ELKHART, Iowa — Mike Wilson glared dejectedly through the mist on his silver-frame glasses at the soggy field of tall, dense brush, tilting the barrel of his 12-gauge shotgun toward the gray clouds.

“All I want to do,” he said, “is see a bird at this point.”

More than two hours into this pheasant hunt, the colorful rooster that one of Mr. Wilson’s hunting partners had shot that morning was now a distant memory. Only one other pheasant had graced the skies since, and it was too far off to even try a shot.

The pheasant, once king of Iowa’s nearly half-a-billion-dollar hunting industry, is vanishing from the state. Surveys show that the population in 2012 was the second lowest on record, 81 percent below the average over the past four decades.

The loss, pheasant hunters say, is both economic and cultural. It stems from several years of excessively damp weather and animal predators. But the factor inciting the most emotion is the loss of wildlife habitat as landowners increasingly chop down their brushy fields to plant crops to take advantage of rising commodity prices and farmland values.