The apocalyptic horror of The Long Night is that all of the animal wildlife that used to populate the Earth is gone. Every species is extinct. In their place, things that used to be people, changed by nanotechnology into distorted parodies of the human form.
Armored in grade-C nanotechne, they are difficult to fight, and fight they will. More aggressive than the usual creatures that populate vanilla Dwarf Fortress, they are opportunistic, and without mercy. They prey upon any weakness. Like blood dripped in shark-infested waters, any wounded creature is swarmed and eaten.
These are the reason my player frequently has human blood on himself and his walker.