Polly wants a cracker, but she wants to make it easier to chew
Every day the Goffin Lab in Vienna offers the same lunch to its customers. At 2 p.m., the guests – a flock of white parrots known as Goffin’s cockatoos – receive an assortment of dried fruit, seeds, cornflakes, bird pellets and a dry, twice-baked toast known as rusk or zwieback.
It’s a perfectly tasty meal for a parrot, and most birds dig right into it. But a few cockatoos are choosier and customize their meals with one final decoration: before eating the rock-hard rusk, they dip it in a container of water. .
Although the gesture is familiar to biscotti lovers with opposable thumbs, the Goffin cockatoo’s behavior appears to be an innovation in food preparation, researchers reported. in a study published Tuesday in the journal Biology Letters. The cockatoos sometimes spent a lot of time and energy on this task, actively bringing the rusk to the water and then waiting for it to soften.
“It’s quite impressive to go to all this effort to change the texture of your food,” says Alice Auersperg, head of the Goffin Lab at the University of Veterinary Medicine in Vienna and author of the study.
This is the first time this food capping behavior has been documented in parrots; it has also been observed in grackles and crows. And it was an accidental discovery for the lab, which typically relies on carefully planned experiments to test the cockatoos’ famous problem-solving skills. “But sometimes we are gifted with serendipitous things that just happen,” said Dr. Auersperg.
Goffin’s cockatoos are known for their ability to use and manipulate objects. In previous studies, Dr. Auersperg and her colleagues, for example, found that the birds could do that Open closed puzzle boxes and make their own tools to obtain food that is out of reach.
But the Goffin Lab researchers generally didn’t pay much attention to the birds’ behavior during lunch, says Jeroen Zewald, a PhD student in the lab and another author of the study. Until one day last summer they noticed something strange. An affectionate male bird named Pippin — “the master of the group,” Mr. Zewald said — dipped his food into the container of water typically used for drinking and bathing. Two other birds in the lab, Kiwi and Muki, also turned out to be dunkers, the researchers noted.
To study the behavior more systematically, Mr. Zewald and Dr. Auersperg studied the birds’ lunch behavior for twelve days. In total, seven of the 18 birds were observed dipping food at least once, they found. (Still, Pipin, Kiwi, and Muki were the undisputed dunkmasters, having many more dunking events to their credit than the other birds.)
But the birds didn’t submerge all their food. They never submerged seeds and only occasionally slipped a banana or coconut chip into the water. Instead, when the cockatoos decided to dip something, it was almost always rusk. (Pipin and Kiwi almost never ate it dry.)
Some birds soaked the rusk quickly, but others soaked it for 30 seconds or more, long enough to give the bottom a soggy bottom.
A delay of up to 30 seconds is remarkable for a migratory bird. “They were willing to wait until it was soaked,” Mr. Zewald said. “And that requires a lot of impulse control.”
On some occasions Pippin and Kiwi even picked up pieces of rusk that had fallen to the bottom of their cages, dragged them to where the water trough was located, and let them soak well before going down.
“It’s a cool study,” says Louis Lefebvre, an expert on innovative bird behavior at McGill University, who was not involved in the new study. “There is an element of adding value to the food by dipping and softening it.”
But there are limits to what scientists can learn from studying birds in captivity, he noted. Dipping behavior has not been observed in wild Goffin’s cockatoos, perhaps because they do not have easy access to dried toast and containers of water. But it would be interesting to see if wild cockatoos would take to dipping if given the right tools, said Dr. Lefebvre. “That’s the next step I hope to see,” he added.
The scientists aren’t sure whether each of the birds developed the dunking innovation independently or learned it by watching its compatriots. But they plan to keep a close eye on the cockatoos at lunch to see if more birds adopt this behavior.
It’s an unexpected new line of research for scientists more accustomed to coming up with their own challenges for the birds. “Instead of presenting them with a problem,” Mr. Zewald said, “they actually had a little problem for themselves, and they solved it.”