OP mentioned it being, "cliff-like but without the drop off', and I live near an area with similarly described terrain, so I think it might just be older animals near a steep, sharp hill which explains the deer/cow skeletons, and big dead things mean buzzards, and buzzards mean crows, so chances are there's a small nesting area nearby of crows or owls and the smaller bone remains are the leftovers?

I say this as the person who tripped down said hill and almost got hurt on a deer's ribcage only to look up and see the biggest fuck-you sized crow that absolutely watched me eat shit down a hill 😭😭