Poweshiek Paradise Lost
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Opposite page: A Poweshiek Skipperling. July 3, 2006. Puchyan Prairie SNA, Green Lake Co., WI. Left: Butterfly milkweed Asclepias( tuberosa) is one of many beautiful flowers found on Midwestern prairies. July 20, 2008. Stinson Prairie SP, Kossuth Co., IA. Frank Olsen in upland prairie, but that upland prairie is number of sites and number of individuals), typically adjacent to lowland prairie and even the Poweshiek, with its distinctive whirring wetlands. However, Poweshieks also occur in flight, is still my favorite, the memory of lowland prairie that has no upland prairie in 245 individuals (seemingly one or more on the habitat patch. every coneflower) in a single part of this same Many mysteries remain. Is the Michigan prairie still fresh in my mind from June 30, habitat (wetlands) an outlier, or just what’s left 1989. there of a more continuous occupation of wet to dry prairie seen farther west? Poweshieks Mike Reese The quintessential tallgrass prairie skipper, Poweshiek Skipperling inhabits the full range appear disinclined to disperse far, suggesting of prairie vegetation types from lowland that caterpillar rearing areas would not be (wet) to upland (dry). It is often found far away from areas used by adults. So do near wetlands Poweshieks and in rolling successfully topography, “Poweshiek Skipperling has experienced breed in both and is possibly tremendous decline in the last two upland and Poweshiek Paradise Lost more restricted centuries, and this continues up to today.” lowland, as the to moister smattering of egg prairie types at and caterpillar by Ann Swengel the western edge of its range. At the eastern plant observations suggest? Then is the extreme of its range, this skipper is known benefit of “up-low” (my term for the presence from sedgy meadows and fen wetlands in of both upland and lowland grassland of any Michigan. The main adult flight period type in a habitat patch) about varying success On a pleasantly warm and sunny day subspecies) were nectaring on coneflowers is typically in late June to mid-July, with of this breeding in up vs. low among years of with a remarkably light breeze, my husband too. Hundreds of Regal Fritillaries, both winter passed as a partially grown caterpillar. major climatic differences (hot vs. cool and Scott and I walked the slopes of Hole-in-the- males and females, chased about in their Documentations of egg-laying sites and wet vs. dry years)? What are the limiting Mountain Prairie in southwestern Minnesota. characteristic frenzy. Although the date caterpillar foodplants are relatively few: factors on its curious and narrow range? What Of the dozen Ottoe Skippers, one male (July 16, 1990) was very late in the flight of wetland species like spike-rush (Michigan) makes it possible for this species to attain departed its pale purple coneflower to chase Poweshiek Skipperling, over a dozen nectared and sedges (Dakotas), as well as dominant amazing densities, and therefore dramatic a lone female Dakota Skipper straggling at on coneflowers and lobelias and fluttered low prairie grasses: Indian grass in the wild and fluctuations in abundance? There is much yet the end of that species’ flight period. Several through the grasses, flashing black above and big bluestem in the lab (Iowa) and prairie to learn, but will we be able to? dozen Arogos Skippers (the midwestern ‘Iowa’ silver-gray below. Although the easiest of the dropseed and little bluestem (Wisconsin). By Poweshiek Skipperling has experienced mid-summer prairie skippers to find (both in far the highest densities of this species occur tremendous decline in the last two centuries, 16 American Butterflies,Winter 2008 17 and this continues up to today. Of course, the difference in landscape but instead only due vast destruction of tallgrass prairie (99% or to a difference in volume of data — decades more in most states) for agricultural use was and centuries of voluminous observation and catastrophic for prairie skippers. Numerous compilation. Since our European colleagues threats such as plowing, prolonged heavy have embraced their devastating conservation grazing, frequent mowings, quarrying, failures, they have been able to change course suburban sprawl, and so on beset prairie and help their particular butterflies and sites habitat in the unpreserved landscape. But obtain better outcomes. Their relentless in the last half century, thousands of acres candor has also given us the opportunity to of never-tilled prairie with wonderful flora learn from their experiences. supporting large Poweshiek populations In the spirit of this British precedent, I’d have been protected. Many tracts amount to like to examine the numerous factors that help hundreds or even a thousand acres or more, explain what makes Poweshiek populations and are managed for their natural value. Yet tick, although it’s unclear we’ll ever decipher stunning Poweshiek declines have continued it all. But we do know a lot about what on these preserves for many years, or even associates with bigger, stronger populations decades, after the habitat was protected, and and conversely with smaller, more localized, these dramatic declines continue up to the and declining populations. While Poweshiek present. Since extirpation (extinction of a inhabits the full range of prairie vegetation population) is hard to prove, I won’t use that (degraded, semi-degraded, and undegraded term about Poweshiek here; instead I call a types of never-tilled prairie), its abundance is population “subdetectable” when it goes from markedly higher in undegraded vegetation at reliably findable to only erratic hit and miss topographically diverse sites that support both records, if found at all. wet and dry grassland. Both subtle swales and This phenomenon is not new. Several rolling hills accomplish this. Large sites (75 decades ago, Jeremy Thomas reported that or more acres) tend to have higher Poweshiek conservation actions to manage for more densities but this pattern is not as strong. caterpillar foodplant led directly to the The factor affecting Poweshiek extinction of the Large Blue subspecies abundance that humans have the most control endemic to England. This butterfly had over, especially in preserves, is land use an obligatory relationship to a particular (management). After all, we can’t easily ant species that required a relatively change the topography of a site from uniform sparse vegetative structure. When the ant to having “up-low” in a way that benefits disappeared, and it did so even when the Poweshieks. Patch size is likewise hard to vegetation had only subtly altered, so did improve, since prairie plantings in previously the butterfly. Subsequently, Martin Warren’s tilled fields are unlikely to be used much landmark analysis in the early 1990s by Poweshieks. Management to improve documented losses of vulnerable butterfly vegetative quality (i.e., reduce non-native populations just as great on protected as on weeds) has, in my observation, rarely reduced unprotected land in central southern England. these weeds substantially for the long term, Frank Olsen (3) These British results have been dismissed and perversely, they may increase instead. as consequences of the highly altered and Even more rarely have I seen the methods Stinson Prairie still harbors many beautiful wildflowers, but sadly Poweshiek Skipperlings have fragmented “semi-natural” habitats on this used to improve vegetative quality tolerated not been seen here in the recent past. island long and densely populated by people, well by localized butterflies present at the site in contrast to our “natural” prairies not all at the outset. We can’t even predict annual Top: An area of Stinson Prairie filled with leadplants Amorpha( canescens). that many years removed from when they fluctuations in abundance (tell me now what Bottom left: Wild onion (Allium stellatum). existed undespoiled. But in actuality, these the next season’s weather will be like), much Bottom right: Plains tickseed (Coreopsis tinctoria). British outcomes are apparently not due to a less change Poweshiek responses to weather. 18 American Butterflies,Winter 2008 19 Frank Olsen (4) 20 American Butterflies,Winter 2008 21 had not previously been used in the area, is visited were preserves managed with fire on a usually started. While effects of these changes rotation of about 3-6 years. may occur quickly, it could take years, even “Idling” (doing virtually nothing for many decades, for the full impact on butterflies from years) has consistently associated with the these changes in management to become fully highest Poweshiek numbers. Furthermore, apparent, especially if this new management Poweshiek abundance also correlated is applied only to a portion of the habitat positively with increasing years since any patch per year. He also noted, in the context management action of any type. To the of Dakota Skipper, that concentration areas extent an area shows signs of brush or weeds for immature stages need to be protected from increasing, Poweshieks fared better when this fire, and the locations of these concentration is addressed in very localized treatments such areas can vary among years within a site. as mowing, brush-cutting, or spot-herbiciding About a decade later, Tim Orwig and only the problem plants. Rotational mowing Dennis Schlicht wrote that prairie-obligate (leaving the clippings lie) or haying (removing skippers are staggered in the timing of their the clippings) in a single cutting of only part life stages, so that no “safe” time exists when a of the site in a given year, especially in late fire can avoid incinerating immature skippers. summer or early fall, also came out on top for Likewise, any management action (burning, Poweshiek, and was well favored by Dakota mowing, haying, or grazing) can interfere and Arogos Skippers and Regal Fritillary with the availability of resources (possibly as well. Areas hayed annually fared more quite limited in location within a site) required poorly for Poweshiek, and heavy grazing at that time by the skippers, possibly in an was also poor.