Trick?

Bright day today.  Gorgeous to me.  The water was so clear, you could see bottom at places that are usually cloudy.  Some of the vegetation has been cleared along the shores as well.  The work of muskrats perhaps?  Today I noticed a birdhouse I haven't seen before.  I looked at it from all angles.  Have I been tricked?

A birdhouse with no hole?  Is there even a roof?

Looks like it has been there a long time.  I don't know.  Do you?

Hope you enjoyed!

~ Robin