THURSDAY, Jan. 11 (HealthDay News) -- Birds of a feather may flock together, but they certainly don't teach each other the compulsive habit known as feather picking.
While observing Orange-winged Amazon parrots, Purdue researchers discovered that abnormal repetitive behaviors are instead influenced by a combination of stress and genetics.
"This has been much better studied in other species like pigs and horses, and it's very consistent with what's found there," said Dr. Andrew Luescher, director of the animal behavior clinic at Purdue University and editor of the forthcoming Manual of Parrot Behavior. Luescher was not involved with the study.
The findings, which appear in the January issue of Applied Animal Behaviour Science, may provide new ways to study compulsive behavior in humans.
Both human and animal abnormal repetitive behaviors settle into two basic categories: stereotypies (the mechanical repetition of the same posture, movement or speech), and compulsive behaviors (such as plucking out feathers).
According to the study, many birds exhibiting these behaviors are euthanized because the behavior appears to be untreatable. And the behavior can be extreme, with some birds plucking out virtually all of their feathers.
The effects can even be economic. A study conducted in Australia a few years ago showed that feather picking by hens caused them to eat more to make up for loss of body heat. This resulted in an 8 percent drop in income, or as much as a $50 million loss for the Australian egg-laying industry.
A fundamental question has been how these behaviors originate. Many experts believe that birds learn from each other.
"A lot of the time I will go in a room and see that three or four animals right next door to each other are feather pickers, but that doesn't mean that they've learned it from each other," said study author Joseph Garner, an assistant professor of animal sciences at Purdue University School of Agriculture. "We wondered if unsocial things in the environment might be responsible for this apparent clumping of behavior."
Garner and his colleagues looked at 64 Orange-winged Amazon parrots, focusing on one room containing 27 birds that had always been housed in the same cage.
Specifically, they were interested in seeing if the neighbors' behavior, number of neighbors, gender, family, age, cage location and distance from the door had an effect on different parrot behaviors.
The birds were videotaped daily from 9 to 11 a.m.
None of these factors had an effect on stereotypy, except for number of neighbors. In this case, more neighbors meant less stereotypy.
"The only real finding was that it was progressively less severe, the more neighbors the birds had," Garner said. "It reinforces this general message of how important physical and social enrichment for these birds really is. Well thought-out physical and social environments should be first thing we think of."
Feather picking, however, was affected by a number of factors, including genetics, gender (it was more severe in females), and location. The behavior was progressively worse in birds housed closer to the door when they had a direct line of sight to the door. Parrots with cages that didn't have a view of the door were less likely to feather pick.
There was no evidence that feather picking was socially transmitted.
"The feather picking in the Orange-winged Amazons has a very strong genetic component," Garner explained. "Another effect, and this blew us away, was where the cage was in the room relative to the door."
If the parrot can't see the door, it didn't matter where it was in the room. But if it could see the door, then the closer it was to the door, the worse a feather picker it was.
"The obvious explanation is it's kind of a surprise thing, the sudden sort of visual arrival of human beings, and this was something we didn't expect at all," Garner said.
The surprise finding leads to a simple solution, however. "It leads to an obvious change to suggest to people," Garner said. "You don't want to have your bird on the edge of a kitchen island or something where someone can come in and surprise him."
The fact that feather picking was more common among female birds parallels the human disorder trichotillomania, or compulsive hair pulling. Little is known about the disorder, but this research in parrots may pave the way for more understanding in humans.
"I think that we could use various animal models as models for human behaviors, but we have to be very careful," Luescher said. "At this moment, we can't say that this behavior in animals correlates to this in humans. There are different types of stereotypy behavior and they differ from each other, but we don't really know how we can group them."
One thing is for sure.
"We busted the myth that feather picking is socially transmitted, at least in the birds we studied," Garner said in a statement. "This is exciting because with the strong heritability of feather picking that we found, it might be possible to breed parrots that don't have the propensity to develop this behavior."
For now, the findings may be able to help some animals.
"The honestly wonderful thing about behavior is that you're kind of like an animal translator," he noted. "There really are things the animals are telling you about their response to the environment which we're designing for them and you can actually begin to understand how they're perceiving them and responding to them, and then adapt the environments."