Parrots seen using pebble as grinding tool
December 19, 2015
Captive parrots of a species known as Greater Vasa have been documented for the first time using tools—and doing so in ways never reported among other animals, scientists say.
The birds used small pebbles or date pits to grind calcium powder from seashells, or to break off bits of shell to swallow, according to the new findings. That’s the first evidence of a nonhuman using tools for grinding, said the scientists.
The birds also sometimes share the tools, which is rare, they added, although at other times they just steal them from each other.
Researchers in the Department of Psychology at the University of York in the U.K. observed the behaviors among 10 captive parrots from the species, native to Madagascar and nearby islands.
“Whether these birds also use tools in the wild remains to be explored,” said Megan Lambert, a doctoral student in York’s Department of Psychology and lead author of a report on the findings published in the journal Biology Letters.
“The use of tools by nonhuman animals remains an exceedingly rare phenomenon,” she added. “These observations provide new insights into the tool-using capabilities of parrots and give rise to further questions as to why this species uses tools.
“Tool use could reflect an innate predisposition in the parrots, or it could be the result of individual trial and error learning or some form of social learning.”
They posted a YouTube video showing the various tool uses and related behaviors, with some of the more amusing sections being entitled “tolerated theft” and “protested theft.”
Observing and filming the parrots from March to October of this year, researchers documented their interactions with cockle shells on the floor of their aviary. Shells are a source of calcium for birds. Five out of ten birds were documented using tools, placing either pebbles or date pits inside shells to grind against the shell, or using them as a wedge to break apart the seashell.
Interest in the shells was greatest from March to mid-April, just before the breeding season; this may be due to calcium supplementation being critical for egg-laying, the investigators said.
Researchers were thus surprised at first to find that the greatest interest in shells came from males, not females. A possible explanation emerged, though: the males were also seen feeding females by regurgitating—a common behavior—before copulating with them. This might pass on the calcium benefits to the females, the researchers proposed.
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