Survey Protocol for the Mardon Skipper

(Polites mardon)

Version 1.1 – March 26, 2007

Photo by Tom Kogut, USFS

USDA Forest Service Region 6, Oregon and Washington

USDI Bureau of Land Management, Oregon and Washington

Authors

RUBY SEITZ is a wildlife biologist, US Forest Service, 57600 McKenzie Hwy, McKenzie Bridge OR, 97413

ANN POTTER is a wildlife biologist, Washington Dept. of Fish & Wildlife, 600 Capitol Way N, Olympia WA, 98501

KELLI VAN NORMAN is an inventory coordinator, US Bureau of Land Management, PO Box 2965, Portland OR, 97208

NORM BARRETT is a wildlife biologist, US Forest Service, 47201 Hwy 62, Prospect OR, 97536

MITCH WAINWRIGHT is a wildlife biologist, US Forest Service, 42218 NE Yale Bridge Rd, Amboy WA, 98601


Table of Contents

Introduction 3

Background 3

Aspects of Mardon Skipper Natural History Related to Survey Methodology 3

Mardon Skipper Description 3

Annual Cycle 4

Activity Pattern and Movement 4

Food Habits 5

Habitat Description 5

Survey Methods 6

Surveyor Qualifications and Training 7

Safety 8

Site Selection 8

Search Methods 8

Conducting an Estimate of Abundance Survey 10

Survey Conditions & Time of Day 10

Number of Annual Visits & Timing 11

Mardon skipper surveys at known sites and within 30 miles 11

Surveying in the Oregon Mardon Skipper Distribution Gap 13

Equipment 13

Data Management 14

Verification Process 15

Permits 16

References 17

Appendix A 19

Photographic Guide to Mardon Skipper and Similar Species 19

Appendix B 23

Butterfly Resources 23

Appendix C 25

Draft Mardon skipper adult habitat suitability model for southern Oregon 25

Appendix D 25

BLM GeoBOB Fauna Survey and Observation Form 25

Introduction

The objective of this Mardon skipper survey protocol is to present methods to:

1)  Conduct surveys to detect adult Mardon skipper presence in potential habitat with a reasonable level of confidence.

2)  Conduct surveys to estimate relative abundance of adult Mardon skipper at a site.

3)  Document survey effort and occupied sites covered during surveys.

These methods establish standards for consistently collecting and reporting field data. The survey protocol is adapted from a Mardon skipper survey methods document developed for Washington State by Ann Potter from the Washington Department of Fish and Wildlife (WDFW)(Potter et al. 2002). The methodology is based upon standardized butterfly survey methods (Pollard and Yates 1993). Significant additions have been made to the original Washington survey protocol. This document is intended for use by the Region 6 Forest Service (R6FS) and Oregon/Washington Bureau of Land Management (BLM). As we learn more about surveying for Mardon skipper, we expect this survey protocol to be updated. The survey methods provided here, alone, are not appropriate for monitoring effects of management or other actions and are not intended for such use.

A compilation of Mardon skipper biology, ecology, threats, management considerations, and research/inventory/monitoring opportunities will be available from the US Forest Service Region 6 and US Bureau of Land Management Oregon/Washington in 2007. In addition see the U.S. Fish and Wildlife Service Candidate Notice of Review (USDI 2005) and the Washington State Status Report for the Mardon Skipper (Potter et al. 1999) for further information.

Background

The Mardon skipper (Polites mardon W.H. Edwards) was designated a Federal Candidate Species under the Endangered Species Act (ESA) in 1999. It is a candidate species in the OR/WA BLM Special Status Species program and a sensitive species in the R6 FS Sensitive Species program. In Washington, it is listed as a state endangered species by the Washington Fish and Wildlife Commission (WAC 232-12-014). In addition, the Mardon skipper was petitioned for listing under the ESA by The Xerces Society and other environmental groups (Black et al. 2002).

Aspects of Mardon Skipper Natural History Related to Survey Methodology

Mardon Skipper Description

The Mardon skipper is a small (20-24 mm wingspread; <1 in), tawny-orange butterfly with a stout, hairy body (Potter et al. 1999). The upper surface of forewings and hindwings is tawny-orange with broad dark borders. The wings from below are light tan-orange with a distinctive hindwing discal band pattern of light-yellow to white rectangular spots. Females are larger than males and have a more distinct ventral hindwing pattern. Males have a small, slender and branched, dark brown marking (stigma) on the upper surface of the forewing.

Like most members of the Hesperiinae (grass-feeding skippers), adult Mardon skippers have a fast, skipping flight, often described as a stone skipping across water. Also like most Hesperiinae, they have bent antennae clubs and a characteristic basking posture in which the forewings are held at a 45-degree angle and the hindwings are fully spread (Potter et al.1999). Mardon skippers typically fly low, usually less than 1 meter from the ground.

The Mardon skipper is difficult to distinguish from many other Hesperiinae species. In the southern Washington Cascades portion of their range, potential Mardon skipper look-alikes that may be present during the Mardon skipper flight period include Juba skipper (Hesperia juba), western branded skipper (Hesperia colorado harpalus = Hesperia comma harpalus), Nevada skipper (Hesperia nevada), Sonora skipper (Polites sonora), woodland skipper (Ochlodes sylvanoides), and sachem (Atalopedes campestris). In the southern Oregon Cascades, all of the Washington look-alike species occur, as well as two additional hesperids that Mardon may be confused with: Columbian skipper (Hesperia columbia), and Lindsey’s skipper (Hesperia lindseyi). Each of these species has slightly different wing patterns; detailed identifying features for these skippers are found in standard field guides (e.g., Pyle 2002; Glassberg 2001). Taxa most closely resembling Mardon skipper are pictured in Appendix A.

Annual Cycle

Mardon skippers are univoltine, completing one life cycle annually. In the Cascade Mountain Range, adults typically emerge in June or July, and are present for two weeks to one month, with individuals living between five to ten days. Adults do not all emerge on the same date, so flight period duration at any given site varies depending on the number of skippers present. In large populations, the flight period may extend for over a month, while small populations may have adults present for only ten or fewer days. Emergence dates vary with elevation, generally occurring earlier at lower elevations. Weather influences emergence and flight period duration, with wet or cold conditions delaying emergence; conversely, warm, dry conditions promote earlier emergence, and both may affect flight period (Potter et al. 2002).

Eggs are laid on or near grasses and hatch after 6 or 7 days (Newcomber 1966), or 13 days (Dave Nunnallee pers. comm.). Larvae feed on grass for approximately 2-3 months (Newcomer 1966; Dave Nunnallee pers comm.). Mardon skippers pupate in a loose cocoon in the grass; it is believed that they over winter as pupae (Newcomer 1966, Dornfeld 1980), though summer and fall larval surveys at one site on the Gifford Pinchot National Forest indicate that Mardon skippers likely over-winter there as 3rd or 4th instar larvae (Beyer and Black 2007).

Activity Pattern and Movement

The Mardon skipper is thought to spend its entire life cycle in one location: it does not migrate. Individuals may move to nearby grasslands or water sources, but preliminary results from an Oregon mark-recapture study found that most Mardon skippers appeared to show little movement from their natal meadows (Runquist 2004). Males have been found “puddling” (a method for obtaining fluids and minerals) some distance from females (Ann Potter, personal communication); Runquist (2004) observed males approximately 1 mile downhill from their natal site.

As described in the Mardon skipper description, the flight pattern of skippers is a diagnostic fast, skipping flight. Mardon skippers tend to fly less than 1 meter above the ground among the grasses, except during courtship or territorial displays.

Food Habits

Adults feed on flower nectar from a variety of sources. Primary nectar plants documented include: early blue violet (Viola adunca), common vetch, (Vicia sativa), and other Vicia species, sego lily (Calochortus spp.) wallflower (Erysimum capitatum), penstemon (Penstemon spp.), common camas (Camassia quamash), fine-leaved desert parsley (Lomatium utriculatum), and spreading phlox (Phlox diffusa) (Newcomer 1966; Pyle 1989; Hays et al. 2000; Haggard 2003; Potter and Fleckenstein 2001). A nectar plant selection study for one Puget Sound population compared use versus availability and found that Mardon skippers avoided Scot’s broom (Cytisus scoparius), shepard’s cress (Teesdalia nudicualis), slender sandwort (Arenaria stricta) and small-flowering lotus (Lotus micranthus), and in separate years, preferred Viola adunca or Vicia sativa (Hays et al. 2000). Beyer and Black (2007) observed nectaring in their two Washington sites mainly on vetch (Vicia species ), strawberry (Fragaria virginiana), clover (Trifolium longipes), wandering fleabane (Erigeron peregrinus), and yarrow (Achillea millefolium) and at their two Oregon sites mainly on cinquefoil (Potentilla diversifolia), narrow-leaved mule’s-ears (Wyethia angustifolia), small-flowered penstemon (Penstemon procerus), rosy plectritis (Plectritis congesta), and vetch (Vicia species).

Most butterfly larvae have specific requirements for food plants. Mardon skipper larvae have generally been thought to feed on Festuca bunchgrasses (Newcomer 1966; Dornfeld 1980; Pyle 2002; Potter and Fleckenstein 2001). In Washington, Mardon skipper oviposition in the wild has been observed on Roemer’s fescue (Festuca roemeri), Idaho fescue (Festuca idahoensis), and red fescue (Festuca rubra) (Ann Potter pers comm). Oviposition on Festuca bunchgrass has been documented on a coastal California site (Runquist 2004a). In addition to Festuca, recent work by Beyer and Black (2007) has confirmed Mardon skipper oviposition on California oatgrass (Danthonia californica) as well some use of tufted hairgrass (Deschampsia caespitosa) and Kentucky bluegrass (Poa pratensis) in southern Oregon and Carex species in the Washington Cascades along with some use of California brome (Bromus carinatus) and western needlegrass (Stipa occidentalis).

Habitat Description

A small, grassland-dependent butterfly, the Mardon skipper appears to have a remarkably disjunct range, with populations in:

·  Low elevation south Puget Sound prairies of western Washington.

·  Grassy meadows and forest openings, between 1800 and 5600 feet, near Mount Adams, in the Cascade Mountain Range in Washington (Gifford Pinchot National Forest, Okanogan-Wenatchee National Forest, Conboy National Wildlife Refuge, and state and private lands).

·  Grasslands between 4000 and 5500 feet in the southern Cascades, near Ashland, Oregon (Medford District BLM and Rogue River-Siskiyou National Forest).

·  Grasslands in coastal northern California (Six Rivers National Forest and Redwood National Park) (and an historic record from near Gold Beach in Curry County, Oregon).

In the Puget Sound lowlands, Mardon skipper is found on glacial outwash grasslands, often referred to as prairies. In a study of habitat quality at one south Puget Sound prairie site (Hays et al. 2000), adult Mardon skippers used open grasslands with abundant Roemer’s fescue (Festuca roemeri) interspersed with (Viola adunca). Adult Mardon skippers selected for short, open, native Festuca grasslands, which allowed access to nectar and oviposition plants. They selected areas with only limited cover of the invasive shrub Scot’s broom (Cytisus scoparius).

In the southern Washington Cascades, Mardon skipper is found in open, grassland sites within the grand fir (Abies grandis) zone (Topik 1989) and Ponderosa pine (Pinus ponderosa) savanna/woodlands, at elevations ranging from 1,800 to 5,500 feet. Occupied sites to date have been found within 35 miles of Mt. Adams. Sites with grassland vegetation, including meadows, grassy forest openings, roadside meadows, and grass-dominated tree plantations support Mardon skipper populations. South Cascade sites vary in size from small, 1 acre or less, to large grassland complexes. Site conditions range from dry, open ridgetops to grasslands associated with wetlands, springs, or riparian habitat.

Southern Oregon Cascades’ Mardon skipper sites are grasslands between 4300 and 5300 feet elevation, that typically include some type of water feature (i.e. spring, riparian, or wet meadow habitat) (Scott Black pers comm.). Runquist (2004) states that Oregon populations are found in short stature, semi-wet meadows in mixed-conifer forest, closely associated with Idaho fescue (Festuca idahoensis) and California oatgrass (Danthonia californica).

In coastal northern California, Imper (2004) classified the vegetation within Mardon skipper grasslands as a Jeffrey pine (Pinus jeffreyi) and Idaho fescue (Festuca idahoensis) association, a component of the Jeffrey pine/grassland subseries within the Jeffrey pine series (USDA 1995). California sites have been found on serpentine soils with marine weather influence, within 10 miles of the ocean, from approximately 1400 to 2000 feet in elevation (Haggard 2003, Imper 2004).

Survey Methods

Mardon skipper surveys are conducted for the adult life stage: surveys for other life stages are impractical and potentially harmful because eggs are laid singly in or near grass clumps, and larvae and pupae are located within silk and grass nests. Adult occurrence is highly temporal and spatially specific: flight periods for any given site may be as short as two weeks and Mardon skippers often inhabit only a portion of a meadow or grassland complex.

Adherence to the survey guidelines below should result in a high likelihood of detecting Mardon skipper if they are present. However, due to their limited sightability (low, erratic flight pattern) and varying flight period dates and duration, it is possible for Mardon skippers to be present at a site, yet not detected. Failure to detect Mardon skippers using this methodology does not demonstrate their absence. The exact probability of species absence is unknown and depends on the detectability of the species and other survey conditions.

Surveyor Qualifications and Training

The Mardon skipper is a small, fast-moving, dull-colored insect from a family that many people do not even see or recognize as butterflies, and few can reliably identify. Each surveyor should have sufficient knowledge and experience to demonstrate skills in executing these survey methods and in finding and recognizing Mardon skippers. Personnel who will be doing these surveys will need to display an ability to identify Mardon skippers and distinguish it from look-alike skippers.

Characteristics of a successful Mardon skipper surveyor also include:

·  Ability to see minute details

·  Very long attention span

Training Objectives:

1)  Prepare surveyors to detect and identify skippers and specifically, Mardon skipper.

2)  Prepare surveyors to distinguish Mardon skipper from Sonora skipper and other common look-alike skippers.