Chicken

Chickens are passive mobs that first appeared in Alpha mode. They have white feathers and wings, with a yellow beak, and a red wattle. The main purpose of chickens is to supply feathers, Raw Chicken and eggs, essential for arrows, food and cakes, respectively. Chickens are 0.875 blocks tall, 0.5 blocks wide and 0.8125 blocks long.

Behavior
Chickens appear to wander around aimlessly, but actually and subtly possess decent pathfinding ability. They will make no attempt to stay out of water, and a common sight is several chickens bouncing up and down in the water. They will follow you if you have wheat in your hand.They appear to be drawn to caves, since they move more easily down ledges than up them. Chickens are also drawn to light in a dark environment and will swim upstream to get to it. Chickens will also climb simple steps, but not a ladder, to escape a pit. It is possible to push a chicken up a ladder, therefore letting them escape a pit you may have trapped them in. This can be prevented by removing the ladder on the bottom, but you will have to jump to get up the ladder. Since the Beta update they seem to be the most common mob. Chickens often spawn alone, but can spawn in groups of 2-6. Like all other passive mobs, they seemingly move randomly in a natural environment. Chickens seem to make attempts at escaping (if trapped/fenced) by constantly jumping into nearby doors or fence gates if available.

Chickens lay chicken eggs which can be thrown at enemies or used as an ingredient in cakes. Chickens lay an egg on every 5–10 minutes (it took 40 minutes for 9 chickens to lay 50 eggs = 7.2 minutes/egg). Since the Beta 1.8 update, Chickens have a 1/8 chance of being spawned from a thrown egg.

When a chicken falls from a height, it quickly flaps its wings, and falls slowly to the ground to prevent fall damage.

Farming
Since chickens can be hatched from eggs, and eventually those chickens lay more eggs, chickens are a renewable resource. You can farm chickens and their eggs quite easily by making water flow push chickens into Iron Bars or Glass Panes. If the blocks under the glass panes are water, you will have a pick-up for eggs in a 1X3 area, and eggs will be laid as long as you are in rendering distance.

Breeding
All passive mobs (excluding squid and villagers) can be bred using Wheat.

Chickens can also be created and bred using Chicken Eggs, allowing them to be easily bred far away from where they naturally spawn. Each egg will have a 1/8th chance in hatching a chick minus a 1/256th chance to get 4 chicks in an egg instead. If you start with 11 eggs you have a 35% chance of creating a colony of at least 2 chickens.

You can quickly make a small colony in a Minecraft day by routinely picking up eggs and farming wheat. If you breed these chickens in an enclosed space, you should have a reliable source of chickens within a few days. Furthermore, since zombies no longer drop feathers (making it harder to craft arrows) making a chicken colony is a great way to get an unlimited supply of feathers and raw chicken.

It takes around 20 minutes for a baby-chicken to turn fully grown. Due to the 1.2 snapshots, chicks follow the nearest chicken until they are fully grown.

History
Raw Chicken was introduced in Beta 1.8 with the introduction of the hunger system. Before this, chickens only dropped feathers on death. In 1.8 Chickens seem to drop Eggs more often than usual, but this is only because animals are, since then, persistent. In 1.8, Chickens need a large area to walk around in or they will start dying on their own. This happens because the chickens push each other into the walls, suffocating for a split-second. To solve the problem, make sure they are surrounded by fences and not solid blocks. Glass can also hold a large number of chickens in a confined space given they are floating on water.

Since 12w07b Chicken have the new AI system. 

Trivia

 * Chickens are the third smallest mob (the first being silverfish, the second being small slimes). They are able to fit through 1×1 gaps.
 * They take no fall damage, and when they fall they make a flapping animation and fall slower than normal.
 * When a chicken is killed, and if it has a boost from the hit or is thrown over a cliff by the hit, the "corpse" will also fall more slowly than normal, and the wings will still make a flapping animation.
 * When a chicken is riding a minecart, it is impossible to attack the chicken rather than the cart as it is completely inside the shape of the cart.
 * Cooked Chicken can easily be obtained by letting chickens fall onto a block of burning netherrack from which they can run off.
 * Chickens are the only Overworld mob (without the use of hacks/inventory editors) that can be bred in the Nether, by building a suitable area and throwing Chicken Eggs inside of it.
 * Chickens are sometimes mistaken for ducks due to their wide beaks and ability to swim.
 * Probably inspired by this, Notch tweeted that he changed the chickens to ducks a few weeks before the end of beta, causing a turmoil on Twitter. A few days later Jeb, still getting feedback on the idea, tweeted that it was just a joke.
 * If you throw chicken eggs at Glass Panes, there is a small chance that the chicken will spawn on the other side of the panes.
 * Despite being a creature that does not give live birth, chicken breeding will cause the chickens to create a baby chicken instead of laying an egg.
 * Throwing chicken eggs in any map after 1.0.0 will spawn baby chickens. However, in SMP, if the map was generated at any time before the full release of Minecraft, the eggs will only spawn adult chickens.
 * You can start "chicken tube" farms in which you contain vast numbers of chickens in a small space to get their eggs to make more chickens or to kill for food, completely bypassing the point of breeding and wheat farming.
 * Baby chicks cannot be lured by wheat like adult chickens.
 * There is no texture for the underside of a chicken's head, allowing you to see through it and see the inside. This is probably an oversight, as chickens are small and never look up.
 * As of snapshot 12w04a, the newly introduced ocelot mobs will attack chickens.
 * Chickens lay eggs an average of once every 7.5 minutes, and each egg has a little greater than 1/8 chance of spawning another chicken. This means that a one chicken can produce a second chicken about once every 55 minutes (~2.5 minecraft days).  Accounting for exponential growth, a large population of chickens can double in size roughly every 40 minutes.