Man hard to tell. I’ve seen cattle fall in deep ditches that were drifted over and die, but hard to tell if that is a deep hole or not. If some were out wandering last fall and got stuck maybe.
Lightning, snow drift/avalanche would be my top 2, but can’t tell the terrain
I would expect the bones to be scattered over a MUCH wider area if they had been scavenged on by anything larger than a mink/birds. Unusual to see just large piles of bones basically
stacked on top of each other.