Nation’s Skies Inundated by Ducks : Wildlife: Wet weather and greater acreage increases population to 80 million. Southbound wings have jammed air traffic radar.

Ducks seem to be everywhere this year, so numerous that their fall migration jammed air traffic control radar at three Midwest airports.

“It may end tomorrow. But we’re on an impressive roll right now,” said Dave Sharp of the U.S. Fish & Wildlife Service in Denver.

Two wet years and a federal crop reduction program have helped North America’s duck population increase by 30%, wildlife officials say.

Ten years ago, wildlife officials estimated North America had 52 million ducks. By 1993 the estimate was 59 million, and this year that had risen to 80 million, Sharp said.

He said the main reasons for the population boom are above-average moisture in the prairie region of the Dakotas and Canada, and the federal Conservation Reserve Program, which pays farmers to take farmland out of production.

“The one thing, without question, was the return of water to the prairies,” Sharp said. “If you don’t have water, none of the other things matter.”

The Conservation Reserve program in the Dakotas and Montana also figured into the equation, improving nest cover so more young could survive.

“Now . . . you’ve got water, cover and fertile feeding areas, so you got females that can lay several clutches,” Sharp said.

This fall’s migratory flight to winter grounds in Mexico and the Texas Gulf Coast was extraordinary.

Waterfowl in Canada and the upper United States “were enjoying a leisurely fall and hadn’t moved much into the end of October. Then two real strong cold fronts swept across the country out of Canada,” said Jeff Nelson, chief biologist of Ducks Unlimited.

That sent millions of birds on their way south all at once.

On Nov. 2, there were so many birds in the air that they blotted out air traffic radar systems in Des Moines, Iowa; Omaha, Neb.; and Kansas City, Mo., Nelson said.

“It just jammed them on the order of a couple of hours as the wave went by,” he said. No accidents were reported, but some flights were delayed for hours, officials said.

The abundance, however, does not extend to some other waterfowl. The autumn Canada goose hunting season was canceled along parts of the East Coast this year because of a decline in the population of geese migrating from northern Quebec.

According to a report for the International Assn. of Fish and Wildlife Agencies cited by Sharp, assorted waterfowl in the United States support a $20-billion annual industry involving hunters, bird watchers and related markets.

Ducks Unlimited, a nonprofit privately funded conservation organization, and other conservationists are concerned about proposals in Washington to cut Conservation Reserve funding in half. Ducks Unlimited is credited with protecting or restoring 7 million acres of North American wetland.

Conservation Reserve now gets $1.8 billion a year with 36.4 million acres enrolled. New legislation would cap acreage at that level, then gradually reduce funding to $990 million by 2002, said John Burt of the Natural Resources Conservation Service in Washington.

Ducks Unlimited is lobbying to make wildlife concerns on an equal footing in the granting of Conservation Reserve contracts.

“We think with some improvements in efficiency in targeting and keeping more closely in line with local prevailing [agricultural land] rents, we can get just about as many acres” as under the old funding, Nelson said.