Scientists have discovered the latest fad sweeping across the sulphur-crested cockatoo parrots of Sydney, Australia: lifting up trash can lids to score a snack. In a new study this week, they detail the recent emergence and spread of this learned behavior, which they say is a common but not always easily observed example of cultural change happening among non-human animals.
Lucy Aplin and her team at the Max Planck Institute of Animal Behavior have long been interested in unraveling the social lives of animals, with a particular focus on birds. Their earlier research, for instance, has shown that great tit birds in the UK can quickly pick up and then pass on a method for solving a puzzle that would yield juicy mealworms—an aptitude for learning that might explain how these birds en masse raided the milk bottles of an English town a century earlier by breaking open the caps so they could steal the cream inside.
This time, Aplin and her team worked with other researchers in Australia to investigate recent sightings of sulphur-crested cockatoos, a native bird, breaking into trash bins across Sydney.
“We are very interested in understanding the potential role of the spread of innovation as a mechanism for behavioural flexibility in changing environments like cities, so when we first saw this new innovation in cockatoos, we knew we had to study if it was spreading via social learning,” Aplin, who heads the Cognitive and Cultural Ecology lab at Max Planck, told Gizmodo in an email.
Their new research, published Thursday in the journal Science, had several different angles to it. First, they surveyed people in various neighborhoods between 2018 and 2019 about whether they had seen the birds trash diving. Ultimately, they collected more than 300 sightings of trash bin lid lifting from 44 suburban neighborhoods, with most involving multiple parrots. Then they actually went out and tagged more than 400 cockatoos (with temporary color marking) found in three hotspots so they could observe the behavior themselves.
From all their work, they determined that, before 2018, trash bin lid lifting was likely only happening in three suburbs. But as this behavior began to spread, they found that it would subtly shift from place to place, essentially creating local flavors of lifting. Birds in one neighborhood might keep the lid propped up the whole time, as opposed to birds that completely flip the lid open, for instance. There were also clear patterns in who did the lifting, with males representing 84% of attempts. Birds of all ages lifted the lids, suggesting the behavior was passed through different groups in cockatoo society, but the most socially dominant males tended to be the most successful foragers, perhaps indicating that they had first dibs on the trash.
“Our study adds to the evidence that other animals have culture, and shows how new innovations can spread across populations to lead to new behaviors,” Aplin said.
Learned behaviors among socially adept animals have been documented many times before, such as with chimps passing along knowledge about tool use. In these sightings, there’s also been evidence of cultural diversity, with different groups of chimps adopting different variations of tool use. But according to Aplin, there’s been less work looking at how humans and the environments we make can directly shape animal culture, especially up close like this.
“These findings show that new cultures can develop rapidly in response to urban, human-provided opportunities, too,” she said.
While it’s possible that trash bin break-ins might become the hottest craze in cockatoo world, the behavior actually spread less rapidly than Aplin and her team figured it would. One possible reason for this delay might just be that it’s not exactly the easiest trick to learn, since it can take months for birds to get the hang of it. Natural barriers like forestland might impede its spread to other neighborhoods, as could the fact that male birds (as opposed to females) tend to stay close to home. City parrots also tend to migrate less, which could affect its popularity there compared to the suburbs. And of course, there’s always those meddling humans to worry about.
“People are beginning to protect bins, as they would understandably like to reduce the mess caused by cockatoos riffling through them!” Aplin noted. “We are really interested in following this human behaviour over time to see what effect that has on cockatoo behaviour.”
Whatever happens to these trash-loving birds, Aplin and her team hope that their research can further shine a light on how animals can culturally adapt to a changing world, just as humans have for millennia.
“Our capacity for innovation and culture is the secret to our success, allowing us to live in many different environments and adapt to many new situations. This work shows that this ability is not entirely limited to humans—some other animals have the capacity for rapid behavioural adaptation, too,” she said. “Anthropogenic change is rapid and ever increasing—understanding these behavioral responses to novel environments is vitally important if we want to understand when and how animals will cope with these changes.”