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Parakeets are perceptive—and they judge.

A researcher at UT’s National Institute for Mathematical and Biological Synthesis (NIMBios) has studied aggression in monk parakeets and determined that the birds develop a social hierarchy based on thoughtfully calculated perceptions of their fellow monk parakeets.

Photo by Greg Matthews
Photo by Greg Matthews

A study published today in the journal PLOS Computational Biology reveals new insight into how socially complex societies evolve and how dominance hierarchies are established. The study’s lead author is Elizabeth Hobson, a postdoctoral fellow at NIMBioS.

Hobson said newly formed groups of the species do not exhibit behavior of perceiving rank, but after about a week of interactions, the birds seem to figure out where they stand. Individual birds begin to direct aggression against those close to them in rank.

But how do the birds infer their own rank and the rank of others in the flock—and then act on it?

“Parakeets appear to be able to connect the dots in their groups, remembering chains of aggression, so if A fights B, then watches how B fights C and how C fights D and how D fights E, then A will use this knowledge to adjust how it interacts with E based on all of the fights in between,” said Hobson.

While some species may use visual or perceptional cues to determine rank, the monk parakeet seems to depend on clues based on newly acquired social knowledge. These clues result in a social structure organized by dominance hierarchies–each animal is submissive to those ranked higher and dominant over those ranked lower than it. Rankings are often stimulated by aggressive encounters, and those receiving higher ranks have greater chances of reproductive success and better opportunities for foraging.

Hobson and co-author Simon DeDeo of Indiana University and the Santa Fe Institute analyzed detailed observations of aggression in two independent groups of captive monk parakeets over the course of twenty-four days.

“We looked for cases where we could clearly determine a winner when aggression took place–often these were cases where a bird approached another and knocked it off its perch. It’s pretty easy to determine the winner in these kinds of events,” Hobson said.

A total of 1,013 wins in one group and 1,360 wins in the second group were analyzed. The data suggested that the birds gathered knowledge by interacting and watching the fights of others. This knowledge seemed to prompt them to change their behavior so they fought only birds similar in rank and avoided confrontation with higher-  and lower-ranked birds.

Thus, the ability to determine rank amongst these socially precocious birds appears to be an act of cognitive complexity learned through the bird’s careful observation of how the other birds interact.

“Our approach provides insight not only into how these parakeets are behaving in their groups, but also into the cognitive skills they would need to exhibit these kinds of strategic behaviors,” Hobson said. “This allows us to start to understand the interaction between social and cognitive complexity and to begin to compare what we see in the parakeet groups to other socially complex species like primates.”



Catherine Crawley (865-974-9350, ccrawley@nimbios.org