Chickens use their beak to interact with and gather information about the world around them. For example, chicks learn what food is by pecking at things in their environment or learning from the behaviour of their flock mates. Birds may also peck at food particles or the feathers of their neighbours. When delivered gently, these pecks are largely benign. But when pecks are delivered forcefully (aggressive pecking) or severely enough to cause damage, they may pose an animal welfare problem (also called injurious pecking behaviour). The first post in this series on pecking behaviour will focus on feather pecking.
Feather pecking is a complicated behaviour that is still being investigated by poultry scientists around the world. It is commonly considered to be re-directed foraging behaviour, which is when chickens peck and scratch at their surroundings in search of food. There are many potential factors that may cause chickens to "re-direct" their foraging behaviour towards the feathers of other birds, including environmental stressors like diet changes (see below for more on risk factors).
Feather pecking can range from gentle investigatory pecks to severe feather pulling behaviour. Feather pecking may occur with any size flock, including backyard flocks, but it does not tend occur to the same extent in cages. This is because feather pecking is socially facilitated, which means birds learn how to do it from each other. Therefore, feather pecking can spread much more easily in an environment where birds can readily interact.
Feather Pecking Types
There are two main types of feather pecking: gentle and severe.
Gentle feather pecking may be expressed as feather nibbling, especially directed towards the tips of feathers. This may be considered a form of allopreening, or when one bird preens (cleans) the feathers of another bird (similar to allogrooming in other animals). The bird receiving the gentle pecks does not seem to mind and will actually stand still while this happens.
Severe feather pecking may, but not always, follow gentle feather pecking. This is when one bird pulls out and sometimes eats the feathers of another bird. It is painful and results in feather loss (which leads to difficulty in regulating temperature), tissue damage, and may lead to cannibalism. It is unclear what exactly triggers birds to begin severely feather pecking one another, so it is important to minimize those risk factors we know about and also prevent unnecessary damage through beak treatment.
Some risk factors for feather pecking to develop in a flock include poor litter quality (e.g. wet litter, or not enough litter), multiple sudden diet changes, poor diet quality (e.g. lacking in fibre or protein), high stocking density, or feed that is too easy to eat (pelleted feed).
Beak Treatment
Beak treatment (also known as beak trimming) is an accepted practice that helps prevent the damage caused by severe feather pecking. It does not compromise a bird's ability to peck, including eating, foraging or feather pecking. But dulling the tip of the beak prevents chickens from being able to tear and damage the flesh of their flockmates. Contrary to popular belief, modern beak treatment techniques do not involve "cutting" the beak at all. The most common technique used in Canada is infra-red (IR) beak treatment. This is where an IR laser is passed over the very tip of the beak when chicks are one day of age and sloughs off after about a week. See the images below for a comparison between an intact beak (left) and a treated beak (right).
Feather Scoring
Feather scoring is a useful tool that can tell us whether a flock is experiencing an outbreak of feather pecking. I am currently documenting feather condition for flocks at a variety of ages to get an idea of what "normal" feather condition looks like for different strains and housing system types.
Damage specifically associated with feather pecking is typically located on the back of the bird, especially near the base of the tail. Birds seem to target this area in particular, potentially because it contains the uropygial or preen gland. This gland secretes an oil that birds use to preen their feathers, and some evidence suggests that the preen oil composition of some birds may be an attractant for feather pecking. Regardless of the reason, finding a high proportion of birds with a score "2" tells us that there is a severe feather pecking issue in the flock.
Part 2 of this series on pecking will cover aggressive pecking, which has a completely different etiology than feather pecking. Finally, Part 3 explores some prevention and treatment strategies for both aggressive and feather pecking.
For more information
Hennovation Feather Pecking Guidelines
Featherwel Practical strategies to prevent feather pecking. See also PDF Guide
Appleby, M.C., Mench, J.A., Hughes, B.O. 2004. Poultry Behaviour and Welfare. CABI Publishing.
Nicol, C.J. 2015. The Behavioural Biology of Chickens. CABI Publishing