I know from personal experience. Years back a yearling that hadn't leaned to fly yet must have fallen out of its nest. He/she landed on my sublevel patio. It was stuck there. So I headed out there to pick him up and put him on the lawn for the parents to find. As I was bending over, the father or mother mockingbird bonked me really hard on the back of my head! I turned around and told it "I'm just trying to help your baby, for crying out loud!" It's as if the parent understood what I was saying as it didn't dive bomb me again.

Cathy