Several members of a captive population of greater vasa parrots are using tools to make their own calcium powder, according to a new study that reports the method was completely self-initiated.
The discovery not only represents a novel usage of tools among birds, but also is the first time that any non-human has been observed making a nutritional supplement to satisfy its own needs. The findings are reported in the journal Biology Letters.
It appears that one extremely smart, creative-thinking bird first devised the technique.
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"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," lead author Megan Lambert of the University of York's Department of Psychology told Discovery News.
Lambert, with colleagues Amanda Seed and Katie Slocombe, noticed the behavior while monitoring 10 greater vasa parrots, which are native to Madagascar but are housed together in an aviary at Lincolnshire Wildlife Park, U.K. The floor of their enclosure consists of soil, cockleshells, wood chips and pebbles.
The researchers noticed that several members of the population used pebbles to break the shells apart and then grind them into a fine powder, which they would lick and consume. When later fed dates, they would use the remaining date pits in a similar manner.
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Parrots are known to nibble on shells, particularly at a certain time of year, but they usually do this with their beaks. The scientists therefore suspect that the pebbles, date pits and crushing might mitigate their discomfort from beak scraping, or prevent rapid beak wear.
"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 explained.
She continued, "This is one possible explanation for why these birds were so interested in the shells just before the breeding season, but ultimately more research needs to be done to determine whether this regularly occurs before the breeding season in these birds."
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Greater vasa parrots are among the most social birds. They have a high degree of social tolerance, spending a lot of time being very close to each other with few signs of aggression. The researchers think such tolerance could promote learning.