With the severed head wrapped in black plastic and stowed in the snowmobile trailer, Anna and the others shuffled back to the Beaver and finished transferring gear and food into the trailer around the moose head. Because of the size and awkward shape of the antlers, the trailer’s lid had to be propped partly open. Adam driving, Bob behind him, and Ridley, boots planted wide on the rear runners like a musher with a mechanized pack of dogs, headed up to the bunkhouse.

The Forest Service plane took off, leaving the ground in a surprisingly short time and disappearing around Beaver Island as the pilot used the length of Washington Harbor to get up to altitude for the flight back to Ely.

The sounds of internal combustion machines, simultaneously anachronistic and a reassuring reminder that Winter Study team was not marooned on an icebound island in the time of the mastodons, grew fainter. Anna wanted to hear the ice singing again, but there was nothing but the quarreling of ravens.

For a moment, she, Robin and Jonah stood without speaking, eyes on the sky where the USFS plane had gone. Then, as if moved by the same impulse, the way a flock of birds will suddenly change directions, they turned and followed the track left by the snowmobile. Ungainly in bulky clothes, boots unsure on the slippery surface, Anna felt like a toddler. Robin, doing a kind of Texas two-step, the soles of her soft mukluks never leaving the surface of the lake, shuffled expertly along.

Partway back to the dock, a supercub was tied down, a tandem-seat fabric airplane used since before World War II for air reconnaissance, search and rescue, hunting – any job that called for flying low and slow and being able to land anywhere the pilot had the guts to set it down. This one was a classic, down to the fat brown teddy bear painted on the tail, and skis where wheels would be in summer. Lines, dropped through holes cut in the ice and held there by lengths of two-by-four, were gripped by the ice when the hole froze again, making as firm a tie-down as any hook set in concrete.