It's "The Silence Beneath The Bark (Le silence sous l'écorce )" by Joanne Lurie, and it's both wonderfully playful and beautifully animated. Seems to exist more as a mood than as a story, but that's not a criticism. (The teeth are a bit ...surprising and I'm not really sure what happens at the end—it turns into a tree, maybe?—but the feathery animation is a keeper, for sure.)
Two tree-creatures hibernating underneath the bark of their respective tree wake up by the quakes produced by the snowfall outside, so they go out to explore and that's how they meet each other.
Attribution(s): All video and stills are the property of Joanna Lurie and other respective production studios and distributors.