I have over 50 graptors including heavily mutated ones…and using the tek bino it’s become clear it’s the highest unmutated stat that determines what type of feather the raptor will give.

One of my raptors has 52 in oxygen as it’s highest unmutated stats while it’s mutated melee comes to 71 where 51 is the original unmutated and it always still gives only oxygen feathers.

I also tried leveling the same graptors health to over 80 in total and it still gives only oxygen feathers.

Thus I can only conclude it’s those unmutated highest stat that determines the type of feather.