The Australian sulfur-crested cockatoos have started lifting the lids of the garbage cans to look for food – and they seem to be learning the trick by copying each other.
Based on studies of where people have seen the birds that display this skill in Sydney’s suburbs, researchers have concluded that the ability is spreading.
When the team led by Germany’s Max Planck Institute of Animal Behavior began their research, only birds in three suburbs knew the trick — but now it’s on display in 44.
The way the trash-opening approach is spreading exemplifies social learning, the team said — proving that it’s not just an innate skill.
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Australia’s sulfur-crested cockatoos have started lifting the lids of the dumpsters to search for food, as pictured – and they seem to be learning the trick by copying each other
The birds use their beaks and legs to pry open the heavy lids of the bins, before shuffling around the rim of the bins until they can flip the lids and access the leftover food, as shown
According to author and behavioral ecologist Barbara Klump of the Max Planck Institute of Animal Behavior, social learning is something that birds and primates share with humans — where it forms the basis of regional cultures.
‘Children are masters of social learning. From an early age they copy skills from other children and adults,” she explains.
‘Compared to humans, however, there are few known examples of animals that learn from each other.’
Usually, she noted, “proving that food scavenging is not due to genetics is challenging.”
This, she explained, is why she was fascinated when her colleague Richard Major — a bird expert at the Australian Museum Research Institute — shared a video of a sulfur-crested cockatoo opening a closed trash can.
In the clip, the bird used its beak and leg to pry open the heavy lid, shuffling along the side of the container until it could flip the lid and access the leftover food inside.
“It was so exciting to see such an ingenious and innovative way to access a food source,” said Dr. clump.
‘We knew right away that we had to systematically study this unique foraging behaviour,’ she continues.
‘Like many Australian birds, sulfur-crested cockatoos are noisy and aggressive’ […] but they are also incredibly smart, persistent and have adapted very well to living with people,” added Dr. Major to it.
The way the trash-opening approach is spreading exemplifies social learning, the team said — proving it’s not just an innate skill
To investigate how common the bin opening behavior was, the team launched an online survey, explained author and applied ecologist John Martin of the Taronga Conservation Society.
“Australian trash cans have a uniform design across the country, and sulfur-crested cockatoos are common all over the east coast,” he said.
“The first thing we wanted to know is whether cockatoos open bins everywhere.”
The survey – which was distributed in Sydney and beyond between 2018-20 (and will be repeated this year) – asked questions such as ‘What area are you from, have you seen this behavior before, and if so, when?’
By comparing the results of the study over different years, the team was able to investigate how the scavenger behavior spread to other other cockatoos in Sydney.
By the end of 2019 (right), survey results indicated that residents from 44 suburbs had observed cockatoos displaying the bin-opening behavior — a rapid spread of the reports in just three suburbs seen at the start of the study. (left)
By the end of 2019, survey results indicated that residents of 44 suburbs had observed cockatoos exhibiting the trash-opening behavior — a rapid spread of the reports in just three suburbs seen at the start of the study.
In addition, the team found that the behavior seemed to spread the fastest locally — suggesting that the ability did not appear spontaneously.
‘These results show that the animals really learned the behavior from other cockatoos in their environment,’ says Dr Klump.
In addition to the study, the team also marked some 500 cockatoos with tiny, distinctive dots of paint in key locations — helping them identify which birds seemed to have learned to pry open bins.
Based on their observations, the researchers estimate that only 10 percent of the birds have learned the trick — and most of them are males. The other birds instead wait for the “pioneers” to open the bins for them before helping themselves.
In addition to the study, the team also marked some 500 cockatoos with small, distinctive dots of paint in key locations — as pictured — helping them identify which birds appeared to have learned to pry open bins.
However, the team noted that there was one exception to this pattern. In late 2018, a cockatoo in a northern Sydney suburb reinvented the bin-opening technique, after which birds in neighboring districts began copying that particular behavior.
“We observed that the birds did not open the trash cans in the same way, but rather used different opening techniques in different suburbs, suggesting that the behavior is learned by observing others,” said Dr Klump.
This is essentially, she added, an example of the emergence of a regional subculture.
Based on their observations, the researchers estimate that only 10 percent of the birds have learned the trick — and most of them are males. The other birds instead wait for the ‘pioneers’ to open the bins for them before helping themselves
The team said they hope their research will improve our understanding of animals living in urban spaces.
‘By studying this behavior with the help of local residents, we are discovering the unique and complex cultures of their neighborhood birds,’ says Dr Klump.
The study’s full findings were published in the journal Science.
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