I don’t do much bird photography unless I just stumble upon it. But most of the people that are into are using 500 to 600mm lenses and might have a teleconvertor on as well that would increase the reach. A lot of them do some heavy cropping as well.
About the only real bird photography I would like to do is to photograph a duck hunt. Don’t ask me why because I don’t know, but I’ve had the idea forever. Weird since I’ve never been a duck hunter.