Seemingly unaffected, buffalo roam the parched South Dakota prairie on America's largest bison ranch while crops wither and domestic livestock suffer and even die because of the drought.

"Nature sure gave them about everything it takes to survive . . . except the bullet," said Roy Houck, who with his late wife, Nellie, started the Houck Buffalo Ranch nearly three decades ago.The hardy bison, native to North America, were hunted to near extinction in the late 1800s for its skins and meat.

Houck's buffalo forage on brown grass and linger near water holes. The ranch has more than 200 ponds, all of which have been drawn down by the drought, and some are almost dry.

Depending on the season, 3,000 to 4,500 buffalo inhabit the 50,000-acre ranch that's fenced into 35 pastures.

After the various herds are allowed to graze in one pasture for a few weeks, the gate to the next pasture is opened, and the huge beasts move into the area to resume foraging.

"The main breeding herd, we don't feed them anything but grass," said the 83-year-old Houck. "We try to supplement the calves a little the first year to give them a boost."

Although the drought seems not to have affected the herd, its impact may show up next spring in a smaller calf crop, Houck said, explaining that this is the mating season.

"These cows won't conceive if they're not in good shape," Houck said, glancing over at the rummaging animals about 30 yards away. "But so far these cows look pretty good."

The ranch hasn't had a decent rain in more than a year, and 100-plus-degree temperatures have been common all summer.

But the drought of 1988 is no match yet for the Dust Bowl days of the 1930s, Houck said.

"The dry dust storms of the '30s still haunt me," he said. "It was so dry in the spring of 1934 the grass never even sprouted."

Not that Houck isn't concerned now.

"If we're forced into another year of drought, we'll probably have to graze our pastures a lot longer than we'd like to," he said. "After going through those dry '30s, you wonder how long it's going to last.

"We've got to be pretty cautious because you can't just load buffalo on a truck and take them to the sale barn."

Buffalo enjoy their freedom and are handled as little as possible.

"When you get them in confinement, they've only got one thought in mind and that's to get away," Houck said. "If you happen to be in the way, that's too bad."

Horses once were used to round up the buffalo. Four-wheel drive trucks are now used.

"Buffaloes don't seem to like horses" and besides can outrun them, Houck said. One of his sons once "got his horse knocked right out from under him" by an angry buffalo.

When buffaloes are 2 years old, they are sorted for bulls and heifers. Most bulls go to slaughter and heifers are kept for breeding.

Between 800 and 1,000 are butchered on the ranch each year, Houck said.

The market for buffalo meat, which is very low in fat, has been good, Houck said. "Right now, we're getting $2 a pound for dressed buffalo meat."

Once an endangered species, buffalo have made a remarkable comeback, said Mary Duvall, executive director of the National Buffalo Association. Buffalo numbers are estimated at between 75,000 and 100,000, she said.

The Houcks began ranching by raising cattle. They switched to buffalo after a March 1966 blizzard that killed more than 200 of their cattle but not a single buffalo.

"They'll just stick their noses down into the snow and eat this grass, and they'll stay fat on it," Houck said. "I wonder how they do it, but they do."