Ottoe skipper (Hesperia ottoe) COSEWIC assessment and status report: chapter 2

Ottoe Skipper
Hesperia Ottoe

Species information

The Ottoe Skipper is a member of the family Hesperiidae, the Skippers. Skippers differ from other butterflies by having a hook on the end of their clubbed antennae. They are members of the order Lepidoptera (Butterflies and Moths).

The adult Ottoe Skipper has a 29- to 35-mm wingspan. Males and females differ in coloration. Males are yellowish orange with a diffuse brownish border on the upper side of the wings and an elongated dark mark (called the brand) on the front wing. The underside is uniform, pale yellowish-orange. Females lack the brand and are dull brown with pale buff markings on the upper side of the front wings. The underside of the wings is pale orange and usually without spots.

The whitish eggs are hemispherical in shape and about 1.3 mm in diameter. The larvae are greenish brown with a dark brown head and a black prothorax (the first segment behind the head). Caterpillars attain a length of 20-25 mm when fully grown.

Distribution

The Ottoe Skipper occurs in isolated populations from southern Manitoba southward to Michigan and Texas and westward to Colorado. In Canada, the Ottoe Skipper was recorded from three localities in southern Manitoba.

Habitat

The Ottoe Skipper is an obligate resident of upland, dry, mixed-grass (bluestem) prairies and sand prairies. It does not occur in true tall-grass prairies.

Biology

Each life history stage of the Ottoe Skipper has its specific resource requirements. There is only one adult generation per year. Adults are active for only a six- to seven-week period, usually from mid- to late June to mid-August. Individual adults may live as long as three weeks.

Adult females usually mate within one or two days after emerging from the chrysalis. They begin laying eggs on the second or third day after emergence. Eggs are usually laid singly on the undersides of leaves of the caterpillar host plants or on the flowerheads of purple coneflowers. Ottoe Skipper caterpillars eat a variety of grass species, all of which are characteristic of their native prairie habitats.

Caterpillars go through six or seven stages, or instars, before forming a chrysalis. During the fourth instar, the larvae stop feeding (usually in late September) and enter an obligatory diapause (a form of hibernation). They pass the winter in this stage, resume feeding in spring, complete development during June or July, and form a chrysalis. Adults emerge two and a half weeks later.

Population sizes and trends

Since the 1950s, over 99% of the mixed-grass and sand-prairie habitat of the Ottoe Skipper in North America has been degraded or converted to agricultural uses.

In Canada, only a small proportion of prairie habitats remain. The distribution of the Ottoe Skipper in North America is fragmented. In Canada, this skipper has only been found in three places in southern Manitoba. The species has not been found at two of these locations since the 1920s. At the third site, the Ottoe Skipper was present in the 1980s but was not found in surveys conducted in 2002 and 2003. It is possible that the Ottoe Skipper no longer occurs in Canada.

Limiting factors and threats

The Ottoe Skipper lives only in mixed-grass and sand-prairie habitats. It is extremely susceptible to any disturbances, such as over-grazing, wild fires, inappropriate prescribed burning, row crop agriculture and mining, which alter the floral and structural components of its preferred habitat. Key adult and caterpillar food resources must be present in the habitat for the long-term survival of this insect.  Both the flower species preferred by adults for nectaring and the grass species preferred by the caterpillars for food are characteristic of native prairie habitats and rarely occur in agricultural habitats, making these habitats completely unsuitable for the Ottoe Skipper.

Special significance of the species

The Ottoe Skipper is one of a very small group of specialist butterflies that occur only in mixed-grass and sand-prairies in Canada. This species was last recorded at one site in Canada in the late 1980s.

Existing protection or other status designations

The Ottoe Skipper currently has no legal protection in Canada at the national level. However, it is listed as endangered under Manitoba’s Endangered Species Act. In the United States, the Ottoe Skipper receives no federal protection under the US Endangered Species Act. It is considered critically imperiled in two states, imperiled in eight states, vulnerable in one state, and is unranked in four states.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The Committee meets to consider status reports on candidate species.

Definitions (november 2004)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and it is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnotea
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)Footnoteb
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)Footnotec
A wildlife species for which there is inadequate information to make a direct, or indirect, assessment of its risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

Page details

Date modified: