I've looked at longer primes from Nikon 200mm/2, 400mm/2.8, etc but I've also seen Telezooms such as the Sigma 150-500 and Tamron 150-600. I know that primes are usually sharper than their zoom counterparts and in many cases more expensive. I've used my 24mm/1.8 over my 16-50 kit zoom and in these focal lengths it is usually not hard to walk backwards or forward to compose the shot.
Are telezooms worth their price in terms of sharpness given their inability to zoom in the telephoto range? (I don't know if it's possible to walk back or forward shooting at this range.) Related do people usually use primes more so than zooms when they are shooting birds or other animals far away?
I'm guessing people prefer zooms?