Parrots in captivity use tools to grind calcium-rich seashells into a dietary supplement of calcium powder, which they consume. This is remarkable: many animals demonstrate preferences for rare dietary elements, and do things such as licking clay to supplement their diet, but never before has an animal been seen making their own supplements using tools.
Parrots need calcium, especially right before the breeding season, because
(i) bird skeletons cannot store calcium* as efficiently as mammal skeletons
(ii) birds lay eggs, which are surrounded by a protective calcium-rich shell.
And these parrots, the greater vasa parrots from Madagascar, were kept with many seashells nearby-- seashells which they would chew from time to time, inflicting costly wear and tear on their beaks. So, one clever member of this captive population came up with a novel innovation: use hard pebbles and date pits to grind calcium powder from the seashells. (See video of tool use here). Tool use was quickly adopted by five of the ten birds in the population, an example of social knowledge sharing.
These are not the only birds to be drawn to seashells for their calcium: sandwich terns eat seashell fragments as well. But these parrots are certainly the only animals to use a tool to grind powder from seashells!
Well, the only animals except humans, that is.
*Perhaps the most important role of our skeletons is to store calcium.
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.