t’s like the sound of a large piece of wood being smacked hard on to water. Not the sharp, narrow crack of a rifle, but something heavier, flatter. Howard Garrett immediately knows what it is.

“That’s a whale,” he says, hurrying to the balcony. “It was slapping its tail. And those are blows – exhalations. There are several. Those blows had different sounds.” For the past four decades, Garrett has been monitoring the killer whales of the Puget Sound with rare intensity. He and his half-brother, Ken Balcomb, are among scores of naturalists, some paid, most volunteers, who track the precise movement of the creatures on a daily, or even hourly, basis.