I don't like anything smaller than 7 1/2 (too many small shot to pick out of birds), use these on dove/quail and sometimes on chukars.

Real preference for chukars is #7.

Pheasants early, #6; later #5 (I stay with #6 in 16 gauge and lower; use 5s only with 1 1/4 oz loads in 12 gauge @ 1200 fps).