“We push ‘em into the open, then we get ‘em in a ball,” he said.

The scattered cattle — a motley assemblage of breeds, including creamy Charolais, hump-shouldered Brahman and Simmental — coalesced into a driven herd, lumbering old bulls and skittering calves, lining up along a rutted dirt road and heading toward what is usually a narrow creek, but which was now more than 150 feet across.

Then things went awry. The front of the herd turned north to walk along the creek — a direction that would take them back to the inundated banks of the Colorado. So Mr. Ashcraft and his other pilots buzzed the cattle until they pivoted east and started swimming across the creek. But the line of cattle, fighting the current, missed a nice break in the trees and couldn’t seem to orient itself toward the desired shore; they started swimming in a swirling circle, which could lead to a panic and drownings.

More buzzing. More mashing. The circle broke up, and the pilots urged the cattle toward a break in the trees. Some cows straggled through, while the rest turned back to the original bank.

“Well, that didn’t work so well,” Mr. Ashcraft grumbled over the radio channel. The men conferred, and decided to leave the cattle to “rest up a little bit.” The sun was setting, and they can’t do this work at night.

It was time to go home and get some rest. Mr. Ashcraft’s phone had filled up with new requests for assistance. At sunrise, he would be in the air again.