Since 2000, 20% of butterflies in the United States have disappeared

Butterflies are popular creatures that can inspire art and play an important ecological role, but you may have noticed that their days have been brighter in recent years. These precious insects are disappearing at an alarming rate, according to new research by SUNY Binghamton faculty.

One published in science Checking butterfly data in the United States has been disturbing. The study looked at 76,000 surveys and revealed a 22% decline in butterfly abundance between 2000 and 2020. It should be said that at the beginning of this century, there were only four butterflies in every five butterflies in the United States in 2020.

“This is the most comprehensive analysis of American butterflies and the size of such a large space,” said Eliza Grames, assistant professor of biological sciences at Binghamton University and co-author of this article.

Butterflies are the most widely monitored insect population in the United States, but most monitoring efforts include based on volunteer and expert scientific monitoring programs, which are restricted by geographical location and focus on individual species.

The new study, funded by the U.S. Geological Survey – using all available surveillance data – records over 12.6 million butterflies to clearly understand the status of butterfly species on the continental U.S.

The study considered changes in collection protocols and regions to produce comparable results for hundreds of species. Using the data integration method, the team looked at how butterfly abundance used enough data variations in regions and 342 species alone.

“Abundance” refers to the total number of individuals of butterfly species in a given area. During the two decades of examination, 33% of butterfly species showed a significant decline in abundance trend. Many people show extreme declines in abundance – 107 species have dropped by more than 50%.

The role of Grames in this national study is to generate range maps for all butterfly species that are invested in analysis. This allows the team to check whether the observations of species are good identification, should be entered into the model, or whether they need to be checked for data quality cleaning purposes. The team can also see that each of these species can be found in the United States and examine spatial patterns.

“We don’t have a map of where the butterflies are,” Grams said. “How do we know which records are good? One of them comes from Inaturalist, a civic science platform where anyone can upload pictures of species. But sometimes people go to Butterfly House and start recording all of these tropical species in Colorado, thus throwing away the data.”

Part of these conservation efforts involves involvement of college students in assessments to collect data and identify risks for a species. In the Grames Conservation Biology class, students are currently conducting IUCN evaluations for Western Captains, which include one of the most unstable species of butterflies, Captain Julia.

“Participating in this assessment allowed me to apply what I learned in class to the reality of things,” said Clara Zook, a Binghamton student.

“It is capable to know that our research can play a role in preserving the species,” Buchholz said.

In addition to the beautiful and inspiring art, butterflies play a crucial role in pollination, helping pollinate food and flowers and contributing to the health of ecosystems around the world, Grames said. This study could help drive important conservation efforts, such as prioritizing the protection of red dangerous and/or endangered species from the International Union for Conservation of Nature (IUCN).

“We have better data to say, ‘You know, we should really consider it in federal protection.’ So we can go in, protect their habitat and hopefully — they can bounce back.”

Collin Edwards, the lead author of the study, responded to these views. “For those who have not yet known about insect decline, this should be a wake-up call,” Edwards said. “We urgently need local and national-scale conservation efforts to support butterflies and other insects. We have never had a clear and compelling picture of butterflies falling as we do now.”

The second project is part of the same USGS group and is investigating the driving force for butterfly loss. A study in the Midwest pointed out that pesticides are the main driver, but there are different drivers in different regions of the United States, such as in the Southwest where people are worried about drought, while in the Northeast, it is more about climate.

Grames said highlighting what is happening with butterflies can help to have a clearer understanding of how the overall decline in insect populations are.

“Insects are decreasing at a rate of about 1-2% each year, which is proposed in several studies,” she said. “This is another study that found a super similar rate of decline, which is indeed gradually declining for the increasing number of insects.”