Reporter at Large (The Skipper and the Dam)
New Yorker, Dec 1st, 1986
Print Friendly Version
BECAUSE California is such a crazy mosaic of habitats and plant communities, many of the
nation's rarest butterflies are found there. Lange's metalmark, for instance, a fiery-red variety of the normally orange-and-gray Mormon metalmark, lives on the Antioch Dunes, east of San Francisco, and has a total range of only fifty acres. The Palos Verdes blue was limited to half an acre on the Palos Verdes Peninsula, in Los Angeles. Four years ago, the spot was converted into a ball field, and that was the end of the Palos Verdes blue-a particularly bitter loss, because it resulted from poor coordination between the United States Fish and Wildlife Service and the local people, who thought they were putting the ball field where the butterfly wasn't. The mountain West also has some rarities. Up in the Colorado Rockies, the so-called Pawnee montane skipper ranges over twenty-five or thirty square miles in South Platte Canyon, southwest of Denver. Unfortunately for everybody, this section of the canyon-where the main stem of the South Platte is joined by its North Fork, and for a considerable distance up both rivers-has been proposed by
the Denver Water Department as the site for a huge dam and storage reservoir. Perhaps fifty per cent of the butterflies will drown if the dam is built. But building a dam in the West these days is a complicated process. A detailed environmental-impact statement, in compliance with the National Environmental Policy Act of 1969, must be submitted. Two separate population and distribution studies of the Pawnee montane skipper, and dozens of other studies as well, have been required for the impact statement for the Two Forks Dam, as the Colorado project is called. A task force of some four hundred people has been working on the document for the last two and a half years. The bill for it so far is coming in at thirty-six million six hundred thousand dollars -a sum that William Miller, the exasperated manager of the Water Department, recently declared to be "approaching a national scandal."
Small, subtly camouflaged, darting from flower to flower, the Pawnee montane skipper belongs to an enormous family of butterflies-the Hesperiidae, or skippers-with some thirtyfive hundred species, distributed over every continent except Antarctica. As butterflies go-and they are among the most highly evolved insects, with four life stages-the skippers are rather primitive. They are, in some ways, closer to moths than to other butterflies. Like moths, they have stout bodies, and they sit with their wings flat out or partly open, but unlike most moths they fly by day and have knobbed antennae. The North American skippers, of which there are two hundred and ninety-two species, not including those in Mexico, tend to be drab-again, like the majority of moths-and sombre-colored. They have names like dusky wing, cloudy wing, sooty wing. It is only to the south, in Central and South America, that dazzling skippers, some with iridescent blue or orange stripes, zip around in the jungle understory. Because the North American skippers are small (seldom more than an inch from wingtip to wingtip) and subdued, and hard to catch and identify, they have been neglected by collectors, even though from an evolutionary and behavioral standpoint they are one of the most interesting groups. Take the two-spotted skipper, which lives in bogs and marshes and ranges from Colorado north to Canada and Maine, and south to West Virginia and Texas, yet never occurs in a group of more than a hundred or two. Only three colonies of the two-spotted skipper are known in all Colorado, one colony is known in Nebraska, none in Kansas. To find the next one, you have to go all the way to Iowa. The explanation for this highly local distribution pattern is that the colonies are believed to be stranded remnants of populations that were much larger during the last Ice Age. The Pawnee montane skipper, found so far in only one place in the world, is also thought to be what zoologists would call a "Pleistocene relict."
The first Pawnee montane skippers -eleven of them-were collected in the summer of 1883 and were sent that fall to W. H. Edwards, of Coalburg, West Virginia, a lawyer and coal-mine owner who was the leading lepidopterist of his day. Only two of the specimens were completely labelled. The labels identified their place of capture as Salida, Colorado, and their captor as one David Bruce. Edwards described more North American butterflies than anybody before or since, but he never got around to these, and they ended up, with the rest of his collection, in the Carnegie Museum of Natural History, in Pittsburgh, which at that time was the center of American butterfly studies. There they languished for several decades, until, in 1911, they finally came to the attention of a specialist in Western lepidoptera named Henry Skinner. He described them and gave them the Latin name Pamphila pawnee montana, having decided that they were a subspecies of a Plains species, Pamphila pawnee, which had been described in 1874. Indeed, the differences between the Pawnee skipper and the Pawnee montane skipper are slight: montana is a bit smaller and usually browner than the consistently lighter, more yellowish pawnee, and montanaparticularly the female-has distinct ochreous-white spots on the undersides of its hind wings, while pawnee's spots are poorly developed. But the brown of some montana is greenish. Others are russet, and still others are yellowish, almost indistinguishable from pawnee. It's not an entirely clean situation.
Nothing more was heard of montana until 1967, when it was independently rediscovered in the South Platte Valley by two collectors-Ray E. Stanford and James A. Scott. Scott is a reclusive soul who has a doctorate in entomology from the University of California at Berkeley, and he makes his living building duplexes. His book "The Butterflies of North America" has just been brought out by the Stanford University Press. He caught his montana near a gold-mining ghost town in South Platte Canyon called Nighthawk. Stanford is a pathologist at the University of Colorado. He took his montana on a tributary of the South Platte named Sugar Creek. The two men didn't meet and compare their catches until a year later. At the time Scott collected his montana, he thought they were a dark variety of pawnee. Stanford suspected he had something new. Back home, he put them under a microscope, and saw that their valvae, or claspers-lateral structures of the male genitalia which enable butterflies to mate and butterfly taxonomists to tell one species from another-were definitely pawnee, but the coloration of the wings was wrong. It wasn't until 1972, when he went to Pittsburgh and, after pulling out dozens of drawers of skippers from their cabinets at the Carnegie Museum, finally matched his specimens with Hesperia pawnee montana Skinner, that he realized what he had. (The generic name Hesperia was reestablished in 1922 for skippers widely but erroneously classified as Pamphila during the late nineteenth and early twentieth centuries.)
There was still a problem, however: Salida, in Colorado's Chaffee County, is seventy-five miles from South Platte Canyon, where both Scott and Stanford had caught their montana. In the summers that followed, the two men combed Salida and the rest of Chaffee County for the insect, but they couldn't find a single one. Stanford began to wonder about the labels on the type specimens in Pittsburgh. He conveyed his doubts to F. Martin Brown, a retired prep-school science teacher and the doyen of Rocky Mountain-butterfly collectors, who had sorted out similar discrepancies in the past. David Bruce, who had been identified as the collector, was an English housepainter who lived for many years in New York. There had been problems with his labels before. Brown managed to reconstruct Bruce's itinerary in the summer of 1883 from his correspondence, and he discovered that during the period when Bruce supposedly collected the montana in Salida he was in fact in a hospital in Red Cloud, Nebraska, recuperating after a fall from a scaffold. Sleuthing further, Brown learned that Bruce had left a butterfly net that August with the children of one William W. G. Smith, in Buffalo Creek, which is in the South Platte Valley, only a dozen miles from Sugar Creek, and that on September 7th the Smith children had mailed him several boxes of butterflies from "the Platte Canyon Valley." Buffalo Creek today consists of a store and maybe a dozen houses. Its population is perhap$ fifty. If anything, it's smaller than it was a hundred years ago, when it was a stop on the old Denver, South Park & Pacific Railroad and the Smith children were romping around with Bruce's butterfly net. It's still a great place to find Pawnee montane skippers.
On the basis of Brown's detective work and their inability to find montana anywhere in Chaffee County, Scott and Stanford decided to change the type locality-the place where the type specimens were collected-from Salida to Buffalo Creek. They also decided, after months spent doing field and laboratory work, and poring over more than a thousand specimens in museums and private collections around the country, and mapping out all the places of capture, that montana was not a subspecies of pawnee but, rather, both were subspecies of another species, leonardus, which ranges to the east. A lot of the taxonomist's work in every branch of the natural sciences consists of splitting or combining species and subspecies in the light of new information. Here Scott and Stanford were combining pawnee and leonardus; they were, in Stanford's words, "revising the leonardus complex."
Not until 1981 were their findings published, in the Journal of Research
on the Lepidoptera. Apart from the excitement it stirred in the small fraternity
of Rocky Mountain-butterfly buffs, their paper, "Geographic Variation and
Ecology of Hesperia leonardus (H esperiidae )," went unnoticed. The Pawnee
montane skipper went from being Hesperia pawnee montana to being Hesperia
leonardus montana. It still didn't have a common name, and nobody except
a handful of Scott and Stanford's colleagues had ever heard of it.
THE South Platte River, in greatly altered form-diverted for treatment and consumption, returned as treated waste water-flows through Denver on the way to its meeting with the North Platte, in N ebraska, and their eventual merging with the Missouri, below Omaha. From Denver's beginning, in 1859, as a cluster of cabins and tepees at the South Platte's confluence with Cherry Creek, the river has provided the city with most of its water, and it still does. The first effort to obtain a stable supply for the city by impounding South Platte water was made in 1905, when the Denver Union Water Company, a private outfit, created Cheesman Reservoir, some twenty miles upriver from the Two Forks dam site. Cheesman Reservoir can hold seventy-nine thousand and sixty-four acre-feet of water. (An acre-foot of water, which is about three hundred and twenty-six thousand gallons, covers an acre of flat ground to a depth of one foot.) The first substantial onstream municipal water-storage facility in the mountain West, Cheesman Reservoir was hailed as the answer to Denver's water problems for all time.
In 1918, the Denver Water Department was chartered as a self-regulating utility to provide water to Denver residents roughly at cost-which is now around forty-four cents a day for the average customer. The department acquired Cheesman Reservoir and also a shallower reservoir fifty miles upstream-the Antero Reservoir, with a capacity of fifteen thousand eight hundred and seventy-eight acre-feet. But by the nineteen-twenties the population of metropolitan Denver had reached three hundred and fifty thousand, and the demand for water had almost caught up with the supply. Drought during the Dust Bowl years of the thirties aggravated the situation, and in 1932 the department put up a third dam on the South Platte, between the two others-the Eleven Mile Canyon Dam, which added ninetyseven thousand seven hundred and seventy-nine acre-feet of storage to the system. These three reservoirs provided enough water for Denver through the end of the Second World War. But by the mid-fifties demand had caught up with supply again, so the department looked across the Continental Divide to the Colorado River drainage. (Western water people speak not of basins or river valleys but of drainages.) Until that time, Denver had been relying mainly on East Slope water-water east of the Divide, caught by the South Platte. The South Platte drainage is huge-just the part above Denver is twenty-seven hundred square miles-but it collects only ten per cent of the state's water. Seventy per cent of the water flows down the great Colorado. That most Coloradans live east of the Divide and most of the water is west of it is one of the state's geographical problems. Another problem is that none of the substantial rivers that run through Colorado stay there. According to the Colorado River Compact of 1922, roughly half of the Colorado's flow must be passed out of Colorado and down to its Lower Basin, where it is piped to cities like Los Angeles, Las Vegas, and, as of a year ago, Phoenix. Colorado is entitled to only fifty-two per cent of the water that remains. (The other Upper Basin states-Wyoming, Utah, and New Mexico-share the rest.) Some Coloradans feel that they're getting the short end of the stick, but twenty-five per cent of the Colorado is still more than all of the South Platte.
In the twenties, George Bull, an engineer working for the Denver Water Department who had done some surveying on the West Slope, quietly filed for water rights to two of the Colorado's tributaries-the Fraser River and Williams Fork. The problem was how to get the water over the Divide and down to Denver. The answer, effected in stages from 1936 to 1959, was this: line with concrete the pilot bore of a railroad tunnel that goes under the Divide (a pilot bore is a tunnel used by tunnel diggers to probe the geology and remove debris from the main tunnel) and run Fraser River water through the pilot bore into South Boulder Creek, on the East Slope; dam South Boulder Creek near Eldorado Springs and shoot the water by a series of tunnels, flumes, siphons, and canals over to Ralston Creek, two streams to the south; dam Ralston Creek and run the water by conduit from there to the city's Moffat Treatment Plant. More tunnelling, of the Vasquez and August P. Gumlick Tunnels (longtime Water Commissioner Augie Gumlick had done so much for the Denver water system that he got his own tunnel), made it possible to divert Williams Fork water into the Fraser, so that today Moffat Tunnel, as the former pilot bore is known, can deliver a maximum of twenty-five hundred and thirty-nine acre-feet of West Slope water a day to Denver.