I was thinking that on islands like the burning savanna there could be snakes that hide in the undergrowth and attack your creatures, and possibly poison them. The snakes could live in holes such as stagmole holes, and might attack the stagmoles to get in, and leave about 2 food on the hole. Killing them could give 2 food, but maybe you should need resistance to poison to eat it. It should be pretty easy to kill, but rather hard to find, and you should be pretty close to it to actually sense or attack it. They should also attack other creatures, not just nichelings, so they might attack rabbits or something.