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FALL 2006

Vol. 07, No. 1


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Monarchs at Mirror Pool

Monarchs at Mirror

Pool


Our hunt begins at Mirror Pool, which is in the northeast corner of the Sheyenne National Grasslands. Although only a short hour's drive west and south of Fargo, it is a landscape unlike anything in the Red River valley. The cloudless mid-August day is rapidly warming, turning this native, eastern deciduous forest humid.

In the stillness of the pond, the reflected sky and trees explain the name "Mirror," one of a series of snaking, riverine oxbow pools, which are formed in old channels when a river changes course. A wooden sign to the east announces that this is the H. R. Morgan Nature Preserve and Interpretive Trail, in honor of a conservationist, a leader, and a sportsman, ND Game and Fish Commissioner 1948-1957.

Another smaller, bullet-ridden one commands, "No motor vehicles beyond this point -- ND GandF."

Not knowing where to start, we follow the trail into a stately stand of basswood and elm trees, our progress punctuated by alternating patches of shade and sunlight, coolness then heat when the mid-day sun manages to break through the natural arbor. The wild plums growing along the path are not quite ripe, the skin a yellowish red and the flesh inside still a little too firm and tart. At every step it seems that a leopard frog jumps ahead or off the trail. So far in our quest, we have seen hawks, deer, ducklings, turtles, a stunning yellow-headed finch, and two blue herons. Dragonflies, grasshoppers, and numerous cabbage butterflies buzz, jump, and flitter around us. Besides the basswood and elm there are the oaks of the sandhills and stands of alder and aspen within this mature forest.

Along the banks of the Sheyenne, which the trail follows, are native species of fern, the highest concentration of this plant in the state. In all, five rare state animals and seventeen rare plants have been recorded in or near H. R. Morgan Preserve and Mirror Pool. One of the five rare animals is the Northern Prairie Skink, a type of smooth-skinned lizard, and the other four are species of butterfly: the Dakota Skipper, the Mulberry Wing, the Broad-winged Skipper, and the Dion Skipper.

But, it is too late in the season for a glimpse of any of these except perhaps the Dion Skipper, which flies in July and occasionally into August, according to Butterflies of North Dakota, the seminal text for lepidopterists in the state. No, our pursuit is for something just a bit more mundane -- a Black or Eastern Tiger Swallowtail.

Even this will be a stretch, advises Gerald Fauske of the North Dakota State University entomology department. A swallowtail butterfly this late in the summer would be part of a second generation, a production dependent upon the conditions, and this has been an abysmal field season, Fauske reports. The numbers and variety of species of butterflies are down, most likely for a variety of reasons. The dry spring and drought conditions throughout much of the state have contributed to a severe lack of flowering plants, the food that butterflies need. And though drought is most likely the biggest factor, insecticide use and climate change may play a role also.

In an attempt to improve butterfly habitat, Fauske recently contributed to an NDSU Extension Service publication "Butterfly Gardening in North Dakota," which details ways in which communities and backyard gardeners can maintain nectar sources for butterflies and host food plants for caterpillars. The idea is to grow a variety of annuals and perennials that will bloom throughout the season. For example, in his own yard Fauske has zinnias and petunias along with yellow and white cosmos, potentilla, and a flowering pear and dogwood tree. Even so, this year he's viewed only common Cabbage butterflies in his garden.

"The Cabbage is a European import. It is kind of like the house sparrow for bird watchers," he says. "I haven't had a year like this ... it's unusual. I haven't even had a Monarch [in the backyard], though I have seen them while out biking."

An avid cyclist, Fauske broke his arm on the third of June in a collision with a rollerblader, an accident that sidelined him for most of the summer. "I wasn't in the field as I should have been. It kept me in the lab, and it's only in the last few weeks [late August and early September] that I've been able to get out. It still hurts to swing a sweep net.

"I was at Mirror Pool last week, and of all the times I've been there, it was the least productive collecting trip. That particular spot has been overrun by exotic vegetation, broom grass and wormwood, non-native species that displace the vegetation that native species feed on, the native species of flower."

There's also the impact of spurge and cattle grazing. Because of competing interests in the management of the grasslands, the Forest Service, Fauske explains, has little choice but to follow a least viable population strategy. In practice this means trying to do whatever they can to satisfy everybody. Biologically, everything is maintained at its lowest level. It is a necessary strategy, but one that has potentially dangerous consequences to plant and animal species.

Given the poor conditions for lepidopterology, we get lucky in our quest. We leave the H. R. Morgan Trail and return along the steaming Sheyenne River back to Mirror Pool. Flying around us in the waist-high slough grass are yellow butterflies with black spots, Clouded Sulphers, a common species that ranges statewide in North Dakota. Next, we locate a Least Skipper; weaving and bobbing among the oxbow pools, the little, copper-colored butterfly is specific to this riverine habitat.

And finally, some Monarchs appear. Already beginning their southward migration to the central mountains of Michoacan, Mexico, their spectacular black and orange markings are strikingly contrasted by the purple of the vervain they feed upon. One large male Monarch, identifiable by his narrower black veins and brighter color, leads us west along the rutted, two-track dirt road in the direction of our vehicle, and we follow along at a jog as he tumbles and glides from one stand of flowers to the next.

--Shadd Piehl


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