Endangered and Threatened Wildlife and Plants; Recovery Plan for the Behren's Silverspot Butterfly

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of availability of documents.

SUMMARY:

We, the U.S. Fish and Wildlife Service, announce the availability of the final recovery plan for the Behren's silverspot butterfly. The recovery plan includes recovery objectives and criteria, and it includes specific actions necessary to reclassify the species from endangered to threatened, and to achieve removal of the species from the Federal Lists of Endangered and Threatened Wildlife and Plants.

ADDRESSES:

You may obtain copies of the final recovery plan from our Web site at http://www.fws.gov/endangered/species/recovery-plans.html. Alternatively, you may contact the Arcata Fish and Wildlife Office, U.S. Fish and Wildlife Service, 1655 Heindon Road, Arcata, CA 95521 (telephone 707-822-7201).

FOR FURTHER INFORMATION CONTACT:

Bruce Bingham, Field Supervisor, at the above street address or telephone number (see ADDRESSES).

SUPPLEMENTARY INFORMATION:

Background

Recovery of endangered or threatened animals and plants to the point where they are again secure, self-sustaining members of their ecosystems is a primary goal of our endangered species program and the Endangered Species Act of 1973, as amended (Act; 16 U.S.C. 1531 et seq.). Recovery means improvement of the status of listed species to the point at which listing is no longer appropriate under the criteria specified in section 4(a)(1) of the Act. The Act requires the development of recovery plans for listed species, unless such a plan would not promote the conservation of a particular species.

The purpose of a recovery plan is to provide a framework for the recovery of species so that protection under the Act is no longer necessary. A recovery plan includes scientific information about the species and provides criteria that enable us to gauge whether downlisting or delisting the species may be warranted. Furthermore, recovery plans help guide our recovery efforts by describing actions we consider necessary for each species' conservation and by estimating time and costs for implementing needed recovery measures.

Section 4(f) of the Act requires us to provide an opportunity for public review and comment prior to finalization of recovery plans, including revisions to such plans. We made the draft recovery plan for Behren's silverspot butterfly available for public comment from January 20, 2004, through March 22, 2004 (69 FR 2725). We did not receive any comments during the public comment period for the draft recovery plan.

Recovery Plan for Behren's Silverspot Butterfly (Speyeria zerene behrensii)

Species' History

We listed Behren's silverspot butterfly throughout its entire range on December 5, 1997 (62 FR 64306). The species is endemic to the coastal prairie in Mendocino and Sonoma Counties, California. The current known range of the Behren's silverspot butterfly is limited to a small number of sites located from the Point Arena-Manchester State Park area south to the Salt Point area. The best available information on the life history of the Behren's silverspot butterfly comes from studies of a closely related coastal subspecies, the Oregon silverspot butterfly. Those studies found that females lay their eggs in the debris and dried stems of the larval food plant, the early blue violet (Viola adunca). The early blue violet is a small, native, perennial herb with pale to deep violet flowers. This violet typically blooms in late spring to early summer and dies back to the perennial rhizome during winter. Early blue violets occur widely in western North America; within the Behren's silverspot butterfly's range, they are associated with coastal grasslands.

Upon hatching, the caterpillars (larvae) wander a short distance and spin a silk pad upon which they pass the fall and winter in diapause (dormancy). The larvae are dark-colored with many branching, sharp spines on their backs. Upon ending diapause in the spring, the larvae immediately seek out the violet food plant. During the spring and early summer they pass through five instars (stages of development) before forming a pupa within a chamber of leaves that they draw together with silk. The adult butterflies emerge in about two weeks and live for approximately three weeks, during which time they feed on nectar and reproduce. Depending upon environmental conditions, the flight period ranges from about July through August or early September.

Behren's silverspot butterfly flight behavior is moderately erratic and swift in windy places, 0.3 to 1.8 meters (2 to 6 feet) above ground surface. Flights usually occur by late morning when temperatures are above about 60 degrees Fahrenheit. Adults may feed on nectar for as long as 5 minutes, returning to the same plant repeatedly. Butterflies may rest on bare ground, in grasses, or on ferns (bracken) and other foliage.

Adult Behren's silverspot butterflies feed on nectar, which is their only food source, besides internal reserves present when they emerge from the pupae. Observations of nectar feeding are few, but based on observations of this and closely related silverspot subspecies, plants in the sunflower family (Asteraceae) dominate as nectar sources, including thistles (Cirsium spp); gumplant (Grindelia stricta); goldenrods (Solidago spp.); tansy ragwort (Senecio jacobaea), California aster (Aster chilensis), pearly everlasting (Anaphalis margaritacea), seaside daisy (Erigeron glaucus), and yarrow (Achillea millefolium). Reported nectar species from other plant families include yellow sand verbena (Abronia latifoli a), sea-pink (Armeria maritima), and western pennyroyal (Monardella undulata).

Recovery Plan Goals

The ultimate goal of this recovery plan is to recover Behren's silverspot butterfly so that it can be delisted. To meet the recovery goal, the following objectives have been identified:

1. Secure self-sustaining wild metapopulations throughout the historic range of the subspecies.

2. Determine metapopulation and range-wide population numbers and monitor them to determine long-term trends.

3. Reduce and eliminate threats, to the extent possible.

4. Protect, conserve, and restore healthy butterfly ecosystems and their function.

As Behren's silverspot butterfly meets reclassification and recovery criteria, we will review its status and consider it for removal from the Federal Lists of Endangered and Threatened Wildlife and Plants.

Authority

We developed our recovery plan under the authority of section 4(f) of the Act, 16 U.S.C. 1533(f). We publish this notice under section 4(f) of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).