Efforts to support, monitor butterfly species grow throughout state

Biologist Doug Taron was giving a tour of Elgin's Bluff Spring Fen earlier this month when he spotted a black-winged butterfly with red-orange crescents and creamy white spots resting idly on a plant close to the trail.

He had reason to be excited.

It was a Baltimore checkerspot, a native to the fen that hadn't been seen there for 10 long years. Seeing it now capped years of efforts by Taron and his colleagues at the Chicago Academy of Sciences to reintroduce the species after its population within the natural area fell to zero in 2013.

The recent success is one story amid myriad efforts going on throughout Illinois to support and monitor different variations of butterflies as they face threats like habitat loss, climate change and pesticide use.

The Baltimore checkerspot is characteristic of fens - a type of wetland fed by mineral-rich ground or surface water - in the upper Midwest. While not officially threatened or endangered, the butterfly's populations are thought to be declining.

Taron, chief curator of the Chicago Academy of Sciences, said the species abruptly vanished in 2013, possibly because of a severe drought the year before that was followed by a fire.

Taron waited three years to confirm the butterfly was truly gone before beginning to work on reintroduction efforts. Ecologists collected female butterflies from other natural areas and set them up with sprigs of their corresponding caterpillar food plant.

Much as monarch caterpillars can eat only milkweed, most butterfly species have one to a handful of corresponding plants from which they can feed. For checkerspots, the one option is a plant called turtlehead, which similarly enjoys the wet, alkaline environment that fens provide.

While typical reintroduction would involve raising the caterpillars to adulthood, Taron and his team found difficulty keeping the checkerspot caterpillars alive over the winter. That's because the species is univoltine, meaning it has only one generation per year, and the caterpillars go into a state of suspended animation over the winter.

Keeping the caterpillars alive during that state was "the hardest part of the process," Taron said.

After years of failed attempts, the team decided to try something different. They began releasing the caterpillars in the summer rather than raising them through the year, trying different sites in the fen year to year.

It turns out letting the caterpillars face the fen alone worked. Taron, who also serves as president of Friends of Bluff Spring Fen, was touring a group of visitors June 9 when he first saw an adult checkerspot perched on a nearby leaf.

Taron was at the site that day because he helps manage the natural area. He also counts different butterfly species at the fen for an initiative sponsored by the Academy of Sciences called the Illinois Butterfly Monitoring Network.

The network comprises citizen scientists who collect quantitative data on butterfly populations through the state. Its goal is to provide information collected with a standardized protocol that allows land managers and researchers to identify long-term trends.

The network is similar to a fledgling partnership between The Nature Conservancy and the state Department of Natural Resources to count regal fritillary butterflies at the Nachusa Grassland natural area in Franklin Grove.

The species, which is listed as a state threatened species, has been on the decline for decades due to habitat loss: the orange and white butterfly is deeply dependent on the open prairie grasslands that Illinois has lost most of to agriculture and other land use and development. The fritillary's host plant is violet, meaning the butterflies exclusively lay their eggs on violet and their larvae exclusively eat violet. As they get older, their diet expands to more native plants like purple prairie clover, spider ward and even milkweed.

"These butterflies require this open grassland habitat that has plenty of that host plant for their larvae, but also has an abundance and diversity of flowering plants for the adults to use when they emerge during the summertime," said Elizabeth Bach, an ecosystem restoration scientist with The Nature Conservancy. "There's just less and less big-scale grassland habitat where it can thrive, and it needs a lot of space. It needs big, connected landscape."

The type of long-term, quantitative data The Nature Conservancy is working to collect on fritillaries is an important practice for all butterflies and insects, said natural area preservation specialist Angella Moorehouse. The numbers help naturalists evaluate the status of different species, such as whether a population may be threatened or not.

Moorehouse, who sits on the Illinois Nature Preserves Commission, added that the numbers provide a clue as to why species are declining outside of habitat loss - a question that researchers don't fully understand yet.

"The trend over several decades is that diversity has dropped. The number of species we count has continued to decline. We're talking protected habitats, we're talking nature preserves that are owned by IDNR and managed by IDNR. They look very similar to what they did, so it's not the habitat. It's not the lack of available resources," Moorehouse said. "Some of these sites are really big, 1000 or several 100 acres. These areas are enough to certainly sustain the butterflies, so there're other external impacts, perhaps climate change or pesticides in the environment. Lots of different things can be happening to cause that. We don't even know all the answers."

To further research and increase habitat for insects, awareness is key, Moorehouse added.

"We understand the vertebrate animals. We like cute, furry mammals and birds and whatnot. There's a lot of public support for those. There's increasing support for pollinators, but it's lagging behind," she said. "Trying to get people to spend the same kind of money on native pollinators versus birds is going to take a lot."

One way people can help is by using nature apps like iNaturalist, where naturalists, citizen scientists and biologists can log their photos of plants and animals. The mobile app helps people identify the different species that they log while creating data for scientists.

Moorehouse said she monitors iNaturalist and similar platforms regularly to find out if there have been any sightings of rare or declining insect species.

• Jenny Whidden is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.