Chicken

The domestic fowl (Gallus gallus domesticus), also called chicken (from Middle High German huon), is a breeding form of the Bankiva chicken, a wild chicken from Southeast Asia, and belongs to the pheasant family (Phasianidae). Agriculturally, they are classified as poultry. The male domestic chicken is called a cock or rooster, the castrated cock a capon. The female is called hen, young leading hens hen. The young animals are generally called chicks.

The domestic chicken is considered the most common pet of man - the average daily world population is estimated at more than 20 billion animals, so there are three chickens for every person. The number of domestic chickens slaughtered each year is significantly higher than the average population and is estimated at 45 billion. This is due to the fact that chickens today reach their slaughter weight in just a few weeks. Due to the long history of domestication, a large variety of different chicken breeds have been created. In the European breed poultry standard alone, more than 180 breeds and colourings are distinguished. In industrial agriculture, hybrid chickens (hybrid breeding of different pure inbred lines) are used, which are not suitable for further breeding. Fattening and laying hybrids are bred and marketed by only four groups worldwide.

External characteristics

Size and weight

The Urhühner are relatively small in comparison to the usual house-chicken-races and -strikes with a maximum-weight of 1,5 kg of the cocks and 1,0 kg of the hens.

Among the domestic chickens there is a great variation in size and weight. The smallest dwarf chickens (Serama) become partly with 250 g as big as a small pigeon. The largest chickens (mostly hybrids), on the other hand, can weigh over 10 kg, comparable to a turkey. The largest chickens, the Brazilian giant chickens (Galo gigante), often grow to over 100 cm.

Building

The shape is also very different depending on the breed and loft. The slender, elongated form of the primeval chicken is known as the country chicken type and is found in many European breeds. Many breeds of American and Chinese origin correspond to the so-called Cochin type with a heavier and spherical build. Otherwise, breeds with genetically very short or also extremely long legs exist. The back line can be slightly rising to the back or also sinking to almost vertical.

Comb shape

The comb, which is always simple and fan-shaped in wild crested chickens, knows many variations. Often the rose comb is seen, which is knobbly and bulbous in shape and usually tapers off to the rear in a spike. Certain breeds exhibit a horn comb with two fleshy horns. Rare is the cup comb, in which two parallel combs join front and back to form a cup. Very small is the pea comb; also the missing comb occurs.

Sexual dimorphism

The external difference between cocks and hens within one breed is striking. The comb is clearly larger in the cock. The neckband consists of long feathers as well as the often sickle-shaped tail. Often the rooster has more color in the plumage compared to the hen. The cock is larger and weighs about 1 kg more than the hen.

Runs

Barrel (actually the tarsometatarsus, also called stand) and toes are mostly unfeathered. However, there are breeds with foot feathering (some feathers up to longer feathers on the toes). Three toes are pointed forward, the fourth toe is pointed backward. Some breeds have five toes, i.e. two toes to the rear (polydactyly). Adult roosters have a spur above the hind toe(s) that serves as a weapon in attacks. This spur can become quite long and pointed in older birds. In a few old chicken breeds, such as the Sumatran, roosters are predominantly multi-spurred.

Spring loaded barrel with polydactyly


Typical cock

Behavior

Domestic chickens can fly varying distances of a few meters depending on the breed, but are ground-oriented birds. The domestic chicken was the first species of bird loyal to its location in which a magnetic sense was demonstrated.

vocalizations

The loud cock-a-doodle-doo cry (crowing) of the cock serves as an acoustic marking of the territory. Mostly the cock crows in the morning at the beginning of sunrise, around noon and around evening. In ancient times, the cockcrow served as a time marker of Roman origin. Gallicinum denotes the middle between midnight and sunrise. It can also crow at any other time of day. To this day, people hold crowing competitions.

The clucking, the usual tone-expression of all adult house-chickens, is a relatively diverse communication-tool, that includes warning, threat and bait-calls however also woe-lutes like discomfort.

Food

In their natural habitat, chickens eat grass, grains, worms, snails, insects and even mice. Chickens are very vigilant while foraging and like to stay in cover-rich landscapes. To find something edible, they often scrape the ground with their feet. In their stomachs, gastroliths crush the hard food. The image of the brown hybrid hen shown here is an example of beak docking, which is practiced in the poultry industry to prevent cannibalism. However, this also makes feed pecking much more difficult.

Laying behaviour

Domestic chickens can lay about 250 to 300 eggs a year (laying breeds) if the laid egg is taken away from them daily. If the eggs were not removed, the hen would start brooding, provided her brooding instinct is sufficiently developed. In modern breeds, however, the brooding instinct has been deliberately bred away or greatly reduced. By changing the feed to wheat only, in most cases the brooding instinct reappears. The brooding behaviour is sometimes disturbed, so that the hen does not finish incubating the eggs and leaves the nest prematurely. This misbehaviour is often shown by hens that have hatched themselves in incubators. The incubation period is normally 21 days.

Social behaviour

The so-called pecking order of the chickens has become proverbial. This is, however, compared to the situation with other socially living animal species, quite flexible. Since chickens prefer sleeping places that are as high up as possible (free-living chickens sleep on trees at night), perches in barns should be placed at the same height as far as possible in order to avoid constant ranking fights for the best sleeping place. The grain feed should also be scattered over a wide area so that lower-ranking animals do not miss out. Regardless of the type of housing, problems such as feather pecking and even cannibalism can occur.

However, a study shows that behavioural disorders (feather pecking, cannibalism) are less prevalent in the dual purpose breed Lohmann Dual.

In the so-called batteries of laying hens, social behaviour is disturbed and the animals suffer from boredom, among other things because of the lack of space, and because they cannot satisfy their instinct to scratch.

According to recent research, chickens have a very pronounced social and communication behavior. Physiological measurements of hens indicate their empathy towards chicks. Likewise, more remarkable intelligence performances are now proven, such as logical solving of problems or tasks even under variable experimental conditions.

Mother hen with day old chick


Hen with docked beak