These Parrots Use Pebbles as Tools to Grind up Seashells

Polly want a mineral supplement?

pebble parrot
Konrad Wothe/Konrad Wothe/Look-foto/Corbis

For centuries, people have taught parrots how to say dirty words and dance. But according to a new study, some parrots have picked up a new skill: using pebbles to grind seashells into calcium-rich powder.

While some birds such as woodpeckers, Egyptian vultures and rooks have been documented using rudimentary tools, the greater vasa parrot is among only a handful of parrot species seen engaging in tool use. In a study published this week in the journal Biology Letters, psychology doctoral student Megan Lambert details how she and her colleagues witnessed several captive parrots at the Lincolnshire Wildlife Park grasping pebbles or date seeds in their tongues and grinding them against cockle shells lining the floors of their enclosures.

“We were surprised,” Lambert tells Sandrine Ceurstemont for New Scientist. “Using tools [to grind] seashells is something never seen before in animals.”

That is, aside from humans. Until now, no other living creature aside from ourselves has been seen using a tool to grind something into powder, Ed Yong writes for National Geographic. For several months, Lambert and her colleagues watched as at least five of the ten parrots turned seashells into dust and lapped it up. Sometimes, the parrots used the stones and pits to crack the seashells into smaller bits, making them easier to snack on.

"What's also particularly interesting is that we observed a lot of tool transfer, where one bird would actually approach group members and steal the tool directly from their beak, and then go on to use it on a shell," Lambert tells Laura Geggel for LiveScience.

Lambert isn’t exactly sure why the birds want to eat the shells in the first place, but it’s most likely for the added calcium. Other egg-laying animals, like gopher tortoises and sandwich terns, have been observed eating seashell pieces, a behavior that scientists believe might help them lay their own eggs, Yong writes. 

Greater vasa parrot using tools

However, only the male vasa parrots were seen grinding up and eating the seashells, leading Lambert to speculate that they may regurgitate the calcium to pass it along to their mates.

“It adds to the rich assortment of tool-related skills in a growing number of species. It is hard to believe that until a few decades ago humans were supposed to be the only species that used tools.” University of Oxford professor Alex Kacelnik tells Ceurstemont.

While this discovery is significant, there are still plenty of questions left to answer. Lambert’s study only focused on the ten parrots kept at the Lincolnshire Wildlife Park, and she and her colleagues only observed and did not perform any experiments on the birds. But Lambert wants to follow up by observing wild parrots to see if they also use tools to help them snack on seashells.

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