In Sydney, Australia, man and bird are waging a fierce battle over the most precious of resources: garbage. For the past several years, a team of scientists has studied sulphur-crested cockatoo parrots in the area that have learned—and even taught other parrots—how to rob garbage bins. And in new research Monday, the team says that humans have now started to devise their own methods to keep the birds out, to varying degrees of success.
Researchers at the Max Planck Institute of Animal Behavior in Germany have long been interested in deciphering the inner workings of animals around the world. Last year, they published a deep dive into the trash-robbing habits of Sydney’s sulphur-crested cockatoos. They found that the practice seemed to be an example of animal culture: a learned behavior that spread from birds in three suburbs to throughout Southern Sydney. As the technique passed from neighborhood to neighborhood, the local cockatoos developed slight variations to the behavior, such as lifting the bin lid entirely open or not—something that happens commonly enough in human culture (think about how different local cultures produce their own varieties of cheese).
The researchers told Gizmodo last year that they were next interested in documenting the human side of this struggle. And that’s just what they’ve done in their new paper, published Monday in the journal Current Biology.
“When we collected data for the original study describing bin-opening behavior by cockatoos, I saw that some people had put devices on their bins to protect them against cockatoos, and I was surprised by the variety of different measures that people had come up with. So I really wanted to investigate the human response to the cockatoos,” lead author Barbara Klump, a behavioral ecologist at the Max Planck Institute, told Gizmodo in an email.
To do so, they surveyed people living in neighborhoods beleaguered by these birds. A major stumbling block to any potential anti-cockatoo trick is that the bins are designed to open and spill their contents when lifted by the automated arm on garbage trucks, meaning they can’t be kept entirely sealed tight. But that hasn’t stopped people from devising a variety of methods, like putting bricks and stones onto the lids, fastening water bottles to the lid handles with cable ties, or using sticks to block the hinges. There are now even commercially available locks that are supposed to unlatch come collection time (one such product can be seen here).
Unfortunately for the humans, cockatoos have learned how to defeat some of the simpler measures. But much as the birds are adapting, people are developing counters right back. As the researchers put it, the parrots and people of Sydney seem to be engaged in a sort of innovation “arms race,” though Klump balked at describing it as a full-on war.
“When cockatoos learn to defeat this protection measure (e.g. by pushing off bricks so that they can then open the bin), people in our survey have reported that they increase the efficacy of their protection measures (e.g. by fixing something heavy to the lid, so that it cannot be pushed off). What we have found is that bin protection (and protection types) are geographically clustered and that people learn about them from their neighbors,” Klump said.
The entire saga, the researchers say, may be a preview of the sort of increasingly common interactions between people and wildlife that we can expect as we continue to build our cities larger and encroach on wildlife habitats. Some animals, like these parrots, may find new ways to adapt to our presence, yet many others won’t. And sometimes, these interactions can be harmful to humans, such as with the emergence of new zoonotic infectious diseases.
What exactly will happen next is anyone’s guess. “One could imagine that it will continue to escalate (i.e. cockatoos learning to defeat higher-level protection types, and people coming up with even better devices to protect their bins) or it could be that one party ‘wins’ the arms race,” Klump said.
For their part, the team plans to keep studying the underlying learning mechanisms that led these cockatoos to become proficient trash collectors, and they hope to document how adept they might become at solving the latest countermeasures meant to keep them from their garbage treasure.