“They’re called birke because they look like the trees—only they aren’t. They’re sprites who prowl the Wood. Once, they fed on idleweed, but folk here keep it stored up for ceremonial or medicinal practices. Now, the birke feed on flesh. And what flesh they like best—” She tapped her brow. “Eyes. That’s why we paint charcoal on our faces. The illusion of hollowed skulls.