Even cloaked in ice, an oldsquaw duck finds Hokkaido's winter climate bearable. The ducks' densely packed feathers trap enough air to insulate them from frigid waters.

Recently, the government has made efforts to protect habitat devoted to a few species, including the red-crowned crane and Blakiston's fish-owl. Also known as Blakiston's eagle-owl, or shima-fukuro, it is arguably the largest of the world's owls and one of its most endangered. But Yulia fears that it may be too late for some species, including the fish-owl. "There are not many of these birds left," Yulia tells me, as we head toward the owl's haunts at the eastern edge of the island. "And you'll see why. Most live in an area once called Nimuoro, an old Ainu word meaning 'the place of many trees.'"

Just after sunset on the bank of a small river near the city of Nemuro, we are waiting for the appearance of shima-fukuro at a feeding station, a small raised wooden platform set on a pole not far from the river. With us is the world's expert on the fish-owl, Sumio Yamamoto, who has brought fish for the owls' evening feeding and put it on the platform. A tall, wry man in his 50s, Yamamoto has studied the fish-owl for 30 years. There was a time when the bird was found all over Hokkaido, he explains, as far west as Sapporo. But changes in the 19th and 20th centuries—the cutting of old-growth trees, which are the nesting sites for these owls, and the construction of dams and channeling of rivers, which eliminated most native fish runs—have reduced its numbers in Japan to only 130 birds.

The sky darkens, and the fish sits. I don't know how long we wait in the dark, talking in low voices and blowing on our hands for warmth. A quarter moon rises, just enough to set the snow glowing. We stop our chatter and listen. A few minutes later we hear a deep sonorous bo-bohhh, the call of a male fish-owl, then the female's plaintive one-note answer, bohhh. Then again, bo-bohhh. Bohhh. So tightly timed is the duet that it sounds like one bird delivering a three-note call.

To the Ainu people the fish-owl was a god of many names. It was Kunneriki, "the god crying at night"; Kotan Kuru Kamui, "the god who protects villages"; and Moshiri Kuru Kamui, "the god who protects the country." The owl's English name comes from Thomas Wright Blakiston, a British soldier, businessman, and amateur naturalist who lived in Hokkaido in the second half of the 19th century. Ironically, Blakiston may have had a hand in undoing the owl's woodlands. In 1861 Blakiston traveled to Siberia with equipment for lumbering, intent on harvesting the abundant trees on the Siberian coast of the Sea of Okhotsk—only to find that the Russian government would not grant him permission to cut. So he went on to harvest the rich forests of Hokkaido, first in Hakodate, and, when timber grew scarce, in the island's eastern reaches.

To replace nesting sites lost in the demise of old-growth trees, the Japanese government has provided more than a hundred nesting boxes. Yamamoto and his colleagues have built several feeding stations to help the owls overwinter. So far, several owl pairs have taken to these man-made solutions to man-made problems. But scarcity of habitat remains the chief factor limiting the population's growth. "These birds are territorial," Yamamoto explains. "When a chick grows up, it needs to find its own nesting territory. It does so by flying perch to perch for short distances. Around here, there's no habitat left that is not occupied by other owls, and there are few trees connecting one wooded area to another."

Farther north, on Shiretoko, there are larger forest areas well suited to the fish-owls. Yamamoto has been planting trees along riverbanks to create corridors of green all the way to Shiretoko—"a big dream on a small scale," he says, which will take 50 or 100 years to complete.

The next morning low clouds scud across a gray sky. Yamamoto leads us into a protected area set aside for the owl, a small stand of second-growth trees not far from Nemuro. The quiet is broken by the hoarse calls of jungle crows and the crunch of our boots along the snowy trail winding among the young Japanese oaks and elms, the occasional slender birch, ash, and alder. I wonder what this world must once have looked like, giant old-growth spruces and firs a hundred feet high and several feet thick. But there, in a spindly elm, Yamamoto spots an owl chick, memorable by itself for the intensity of its wild gold eye; then in another tree, another chick. Then the female, mother of the chicks, flies across our line of vision; and there, not far from her, perched on a thin limb of a young oak tree, is her mate, a magnificent creature, his great ear tufts alert to the impertinent crow hovering and croaking above his limb.