An Archer killing a rabbit.
Deer will stop and appear to look around if a player approaches them.
Various kinds of Animals exist in Kingdom which serve as the primary source of income in the early game, later being replaced by more efficient farming. Only free-roaming archers can hunt animals, stationed ones or accompanying knights will ignore any animals.
Rabbit
Rabbits are the first source of money that the player will encounter, and most efficient at that. They quickly spawn on patches of tall grass, also known as rabbit bushes, ignoring the player and archers while hopping around aimlessly. They take only one hit to kill and will drop a single coin upon death. Archers will ignore rabbits at night-time.
Rabbits usually spawn from rabbit bushes, which regularly appear on large grass patches that will disappear if a building is constructed in the area. Letting a grass patch expand will usually spawn up to two rabbit bushes in the area, allowing more rabbits to spawn.
Deer
Deer are much more difficult to hunt than rabbits, as they take more than one hit and flee if the players gets too close, however they are much more rewarding. Experienced players can easily make huge amounts of money by herding them towards groups of archers. They take 2 hits to kill and will drop 2-4 coins upon death. Archers will continue to shoot at deer at night-time if they get close enough to the base.
Herding Deer
When the player gets too close to a deer, it will start running in the opposite direction which the player was approaching from. However, the player's horse is faster and has enough stamina (especially when affected by the Well-Fed Buff), so it is relatively easy to outrun the deer, and by running in same direction, when the player gets in front of the deer, it will turn around and start running in the opposite direction from the player's position again.
It is best to herd deer either during the day or right after an enemy attack, to ensure that you do not accidentally encounter a horde of enemies.
The most efficient way of herding deer involves use of the Great Stag mount that can be found after unlocking it on the third island. With this mount you can persuade deer to run up to your archers, even run into the middle of your base. They will continue to follow you until they get attacked by an archer at which point they will run as usual. After they flee you can easily go up to them and persuade them to run into your base again.
Another one of the methods of killing deer is by use of the Great Bear mount that is found after unlocking on the fourth island. This mount can actually kill deer by using its pounce. Be warned that you need to hit the deer twice for it to actually die. The pounce can also kill rabbits but the actual area that the charge damages is quite weird as it is based off of its movement animation.