North Dakota Nature Notes
The Dakota skipper is one of the rarest butterflies in North America.
The Dakota skipper is well-named. This small, stout-bodied butterfly is a powerful flyer that seemingly skips rapidly from flower to flower on the Dakota prairies where it can be seen during June and early July.
If you can find one – the Dakota skipper is also one of the rarest butterflies in North America. The Dakota skipper once ranged from northeast Illinois to southern Saskatchewan, but now is found most often only in western Minnesota, northeastern South Dakota and eastern North Dakota.
Mid-June to early July is a good time to look for a Dakota skipper – that is the brief flight period of the adult butterflies that can last up to three weeks (often less). They are tawny-orange to brown butterflies with a one-inch wingspan. Their flight is distinctive: fast wing beats that seem to blur, they move so quickly.
The Dakota skipper actually spends most of its life as a caterpillar. The larvae hatch from eggs in late July and feed at night on grass leaves until late summer or early fall when they become dormant. The caterpillars overwinter near the ground in shelters constructed of silk and debris usually at the bases of native bunch grasses. Come spring, they continue their development until pupating in June.
Then the adults emerge and begin their brief, busy life. This is when they feed and breed; if food resources are sufficient, a female Dakota skipper may lay up to 250 eggs to launch the next generation in July. Good nectar sources are critical. Dakota skippers will visit a wide variety of prairie flowers but are especially attracted to narrow-leafed purple coneflowers. Other good nectar sources include wood lilies, harebells and blanketflowers.
These are plants found in either moist bluestem prairies or dry, upland prairies with needlegrasses on ridges and hillsides. Dakota skippers are dependent upon these habitats; they are a prairie-obligate species. Locations with intact prairie are where to find them, and the Sheyenne Delta region in eastern North Dakota is a good place to look. The soils here are sandy, deposited in a delta formed thousands of years ago when the Sheyenne River flowed into Glacial Lake Agassiz. These sandy soils discouraged agriculture and large tracts of intact tallgrass prairie have survived in the region. During the Dust Bowl and Great Depression, the federal government purchased struggling farms in the Delta to create the Sheyenne National Grasslands, which is managed by the U.S. Forest Service.
The Nature Conservancy’s Brown Ranch is located along the southern edge of the Sheyenne National Grasslands, near Milnor, North Dakota. More than 20 species of butterflies occur on Brown Ranch and its 1,531 acres is a good destination for exploring their prairie habitat in June.