For the most part, chickens and other poultry species mind their own business and don’t bother other birds except for positive social activities. However, some negative behaviors, especially aggression, affect bird welfare and productivity.
Dr. Richard Blatchford, associate poultry specialist, Center for Animal Welfare, UC-Davis, works with bird owners to help solve behavior problems. While some negative behavior can be stemmed by selecting breeds that are less prone to physically arguing with one another, aggression isn’t always avoidable.
Aggression in chickens goes back to the Roman Empire, the first civilization to develop chickens as an agricultural species. “They had chickens to lay eggs and chickens for meat,” Blatchford said. “They even had some for particular dishes and had management guides that were more like a cookbook.”
The Romans also used chickens for fighting and to portend omens. Unfortunately, when the Roman Empire crumbled, all records and documents on agricultural chickens were lost, leaving only fighting chickens. After this, several short-tailed, lean, muscular breeds dominated, and these birds were quite aggressive. Most domestic chickens are descendants of these breeds, and aggression problems can usually be traced to old genetics.
While some birds are naturally aggressive, others are genetically aggressive. The latter are more difficult to manage because they are wired to be that way – it’s difficult to change their behavior. However, there are ways to manage aggression, whether it’s among birds or toward humans.
“Chickens form a strict social hierarchy,” Blatchford said. “Aggression is involved in that.”
Social structure in a flock involves pairs. One bird is dominant, the other is subordinate. “All birds will have this relationship with every other bird in the flock,” said Blatchford. “Chain all the paired relationships together and there’s a dominant hierarchy. They usually develop this when one bird pecks the back of the head of another bird – hence the term ‘pecking order.’”
Some aggression is normal when new birds are introduced. “They have to be able to work out a social structure,” he said. “When birds are creating their social hierarchy, there’s a heightened level of aggression. It’s the way they determine how to create pairings.” Birds near an aggressive bird may be hunched down, showing subordinate behavior.
Introducing new birds will likely disrupt an established social structure, which means the entire flock will rework the social structure. Hens can move up or down the social ladder depending on age and whether new birds are added or removed. While there may be aggression as new birds work their way into the flock, most will stay to the side to avoid confrontation. It’s important to provide hiding places so birds can get away from more aggressive birds.
Turkeys housed by age in small groups can exhibit natural behavior and tend to remain less aggressive. Photo by Sally Colby
Always introduce new birds slowly. If possible, first provide visual access without contact so they get used to seeing each other before the groups are physically introduced. A separate fenced area that allows groups to see one another helps lessen aggression.
Birds require some level of aggression to develop social hierarchy. Once a hierarchy is developed, birds typically maintain it through posturing.
“Allow them to be moderately aggressive with one another,” said Blatchford. “This can be tricky because they can get aggressive and kill each other.”
If birds are stressed and injured, it’s time to intervene. Birds may have to be removed and separated. Aggression causes problems when there’s too much chasing and when the aggression leads to injury or extreme fear that results in hens not coming out of the coop for feed or water.
Always supervise new additions and be prepared to break up large-scale aggression before birds injure or kill.
Enrichment can often help reduce aggressive behavior. “Because aggression in chickens is a head/beak-related behavior, if you can get them to redirect their head and beak in another direction, you can reduce aggression because they can’t do both at the same time,” said Blatchford.
A bale of straw or hay in the birds’ open area provides effective enrichment. Birds will naturally peck and pull at the bale as part of their foraging behavior. However, in some cases, a dominant bird may take over the bale, guard it and chase other birds away. If possible, provide more than one bale and keep the bales far apart – one bossy bird can’t patrol two or more areas.
Perching structures can also be a source of aggression. Provide enough perching to allow every bird to perch at the same time. Ideally, perches are all at the same height to avoid dominant individuals from protecting higher spaces. Perches should be spaced at least one foot apart.
Another point of aggression is roosters, and sometimes hens, attacking humans. Blatchford reiterated the fact that this is territorial behavior – roosters are protecting their flock and someone entering their space can illicit an attack.
The normal human response to a rooster attack is to run away or put a foot out and hope they attack that instead. Those responses are exactly the behavior the rooster is seeking.
“The rooster expects you’ll either fight back and challenge him or you’ll run away,” Blatchford said. “If you run away, the rooster wins. If he attacks you and you attack back, that only increases his attacking.”
Instead of an aggressive response, he said it’s better to scoop up the rooster, roughly stroke him from head to tail several times, then put him down. The rooster’s response is usually confusion as he looks around before wandering off.
“Hold your ground until he has left and is no longer interested in you,” he said. “Then you’ve won the interaction … This may mean willingness to be in a standoff with the rooster. He may be threatening but not attacking – just stand your ground until he moves away. Sometimes that can take a while.”
Remember that chickens are constantly working on social hierarchy within the flock. “Try to increase positive behavior,” said Blatchford. “Understand what birds want to do and why and give them the opportunity to do positive behaviors.”
by Sally Colby
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