Crafty cockatoos have learned to open household wheelie bins so they can eat food waste, and this behavior is spreading amongst nearby cockatoos to create a local dumpster-diving culture — but people are becoming more innovative in designing devices to protect their wheelie bins too
“It’s moves and counter-moves, and it’s all we gotta look at.”
— Plutarch Heavensbee in The Hunger Games: Catching Fire by Suzanne Collins (2009)
Sulphur-crested cockatoos, Cacatua galerita, living in the southern part of Sydney Australia, have learned to open household wheelie bins in search of discarded food. As they search for fruits and bread (their favorite snacks), the clever parrots throw garbage on the streets and sidewalks and create a mess. Of course, their feathered friends are watching and learning, so this skill is rapidly spreading throughout the cockatoo community and is creating a local psittacine dumpster-diving culture.
Disgruntled humans are fighting back with a few counter-measures of their own, including bricks, pool noodles, spikes, shoes and sticks. The goal is to stop the parrots from flipping the lid open and accessing the rubbish whilst the container is upright, but allowing the lid to fall open when the wheelie bin is tilted by the automated arm on a garbage collection truck to empty its contents.
Bin protection devices have met with varying degrees of success. The simplest rubbish bin protection methods, such as a rubber snake placed on the bin lid to scare away the cockatoos, don’t work very well. And heavy objects, such as bricks, only slow down the attacking cockatoos, who push them off the lid. But other, more sophisticated, wheelie bin protection methods appear to be working. Well, so far.
“When I first started investigating bin-opening behaviour, I was very surprised by all the different measures that people have developed to protect their bins from cockatoos”, said the study’s lead author, behavioral ecologist Barbara Klump, a postdoctoral researcher at the Max Planck Institute of Animal Behavior. “This observation actually inspired the current study.”
But the crafty cockatoos are devising new ways to defeat the increasingly sophisticated rubbish bin protection measures that people are inventing. This has led people to watch what their neighbors are doing so they can adopt any wheelie bin protection devices that have proven effective.
Moves and counter-moves: Sydney’s “Battle for the Bins” is a classic example of cultural evolution in the form of an interspecies innovation arms race that involves “learned behavioural change in two populations/species”, according to the study’s authors.
Although Dr Klump and her team originally began by studying the cockatoos (ref), they wanted to better understand the human side of this escalating arms race. To do this, Dr Klump and her team examined 3283 wheelie bins across four Sydney suburbs where cockatoos open them and documented 52 combinations of techniques designed by people to deter the cockatoos from flipping open the rubbish bin lids, noting that such protection methods varied between 0% and 50% across the suburbs. The researchers classified these protection devices according the level of alterations made to the wheelie bin (Figure 1A).
Originally, Dr Klump and her team found that bin lid opening was first observed only in cockatoos living in three Sydney suburbs in 2018, but by 2019, this nifty little trick had spread so quickly throughout the cockatoo community that it was reported to occur across 44 suburbs.
The researchers then mapped the human response to the cockatoos to see where and when various protection devices were adopted geographically.
“[B]ins close to each other on the street or in walking distance are more similar in their protection type compared to those that were close in geographic space but out of sight”, Dr Klump told me in email. “This suggests that people copy how they protect their bins from neighbours or people on the same street and very nicely shows that they learn from each other.”
The researchers also gathered responses from 1134 Sydney residents in an online survey (here). These surveys revealed how bin protection methods changed over time, from no protection to increasingly elaborate protection methods.
Of the respondents that provided sufficient information regarding how they designed their bin protection method, the team found that 64% reported using social information for inspiration, and of these respondents, 60% reported that they copied methods used by their neighbors or other people on their street. These findings supported Dr Klump and her collaborators’ experimental findings that similarities in wheelie bin protection methods tended to cluster amongst neighboring houses.
Not only are people demonstrating that they are learning from their neighbors how to build better bin protection devices, but the cockatoos are learning better ways to defeat these innovations by watching each other.
“It’s not just a social learning on the cockatoo side, but it’s also social learning on the human side,” Dr Klump remarked. “People come up with new protection methods on their own, but a lot of people actually learn it from their neighbors or people on their street, so they get their inspiration from someone else.”
The survey data also revealed that 61% of people who protected their bins escalated their protection method over time (Figure 1D).
A subset of survey respondents also commented on why they changed their method of protecting their wheelie bins. The most frequently cited reason was in response to the cockatoos. As one survey respondent stated: “Bricks seemed to work for a while, but [the] cockies got too clever. Neighbours on other [the] side of [the] highway suggested sticks. They work.”
Scientists once thought that only humans have culture, but as this study reveals, cockatoos are very capable problem solvers whose innovations spread quickly throughout their community.
“We know that a lot of animals are similar to us in the way they learn [from each other] and have their own local traditions,” Dr Klump said. Such animals include whales, chimpanzees, parrots and, surprisingly, even insects.
Dr Klump already has plans to study how these urban cockatoos adapt to the increasingly sophisticated bin protection methods that people are inventing.
“Next year, I will start my own research group at the University of Vienna in Austria”, she told me in email.
Dr Klump expects human-wildlife interactions such as these will increase in the future as cities increasingly become the last refuge for wildlife.
“As cities expand, we will have more interactions with wildlife,” Dr Klump said. “I’m hoping that there will be a better understanding and more tolerance for the animals that we share our lives with.”
Barbara C. Klump, Richard E. Major, Damien R. Farine, John M. Martin, and Lucy M. Aplin (2022). Bin-opening and bin-protection in cockatoos and humans: beginnings of an inter-species innovation arms race? Current Biology | doi:10.1016/j.cub.2022.08.008
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