Biologists have come up with a new way to decide whether to combine similar animal behaviors. It can help all animal behaviors.
Biologists often study the social life of animals by gathering observations about several types of behavioral interactions. These interactions can be things like intense fights, small fights, cooperative engagement in food, or grooming each other.
But to analyze animal behavior, researchers need to make decisions about how to classify these interactions and how to encode these behaviors while collecting data. It turns out that this question can be complicated.
University of Cincinnati researchers investigated this difficult question while studying monk parrots. In a new research published in the journal Current animal scienceThe team asked: How would you correctly classify two seemingly similar behaviors? The study was led by Annemarie van der Marel, a postdoctoral researcher at the University of California, who has worked with PhD students at the University of California, Sanjay Bracher, Claire O’Connell, Chelsea Carmenetto and Associate Professor Elizabeth Hobson.
“Biologists have to deal with this question: Are the behaviors that we classify as unique that animals really consider unique?” Hobson said. “How do animals classify these behaviors?”
Biases can easily lead researchers to delude these appeals of judgment. “If you look at chimpanzees, smiling is an aggressive behavior.” Van der Marel said, “But to humans, smiling is friendly.” The behaviors look similar to us, but the nuances of how the behaviors are used are completely different.
Monk parrots are very social parrots that live in large colonies where they often interact with other individuals. O’Connell said that parrots spend a large proportion of the day fighting, especially higher-order birds, making them easier to distinguish from lower-ranked birds in the dominant hierarchy. Aggressive birds appear in several ways. They bite of course. But monk parrots also like to perch another parakeet through threat or sheer force.
Biologists at the University of California have observed two types of “king of the hill” behavior: “displacement”, in which a bird rushes to another bird and can bite to force that bird to turn away, and “crowding,” where the threatened bird moves before the aggressor is within its biting zone. The team coded these behaviors as distinct because they appeared to differ in level of aggression, with displacements emerging as a more severe form of aggression with a higher likelihood of infection.
Parrots also use these behaviors somewhat differently, with much more displacement than crowding.
The question is: Have birds primarily used these behaviors in the same ways, so that they can be treated as the same types of events in later analyzes?
Combining two behaviors has significant research benefits such as creating a richer data set for future analyzes. Hobson said clustering also carries risks – by generalizing, scientists may miss the nuances of behaviors that convey important information when viewed on its own.
To get to the core of this question, the team resorted to computational analysis. They have devised a new computer model that compares true patterns of aggression with random patterns. This approach allowed the team to test whether treating the two behaviors as interchangeable caused any changes in the social structure. “In addition to being a great laboratory hook experience, it was an exciting opportunity to learn how to use simulations to help answer research questions,” said Brascher.
In the University of California study, their computational analysis supported the grouping of the two behaviors. For the UCSD team, these results will help them plan their future analyzes as they work to understand the complex social lives of these parrots. On a larger scale, Van der Marel said the new framework could also help other researchers in the field of animal behavior to make informed and data-driven decisions about when to group behaviors together and when to separate.