Name Travis Booms
Occupation Wildlife biologist
Age 33
Abode A cabin with an outhouse and no running water in Fairbanks, Alaska
Coldest temperature ever experienced
-72 degrees F, with -107-degree windchill, at the summit of the Greenland Ice Sheet
Fuel of choice Three king-sized candy bars per day, or five cases total, during one Greenland summer when he logged  700 miles of tundra hiking

When I first meet Travis Booms, he is hunched under the weight of two huge backpacks, which he has humped across more than six miles of dry, open tundra. Hiking on tundra is like hiking on thick memory foam: The ground only grudgingly yields distance. Without breaking stride, Booms says hello to me and excuses himself so he can stagger the last few yards to the lakeshore, where he slips the packs off, collapses onto his back, and calls out, "Honey, I'm hooooome!"

Home for Booms, from the end of June through early July, is the middle of the Yukon Delta National Wildlife Refuge, among a scatter of extinct volcanoes called the Ingakslugwat Hills. None of them is very tall, but the delta is so flat that The Volcanoes, as the hills are informally known, are the only suitable habitat for Booms' study subject, the gyrfalcon. Lest I get my hopes up, though, Booms warns me that the most I am likely to see of the raptor is a blur at the edge of vision, moving swiftly out of sight.

Alaska's totemic creatures are not usually so shy -- polar bears, caribou and salmon often frolic in front of cameras or hurl themselves upstream for documentaries. The gyrfalcon does none of these things. It lives only in Northern climes and rarely strays down to the Lower 48. It has three color variations, white, gray and dark. Almost all of Alaska's gyrfalcons are gray, and perhaps 40 live in the 300 square miles of The Volcanoes. This may not sound like a lot of gyrfalcons, but consider: You would have to search 3,000 square miles to find so many anywhere else in the world.

Booms, 33, is quiet and predisposed to solitude, with a field biologist's leanness and reserve. He grew up in Wisconsin and was studying Cooper's hawks at the University of Wisconsin-Stevens Point when, in 1998, he was asked if he wanted to go to Greenland to help with a peregrine falcon project as a last-minute substitute. Six days later he was on a military transport plane. "That summer," he says, "I caught my Arctic Bug." Although he was in the heart of gyrfalcon country, he didn't actually see one until two years later -- in a remote valley, white against gray granite, through a tatting of light snow. Smitten, he came to Bethel, Alaska, in 2002, to volunteer in the refuge. The refuge biologist told him of The Volcanoes and their gyrfalcons, noting that aside from the odd survey, the birds were basically ignored. Booms flew over and was, he says, "blown away." In 2004, he started his Ph.D. at the University of Alaska in Fairbanks, where he still lives.

Studying gyrfalcons is grueling and often thankless work, and the sheaf of information on them is thin. "That's why I like it," Booms says. For his Ph.D., he worked to fill gaps in the birds' basic biology: whetherthey migrate, whether they nest in the same place each year, what they eat, how hard it is to find them. He spent three or four months at a time hiking prodigious distances across the open tundra, alone save for the occasional moose, visiting nest sites to which he gave colorful names: the Horseshoe (a three-quarter crater), 401K ("because when I first saw it, I thought it looked like a nice place to retire"), Devil's Tower ("you'll see").

Now, as a biologist with the Alaska Department of Fish and Game, Booms has a more urgent focus. The gyrfalcon is uncommon and its population might fluctuate from year to year, but it is generally stable. What concerns Booms is the raptor's long-term viability, especially in the face of climate change. It is too narrowly, perfectly, unfortunately suited to this tundra environment not to be affected by climate perturbations, and the surest way to detect those effects is to count all the birds, year after year. But counting all the gyrfalcons in The Volcanoes is not as simple as just counting all the gyrfalcons in The Volcanoes. You also have to know which one is which.

In any given year, Booms tells me, gyrfalcons will occupy 85 to 100 percent of the suitable territory in The Volcanoes, which sounds like a good thing. But if those gyrfalcons are different gyrfalcons from year to year, that would raise a red flag. We're walking near the Horseshoe, stopping at perches. At each, Booms riffles through tufts of grass, peers into rock crevices, and picks through the gore that litters the ground. He finds a feather and puts it in an envelope, which he tucks in his pocket.

At first, Booms  tried to capture gyrfalcons with nets, nooses and other conventional means. Sweltering in a blind, dogged by mosquitoes, he watched as, hour after hour, the birds ignored his ingenious efforts. He now puts a unique sequence of colored bands on each bird's leg when it's a chick (it's easier to catch then), but that isn't much better. Gyrfalcons have feathered tarsi -- what Booms calls their "pants" -- so even with binoculars the bands are difficult to see, much less read, particularly when the bird is in flight. Now he uses feathers to identify individuals; even small feathers have enough genetic material on them to give a DNA fingerprint.