In the course of its normal operation, your dryer vent exhausts stale, warm air from the appliance to the outdoors. That’s fine, in theory. But on a frigid winter day, that warmth can become a beacon that lures shelter-seeking pests of all types. Fortunately, dryer vents typically come with a damper that, among other functions, prevents creatures from tunneling in. Perform due diligence, though, and double-check that the damper hasn't become damaged or stuck open. As well, examine for cracks along the seal between the vent and the surrounding wall.