Every evening around sunset, hundreds of birds gather in the trees (primarily oak) above my apartment complex. It's happened for as long as I can remember, and lasts from sunset until it starts getting dark. They have high-pitched squeaks, but seem to be bigger than I thought (I broke out the binoculars tonight to get a better look at them). They're brown and mottled, and have long, straight beaks. Any ideas on what species they are?