Monday, May 20

Polly wants a cracker, but wants to make it easier to chew

Every day the Goffin Lab in Vienna offers its customers the same lunch. At 2pm, diners – a flock of white parrots known as Goffin’s Cockatoos – are treated to an assortment of dried fruit, seeds, cornflakes, bird pellets and a dry, twice-baked toast known as rusk or zwieback .

It’s a perfectly palatable meal for a parrot, and most birds enjoy it right away. But some cockatoos are more demanding, personalizing their meals with one final gesture: before eating the rock-hard rusk, they dip it in a tub of water. .

While the gesture is familiar to biscuit lovers with opposable thumbs, for the Goffin’s cockatoo the behavior appears to be an innovation in food preparation, researchers reported in a study published Tuesday in the journal Biology Letters. The cockatoos sometimes devoted a lot of time and energy to this task, actively carrying the rusk through the water and then waiting for it to soften.

“Going through all this effort just to change the texture of food is really impressive,” said Alice Auersperg, director of the Goffin Lab at the University of Veterinary Medicine Vienna and an author of the study.

It is the first time this food-dunking behavior has been documented in parrots, and it has also been observed in grackles and crows. And it was a serendipitous discovery for the lab, which typically relies on meticulously planned experiments to test cockatoos’ renowned problem-solving abilities. “But sometimes we are gifted with accidental things that just happen,” Dr. Auersperg said.

Goffin’s Cockatoos are known for their ability to use and manipulate objects. In previous studies, Dr. Auersperg and her colleagues had found, for example, that birds could open closed puzzle boxes and make their own tools to get food out of reach.

But researchers at the Goffin Lab typically didn’t pay much attention to the birds’ behavior during lunch, said Jeroen Zewald, a doctoral student in the lab and another author of the study. Until, one day last summer, they noticed something curious. An affectionate male bird named Pipin – “the gentleman of the group,” Mr. Zewald said – was soaking his food in the tub of water typically used for drinking and bathing. The researchers noted that two other birds in the lab, Kiwi and Muki, also turned out to be swatters.

To study the behavior more systematically, Mr. Zewald and Dr. Auersperg spent 12 days observing the birds’ feeding behaviors. In total, they found that seven of the 18 birds were observed dunking their food at least once. (However, Pipin, Kiwi, and Muki were the undisputed dunk masters, racking up many more “dunk events” than the other birds.)

But the birds didn’t soak up all the food. They never soaked the seeds and only occasionally slipped a banana or coconut into the water. Instead, when the cockatoos decided to soak something, it was almost always rusks. (Pipin and Kiwi, in fact, almost never ate it dry.)

Some birds soaked the toast quickly, but others let it soak for 30 seconds or more, long enough to give the toast a soggy bottom.

A delay of up to 30 seconds is notable for a peckish bird. “They were willing to wait for it to soak in,” Mr. Zewald said. “And that takes a lot of impulse control.”

On some occasions, Pipin and Kiwi even recovered pieces of rusk that had fallen to the bottom of their cages, dragging them to the perch where the water tank was located and soaking them well before chewing them.

“It’s an interesting study,” said Louis Lefebvre, an expert in innovative bird behavior at McGill University who was not involved in the new research. “There’s this element that adds value to the food by soaking it and softening it.”

But there are limits to what scientists can learn from studying birds in captivity, he noted. Soaking behavior has not been observed in wild Goffin’s Cockatoos, perhaps because they do not have ready access to dried toast and water tubs. But it would be interesting to see whether wild cockatoos would start swatting if given the proper resources, Dr. Lefebvre said. “This is the next step I hope to see,” he added.

Scientists aren’t sure whether each of the birds developed the dunking innovation independently or learned it by observing their compatriots. But they are planning to keep an eye on the cockatoos during lunch to see if other birds adopt the same behavior.

This is an unexpected new line of research for scientists who are more accustomed to devising their own challenges for birds. “Instead of presenting them with a problem,” Zewald said, “they basically had a little problem of their own and they solved it.”