Heat-seeking snowflakes. In arctic regions there exists a sort of vamperic Eumetazoa which cluster together as they float on cold drift winds by the billions. They look indistinguishable from falling snow at first, until they swarm on anything alive leaving only desiccated husks to be buried in the ice.

Needless to say my cold regions are lifeless deathtraps outside creatures that have adapted to not produce heat signatures at all.