Some wild cockatoos whittle tree branches into utensils that they use to open and dig into the seed-laden pits, or stones, of tropical fruit.
This is the first known instance of wild, non-primate animals making and using tool sets, say Mark O’Hara and Berenika Mioduszewska at the University of Veterinary Medicine, Vienna.
O’Hara, Mioduszewska and their colleagues regularly study wild Goffin’s cockatoos (Cacatua goffiniana) in Indonesia. They occasionally capture the small, white parrots and keep them in an outdoor aviary to observe their behaviour before releasing them.
In the Indonesian islands, Goffin’s cockatoos are the only known species to eat sea mangos, a small, tropical fruit toxic to humans. The researchers offered the hard-pitted fruit to the 15 cockatoos in their aviary. Immediately, two of the larger and apparently older male birds grabbed a sea mango and flew into a tree to strip wood from the branches with their beaks. They also cut off whole branches and dug into the remaining stump to mine out pulpy wood.
Using their tongues and beaks, the parrots crafted the wood slivers into usable tools of three different sizes and thicknesses, O’Hara says. Then, aiming with their beaks, they artfully jabbed their cutlery into the fruit’s pit.
“After I gave them the fruit, I looked back and was just blown away seeing a [bird] using tools on it,” says O’Hara.
The researchers collected the birds’ discarded tools and created 3D models of them to better understand how they were made and the purposes they served. The thinnest tools were sharp like knives and let the birds pierce the pit’s parchment-like coating, O’Hara says. Medium-sized tools worked like spoons, allowing the birds to dig into the pit and pull out nutritious seeds. Sometimes the cockatoos also used the thickest tool as a wedge, prying the pit apart at its natural crack, which made it easier to shove their knives and spoons inside.
“They definitely knew the fruit, and they knew what to do with it,” says O’Hara.
The other 13 birds in the aviary nibbled on the fruit – but not the seeds – without using tools. This means tool use isn’t innate to the species, but unique to a few creative and innovative individuals, he says.
Just outside the aviary, O’Hara’s team filmed one bird pushing a piece of wood against a sea mango. But deep in the rainforest, the researchers found perhaps their hardest evidence of the parrots’ tool use in the wild: a half-eaten sea mango on the jungle floor, complete with a whittled wood fragment still thrust into its pit.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2021.08.009
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