I've caught a couple Seagulls, a Duck, and 3 or 4 Pelicans, I've had people tell me "Watch out for the wings! They'll beat you to death, or they'll break your wrist!!!... it's a Chicken wing ok? I've also had people tell me to "Look out for the beak"!!!... but you can easily hold thier beaks closed.
I usually hold the bird between my knees while sitting and remove the hook(s), and once the bird realizes you're trying to help them they stay pretty calm. Once the hooks are out I return them to the water and they swim off pretty fast for about 5 or 10 feet then turn around and look at you... then they just kind of saunter away.