Mardon Skipper

A skipper found in Western Washington, Western Oregon, and Northwestern California.

WSU Vancouver

June 10, 2022

Geography

Range Map

Mardon skipper (Polites mardon) is a rare skipper found in the Southern Puget Sound, the Eastern Cascades in Washington, the Cascades in Southern Oregon, and some areas in Northern California.

Study Area

Several sites were evaluated in Washington and Oregon. There are four known populations that are isolated from one another.

Natural History

Species interactions

Host Plant

Mardon skipper host plants include various native bunchgrasses and sedges.

Host Species

Species that are known to be hosts for the caterpillars are California oatgrass (Danthonia californica), Idaho fescue (Festuca idahoensis), and red fescue (Festuca rubra), pictured here.

Closeup of reddish tan red fescue seedheads.

Nectar Plants

These skippers are generalists, feeding on a variety of flowers for nectar, including early blue violet (Viola adunca) and common vetch (Vicia sativa) has been observed.

Habitat

Mardon skippers are open meadow and grassland obligates. They are found at both low and moderate altitudes.

Open meadow against a blue sky in the Klamath Mountains. — Mardon skipper and habitat

Population Dynamics

Although Mardon skipper is found in two isolated populations, this butterfly is thought to show metapopulation dynamics over time.
Males are more sedentary than the females, as they perch to wait for females and mate.
Some studied sites, such as prairie in the south Puget Sound, are seeing disappearances of Mardon skipper from previously occupied sites.

Life Cycle

Adult

Mardon skippers are univoltine, but have produced two generations in captivity. Flight period is generally from May to July.

Eggs

Females lay their eggs singly into the base of the bunchgrass host species.

Caterpillars

Caterpillars feed on Fescue grasses for about three months after hatching from their eggs.

Chrysalis

Caterpillars form a nest and then produce a chrysalis at the base of the host plant bunches, and they spend the winter in this nest.

Conservation

Listing Status

The Mardon skipper was listed as a candidate species in 2000 under the Endangered Species Act. It was removed in 2012 as a candidate species; however, this skipper is state-listed as endangered in Washington.

Nature Serve listing is "imperiled" for Washington state with no status in Oregon and California.

Status for listing continues to be reviewed by the USFWS.

Recovery Efforts

There are various recovery efforts for Mardon skipper, and many strategies are similar as for other butterflies.

Livestock management, wildfire prevention, logging and vegetation management, and invasive species removal are some of the tactics used by managers.

Population Trends

We analyzed data from five sites 2014-2020. Most sites had no trends across this short time period. Sites were variable through time (see example), which is typical of insects.