Ottoe skipper (Hesperia ottoe) COSEWIC assessment and status report: chapter 5

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Habitat requirements

In Canada, H. ottoe is (or was) an obligate resident of upland, dry, mixed-grass (bluestem) prairies and sand prairies. In the United States, this skipper occurs in similar types of prairies, often those with topographic relief (Dana 1991, Swengel and Swengel 1999, NatureServe 2003). Hesperia ottoe does not occur in true tall-grass prairie, and females were never observed ovipositing in mesic parts of mixed-grass prairies (Dana 1991).

In Spruce Woods Provincial Park, the sand and mixed-grass prairies occur as 1- to 20-ha openings among spruce (Picea sp.) and Bur Oak (Quercus macrocarpa) groves. The terrain in these areas is generally hilly and the prairies often occur on the hills (formerly sand dunes). Bunch grasses, such as Little Bluestem (Andropogon scoparius), are common on the higher ground, while Big Bluestem (A. gerardii) is more common in lower areas or at the bases of the prairie hills. Cactus (Opuntia sp.) and Wild Onion (Allium sp.) occur on some of the drier sites. Wild Bergamot (Monarda fistulosa) and Snowberry (Symphoricarpos albus) are common along the margins of the prairie openings.  Similar vegetation is present at the other mixed-grass/sand prairie sites near Aweme. Purple coneflower (Echinacea angustifolia) is rare at Aweme, but frequent in the small, remnant, mixed-grass prairies west of Shilo. This flower was not observed at Spruce Woods Provincial Park during 2003.

Trends

The historical distribution of H. ottoe in North America will never be precisely known as much of the mixed-grass prairie and sand prairie habitats had been severely degraded by overgrazing or converted to row crop agriculture before any surveys for this and other prairie insects were initiated.

In Manitoba, most mixed-grass prairie and sand prairie sites outside of Spruce Woods Provincial Park, including those at Aweme, have been degraded by overgrazing and invasion of exotic plants. Most prairie sites west of Shilo have been converted to row crops, such as potatoes, or are being mined for gravel. The remaining areas of relatively intact mixed-grass prairie are very small; it is doubtful they could support populations of H. ottoe.  Relatively undisturbed sand prairie habitats that could potentially support a population of H. ottoe still exist in Spruce Woods Provincial Park. However, this skipper, which was first reported from the park in the 1980s, was not found during a five-day survey of the park in 2003. It is possible that the skipper was missed because this survey may not have been conducted at the optimal time of year (Duncan, pers.com. 2005).

Protection/ownership

The single site where H. ottoe was last recorded is in Spruce Woods Provincial Park. The Aweme site is now protected in the Criddle/Vane Homestead Provincial Park managed by Manitoba Wildlife.