The population of butterflies in the United States has declined significantly over the past two decades. Through its monitoring program, Colorado’s Butterfly Pavilion is looking for volunteers to help contribute to the research and conservation of the important pollinators. 

The Westminster-based invertebrate museum’s Colorado Butterfly Monitoring Network is entering its 13th year of having Coloradans collect vital information about the health of the state’s butterfly populations. 

“Butterflies are essential to our ecosystems,” said Shiran Hershcovich, the Butterfly Pavilion’s lepidopterist. “The Colorado Butterfly Monitoring Network becomes such a big piece of this conservation puzzle because understanding our systems is that first step, so we can take science-informed action. Our time to course correct for protecting invertebrates is short, it’s quite urgent, so we want to make sure that every step we take is the right one and the most impactful.”

As the annual program kicks off, the Butterfly Pavilion is looking to expand its network beyond its historic participation to other parts of Colorado, including the Western Slope. 

“Right now, we have a good picture of the declines that are happening across the Colorado Front Range, but there are areas in our state where we have no real clue of what’s going on with butterfly populations,” Hershcovich said. “So, we are lacking critical data on even which butterflies are out there, which butterflies really need help and which butterflies need urgent restoration efforts.”

Butterflies on the decline 

The data collected by volunteers on hikes and walks through the program has been used to give glimpses and a bigger picture look at what is going on with the pollinators. Most recently, the data was among the citizen science programs that informed a scientific study of butterflies in the United States.

The study, published in March, found that the overall abundance of butterflies declined by 22% between 2000 and 2020, or by around 1.3% each year. It found that 107 butterfly species declined by more than 50% and 22 species declined by more than 90%.

“That’s quite a drastic decline,” said Hershcovich, who was one of the study’s co-authors. “Unless we really work to secure their future, those numbers are going to keep going down. It’s quite a dangerous time to be a butterfly.”

The overall decline matters because butterflies are “excellent ecosystem indicators,” Hershcovich said.

“As soon as the habitat is damaged or degraded, one of the first things that tends to respond to those changes is butterfly communities,” she added. “This is because, due to their ecology, they have such a close relationship to plants. They depend on very specific host plants to even be able to grow their next generation. So if those plants decline or disappear, so do those butterflies.”

As pollinators, butterflies also play a critical ecosystem role in helping plants reproduce. 

“Those plants, in turn, give us the food that we eat and even the air that we breathe,” Hershcovich said.

For this reason, looking at the conservation of butterflies means a lot more than protecting one species. 

“We are protecting an ecosystem, a complex home full of diversity, full of invertebrates,” Hershcovich said. “And those invertebrates, in turn, will feed the birds that we love to see, and the bears, and all of the other wildlife to have a complete, healthy home. And of course, we depend on these healthy systems as well. If they don’t survive, we don’t either.” 

The nationwide downward trend for butterfly species has been seen in Colorado as well, the result of what Hershcovich referred to as a “complicated cocktail of conditions.” 

“Butterflies are losing the habitat that they have depended on for countless generations,” she said. “Their former homes are now sprayed with deadly pesticides, and the plants that they rely on are suffering from herbicide use … And this is all happening against the backdrop of changing climates and more extreme climatic events.”

Expanding the network 

As the Butterfly Pavilion seeks to expand its monitoring program across Colorado, the goal is to one day have data from every county. 

The monitoring program started in 2013 with five volunteers. Now, the organization has trained over 200 volunteers from 13 Colorado counties. 

Volunteers are asked to select a favorite hike, route or neighborhood walk that they can walk for 30 minutes to an hour a minimum of three times between May to September, depending on weather and region. While walking, they report any butterflies they saw, habitat information and add the information to the Butterfly Pavilion’s database. 

“It really gets everybody to be an active participant in conservation and science, and it has ramifications that stem way beyond that,” Hershcovich said.

The individuals are trained and equipped by the organization to identify butterflies and report the right information. Right now, interested residents can sign up for a virtual training on the Butterfly Pavilion’s website through mid-June to join the 2025 monitoring network.