Feather pecking

Feather pecking is a behavioural problem that occurs most frequently amongst domestic hens reared for egg production, although it does occur in other poultry such as pheasants,turkeys,ducks and is sometimes seen in farmed ostriches. Feather pecking occurs when one bird repeatedly pecks at the feathers of another. The levels of severity are recognised as gentle and severe. Gentle feather pecking is considered to be normal investigatory behaviour where the feathers of the recipient are hardly disturbed and therefore does not represent a problem. In severe feather pecking, however, the feathers of the recipient are grasped, pulled at and sometimes removed. This is painful for the receiving bird and can lead to trauma of the skin or bleeding, which in turn can lead to cannibalism and death.

Feather pecking is one of the major problems facing the egg industry in non-cage systems and is set to become an even greater issue with the EU legislation (Council Directive 1999/74/EC) ban on the keeping of laying hens in barren battery cages which came into force in 2012, and the prospect of a ban on beak-trimming (see below). Reducing feather pecking without resorting to beak-trimming is an important goal for the poultry industry.

Feather pecking is considered to be re-directed behaviour, developing either from ground pecking or pecking during dustbathing, although the former hypothesis is now the more favoured. Captive birds are very often kept in barren environments with limited foraging opportunities and in addition, are usually fed a nutrient-dense diet which can be eaten in a few minutes rather than the hours it would require to acquire during normal foraging. In combination, these cause the birds' foraging activity to be re-directed to the feathers of their conspecifics.

Sometimes, feathers that are removed are then eaten, in which case the behaviour is termed "feather eating". Whilst there may be a positive association between feather pecking and eating, at least in the individual bird, this is likely due to an overall higher pecking motivation.Eating feathers increases gut transit indicating that feather pecking and feather eating have a different motivational basis.

Early experience can influence severe feather pecking in later life. Commercial egg-laying hens have often already begun feather pecking when they are transferred to the egg laying farm from the rearing farm at approximately 16–20 weeks of age, and plumage quality can then rapidly deteriorate until peak lay at approximately 25 weeks of age. Severe feather pecking can either begin or persist beyond this age although it rarely begins after 40 weeks of age.

...
Wikipedia