I came across a family of grey squirrels at the Fletcher Wildlife Garden today. There were a couple of youngsters, one grey, and one black (the melanistic morph), with a grey mother. They had renovated a roosting box put up a couple of years back. In the box, the entrance hole is at the bottom front (it is designed for birds to use for roosting in winter), but squirrels prefer to have entrances high up and so they made this one at the top side. Junior couldn't resist sticking his head out when I stopped for a photo. As for the use of the roosting box by squirrels, I've found that the overwintering birds, if they are cavity users, rely on nest boxes and tree cavities, or even huddling against the trunk of a spruce or fir. We put up the roosting boxes mainly to show people what they look like, and to provide additional places for birds, if they wished to use them.