The boreal forest stretches across Canada and Alaska, a huge expanse of woods, wetlands and wilderness. And it’s full of magnificent forest owls that depend on mice and other rodents for food. Those populations can boom and bust, so in lean years, hungry owls often fly as far south as the northern U.S. to find food.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.