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Imagine walking through the woods and the forest steadily grows brighter. Suddenly you emerge into an opening – flooded with bright, warm sunlight, bathed in brilliant, knee-high whirls of green leaves and the bluish-purple flowers of wild lupine. The scene, now punctuated with bursts of orange butterfly weed, was once overshadowed by a dense cover of jack pine.
The beauty of nature is that this picturesque scene will once again grow back into a forest stand. But for a short time, ecologically speaking, it will be an equally beautiful barrens opening and home to the federally endangered Karner blue butterfly. In time, the emerging tree seedlings will mature and form a canopy, shading out the wild lupine. A nearby stand of timber may be harvested, opening the forest floor again and the wild lupine seeds waiting in the ground will once again flourish and bloom. The Karner blues move back in and again find a home.
The Karner blue butterfly (Lycaeides melissa samuelis Nabakov) lives in grassy and partly shaded areas on the dry, sandy soils of central and northwestern Wisconsin. About the size of a postage stamp, the Karner blue male is sky blue, while the female is darker blue and brown with bright orange spots along her outer wing edges. Both males and females look alike on the underside.
The Karner blues pass through winter as eggs and hatch in April. The butterflies have a larval (caterpillar) stage which feeds exclusively on wild lupine plant (Lupinus perennis).
In mid-to late May, the larvae turn into chrysalis, emerging as butterflies in early June. The adult butterflies feed on wildflowers through June, then lay eggs on the wild lupine in July. This second brood of the year will go through the same life cycle later that summer, except that their eggs will not hatch until the following April.
The diminutive Karner blue butterfly has fed on wildflowers in Wisconsin since the last Ice Age. At one time, Karner blue populations were found from Minnesota to New England. In modern times, the butterfly's populations have become increasingly rare in much of its national range, and it is increasingly vulnerable to extinction.
Karner blues are completely dependent on the wild lupine as their sole food source during their larval stage. Wild lupine grows in open sandy areas that can contain some trees. Lupine habitat becomes more rare as other vegetation grows and shades the stand. Sunny locations are also developed by people. Because of this habitat loss and decreasing butterfly populations, the U.S. Fish & Wildlife Service listed the Karner blue butterfly as an endangered species in December 1992. This listing began a program to recover Karner blues across their entire national range.
Interest in saving the little colorful flit brought together a diverse partnership of public and private groups who have developed a remarkable and flexible conservation plan. The plan helps Wisconsin landowners and land managers continue routine land uses in areas where Karners live while protecting the butterfly and still complying with the Endangered Species Act.
Landscapes change too slowly for people to see, day to day, but nature is a shifting mosaic. The mix of open spaces, ground cover, shrubs and trees grow slowly. If you could speed up time, you would see these shifting patches as the land naturally matures and human activities change the land.
Wild lupine is a "disturbance dependent" species that thrives as lands are opened, more sunlight reaches the forest floor and the soil is turned over. "Disturbances" like tree cutting, grazing animals and forest fires open the canopy. In modern times, more open habitats like pine barrens and oak savannas have become rare as wildfires were contained and wild herds of grazing bison and elk were heavily hunted. These natural ways of clearing the land were replaced by timber harvests, prescribed burning, and brushing and mowing of rights-of-way along roadsides and utility line corridors. These human actions can encourage the growth of wild lupine and other wildflowers, and such activities are important conservation strategies proposed in the Karner Blue Butterfly Habitat Conservation Plan (HCP).
The 26 partners in the HCP plan engage in a wide variety of land uses across diverse habitats on the nine million acres of Wisconsin that they manage. All have ideas for conserving and promoting butterfly habitat, whether they manage conservancies, commercially managed forests, utility and road corridors, and a variety of public forests, parks and natural areas to help sustain the rare butterfly.
The HCP aims to conserve wild lupine habitat in ways that are biologically sound and economical for landowners. The plan identifies ways to set back natural succession and provide the sunshine wild lupine needs to persist. This might be accomplished by changing the time of year when roadside rights-of-way are mowed or raising the mowing height when butterflies are in their egg stage. It can be accomplished by cutting timber or burning prairies in patterns that provide continuous shifting habitat, or by artificially planting suitable open areas with wild lupine.
Though the butterfly is tiny and its habitat occurs in small patches, the proposed statewide HCP for Karner blues is considered the largest conservation effort in the nation. Wisconsin is home to the largest remaining populations of Karner blues in the world, and the 26 HCP partners are committed to protect more than 265,000 acres that will conserve the Karner blue butterfly and meet the intent of the federal Endangered Species Act (ESA) – but it won't be managed in a traditional way.
HCPs are more typically designed to protect individual organisms of an endangered species on a particular tract of land. Though the insects are small, it's important to protect them on a larger scale. In my role as HCP project coordinator, I believe conserving endangered and threatened insects is not easy. You can't expect to protect individuals, so we aim to conserve butterfly populations. We think that the cooperation of our 26 partners on the large amount of land that they manage will adequately conserve the Karner blues. Smaller private landowners whose parcels contain butterfly habitat would be welcome to join the conservation effort, Lentz said. We will be evaluating if this practical approach works and we can sustain Karner blue butterflies on the larger land holdings."
Since the habitat needs to be disturbed periodically to maintain the open conditions, a hands-off approach would doom Karner blue habitat as natural succession would grow taller vegetation that would shade out lupine. The new HCP approach gives landowners more leeway to design conservation strategies that are effective on their land, continue land uses the owners select and are less costly to carry out.
By designing habitat plans with the Department of Natural Resources and groups like the Audubon Council, the Sierra Club, and the Wisconsin Woodland Owners Association, the HCP partners received a broader perspective of options. The landowners are still clearly in the driver's seat and assume responsibility for being good land stewards, but the self-designed management plans are better tailored to the property and are more likely to succeed than a plan developed by top-down, inflexible regulations.
The Wisconsin DNR and the Fish and Wildlife Service will closely monitor if enough people who own parcels that are critical to the butterfly's survival can be persuaded to take part in the program. It will test if a flexible system can still protect wild lupine, Karner blue habitat and butterfly populations into the future.
Time will tell if this model works for managing endangered and threatened insects. It has been 70 years or more since many of the jack pine timber stands were harvested on their natural rotations. For a short time after those harvests, Karner blue butterflies will flourish. As the forest matures and the lupine gradually ceases to bloom, the plan is to harvest contiguous tracts and patches of mixed age tree stands. Then the lupine seeds waiting in the ground will be released and butterflies will move onto fresh habitat.. The thoughtful strategies that public foresters and private landowners consider can help restore open pockets of green lupine, purple flowers, orange butterfly weed and the flitting Karner blue butterfly.
David Lentz coordinates the Karner Blue Butterfly Habitat Conservation Plan Project for DNR's Bureau of Endangered Resources in Madison.