Bird Identification: CLOSED: what is the bird doing, 0 by Chillybean

Chillybean wrote:
You can probably rule out female House Finch, since she has no red on her. I've never heard of a finch doing this behaviour, but birds often surprise me. Any other parts of the bird red?

Is your friend located in your area? Even without a picture, this can help with ID. I am wondering if a female Northern Cardinal if this is not in California. Cardinals of both genders often beat up on their reflections. I'll post a picture of a female we had last summer. We pulled the car out of the garage to help the Barn Swallows, to give them peace, but it caused another problem. :)

No, its not mating, but more than likely defending territory. As your friend is experiencing, birds do not recognize glass as being glass. The lighting plays a large part of that. She can cover up the other side, or point an inside light toward the window.