I have a question about a pair of Blue Grosbeaks that have displayed a particular interest with trying to come through the windows specifically the French doors and transom on our back porch adjacent to our deck table and chairs.  

The pair are quite persistent.  The male is aggressively attempting to tap on and penetrate the window while the female attempts to urge him on.

Have you ever seen this type of behavior before.  Common place?  What is it that they seek?

Thanks
A.J.