Sacramento Fish & Wildlife OfficeServing the people, conserving the fish, wildlife, and plants of California
Tiny Antioch Butterfly to Gain Ground through Voluntary Partnership
Safe Harbor Agreement with PG&E to Help Endangered Species
April 12, 2010
Al Donner (916) 414-6566
Photo: Al Donner, USFWS
An agreement between the U.S. Fish and Wildlife Service (Service) and Pacific Gas and Electric Company (PG&E) is expected to provide important habitat benefits for a rare butterfly that has been on the brink of extinction in eastern Contra Costa County.
Termed a Safe Harbor Agreement (SHA), the voluntary pact between the federal government and the utility will help PG&E to improve native habitat on its property for the Lange’s metalmark butterfly. The agreement covers 12 acres of sandy dunes owned by PG&E, the location of two large transmission towers on the south bank of the San Joaquin River.
PG&E’s land is important to the survival of the rare butterfly and two endangered plants because it brackets the 14-acre Sardis Unit of the Antioch Dunes National Wildlife Refuge. The Service has been carrying out recovery efforts for the Lange’s since 2006, when its numbers had declined to an all-time low of just 45 specimens. The refuge is the only place where the Lange’s exists.
Recovery of the Lange’s continues to be a challenging effort. Since the recovery effort began, the Service and other partners have improved Lange’s habitat on the refuge and a breeding program is helping to restore the butterfly population. Butterfly breeders at Moorpark College in Southern California are raising and hope to release 200 larvae on the refuge this summer.
Especially critical is the restoration of habitat, and that is where PG&E comes in. The Lange’s feeds only on naked stem buckwheat. But populations of that native plant have declined, crowded out by non-native grasses and plants. On the refuge, staff and volunteers have been carefully removing non-native plants and planting buckwheat to improve food supplies for the Lange’s.
The SHA with PG&E will encourage buckwheat and butterflies to return to the PG&E property, expanding its range and thus improving its chances for survival. PG&E is expected to actively manage non-native vegetation (including winter vetch, rip gut brome, yellow star thistle) on the sandy soil along the southern bank of the San Joaquin River. The careful removal of non-native plants will help the butterfly’s primary food plant to grow, providing opportunities for the butterfly population to expand. As part of the agreement, PG&E will organize at least two volunteer days with about 20 people each for the exacting task of pulling out weeds without disturbing the native plants. The SHA gives PG&E protection from violating the Endangered Species Act (ESA) if it accidentally harms a protected species as it restores habitat for the butterfly.
In the last three years the Service, aided by butterfly experts and volunteers, has energetically been helping the species recover. The captive breeding program has returned about 30 Lange’s adult butterflies and nearly 100 larvae to the site, as vegetation management improves food conditions for the butterfly. Refuge staff and volunteers have been removing the invasive plants, helping the Lange’s to spread on the small refuge.
Under the agreement, PG&E will manage vegetation on its adjoining 12 acres to control invasive plants and allow more naked stemmed buckwheat to grow. That should give the existing Lange’s population more areas in which to lay their eggs and expand their population. PG&E will remove tree-of-heaven plants on the parcel, a significant threat to the native species, and other non-natives as part of its normal maintenance. Overall, PG&E has committed to reducing the non-native plants on the parcel and the Service will try to restore native species, in areas away from the vital transmission towers.
The Service encourages partnerships such as these because they provide a net benefit to the imperiled species while protecting landowners who might incidentally harm a species. In Antioch, PG&E and the federal government are neighbors who are working together to help a tiny butterfly recover from the brink of extinction.
The Lange’s metalmark is a reddish-orange butterfly with only a 1.5-inch wingspan. Listed as endangered in 1976, the refuge is its last known home.
The Antioch Dunes refuge was established in 1980 specifically to protect the butterfly and two endangered plants, the Antioch Dunes evening primrose and Contra Costa wallflower. The refuge covers 55 acres of sand dunes along the San Joaquin River, along a deepwater channel in an area that has mostly been developed for heavy industry. Extending the favorable habitat for the Lange’s to PG&E’s parcels is a significant benefit for a species without anywhere else to live.
Last updated: December 6, 2017