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PACIFIC SOUTHWEST REGION: Preventing Extinction of Lange’s Metalmark Butterfly Through Captive Breeding, Habitat Restoration
California-Nevada Offices , July 1, 2015
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Adult Lange's Metalmark butterfly.
Adult Lange's Metalmark butterfly. - Photo Credit: Louis Terrazas
Lange's Metalmark larvae.
Lange's Metalmark larvae. - Photo Credit: USFWS
Antioch Dunes National Wildlife Refuge, Stamm Unit with freshly dredged sand.
Antioch Dunes National Wildlife Refuge, Stamm Unit with freshly dredged sand. - Photo Credit: Don Brubaker
Adult Lange's Metalmark butterfly.
Adult Lange's Metalmark butterfly. - Photo Credit: Ken-Ichi Ueda for USFWS

By Caroline Prose

 

It was not a usual sight on a wildlife refuge. A slurry of sandy sediment gushed through a massive hose, eventually spreading across several acres of federally protected land. But Service biologist Louis Terrazas smiled at the scene. “When an entire ecosystem depends on the blowing sand of a dune, and that sand is gone, you have to build it again,” he said.

Hope, in the form of sand for the Antioch Dunes National Wildlife Refuge and its hotspot for two endangered plants and an endangered butterfly, flowed onshore in a wet mess that would eventually dry into the contours of a new dune, to be shaped by the wind and colonized by life again.

The conservation flagship at Antioch Dunes is Lange’s metalmark butterfly (Apodemia mormo langei), an endangered species at risk of extinction. The butterfly was listed as endangered in 1976, followed by the establishment of the Antioch Dunes in 1980. The refuge located along the San Joaquin River in Contra Costa County in northern Calif., hosts the only population of the Lange’s Metalmark in the wild. It is the only national wildlife refuge created specifically for a butterfly and plants.

Loss of habitat at Antioch Dunes has contributed to its struggle, with riverine sand dune habitat having been reduced to ten percent of its former home, from 494 acres to roughly 55 acres, Terrazas explained.

The two federally listed plant species are the Contra Costa wallflower (Erysimum capitatum var. angustatum), and the Antioch Dunes evening primrose (Oenothera deltoids ssp. howellii). An on-going captive propagation program for Lange’s Metalmark with subsequent reintroductions on restored habitat at Antioch Dunes is helping to prevent its extinction, and will provide stock to colonize the newly created dunes.

Adult LMBs are small with a wingspan from 1 to 1-1/2 inches. The dorsal surface is mostly black with white spots, and the forward part of the inner forewing has a reddish-orange background. During their approximate 1-week lifespan in the wild, the adults mate, and the females lay eggs in small clusters of two to four directly on their food plant, the naked-stemmed buckwheat (Eriogonum nudum var. psychicola). The larvae hatch at the onset of Fall or Winter rains, then enter a period of dormancy during the Winter, and resume feeding through the spring and summer. They mature and metamorphose into pupae in mid-summer. About 2 weeks later, the adults emerge. The once-a-year peak flight period occurs about 2 weeks after the first butterflies emerge from their pupae, and is in synchronization with the flowering of the buckwheat.

Between 50-100 years ago, the butterfly’s population size at the Antioch dunes was estimated to be about 25,000 individuals, but has dropped sharply. The 2005 survey showed that the population had declined below the “trigger” number of 336 individuals specified in management documents for refuge, which prompted immediate implementation of remedial conservation actions. In 2006, only 45 adults were observed during the peak flight period.

In response, the captive propagation program started in 2007, in part with funding from the Central Valley Project Improvement Act Habitat Restoration Program. The program is located at Moorpark College in Moorpark, California, and is managed by the Urban Wildlands Group, a non-profit organization in Los Angeles. It serves to prevent extinction of the LMB in the wild, and provides a source of individuals to reintroduce and supplement at the refuge. In August 2008, the first Lange’s Metalmark butterfly mating in captivity was documented.

“The species is holding on by a thread,” says Dr. Travis Longcore, Science Director for the Urban Wildlands Group. “After all it has been through, we would be failing our responsibility as stewards if it were to slip away now.”

The goal of the captive propagation program is for the maximum number of Lange’s Metalmarks recorded on the peak day of surveys at the refuge to exceed 500, which would give a margin of comfort over the trigger number. According to Longcore, a lot of work is still needed. In 2014, 139 LMBs were counted in August and September. While still of concern, this was the highest number surveyed since 368 LMBs were counted in 2008, and more than 100 LMBs had not been counted since 2009. Also, in the Spring of this year, many larvae have been observed.

The Antioch Dunes NWR consists of two units: the 41-acre Stamm unit and the 14-acre Sardis unit. These comprise the remnant of a formerly large sand dune ecosystem that consists of an isolated island of natural habitat. The sand originated at the end of the last Ice Age when summer winds swept across floodplains along the western foothills of the northern Sierra Nevada, picked up sand, and deposited it as dunes. Unfortunately, over time, sand dune habitat at Antioch Dunes has been lost through removal of sand for construction, agricultural and industrial practices, and recreational use. Additionally, competition from non-native plants has contributed to a reduction in the number of buckwheat plants. There is a direct correlation between the number of mature buckwheat plants at the refuge and the population size of Lange’s Metalmarks.

There were also a number of large wildfires on the Stamm Unit between 1999 and 2006 that greatly decreased the LMB population: a 19-acre fire in 1999 decreased the LMB population from 1,079 in 1998 to 511 in 1999; a 24-acre fire in 2002 decreased the population from 417 in 2001 to 208 in 2002; and an 11-acre fire in 2006 decreased the population from 92 in 2005 to just 5 in 2006. There are other unknown factors at work, but the weeds and wildfires had a major role in the decrease of LMB from 1999 to 2006.

Facing this critical situation, Fish and Wildlife Service managers set about recreating a new dune. Over the last few years, about 40,000 cubic yards of clean sand have been deposited from dredging operations in the San Joaquin River to augment and create an additional five acres of sand dune habitat on the Stamm unit. This will continue for several more years in other areas of the unit. Additionally, refuge staff continue to restore and manage habitat through mowing and scraping non-native vegetation with heavy equipment; weed whacking; hand-pulling of non-natives; and application of herbicides.

Further restoration efforts include planting and seeding of naked-stemmed buckwheat, Contra Costa wallflower, and Antioch Dunes evening primrose. This year was an exceptional year for the wallflower with over 9,400 plants counted. Also, about 100 primrose plants were counted in the newly created sand dunes.

In fiscal year 2015, the CVPIA Habitat Restoration Program will continue funding the captive propagation program. With on-going captive propagation and restoration of habitat at Antioch Dunes that will include provision of new food plant sources, the goal is for the butterfly to successfully colonize and expand its population over the course of a few seasons. All combined, there is hope that the LMB population will increase in 2015 and beyond.

-- FWS --

 

Caroline Prose, serves as the program manager for the CVPIA Habitat Restoration Program in the Pacific Southwest Region located in Sacramento, Calif.



Contact Info: Jon Myatt, 916-414-6474, jon_myatt@fws.gov
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