Hunting and foraging
Hunting and foraging is an alternative to farming and fishing in order to gather food. This type of food gathering can only be done by citizens. When hunting or foraging, citizens do not receive a gather bonus from Town Centers, Capitols, or improved granaries.
Hunting (harvesting animals for food) is the fastest of all food gathering methods (except space farms in the AoC expansion) because you may have large numbers, over twice as many as mines/forages if you wish, gathering from them at once. Also, the hunt gather rate per citizen is greater than the forage gather rate (assuming you have at least equal distance to a Town Center/Settlement/Granary).
Hunting can be tricky at times due to the phenomenon called "sterile hippos" or "gay hippos," when your herd (most often the large 290 food animals like hippos, walrus, and elephants) do not reproduce more animals than the size of the original herd. Normally you start out with 2 hippos, where the adult (large) hippos will periodically create another hippo until they reach the maximum number around 8. If you have sterile hippos you can only have 2-3 hippos at one time so they must be eaten wisely or you will run out of your herd.
Also, animals have either 115(ish maybe 135) food if they are a medium sized animal such as horses, goats, ostriches, or giraffes. Large animals have 290 as listed above. The smaller animals like goats have larger herds than large animals. Not only that, they are also horny bastards and reproduce much faster. If these animals are killed by a military unit or building instead of a citizen they only have a very small amount of food left. So it is strategical to both kill enemy hunt and protect your own.
Foraging is limited to the use of forage patches. As mentioned in #Hunting, it is slower of the two food gathering methods. On the default random map scripts, players receive two forage patches when the starting epoch is the Prehistoric Age. Otherwise, each player gets one.