Bats, of all things. Deep in Yellowstone National Park's outback, where we had hoped to see wolves and grizzlies and elk and moose, we seemingly were under siege by a bevy of bats.

Unlike wolves and bears, the park's popular poster children, bats have absolutely no charisma. They are the denizens of the night and nightmares, of Bela Lugosi movies. While these furry mice-with-wings might be the only known mammals that can fly without the aid of an airplane, they are not at all cute or cuddly to me or my wife. Hence our mixed emotions when, as we were paddling into Shoshone Lake's sunset, we suddenly found ourselves swarmed by dive-bombing bats.

Fortunately, we were not the objects of the bats' aerial acrobatics. Truth is, they didn't even seem to notice us. While we were plying the lake's waters to enjoy the sunset, the glassy water and the stars that would shortly appear, the bats were focused on their nightly meal. "Little Brown Bats," which biologists know as myotus lucifugus and which we later guessed that these guys probably were, are pretty voracious critters for their size. In a minute each of these bats with their 9-inch wingspans can devour a half-dozen insects, and in 15 minutes they're gorged.

Skimming the lake's surface to wash down their meals, and to snatch any insects that might be hovering above, or on top of, the inky black water, the two dozen or so bats darted left and right and up and down about us. With their on-board sonar they deftly dodged us while concentrating on the meal at hand. Then, just as quickly as we had come upon them, they were gone, vanishing into the darkness that bonded the sky and the lake's surface together.

Just like that the watery wilderness and its surrounding forests had revealed an unexpected aspect of Yellowstone's wild kingdom. While Shoshone Lake is known for its moose, and lies within bear habitat, no one had told us to expect bats during our four-day paddle around the lake.

"In reality," Roy Renkin, one of Yellowstone's staff biologists, told me after we returned, "there is very little known about the bats in the park. What is known is based on distribution maps that are published somewhere else."

Renkin and other Yellowstone biologists can tell you that bats will roost in the attics of old buildings and that at Grant Village they like the backside of a particular sign, apparently because it is warmed by the
rising sun. But while tomes have been written on Yellowstone's charismatic mega-fauna, it's tough to find a chapter devoted to the park's bats.

So while biologists know that as many as nine species of bats might be flitting about the park after dark during the summer months, in reality only five have been confirmed by sightings. As a result, Renkin was hard-pressed to say exactly which species we encountered, or explain where in the Shoshone area they spend their days.

"Roosting kinds of habitat (in Yellowstone) is not very limited for males and non-reproductive females," he said. "I'm thinking about the little brown bats. They'll roost temporarily, one-night-stand activity, in tree cavities and rock outcrops, those kinds of things. It's the child-bearing segment, or the pup-bearing segment of the population, the females, whose roosting habitats seem to be very limited. ... Where they would roost out in nature is really a big hole. No one really knows."

While bats, of course, like caves, Renkin couldn't think of any in the vicinity of Shoshone Lake. However, he did point out that there was one case, reported back in the 1980s, of a bat roosting behind a rock in a thermal area near Madison. It's possible, he suggested, that the Shoshone bats hang out in the geyser basin on the lake's western shore, but again there's no documentation.

Most Yellowstone visitors no doubt know about as much about bats as they do about Shoshone Lake; in other words, not much. Squeezed between the Pitchstone Plateau and Craig Pass at an elevation of 7,791 feet, no roads snake back to the seven-mile-long lake where mechanized locomotion is banned and humans visit by foot or muscle-powered craft or not at all. A bowl-shaped depression blown out of the landscape by the park's prehistoric volcanics, Shoshone with its 28 miles of shoreline officially is the largest backcountry lake in the Lower 48. Little vegetation grows in the lake's clear, cold waters, which during their storm-tossed churning can resemble an inland ocean, one that's cruelly unforgiving to the unprepared.

Unless you hike or paddle to Shoshone Lake, the only way to glimpse it is to stop at Shoshone Point on Craig Pass and gaze southward. Yet in spite of its remoteness, it's highly popular with Yellowstone's backcountry travelers.

"Shoshone is the busiest backcountry destination in the park, as you may have seen some evidence of," Pat Navaille, who spent many years patrolling the lake and its surrounding backcountry before moving on to Glacier National Park, told me. "It gets a lot of use, a lot of the type of use that produces a lot of impact."

Negative impact, to be sure. In 1992, backcountry use around the lake, with its 23 campsites and 50-some miles of trail, was so high park officials banned wood campfires because the users were stripping the forests to feed their fires. Before the prohibition took effect, Navaille recalls a two-year period during which 5,000 or so trees were illegally cut down for firewood.

In spite of the heavy use, Shoshone Lake remains something of a haven for shorebirds, particularly along the western shore. There an extensive marshland has created the richest area, biologically speaking, on the lake. Thermal activity related to the nearby geyser basin warms the marshland and nourishes its vegetation. During our trip, gangly-legged great blue herons stalked through the marsh, using their keen eyesight, quick moves and sharp beaks to pluck meals from the water. Stilts, avocets, mergansers, king fishers, trumpeter swans and other waterfowl also frequent the area, particularly in the springtime.

While no bald eagles have been spotted nesting along the lake in recent years, there are a few osprey nests, which the attentive paddler can spot. Perhaps there would be more if the lake weren't so
deep. How deep it is, no one really knows. While a 1966 study that indicated Shoshone is 205 feet deep, but adds that today's high-tech fish finders have reported depths surpassing 300 feet, making it tough for a bird of prey to pluck a meal out of the water.

The meals are there, too. Although initially barren, in 1890 Captain Frazier Augustus Boutelle, a Civil War veteran and the second military officer to serve as the park's acting superintendent, was determined to see the park's barren waters stocked so "the pleasure-seeker in the park can enjoy fine fishing within a few rods of any hotel or camp." Lake Michigan mackinaw, better known today as lake trout, were then shipped by train and packhorse to Yellowstone where they were dumped into both Lewis and Shoshone lakes. Today both lake trout and brown trout make the lake a vibrant fishery.

But the trout shun warm waters, and soon after Shoshone is free of ice in summer they head for deep water. For that reason, says Terry McEneaney, Yellowstone's staff ornithologist, osprey and eagles don't flock to the lake. The raptors, he says, prefer shallow waters for their fishing. The Lewis Channel, which connects Shoshone and Lewis lakes, is more to their liking, as evidenced in the fall when eagles arrive to snag some of the brown trout that spawn in the channel. Joining the bald eagles are trumpeter swans and tundra swans, which enjoy the channel's succulent vegetation.

What Shoshone lacks in quantity, though, it makes up in variety, as evidenced by the bats and some unusual migratory birds that stumble upon the area. One year, for instance, an Asiatic form of Murrelet was spotted.

"It goes to show you that some rare birds can show up on those lakes," says McEneaney. "In some of the meadows around Shoshone Lake you might get Great Gray Owls, northern Goshawk. Stellar jays are pretty typical around there, gray jays. Red crossbills, white-winged crossbills, they come by."

What some birds struggle with once they arrive in the area is the underlying geology, according to the birder.

"It screws up birds that are migrating," McEneaney says. "What happens is there is a lot of electromagnetic rock in that area. If you go south down onto the Pitchstone Plateau a compass will go crazy. Migrating birds, birds like pigeons, that are very sensitive to electromagnetic changes, we've had a number of birds that have been a little confused down there.

"Particularly homing pigeons. One time I can remember a homing pigeon that couldn't fly
out of there. It just kept flying in circles," McEneaney says. "Every once in a while we will see
birds like swans get a little confused about getting out of there."