Chipmunk Door

I received this mini door (about 10 inches high) from my grandchildren last year, after they had visited and been intrigued by a hole at the base of this tree. Each day they had placed various toy critters and dolls near or in the hole, all the while carrying on an endless story.

Chipmunks use the door now, but when the grandchildren return, it will be overrun with other creatures.

Whoever thought to make this little door?