Animals as Units Edit
Unlike most other resources, wild animals are normal in-game units and have therefore a certain amount of hitpoints and in some cases (for instance Elephants, Hippos and Walrusses) even an attack value. To balance the danger posed by wild animals that attack back, those animals contain higher amounts of food than non-attacking animals.
Wild animals do also reproduce. All mature wild animals can spawn offspring. Even freshly born offspring provide the same amount of food as a mature one and, if not killed, grows slowly to maturity and can spawn offpring itself.
Potential Problems Edit
Unlike other resources, wild animals roam a certain area and flee if attacked. This can mean they die far from a resource drop off point, slowing down the gathering process.
Another problem is the fact that young animals stay close to the mother and it is therefore possible that citizen accidentally kill two animals at one, which leads to a loss of food through decay.
The third problem is, that animals are normal units and can therefore be killed by military units. A wild animal that is killed by a military unit decays a lot quicker than an animal killed by citizen, so a lot of food is lost through decay. This can be exploited to starve human opponents off food by killing the wild animals near the opponents base in a raid.