KENT ISLAND — Researchers published findings regarding American herring gull plumage and aggression on June 4 in the journal Animal Behavior. The research was conducted on Canada's Kent Island in New Brunswick.

As part of the study, researchers used plastic models painted to resemble gulls of different ages. These models were placed near real nesting gulls, and their behaviors were recorded. Adult gulls exhibited less aggression toward gray and brown models, which represented 1-year-old gulls, than toward models representing adults, which were bright white, gray, and black.

Nesting gulls were nearly 1.5 times more likely to be hostile toward adult models than they were toward models depicting the youngest gulls. Nesting gulls acted aggressively toward the youngest models in approximately 30 percent of encounters. Additionally, nesting gulls waited about seven seconds longer before reacting aggressively to youngster models compared to adult models.

Molly Hill, an undergraduate at Yale University, described the density of nests at these locations. "At these colonies, there'll be a nest every two to three feet, sometimes," Hill said. She also characterized the aggressive actions of nesting gulls with models. "The gesture essentially conveys 'this is my territory, this is my grass, I'm building a nest here, you should go away,'" she said.

Gavin Leighton, an evolutionary biologist at Buffalo State University, was not involved in the research. Leighton stated that the experiment aims to explain certain plumage characteristics. "The experiment 'works toward answering why so many seabirds have this nonadult plumage retained for so long,'" Leighton said.