Researchers from the University of York and the University of St. Andrews in the United Kingdom observed greater vasa parrots (Coracopsis vasa) using pebbles and date pits to extract a fine calcium powder from seashells that they would then lick off the shell. Their observations were published in Biology Letters. The birds were in essence creating their own nutritional supplements from materials readily available in their cages. While parrots are known to use their beaks to extract calcium from shells, this study shows the first known example of them using tools to accomplish the task.
According to a quote from study author Megan Lambert (University of York) published in Discovery News: "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."
Tool use was greatest right before the breeding season when birds require extra calcium for developing eggs.