Greater Vasa Parrots Make Tools To Grind Seashells Into Nutritious Calcium Powder

Greater vasa parrots take a novel approach to making sure they get their daily vitamins. In a recent study of ten captive parrots, psychologists from the Universities of York and St. Andrews discovered these resourceful birds can make grinding tools to acquire calcium from seashells.

While shells are a known source of calcium for birds, this is the first time a species has been observed making a nutritional supplement to satisfy its own needs, according to a news release.

Greater vasa parrots (Corocopsis vasa) are native to Madagascar, but a population housed together in an aviary at Lincolnshire Wildlife Park, U.K., were filmed for this eight month-long study. In total, five of the birds were documented grinding pebbles or date pits against cockle shells to make calcium powder, or at least break off small enough pieces to eat. This method was completely self-initiated by the birds and represents the first time a nonhuman has been seen making tools for grinding, as well as one of the few reports of nonhumans sharing tools directly.  

"Without witnessing the first tool using event, it's difficult to know how this behavior started, but the social system of these birds, and the fact that they share tools, would certainly support a scenario where tool use was transmitted socially after observing one innovative individual," Megan Lambert, lead author and a Ph.D. student in York's Department of Psychology told Discovery News.

Shells were of great interest to the birds between the months of March and April, which researchers believe is tied to the breeding season and a need for calcium supplementation for egg-laying. While males were more commonly seen grinding shells, they often engaged in regurgitative feeding with females before mating, suggesting they were passing along the calcium benefits.

"Unlike mammals, birds cannot efficiently store calcium in the skeleton and so may still require an extra boost during the breeding season to assist with the formation of their eggshells, which are made almost entirely of calcium," Lambert added.

Previously, parrots have been observed using their beaks to break shells apart. Therefore, researchers speculate the use of tools is a way of mitigating the pain of beak scrapping or wear.

"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," Lambert concluded in York's release. "Whether these birds also use tools in the wild remains to be explored, but ultimately these observations highlight the greater vasa parrot as a species of interest for further studies of physical cognition."

Their findings were recently published in the journal Biology Letters. 

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