The ponderosa and the flammulated.

Needed now: more data on one of the nation's most threatened forest types and a little-known bird that lives there.

NEARLY EVERYONE old enough to watch TV is familiar with the debate over the endangered spotted owl and the remaining old-growth forests of the Pacific Northwest. In the Rocky Mountain region, too, there are old-growth forests in danger of disappearing, and these forests aren't receiving nearly the publicity claimed by those in Washington, Oregon, California, and Alaska. Few people have noticed that old-growth ponderosa pine is disappearing at an alarming rate. Only recently have most forest managers begun taking stock of it, and they've discovered that in many areas there is virtually no old-growth ponderosa left. It is by far the most endangered forest type in the Rocky Mountain West, and perhaps in the entire country.

Old-growth ponderosa forests appear to have little in common with Pacific rainforests, but old-growth ponderosa, like its more verdant relative, is home to an owl species that appears to be dependent upon it. Until 13 years ago, little if any research had been done on flammulated owls; just over a century ago the species was unknown to science. No one knew what kind of habitat the bird depended on for survival, whether it was a year-round resident or migratory, or even what prey species it depended upon.

In 1979, Dr. Richard Reynolds, working at the Manitou Experimental Forest in Colorado's Front Range, began an extensive study of flammulated owls. Reynolds and his assistant, Brian Linkhart, concluded that flammulated owls have remained a mystery for so long because they are so small and because they are strictly nocturnal.

Just over six inches long, the flammulated owl is the smallest of the screech owls. Reynolds and Linkhart were immediately captivated. Over the next 13 years they banded and weighed more than 200 birds, fitted many with radio transmitters, and spent countless hours in the dark observing them.

When motionless, flammulated owls are nearly invisible, and with good reason. Accipiters, which have keen eyesight, are one of the owl's biggest predators; Reynolds and Linkhart retrieved several transmitters from the nests of sharp-shinned and Cooper's hawks. At night a flammulated owl's biggest worry is other owls.

Reynold's and Linkhart's base of operations was an experimental forest that has large areas of ponderosa pine and Douglas-fir older than 200 years. This ecosystem, largely overlooked in studies of flora and fauna diversity, has been decimated by civilization.

"There is almost no old-growth ponderosa left in our jurisdiction," says Dennis Lowry, wildlife biologist for Arapaho/Roosevelt National Forest. "Of 194,000 acres of ponderosa pine on Arapaho/Roosevelt, only 337 acres are old-growth. That's 0.2 percent. Our inventory is not yet complete, but we don't expect those figures to change significantly. Colorado's other national forests are pretty much in the same boat."

Claudia Regan, an ecologist for the U.S. Forest Service, says, "Old-growth ponderosa is unquestionably the most endangered forest-habitat type in the Rocky Mountain West." She had trouble locating stands of it that might serve as study areas. It's obvious that forest managers must try to balance the interests of industry, recreation, and wildlife in these areas with little understanding of the ecosystem's makeup.

Ponderosa pine is one of the West's most commercially valuable trees. These forests occur at relatively low elevations that often remain snow-free for much of the year, making them accessible all year. More than a century ago the timber industry discovered their potential value.

Property owners, too, have discovered the ponderosa forests in recent years as they move away from the city. With the exception of a few mountain parks, the once-extensive old-growth ponderosa forests of Colorado's Front Range are now almost entirely housing developments. A spokesperson for Jefferson County Open Space says that, conservatively speaking, 85 to 90 percent of this habitat is now in private hands.

Flammulated owls live mainly in forests of yellow pine (a group of closely related species that include the ponderosa) from southern British Columbia through the highlands of Mexico and Guatemala. Nesting birds have been reported from the Rockies to the Pacific, and from southern British Columbia to Veracruz, Mexico.

Although there is no substantiating data yet, most researchers believe that flammulated owls from the northern forests migrate to Mexico and Central America for the winter. The owls generally return to Colorado in May and set up housekeeping around a cavity (they are obligate cavity nesters). Two or three eggs are laid, and after 22 nights the chicks hatch. The young leave the nest after 23 nights, but the adults continue to feed them for several more weeks. The chicks disperse in late August, and the adults remain in the area until early October.

After 13 years of monitoring, researchers saw a record set during the 1992 breeding season: A pair of owls remained together for a fifth consecutive year. Researchers have never observed a mated pair that showed up the next year paired with different birds. "But we still don't know if they mate for life," Linkhart says. "They definitely have great fidelity to territory." If a pair of owls breed in a territory one year, both will try to return to that territory the next. If both survive, they will mate again.

Flammulated owls appear to be strictly insectivorous. There have been reports of their preying on everything from small mammals to sleeping birds. But Reynolds and Linkhart discount these reports, and believe that people may be crediting the birds with a fierceness that is a characteristic of other owl species. For one thing, a flammulated's claws are probably too delicate to kill a small bird or mammal.

Up to four times as many insects are associated with ponderosa pine and Douglas-fir as with any other western conifer, completed research shows. Many of these insects are found only in ponderosa-pine/Douglas-fir forests.

Many of these species--particularly those the owls depend on early in the breeding season (May and June)--belong to the Noctuid family of moths (appropriately called owlet moths). Flammulated owls often experience late snows and nights of below-freezing temperatures in much of their range. Many Noctuids have a natural "anti-freeze" in their bodies, and can remain active at much lower temperatures than most insects. Without these insects' ability to remain active in cold temperatures, flammulated owls would not be able to use much of the habitat in which they currently breed.

Like all owls, flammulateds cough up pellets. Unlike other owls, however, it is hard to find the flammulated by an accumulation of its pellets, because the pellets consist almost entirely of insect exoskeletons, which break up quickly.

Warblers, bluebirds, and many other insect-eating birds can fill their beaks with a veritable smorgasbord of bugs before returning to their nest. Flammulated owls bring only one prey item back to the nest in each trip. While the eggs are being incubated and the chicks are small, the male does all the hunting. He makes many trips to and from the nest each night. And since foraging habitat may be hundreds of yards from the nest, he expends a tremendous amount of energy while the chicks are fledgling. By the time they leave the nest, the chicks usually outweigh the adults.

By following owls fitted with transmitters, it was discovered that flammulateds prefer to hunt for insects in old-growth ponderosa pine and Douglas-fir. Their home ranges averaged 14.3 hectares (34.6 acres), and always included some old-growth ponderosa. The more old-growth ponderosa, the smaller the home range; the number of nests was greatest in areas of continuous old-growth ponderosa.

To understand just why flammulated owls are tied to old-growth ponderosa forests, it is necessary to look at the forest's characteristics:

1. Ponderosa/Douglas-fir forests are favored by more insect species than other conifer ecosystems.

2. Old-growth forests in general have an abundance of cavities and snags necessary for nesting.

3. Many conifers form dense groves, but old-growth ponderosa typically forms open, park-like stands.

The trees are widely spaced and have extensive grassy or shrubby understories that support much of the owl's prey. Late in summer, when fledglings are still mastering the art of flight, dropping from low understory perches to catch bugs is a favorite foraging technique. The open nature of the forest allows the owls to catch insects in midair, or to hover around the tree's crown and glean insects from the needle bunches.

Fire plays an important role in shaping old-growth ponderosa forests. Periodic burning rejuvenates the underbrush, and kills any seedlings that compete with older trees. Forest fires seldom are hot enough to harm the mature trees.

For decades, though, we humans have fought forest fires tooth and nail. Even today, as we come to understand its role in forest ecology, fire is seldom allowed to burn in ponderosa forests. These forests are far too valuable to the timber industry to let even a few trees succumb to fire. Also, the large numbers of people now living among the trees probably would not understand the potential benefits of letting a fire go unchecked in their neighborhood. Consequently, most of the remaining old-growth ponderosa forests are not in very good shape, from the flammulated owl's perspective. Since the arrival of Europeans, tree density has risen from as few as 23 trees per acre to as many as 850 trees per acre--hardly enough room for an owl to maneuver.

Interestingly, one of the principal foes of old-growth offers a possible solution to the ailing ponderosa forests. Selective logging--cutting only the young trees out of old stands--is one way to bring back the characteristics of old-growth forest. This idea is still untried on a large scale, but the hope is that by cutting the young trees and reseeding the area with grasses and shrubs, foresters can reproduce the conditions typically found there.

Controlled burns are another way to improve the health of this ecosystem. Reintroducing fire to a habitat that evolved with fire is almost always beneficial, but with as many as 850 trees per acre in today's ponderosa forests, some sort of selective logging would be needed before a controlled burn could be attempted.

All we have now are some ideas on how we might improve the old-growth that remains. We have precious little data on species that depend on this habitat--like the flammulated owl. We don't even know how long it will be until the flammulated's habitat becomes too fragmented to support it.

"Old-growth forests are special places," Reynolds says. "They possess unique qualities that distinguish them from less mature forests. Many plants and animals attain their highest population density and productivity in old-growth forests, and some species--such as the flammulated owl--may disappear without sufficient acreage of old-growth ponderosa pine."

Cathy and Gordon Illg operate a writing and photography business from their home in Golden, Colorado.