When we spent the weekend before Memorial Day in Winthrop, clumps of ellow Balsamroot — a variety of sunflower — were blooming in the hills, and swallows were landing in the street to gather material for nest-building. West of town, the North Cascades Highway was still blocked by snow. I remembered a trip to Winthrop nearly 20 years ago, when the area was also balanced on the cusp of winter and spring. I went out with a Forest Service employee named Tod Johnson to check lynx habitat in the mountains north of the highway. Conditions were still so wintery that we used snowmobiles to travel up the logging roads.

On this survey, we were checking to see if hares, on which the lynx prey, preferred a thick tangle of young lodgepole that had grown naturally, or a less-dense stand of young lodgepole that had been artifiically thinned. We found lots of hare pellets in the thinned stand. But in the tangled, natural stand we found even more. On a snowy stretch of narrow road, we also saw what seemed to be lynx tracks. They were too widely spaced to have been made by a lynx walking normally. The animal must have been running. Toward what kind of a future was at the time very much an open question.

The lynx's future remains uncertain. After decades spent navigating the labyrinth of state and federal politics, agencies and court, environmentalists have won legal protection for them and their habitat. And yet Lynx populations in Washington and elsewhere still face threats, among them a phenomenon that was barely considered in the early 1990s: rapid climate change.

Lynx are designed for deep snow. They're specialists. Basically, they're like bobcats (which evolved from them) with broad paws that act as snowshoes. Farther north and in the chilly Midwest, they're found at low elevations. As you move south, lynx habitat gets higher and higher.

In Washington, lynx habitat lies above 4,500 feet. A predator adapted to deep snow needs a prey species that is also adapted to life on the drifts. That would be the snowshoe hare. Lynx will eat other things — one wouldn't want to be a squirrel that caught the eye of a hungry lynx — but mostly, they eat snowshoe hares. The hares, in turn, need greenery that is tender enough to nibble, high enough off the ground so that it won't be buried by snow, but low enough for a hare standing on the snow to reach. That would be lodgepole pine from 15 to 40 years old. Therefore, lynx need extensive stands of young lodgepole. They also need small areas of old-growth for denning; a lack of big open spaces such as large clearcuts or even roads, which they're reluctant to cross; and various other things. But hares and young lodgepole are basic.

On the day when the Forest Service's Johnson and I were looking at the lynx-hare connection, lynx populations all along the northern tier of states bordering Canada seemed in decline. In the Kettle Range, which juts into Washington from the Canadian border east of the Okanogan valley, they had been largely trapped out when fur prices were high in the 1970s. The population in the Okanogan National Forest and the adjoining Loomis state forest seemed to be as healthy as any in the United States. But it was threatened by logging, road-building, poaching (Washington had outlawed lynx trapping,in 1991.) fire, and loss of connection to the larger lynx populations north of the border.

In 1991, Conservation Northwest, then the Northwest Ecosystem Alliance, and other environmental groups petitioned the U.S. Fish and Wildlife Service to list the lynx population of the Okanogan region of north-central Washington. The Fish and Wildlife Service (FWS) refused, saying that because the lynx traveled freely back and forth across the Canadian border, there was no evidence that the Okanogan animals made up a distinct population. (The state of Washington treated the border as a hard barrier and decided that south of the border, the lynx was in trouble. East of the Okanogan, it concluded, outside the Salmo-Priest Wilderness, which lies in the Selkirks northeast of Metaline Falls, all lynx populations were "vulnerable due to low numbers, forest maturation, past habitat alteration, reduction of conductivity to British Columbia, reduced lynx immigration from core populations in Canada, and reduced reoccupation of suitable habitat.")

Environmental groups then petitioned the FWS to list all lynx in the Lower 48. The FWS resisted. Some people said Clinton administration officials were afraid to use the Endangered Species Act lest opponents react by repealing or gutting it — in other words, don't use it or lose it.

Just east of the Okanogan National Forest, the state's Loomis forest had no restriction on logging or road-building. (Roads don't only inhibit lynx movement; they also allow poachers to ride snowmobiles into lynx territory.) Largely to protect lynx habitat, Conservation Northwest led an effort that ultimately raised $16.5 million to buy the Loomis from the state trusts so that the state could manage it for conservation. (The campaign raised enough money to meet the state's origiinal price, but a local legislator called for another appraisal, that appraisal jacked the price at the last minute by $3.5 million, and only a large contribution by Paul Allen let Conservation Northwest close the purchase before the deadline.) The deal was finally approved at the beginning of 2000.

Later in 2000, after losing consistently in the courts, the Fish and Wildlife Service finally listed the lynx as threatened. It also started working on a critical habitat designation that covered lynx territory in Washington, Montana, and other states along the Canadian border all the way to Maine, plus Colorado, where lynx had been reintroduced in 1999. The Bush administration then came up with a critical habitat rule that excluded national forests, slashing the draft designation by 90 percent, to 1841 square miles. Needless to say, environmental groups sued. Then, the Department of the Interior Inspector General reported that Deputy Secretary of Interior for Fish, Wildlife and Parks Julie MacDonald had manipulated scientific findings — including he Endangered Species Program's scientific reports — to favor businesses. In 2007, the FWS acknowledged that the rule "may not be supported by the record, may not be adequately explained, or may not comport with the best available scientific and commercial information," and withdrew it.

Two years ago, the government issued a rule that protects some 39,000 square miles. Environmental groups sued once again. They pointed out that the new rule didn't explicitly consider the effects of climate change.

All lynx populations are threatened by climate change. If there's more rain and less snow, the big paws of lynx won't do them much good, and snowshoe hares will make themselves scarce. To find suitable habitat, the cats will have to go higher. As pockets of habitat grow more isolated, connections among them will grow more important.

The threat of climate change hangs heavily over the long-term future of lynx in the Pacific Northwest. "The lynx, like the wolverine, is highly dependent on a highly persistent snowpack," says Dave Werntz, science and conservation director of Conservation Northwest. "All predictions are that we will be losing our snowpack." And, in fact — this year (and other outliers) notwithstanding — snowpack in the western mountains has already started a steep decline.