One Snowy Night by Nick Butterworth

From chapters.ca:
Percy the Park Keeper always feeds the animals in the park where he lives. But one cold winter's night Percy discovers that his little friends need more than food and he must find a way to help them find a warm place to sleep for the night. Percy's hut is nice and warm but Percy discovers that if you invite one animal in you'll have to invite them all in and his hut is only small - it's certainly going to be a squash!