Your backyard chooks won’t truss up an unpopular flock member and pop them in the pot, but they may exhibit cannibalistic behaviour by pecking and tearing at their unfortunate flock mates.
Outbreaks of cannibalism happen mostly in larger flocks but it can occur in small groups and in even the best of housing systems, including cages, floor pens, aviaries and in outdoor, free-range flocks. It happens in all types of poultry, including chickens, ducks, turkeys, quail and pheasants. Birds will mostly show cannibalistic behaviour when they are crowded or when feed is restricted.
The act of pecking at each other is natural amongst birds as they establish dominance — the ‘pecking order’ — and sort out their respective positions in the flock. Cannibalism is not dominance behaviour, however, and may occur long after dominance relationships have been established. Cannibalism may begin with feather pecking and is usually directed toward the body, toes, tail and especially the vent area. Cannibalism differs from dominance in that it actually causes physical harm, sometimes even death. Preventing cannibalism amongst your birds is much easier than treatment.
Cannibalism is believed to be caused by a combination of genetic and environmental factors and outbreaks can occur in the best-managed flock. Some of the more common causes include:
- The propensity of different breeds to feather peck.
- Overly large flocks in crowded conditions.
- Insufficient feed, water, perch or nesting space.
- Dietary deficiencies, particularly vitamin deficiency or a lack of salt.
- Bright lighting.
- Injured birds left exposed in the flock.
- Keeping different ages or colours together.
- Injuries that bleed as a result of enclosures in poor repair or from fighting among newly mixed birds.
- Diseased birds or individuals with low body weight.
- Barren environments that restrict or limit natural behaviour, especially normal nesting and foraging behavior.
- Sudden changes in diet, e.g., to a less-preferred food.
Because cannibalism is a learned behaviour that, once established, will spread throughout a flock there is no ‘cure’ as such. Apart from the mechanical debeaking carried out in some commercial flocks prevention is the only way to reduce or eliminate the behaviour. The first step is to select a genetic stock (breed) that is not prone to cannibalism.
Other than genetic factors, limiting the size of the flock and giving your birds the most natural environment and best care possible is the most effective way to prevent cannibalism. This includes providing an adequate diet, safe housing and environmental enrichment. In caged or permanently housed flocks careful lighting control will reduce incidences of cannibalism.
Providing a diet that meets all the nutrient needs for the age and the type of flock is critical. Cannibalism has been linked to deficiencies in protein, sodium and phosphorus. As chicks grow their protein requirements change and need to be adjusted based on a recommended feeding schedule.
Ensuring adequate feeder space for all birds to eat simultaneously will help avoid having underweight birds, who are invariably at the bottom of the pecking order and are therefore the most likely victims of cannibalism.
Light intensity and the period of light and dark can influence cannibalistic behaviour. In commercial flocks photostimulation programmes are often used to encourage laying but these should be delayed until the birds are physically mature, after 20 weeks of age. Dim lights are often used to prevent cannibalism. If reduced lighting is used, 5-10 lux (about 0.5 to 1.0 foot candles, just enough to read a newspaper) from incandescent or fluorescent bulbs is recommended.
Chickens are attracted to blood and any injury that bleeds can lead to an outbreak of cannibalism as flock mates subsequently peck at the injury, encouraging others to follow suit. It is important to keep enclosures in good repair to prevent injury from sharp wire or from a bird becoming trapped in mesh and injuring itself in its struggle to get free.
Any bird that shows cannibalistic tendencies should be culled, and injured birds, victims of cannibalism and dead birds should be immediately removed from the flock.
Environmental enrichment is the most effective way to prevent cannibalism. The best way to provide an environment in which birds are less prone to pecking other birds is to give your flock the opportunity to free range in an environment that mimics as closely as possible their natural foraging behaviour. That means giving them sufficient space to forage about for much of the day amongst trees and plants with dense ground cover and insect-rich mulches. A chicken’s natural behaviour includes spending a large portion of the day searching for food. In an environment that prevents the expression of this normal foraging behavior, such as an enclosed house or shed, the instinct to peck can be redirected toward flock mates and may lead to cannibalism.
Failing a natural free range environment, you can try putting objects in their pen or henhouse that will provide a greater variety of behavioural outlets. For hens, the kind of environmental enrichment that reduces the incidence of cannibalism include nest boxes, perches and other objects that might redirect pecking away from flock mates.
The cloaca is highly attractive to hens prone to pecking and some outbreaks of cannibalism begin during oviposition. A dark nest box provides a safe place for egg laying and prevents exposure of the everted cloaca during oviposition to potentially cannibalistic flock mates. Hens can also escape aggressive vent pecking by being able to perch high enough off the ground that they cannot be reached by hens on the floor. Pullets are more likely to use perches as a refuge if they are reared with them from an early age.
Pullets reared on a litter type that is attractive for scratching and pecking are less likely to develop cannibalistic behaviour. It is important to provide foraging opportunities such as straw, green leafy vegetables or grass clippings, or to feed small grains in deep litter. A mash diet, rather than pelleted feed, may also help prevent outbreaks of cannibalism because chickens sift through the variety of ground particles and take longer to consume their feed. One popular trick is to hang a couple of cabbages in the pen, which encourages the birds to peck at the leaves rather than each other.
Carefully selecting a breed that is docile, together with the management practices described above, should prevent most cannibalism. However, if an outbreak does occur, it is essential to stop the behaviour before it spreads. It’s difficult to stop a substantial outbreak altogether but some options include:
- Separate any birds seen to severely peck at others, especially if directed at visible injuries or the vents of other birds.
- Remove victims of cannibalism and care for them separately.
- Add enrichments, especially foraging-related devices.
- Add additional feed and water space.
- Add nest boxes and perches.
- Use an antibiotic wound spray on the everted cloaca of hens with vent trauma (in small flock situations).
Beak trimming, or debeaking, is the practice of cutting off a small portion of the bird’s upper beak, blunting the sharp point and reducing the damage a bird can do by pecking. It is generally only carried out in larger commercial flocks of either caged or barn-reared hens.
Debeaking is associated with both acute and chronic pain and should never be undertaken indiscriminately, or by an inexperienced poultry keeper. Neuromas — tangles of severed nerve endings in the amputated beak stump — can result from beak trimming carried out incorrectly or with inadequate tools.
The avian beak, like the human hand, is very sensitive to touch, temperature and pressure. Chickens use their beaks not just to gather food but to explore and manipulate objects in their environment, to preen, dust bathe and in nesting and social interactions. Beak trimming is not only painful, it deprives the bird of important sensory information.
Like many large scale farming practices it is something that makes any animal lover, including the farmers themselves, uncomfortable. There is little doubt that, like battery cages, debeaking will eventually be banned in Australia (it already is in Europe). Genetic research and selection of more docile breeds less likely to practice cannibalism will in the future have to replace the practice of debeaking.
In the meantime however, until alternatives to beak trimming are developed the commercial poultry farmer must balance the potential painfulness of the practice against the likelihood of a cannibalism outbreak.
If the decision is to beak trim, the procedure should be done between seven and 10 days of age and only by properly trained personnel, preferably a veterinarian, under controlled conditions. Beak trimming errors can add additional pain and suffering to an already stressful procedure, and may fail to prevent cannibalism. Even for larger flocks, there are management and environmental alternatives to debeaking and we are happy to assist commercial operators to make the transition.