On this late June morning, a dozen wildlife experts and summer staff were standing in a parking lot near a small pond at the Ringgold Wildlife Area, butterfly nets in hand, awaiting instructions.
“When we catch one in a net, one of us will come to you and swap out your net so we can catch as many as we can in the 30 minutes,” Stephanie Shepherd, wildlife biologist with the Iowa Department of Natural Resources Wildlife Diversity Program, told the group. “We will hold them, then process them at the end of the survey.”
The “one” is regal fritillary butterflies, a species of special concern in Iowa, and the focus of this Iowa DNR-led survey over two summers that will provide a better understanding of the butterfly’s population. Regal fritillaries are only found where their host plants – bird’s foot violet and blue prairie violet – are present and often that’s on remnant prairies.
The survey occurs from middle June to middle July that corresponds with the butterfly’s life cycle. Adult males emerge in mid-June, two weeks before females. When females emerge, mating occurs immediately and the males die off. Females remain through July and August waiting for another growth spurt from the host plants, then they begin laying their eggs – thousands of eggs – but not on their host plant itself.
The eggs develop and hatch in the fall, then the larvae overwinter in leaf litter, emerging in the spring then search for the violets to begin feeding on its leaves.
Due to its low population and specialized habitat needs, regal fritillaries are a candidate for listing by the U.S. Fish and Wildlife Service; which may come at the end of the year. Because of this consideration, a number of states have been conducting studies on the butterfly – independent of each other.
“It is an iconic species for the state, associated with our prairies. We’re trying to get a sense of its status, then set up a landscape management plan,” Shepherd said.
The strategy is to stalk the butterfly rather than chase it, she said, as the crew began to spread out.
Three survey sites have been selected for today and each survey is timed to last for 30 minutes. Sites are separated by a few miles and have been surveyed many times since the butterflies emerged in mid-June. This is likely the final year of the survey.
“We will try to stay together as a group,” she said walking to the prairie. The regals began flying as soon as the staffers had crested the hill.
“Oh! There’s one! There’s one!” was heard as everyone’s pace quickened, nets at the ready. A whoop of success was heard coming from out of sight. Once netted, either Shepherd, or another staff, would hustle up and trade out the nets.
The butterflies were gently removed from the nets, placed in a glassine envelope, then into a plastic case in a small cooler. The coolness will calm and slow the butterfly and make it easier for staff to work them up. Each butterfly had its location and sex recorded, received a unique marking, and then was released.
The first effort netted 32 regals. This week netted another 27. So far in 2024, staff have caught, marked, data recorded and released more than 150 regal fritillaries.
Regal fritillaries share these southern Iowa grasslands with other vulnerable wildlife species – prairie chickens, barn owls, bobwhite quail, and northern prairie skinks. One outcome of the survey ideally would be a system for monitoring them into the future, providing a way to set up a methodology which doesn’t involve handling the butterflies and that might be expanded to the state level by citizen scientists, she said.
Icon of the prairie
Unlike the monarchs, regal fritillaries live here all year long and have only one lifecycle per year. Their survival as a species relies on the larvae surviving the winter and, in the spring, the small caterpillars finding their way to the violets.
These violets can occur in all types of prairies – tallgrass, shortgrass, remnant and reconstructed – but are most often found on unplowed remnant prairies. Thus regals are mostly found anywhere there’s a remnant prairie of decent size (at least 40 acres) with violets as part of the plant community. The violet seed is difficult to harvest and therefore it is expensive so it doesn’t get included in seed mixes for reconstructed prairies very often but when it is present, it appears the butterflies can use reconstructed prairies, too. The DNR’s Prairie Resource Center, at Brushy Creek, is working to include bird’s foot violet and/or blue prairie violet in certain seed mixes to help expand the habitat that can support Regal Fritillaries.