>>96079721
that could work, what could also be used is some alternative appearances of harpies in stories and myths and later interpretations

for example, if we separate dark elves harpies from beastmen harpies by making the former more conventionally alluring and the latter more monstrous, we could give to the former the singing voices of syrens (which were bird women, not mermaids, in the odyssey)
while in another story we see harpies harassing aeneas's men who were famished, and they harassed them by swooping over the tables they were preparing to eat at and almost literally shitting on the tables and the food, since these bird-women had holes in their chest from which they let loose some kind of foulness, these would be a separate niche that the more monstrous version of beastmen harpies could use

another element of differentiation could be feathered wings or leather wings, or whether the harpy is more humanoid, with arms, or more birdlike, without human arms

medieval or renaissance depictions of the monster could also be a source of inspiration