I note that nobody has wondered how to apply these things ( CTA, ADSB, etc ) to flocks of soaring birds. There is a bunch of pelicans which commute between the river near Waikerie and lake Alexandria. I have seen them at 12,000 ft. They are wonderful to watch , the gaggle splits up as they glide along, but as soon as they find a thermal, they all come together again. They are big birds. Bigger than the plentiful eagles.
Personally, I would prefer to hit a pelican instead of a Cessna, but they do have the potential to stop your engines or penetrate a windscreen. And there are thousands of then, outnumbering us lot at least a thousand to one. But all you have to do to avoid them is to fly above the thermals. Yep, coming to land and taking off are problem areas.