Have you ever seen a Karner blue butterfly? You may have. It’s a species of endangered butterfly found in the Great Lakes states, and some eastern states. According to the US Fish and Wildlife Service, it’s most common in Wisconsin.
The male Karner blue butterfly is silvery blue, with narrow black margins. The female is grayish brown with orange crescents on its wings. The species of butterfly has been federally listed as an endangered species since 1992, due to loss of its natural habitat and a narrow food source.
Chelsea Weinzinger is the Karner Blue Butterfly Recovery Coordinator at the Wisconsin Department of Natural Resources. She says the local landscape is important to the existence of the species.
“One of the main contributing factors is their dependence on wild lupine. That is their only host plant, so that means when Karner are in their larvae stage, they can only eat wild lupine. In the Karner’s case, there is only one species of wild lupine, and that’s the only one that they can eat,” says Weinzinger.
She adds that another limiting factor is that lupine prefers to grow on sandy soils, such as savannah. They can also grow on prairies and along roadsides, but these habitats themselves are at high risk of being lost. And there are other factors, such as nectar resource availability, and climate, which threaten the butterfly.
According to the DNR’s abundance data, the population of the Karner blue butterfly may be improving. 2015 to 2017 marked the highest population estimates for the butterfly, with 2016 being a record year. Weinzinger says that these Karner blue butterfly populations appear to build up and hit a peak, then crash and start to build themselves up again, a cyclical trend observed at certain sites.
Weinzinger says monitoring and recovery efforts are crucial to the recovery of the species.
“Monitoring the species is an important way to work towards recovery. Another important thing the DNR is working on is habitat restoration. Working towards keeping those habitats, like barrens and savannas, we want to keep them open and prevent the canopy from closing completely in those areas.”
And the Wisconsin Department of Natural Resources is asking for your help with the Karner Blue Butterfly, including volunteering to survey the butterfly. Anyone interested in volunteering can find more information here. There is also a virtual field day on June 11th at 1pm. To sign up for that program, email Chelsea.Weinzinger@wisconsin.gov.