The Final Countdown: Taking Stock of an Endangered Butterfly

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It’s late August. Here at the Antioch Dunes National Wildlife Refuge, the fall’s late bloomers have unfurled their petals to entice the pollinators hustling these parts. An assemblage of honeybees joined by their kith and kin patrol the petals, self-absorbed in their singular mission to collect nectar and, with it, a pinch of pollen. Among them idle Acmon blues, hairstreaks, and cabbage white butterflies, each showing off their own rendition of mosaic-scaled wings intricately tatted with eye spots, patches, and splashes of color. And overseeing the morning rush hour under way swoop dragonflies, hovering and bearing down on their targets like predator drones.

But all of these are distractions from our purpose here today. It’s late August, the peak flight period of the federally Endangered Lange’s metalmark butterfly. And we’re here to count butterflies.

Shortly after arriving at the refuge, U.S. Fish and Wildlife Service refuge biologist Louis Terrazas takes my wife Sarah and I aside and asks if we’d like to see a Lange’s metalmark butterfly before the training gets underway. You see, I’ve visited the Antioch Dunes National Wildlife Refuge perhaps a half-dozen times or more between now and when I first wrote about the  dunes for Bay Nature magazine in 2005. But in all those visits, I had never made it to the dunes in August or September, when the Lange’s emerge from their chrysalis as imagoes (the mature butterfly) and begin their short-lived adult lives.

It’s a short walk down the sandy road into the Pit Floor, and then a few feet off-trail into a meadow of delicate Antioch Dunes buckwheat, the Lange’s host plant. It’s no more than a few seconds before Louis spots a butterfly pin-balling off invisible barriers in the Lange’s trademark erratic flight. The butterfly – a female, judging by its larger size – alights on a buckwheat bloom and flexes her wings. That’s one of the Lange’s stand-out traits – the other butterflies that frequent these dunes are more close-lipped, keeping their wings tucked in the upright position rather than splayed for the world to see. But the Lange’s is anything but shy. Once they’ve landed, they typically stay put for minutes at a time, long enough for Sarah to preserve on film (a flashcard, really…) portraits of this vanishing species.

Back at the orientation, USFWS refuge biologist Susan Euing takes charge, giving the assembled volunteers the rundown on the census we’re about to undertake. Despite this being a butterfly count, only Lange’s metalmark butterflies count during today’s transect surveys, so we have to be able to discern between our target and the other butterflies in flight. Then we’re assigned tally counters, metal pucks with a push-button that activates the 4-digit odometer to keep track of each Lange’s we come across in our surveys.

Outside the protective fold of the Pit Floor where we’re puttering around, readying our gear, the Delta winds whip the air in swirling eddies, the gusts arriving from every which way. It’s these winds that first distributed the Antioch Dunes here from their glacial-ground origins in the Sierra over 500,000 years ago, piling them along the south bank of the San Joaquin River in dizzying drifts some 120 feet above sea level and as much as 800 feet inland. At one time some 5,000 to 8,000 years ago, these sands extended along the San Joaquin River for two miles, then skirted the eastern flanks of Mount Diablo south along the western edge of the San Joaquin Valley and continuing on to connect with the Mojave Desert.

This connectivity acted as a corridor for an array of true desert plant and wildlife species that radiated north and adapted to the unique environs of the Antioch Dunes. In time, too, this connectivity was severed, leaving the new inhabitants of the Antioch Dunes to survive on their own. Such isolation lead to specialization and speciation, laying the groundwork for endemism – where a species becomes localized until it becomes confined and belongs exclusively to a certain location. Among those endemic species were the Antioch Dunes evening primrose (Oenothera deltoids howellii), the Contra Costa wallflower (Erysimum capitatum angustatum), and the Lange’s metalmark butterfly (Apodemia mormo langei).

Lange’s metalmark butterfly (Apodemia mormo langei) • Courtesy G. Kareofelas, Bohart Museum of Entomology, University of California, Davis

At the Antioch Dunes, there’s an even greater assemblage of insects found here alone (dune “endemics”), many of which have since eclipsed into extinction. But at the time, the Lange’s, the wallflower, and the primrose represented the three species whose scarcity warranted their protection, leading to their listing under the Federal Endangered Species Act in 1976 (Lange’s) and 1978 (both plants) and the formation of the Antioch Dunes National Wildlife Refuge in 1980.  Even today, the Antioch Dunes remain the only federal wildlife refuge in the United States established for the protection of plants and insects.

We know so much about the insect fauna of the Antioch Dunes from the swarm of entomologists who have been drawn there over the last two centuries after the dunes became acclaimed among naturalists for their untold abundance of insect life. In 1955, the dunes even found their way onto the pages of Life magazine in the way of a fold-out six-panel feature spread illustrated by famed artist Dr. Walter Linsenmaier.

But in all those years of study and collection, the dunes were also being exploited for their exceptional sands. Beginning in the late 1800’s, various and sundry sand mine operations made a business of removing sand by way of train cars on dedicated Atcheson, Topeka, and Santa Fe Railroad spur lines. Following the 1906 Great Earthquake, demand for sand intensified the demand for manufacturing bricks. By the late 1970’s, the once-towering pillars of sand had been depleted in most places to bare earth. The quarries continued removing sand up until the very day the refuge was formally established in 1980. Today, the mined-out Pit Floor is a stark reminder of the exploitation that took place over the last 200 years, an example of the depths – literally – the mine operations excavated the dunes to extract sand.

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These days, the refuge is divided into two separate units, which bookend the Georgia-Pacific gypsum plant in their midsts. The westerly Stamm Unit, a 55-acre parcel shaped like the handset of a rotary phone, and the easterly Sardis Unit, a square 12-acre parcel. One either side of the units hulk industrial compounds: the Kemwater North American Company to the east, the Fulton Shipyard to the west, and a city wastewater treatment plant and transfer facility to the south. The Sardis Unit, east of the Georgia-Pacific gypsum plant where drywall is manufactured, is perpetually dusted in a fine white powder, which leaves everything downwind looking flocked – your boots, pant cuffs, and the west-facing surface of every branch and leaf blade. Every footstep ignites a ‘poof!’ of powder.

Fortunately, there is no rabble of white-winged Lange’s haunting the gypsum-confectioned Sardis Unit. In fact, since 2010, the Sardis Unit is the only of the two parcels that continues to support Lange’s metalmark butterflies. But for whatever reasons, the Lange’s are more prolific on the central and eastern boundaries of the Sardis Unit, especially in the protective bowels of the Pit Floor.

All of this bears out during the butterfly count. Beginning on the plateau east of the Pit Floor, we line up at arm’s length in much the same way rescuers might during a search party, except the bodies we’re searching for are the size of a quarter and winged. In 1999, the peak count numbered 2,342 in a single day; last year, the 2012 peak count numbered 32 individual butterflies.

In the shadow of the monolithic PG&E tower, our first few Lange’s imbue us with hope that we can top last Thursday’s peak count of 23 butterflies. As the day progresses, our day’s count climbs in fits and spurts. After knocking off the upper terraces, we drop into the Pit Floor where the buckwheat plants erupt in thickets. So too do the Lange’s, which appear to be thriving in this metalmark Mecca. Every butterfly we glimpse brings us to a momentary standstill as we key out the individual’s traits: cabbage, cabbage, buckeye, Lange’s! Each Lange’s is assigned a volunteer as a babysitter to make sure there’s no double-counting if the butterfly flushes and skitters ahead of our transect. Although they’re nowhere near as abundant as we’d like, by day’s end we’ve tallied 28 Lange’s, topping last week’s peak count.

This doesn’t break any records, but at least we didn’t get skunked. And it marks an upward swing from last year, reassuring us that even if things aren’t getting markedly better, they’re also not getting markedly worse. The counts will continue through September until the butterfly’s short lives are spent and the flight period sets for the season. And next year, a new wave of volunteers – myself included – will take up the front lines in the uphill battle against extinction.

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Throughout September this year, wildlife biologists at the Antioch Dunes National Wildlife Refuge will continue to conduct their annual Lange’s metalmark butterfly counts to determine the health of this rare butterfly species. For more details and directions, visit the refuge website: http://www.fws.gov/refuge/antioch_dunes/Get_Involved/Butterfly_Survey2013.html

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