Meet Snow Fog.
He is the frost-bitten version of the Gray, and is, therefore, no less ravenous.
In fact, it is much easier for winter's Gray to eat the entire mountain in one murky chomp, because the Sun rarely makes an appearance this time of the year. And when it does, the latter is brief.
There is simply no one left to fight the Gray.
Except for the birds that travel between these two worlds.