. But when we pull that together, that adds up to just over a 20% decline in our butterflies over the last 20 years. Now that starts getting really high, really scary, really alarming. Butterflies are critical animals to any space they are in. They are pollinators. As they visit one plant to another, they help those plants reproduce. Those plants, in turn, give us those little luxuries that we love to enjoy, like food and oxygen. Butterflies are absolutely essential in our spaces.
EO: What about butterflies makes them a useful gauge for the overall health of the ecosystem?
SH: In Colorado, butterflies have such a close relationship to plants around them. They’re so sensitive to temperature changes that they can be considered an indicator species to rapidly evaluate the health of a natural system around us. So when habitat is degraded or damaged, one of the first animals to respond really quickly to those changes are going to be butterflies and their fellow pollinators. So it’s really important to understand how butterfly communities are changing year after year.
EO: Butterfly populations are dropping across the US. Colorado’s numbers certainly echo that trend. What seems to be the biggest cause of declines in Colorado?
SH: It is such a melting pot of pressures right now. It’s not just extreme climate events and not just a rapidly changing climate. It’s not just widespread pesticide use, and it’s not just habitat loss and habitat change. It’s really the combination of them all that makes it a really tough time to be a bug out there.
EO: You mentioned climate change. Why is a warmer climate especially a problem for butterflies here in Colorado?
SH: We have butterflies that are adapted to such unique alpine systems. They need changes in temperature and daylight. They need cold nights to be able to time their cycles. They have developed these systems and timings for millennia, and now the rug is being pulled under them really rapidly. The seasonality of each year that they were used to is now changing around them. So butterflies might emerge earlier due to warmer temperatures and find that there’s no blooms quite ready for them out there to forage in. Monarchs, for example, or other migratory animals, might be hanging around longer because the cues that they need to start their migration might not be quite there — only to find that when they start their migration, they’re hit with a blizzard. So those changes in phenology are causing a mismatch in seasons that can be really stressful for our native animals.
EO: One of your favorite spots to see butterflies is in Rocky Mountain National Park. Where is it and what do you love about that spot?
SH: Well, in general, I love watching butterflies in the mountains. I just returned last weekend from the San Juan mountain range (in southwestern Colorado), and what I love about this is the explosion of life we get in the summer as alpine blooms start turning the ground all of these different colors. The ground basically turns yellow and purple with all of these explosions of blooms, and butterflies, of course, are so happy to see these changes. Butterfly season in the mountains is so dramatic, and so short, that the explosion of light that comes with it is fantastic. So we see the bumblebees and the butterflies, and we see all sorts of green and blue and red and yellow around us. So it feels like walking into a painting that is alive. There’s nothing like monitoring for butterflies in the mountains.
EO: Spotting butterflies sounds like such a great way to introduce children to science. How big of a role do kids play in your network of butterfly spotters?
SH: Children have such an inner sense of curiosity. They still have that inner scientist that we all kind of come ingrained with. We all start very curious, and curiosity is that muscle that we just need to keep on going and cultivating. So we love having families monitor with us. Children can be great spotters and great motivators in not just building that curiosity, but wanting to protect the world for generations to come.
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