Bears have been coming down from the mountains, wanting a drink. Thirsty groundhogs are believed to be gnawing on radiator hoses. Even squirrels have been seen spread-eagled on the cool boards of outdoor walkways, seeking a break from the weather.

Birds are panting. Bees are fanning their muggy hives. And box turtles have wisely sought the peace of their hot weather slumber called estivation.

All around, as humans groaned through another slightly less sultry day of the July heat wave, other creatures have been trying to cope. The animal world has been sweating it out -- except for moles, which don't perspire, and the two-spotted spider mite, which loves this weather -- awaiting the cool and the rain.

Plants and animals, it seems, can be just as bugged by the heat and drought as people and, like us, will resort to an amazing array of mechanisms to stay cool, according to naturalists surveyed yesterday.

Bears, for example, have been boldly sauntering out of the parched Catoctin Mountains in search of water.

There have been 18 bear sightings in the Chesapeake and Ohio Canal National Historical Park in the last two weeks, the first such sightings ever in the park, Douglas Stover, chief of the park's resource management, said yesterday.

The sightings have occurred between Harpers Ferry, W.Va., and Antietam in the park, which parallels the Potomac River along the old C&O Canal, Stover said, although a bear also was seen in late June in Germantown.

"What brings the bears down from the mountains is mainly lack of water," he said. "This park has never seen or reported any bear activity. This is very unusual to see this."

Stover said groundhogs, too, have been acting oddly -- apparently chewing on car radiator hoses and on building air-conditioner condensers in search of liquid. He said park officials have started putting out bowls of water to keep the groundhogs from damaging equipment.

Many mammals keep cool by burrowing, like the groundhog, but almost all mammals also sweat to stay cool, said Charles Handley, curator of mammals at the National Museum of Natural History.

Except for the mole, an Australian anteater called an echidna and water-dwelling mammals.

Why don't moles sweat? "It's odd," Handley said. "Shrews do." But the mole leads a cool, subterranean existence and has no need of perspiration.

Why don't echidna's sweat? Handley laughed. "I don't have the slightest idea."

Squirrels also maintain a dignified cool. Although they can perspire, Handley said, the ones that live at his house chill out by lying on their stomachs on his outdoor wooden walkways. "I've never seen a sweaty squirrel," he said.

Birds also get by without breaking a sweat. But like dogs, they pant to keep cool.

"That's something that you see when they're hot," said Holliday Obrecht, a wildlife biologist at the U.S. Fish and Wildlife Service's 12,000-acre Patuxent Research Refuge, in Laurel. "It's a method of heat exchange. They open their mouths up wide. You can see them panting at a rapid rate. They have a pretty good insulation of feathers on their bodies, and heat exchange is either through their legs or their mouths."

Toads cope by burrowing under leaves or dirt, Obrecht said, and box turtles estivate: "They're not really hibernating, but it's a kind of prolonged sleep that they go through during real hot weather."

Trees, too, have ways to deal with heat and drought -- in one mechanism, actually closing the pores, or stomates, on the backs of leaves to retain moisture and maintain their internal water pressure, he said.

Some trees also reproduce wildly in a kind of survival response to stressful weather conditions, he said, adding that the hot, dry summer weather could produce a bounty of seeds and acorns in the fall for deer and squirrels.

"When they get under stress, there's no guarantee that they're going to survive . . . so they put all their energy into reproduction," he said.

Among the insects, Obrecht said, bees have been busy in the heat.

"Honey bees get very, very active," he said. "The warmer it is, the more active. . . . They also have to worry about keeping the hive cool in this kind of weather. Sometimes you'll see them, and their wings will be beating to keep the hive cool. Like a million little fans."

Certain bugs, though, thrive on hot weather, said Julie Steele, an entomologist with the plant and pest diagnostic clinic of Ohio State University.

The minute, eight-legged, two-spotted spider mite, for one.

The mite, an almost translucent leaf-eating bug about the size of a period, reproduces much more rapidly in hot weather, Steele said. "They can produce a new generation every three days when it's up in the 90s."

She said mites are being seen in numbers like those during the drought of 1988. They are partial to soybeans and all kinds of flowers.

Flies also are having a ball, she said. "Just your typical flies that breed in garbage and manure. They breed much more quickly when it's hot. It's just a shortened time in their development. What normally might take a week, they can do in five days or four days."

For others, these times are potentially the toughest.

The National Zoo's giant panda, Hsing-Hsing, is large, furry, old and ailing.

But he is faring well, zoo spokesman Bob Hoage said.

"He doesn't go out in weather like this," Hoage said. He can stay in his air-conditioned quarters, and unlike many of his fellow creatures lately, "he's had a string of good days."