GRASSLANDS

Traditional tallgrass prairie restoration efforts have focused primarily on planting and managing the dominant species of prairie vegetation. Meanwhile, little is known about techniques for restoring prairie insect species, many of which play important roles in pollination and seed dispersal. The regal fritillary (Speyeria idalia) is a prairie endemic butterfly that was once abundant in the Midwest, but now occurs in small, widely-separated populations. The regal and its host plants~bird’s-foot violet (Viola pedata) and prairie violet (V. pedatifida) in Iowa--are found almost exclusively in unplowed native prairie. We have initiated an experiment to restore the regal fritillary at the 5,000-acre Neal Smith National Wildlife Refuge (NWR), which is located just east of Des Moines. Here we report on previous research as well as our progress to date in restoring the regal fritillary. During 1995-1997, Liesl Kelly and I conducted research showing that most Iowa populations of regals are small (Debinski and Kelly, 1998), and that individual regal fritillaries in Iowa weigh less than regals found in neighboring states (Kelly and Debinski, 1998). We noted that states with higher-weight regal fritillaries had correspondingly larger violet populations, which led us to speculate that limited food supplies may be a factor in the decline and lower weight of regals in Iowa. Leslie Ries (1998) examined the question of rarity in regals by studying their behavior in relation to land use patterns. She found that regals have a low probability of leaving a prairie and that when they do leave a prairie, they typically return within a few minutes. She concluded that the regal may be constrained by such behavior from dispersing and recolonizing fragmented landscapes, such as those found in Iowa. Finally, as a result of my own observations and conversations with others (Wagner, personal communication), I have come to the conclusion that introducing individuals from captive-reared stock is not an option because laboratory rearing of this butterfly is extremely difficult. During 1998 we began an effort to restore the regal fritillary and its host plant at Neal Smith NWR. The Neal Smith NWR (formerly known as Walnut Creek National Wildlife Refuge) was established in 1991 as a prairie restoration project of the U.S. Fish and Wildlife Service (Drobney, 1994). Most of the property was in agricultural production prior to restoration, although there were some scattered prairie remnants that totaled less than a few hundred acres. We know that the regal fritillary was not present at the refuge prior to its establishment. In 1994, Erwin Klaas (Klaas and Bishop, 1995) conducted a survey of butterflies on the refuge. He found a total of 51 species, but no regals. We began our work at Neal Smith NWR by setting up experimental plots to test hypotheses regarding the use of fire and bison grazing to restore prairie violet. Specifically, we hypothesized that violets would grow faster and more vigorously in burned and grazed treatments. The violets are short in stature (5-6 inches), so one might expect burning or grazing to have a positive effect on the violets by decreasing competition with other taller plants. Consequently, caterpillars may have a higher survival on violet plots that have been burned or grazed. Testing the effects of buming becomes problematic, however, if the butterflies are introduced prior to burning because regal larvae overwinter as first instars in the leaf litter. As a result, we burned the treatment plots prior to the time that pregnant female butterflies were introduced and will not burn any violet plots once our introductions have been made. During 1998-1999, we planted 20 plots with 99 violets/plot. We established five plots in each of four areas, each undergoing a different restoration treatment: 1) burned, 2) grazed, 3) unburned in a dense restored planting, and 4) unburned in a sparse restored planting. Around each of the violet plots, we are planting 20 species of nectar plants, such as beebalm (Monarda fistulosa), butterfly milkweed (Asclepias tuberosa), and pale purple coneflower (Echinacea pallida) to provide additional nectar for the butterflies. Our goal is to introduce pregnant regal females to each of the experimental plots in cages so that they lay their eggs on the violet plots. In most butterfly species, males emerge prior to the females and wait for the females to emerge. Females are mated soon after emergence, so most females can be presumed to be mated a few days post-emergence. During the summer of 2000, we began introducing female regals to the refuge from Ringgold Wildlife Area in Ringgold County, Iowa. This area was within the 38-county ecotype zone that is specified by the refuge for species introductions, and it had a large population of butterflies that year. We netted the butterflies, stored them in a cooler during