Striking across the flats, they stopped on the edge of a hollow running through the highest part. The mist was driving nearer before a cold wind, and the moon was dim, but they could see for some distance toward the west across the level stretch of sand. Nothing broke its smooth expanse, but the sound of the sea had grown louder and the wild fowl noisier.
After a few moments, Andrew struck into the hollow and began to follow it up. The sand was softer here, though there were spears of ice on the muddy pools; but the men's figures no longer cut against the sky, and Whitney knew the need for caution. The gutter got deeper as they went on, until they could not see beyond its banks, and soon it began to wind off to one side. When Andrew stopped at the turning, a wild cry that was like a hoarse laugh came out of the dark.
"What's that?" Whitney asked.
"A black-backed gull," said Andrew thoughtfully. "They're suspicious brutes and a nuisance when you're trying to crawl up to a flock of duck. In fact, it often looks as if they laughed because you'd lost your shot."
"Do you think something has disturbed the bird?"
"We'll know in a minute."
A mournful wail that ended in a quavering tremolo fell from the air as the harsh laughter died away.
"That's a curlew going over," Andrew said.
Then a shrill screaming broke out; and Andrew turned toward the bank and began to climb out of the hollow.
"Oyster-catchers now; they're all off," he said.