Nature Done Wright

A friend writes:

My daughter and I saw something very strange this morning when we were having breakfast. 

Flocks of birds (mostly Robins) gathered on the roof of her red Subaru in our driveway. It looked like a clip from the movie, "The Birds."

The birds kept flying in continuously and appeared to be having a huge convention with a delectable breakfast. To our knowledge, there wasn't any food on the roof for them to feast on.

The birds remained there for 35 minutes or more, and we could not tell if they were feasting before migrating south or preparing for bad weather due in this area over the weekend.

Can you explain?