[off-topic]
To nitpick, the terrain doesn't have to be icy in order for trenches or snow caves to be constructed. It's enough that the snow hardens, which it pretty much always does after some time on the ground. Usually it's only the surface snow (the top inch or so) that's too powdery to be used for even snowballs.
[/off-topic]
"One of the bitches actually gave birth while she was attacking, and her puppies joined in on the carnage."
--the awesomeness that is Boatmurdered.