chicken origans and behaviour
To best manage your flock it is important that you understand where chickens come from and their behaviour characteristics.

The origins of chickens
Photo of  Red Jungle Fowls
Photo of Red Junglefowl in their natural habitat.  As you can see they are very similar in looks to modern domestic chickens, particularly the bantam chicken breeds.
Photo courtesy the internet.
All currant and past breeds of chickens originate from the Red Junglefowl which is found in the jungles of South East Asia. 

Red Junglefowls form social groups with a dominant male.  The social structure or pecking order is almost identical to that of the modern chicken.
They can fly, but only to get to the lowest branches of the forest canopy to roost at night.  They are omnivorous and feed on insects, seeds and fruits.  Their eyes have evolved full colour vision to detect coloured fruits but have almost no night vision.   As their habitat is tropical the breeding season is very long, which is why domestic chickens lay eggs over an extended period of time each year.

These birds were first domesticated in Asia at least five thousand years ago.  By 1500 BC the domesticated version had spread to Egypt and was imported into Europe around 500 BC.  Today there are more chickens on the planet than any other species of bird.


Recognition and memory
Chickens can recognise  one another by the shape of the comb, wattle and head, as well as the colour of the plumage.  Research has shown that they can distinguish around  a hundred individual chickens, which is at odds with the theory behind the Night Introduction Method that chickens will not notice a new chicken added to the flock at night.

But while they have good recognition skills their memory retention is fairly poor.  If a chicken is removed from a flock for two to three weeks then other chickens will not recognise it when it is returned.  The returned chicken is treated as an outsider and has to re-establish itself within the pecking order.

Chickens use various sounds to communicate with one another, researchers have identified at least thirty different sounds that they use.  I have  observed at least half a dozen.  The most well know call being the cackle after a hen has laid an egg, but the most startling one that I have heard is a low growling sound omitted when a hawk or eagle is circling above.  This sound is quite different to the one used when ravens are around, so they clearly have the ability to distinguish between predatory birds.

As well as sounds they also use visual signs to communicate with one another.  This is done by displays or changes in posture such as head up or head down and the ruffling or flattening of feathers.  Visual signs are a particularly important  part of mating behaviour.

the pecking order
Chickens have a well defined social structure known as the pecking order.  It is called this because they use their beaks as a fighting tool to establish the order of dominance within the flock.  If there is a healthy adult rooster it will be on top of the pecking order but young roosters are often subordinate to dominant hens.  There is in fact more than one pecking order because as well as the overall order there are separate pecking orders divided along sex lines.

Young chicks begin to establish their own pecking order almost as soon as they hatch and the adult chickens will reinforce  it as the chicks mature.  My observation is that chicks raised by their own mother will integrate more easily into the flock's established pecking order than those raised separately in a brooder. 

Once a pecking order of dominance has been established it remains relatively stable, but as soon as new chickens are introduced the entire order will be rearranged.  This can cause great stress to individual chickens and the flock if handled poorly.  See Introducing New Chickens To An Established Flock for details.

Part of the pecking order involves the weaker birds being able to run away from an aggressive dominant bird so it is important that the chicken run is big enough to allow this to happen.  This is especially important if you are running roosters.

behaviour variations
All chickens have basic character traits hard wired into their genetic makeup but the different breeds have developed their own genetic behaviour variations.  Some are more flighty, some more aggressive while others, especially the hybrid breeds, have had all the natural mothering instincts bred out of them. 

Make sure you choose a breed of chicken that is best suited to your needs.  For information on the characteristics of some of the breeds available see the Chicken Breeds I Have Kept section.