Ranger Takes Falcons Under Wing : Environment: Steve Ulvi treks the Alaska wilderness to study the endangered birds. He and his colleagues have helped the species bounce back from DDT poisoning.

The peregrine chicks hiss and peck as Steve Ulvi reaches in with gloved hands to gently cradle the birds in his lap, one at a time, while attaching leg bands.

The adult falcons soar, swoop and shriek as Ulvi goes about his biology business. They sometimes miss his head only by inches.

The three balls of fluff are all head, stomach and beak now, but their elbow-like wings will feather out soon and carry them from this narrow aerie ledge in the sub-Arctic to South America--one of nature’s longest migrations.

“Look at your pretty new bracelets,” Ulvi says softly to the fledgling birds, whose numbers have increased again since DDT use was outlawed in the United States in 1972.

However, the toxic chemical still is used in some South American and Central American countries where the peregrines winter.

The pesticide began its deadly work slowly and silently about two decades ago. Peregrines ingested it after eating their prey, which range from robins to mallards. It passed through their streamlined bodies and thinned eggshells, which broke in the nest, wiping out the hatch.

Their population dwindled to such an extent in the United States that they were placed on the federal Endangered Species List.

Largely because of that protection, they appear to be thriving across their summer breeding grounds in Alaska and may be “delisted” soon, Ulvi says.

“It’s a significant management success story,” he said.

The 40-year-old Ulvi is a ranger and chief of resource management at Yukon-Charley Rivers National Preserve when he isn’t climbing bluffs of rocks, guiding inflatable rafts down the sparkling clear Charley River and bird-watching with two spotting scopes.

He has been counting beaks on this river for 11 summers.

Along with a dozen other “cooperators,” Ulvi gathers a variety of information for a federal computer database.

The information ranges from feathers and bone scraps to blood samples. It is used to flesh out density population figures, migration routes, food chain data and habitat details.

“The upper Yukon is a body of peregrine biological and ecological data that is unprecedented and unmatched anywhere in the world,” he said. “It gives us a huge database about a high-density and expanding population. There is no other place with these kinds of sample sizes.”

Still, little is known about this most fearsome of raptors, the peregrine falcon.

“We don’t really know their migration routes. Adult birds banded here have been found on the East Coast and in south Texas. We don’t know if they move in family groups or alone. We don’t know, really, how long the trips take. We don’t know a lot of things.”

That’s one of the reasons why Ulvi is cradling the chicks while perched precariously on this narrow shelf of crumbling rock about 450 feet above the Charley River.

Peregrine falcons are not the largest of raptors. But they are fiercely territorial when protecting their young, although they may abandon aeries if drastically hassled.

“We’ve seen peregrines in defense of their nest drive off grizzly bears, eat an ermine that crawled into their aerie and regularly drive off golden and bald eagles,” he said.

What is known about the birds is that peregrines generally reach adulthood in two years. Adult females generally lay a clutch of four eggs early in May, with the chicks hatching 33 days later.

They are the most majestic of hunters, capable of 200-m.p.h. speeds when diving on a flying food source.

Peregrines symbolize the sport of kings--the use of falcons to hunt game. It is a practice that reached its peak during the Middle Ages in Europe but which goes back at least 4,000 years to Asia.

Ulvi runs the Charley twice a year.

Scaling the ledges, sometimes rappeling down sheer cliffs, he attaches two bands to the legs of each chick.

One is a U.S. Fish and Wildlife Service aluminum band that tracks the bird should it be trapped as an adult or if its carcass is found anywhere in the Americas.

The other is a colored metal band with large numbers that can be read a quarter of a mile away through a 1,400-millimeter scope. That helps identify the dispersal habits of adult birds that were banded as chicks a few years earlier.

On this trip, Ulvi sights eight active aeries. He succeeds in banding 10 of a dozen known chicks. The others were in an area even he couldn’t reach.

That number is down slightly from the typical nine or 10 aeries, but Ulvi says he may have missed some birds and others may have been exhibiting abnormal behavior because of a 30,000-acre wildfire that had scorched the area two days earlier.

The Charley is just one wilderness watershed favored by peregrines. Still more live high atop the 1,500-foot ridges lining the upper Yukon River in this remote section of east-central Alaska.

Other peregrine populations are found along the Upper Tanana, Colville and Sagavanirktok rivers, the latter two on Alaska’s North Slope.

The Yukon-Charley Rivers National Preserve was formed in part to help protect the birds, which breed here in concentrations found nowhere else in North America.

It’s a trackless area of 2.5 million acres, but with fewer residents now than during the heyday of the Klondike Gold Rush in the late 1890s.

Park headquarters are a couple of small, wood-frame buildings on the outskirts of Eagle, a bush community of about 160 strongly independent residents whose road to the rest of the world is closed by snow in winter. That leaves them with the frozen Yukon or the airport.

Although the reserve encompasses a wilderness of untouched beauty, it’s one of the National Park System’s least penetrated parks.

Most of the rangers travel the backcountry during the short but bright Alaska summer, conducting Dall sheep surveys, studying Arctic steppe vegetation or monitoring lightning-generated wildfires.

Volunteers greet visitors from a small A-frame shed with a mosquito net for a door. Headquarters, about 100 yards away, has no banks of pay phones and only an outdoor privy. Eagle’s patchwork of unsurfaced streets are rutted and dusty.

But all that suits Ulvi just fine. Or at least it has since the mid-1970s, when he arrived from Oregon with his future bride, Lynette, to homestead upriver from Eagle, just a few miles from the Canadian border.

He was one of the many “intriguing folk” discovered by author John McPhee in his book “Coming Into the Country.” McPhee described the then-25-year-old Ulvi as a “cinematically handsome man,” self-sufficient and comfortable in the wilderness.

He recounted how Ulvi and a friend survived, but barely, a canoe trip in the midst of floating ice on the Yukon River--chunks large enough to crush the craft like an aluminum can.

Ulvi not only survived but thrived, proving to be one of the Park Service’s best local hires, federal officials said.

While living in the bush, he fathered two children, ran trap lines with sled dogs, canned, fished, hunted, gardened and read in the family’s handcrafted cabin during the long, dark winters that often see temperatures plunge to 60 degrees below zero.

But the family is now in Fairbanks, where the children have discovered ballet and soccer and Lynette is a seamstress.

That familial tug has made this his last banding trip on the Charley, perhaps his last ride on the 106-mile river for a number of years.

He is quitting the Park Service this fall to return to the University of Alaska-Fairbanks where he is one statistics course short of a bachelor of science degree and perhaps another career change.

“I want to come back here with my grandkids someday,” he said. “I want them to see the peregrines. I want them to see what I’ve seen, what this is all about.”