Automatic Dung Production
Animals crap all the time, not just when they die, so a certain amount of dung should appear on the ground at certain intervals based on animal populations and mass. The more animals, the more poo. This would make it easier for towns without a natural food source to survive, and provide a better reason for keeping animals alive than preventing extinctions. Smaller animals would produce less, while larger animals produce more.
It could appear on the ground much the same way that projects finish in deviations of your original goal. For each animal there would be a certain increase in the base amount (Squirrels add 100, elephants 1000, etc....), and the amount that appears per day would be based on a range of percentages (Like 15% to 50%) of the total grams of fresh dung.
Predatory Animals Keeping Balance
In areas that are untamed by humans, something has to keep the animal populations in order. Like the animals themselves. In a natural ecosystem, animals attack and kill each-other all the time, whether for food, fun, or self defense. Violent animals already attack humans, so getting them to attack prey animals at random shouldn't be too hard to do.
I've spawned in places with hundreds of certain animals whose numbers just keep growing, that doesn't happen in a natural, balanced ecosystem.
Scavenger Critters
Some of the animals in the Cantr roster are scavengers, and they could be used as a way to keep all the clutter on the ground in line. It would provide more incentive for people to lock up their resources.
Based on animal size, scavenger creatures could add a percentage to the decay rate in an area, raw meat, milk, grass, corn, and other produce would 'degrade' faster due to the animals eating it. If an area is over-run with scavengers then people may want to start exterminating them. Different types of animals would cause the decay rate to rise for a specific resource type. Squirrels eat nuts, cows eat grass, wolves and a number of other predators eat meat and will often feed on dead bodies in the absence of live prey.
