Study finds first evidence of statistical inference beyond great apes.

A New Zealand-based PhD student has teamed up with a parrot called Blofeld and, together, they have raised the “spectre” that the birds are much smarter than we thought.

The parrots can, it appears, make complex mathematical judgments about probability, according to a study published in the journal Nature Communications.

Until now, only two members of the great apes clan – humans and chimpanzees – were thought to be able to detect the relative frequency of an object.

To understand that bit of maths minutiae, take an example from the confectionery domain.

Say you like black gummy bears and someone puts twenty in each of two glass jars. Then they add 100 orange bears – which you hate – to the first jar, and 4 orange bears to the second jar. And give both jars a good shake.

If you get a blind lucky dip which jar would you plunge your hand into?

Each jar has the same number of black bears, but odds on you’ll go for the second jar. It has the highest proportion or “relative frequency” of black bears, which ups the chances you’ll get your preferred sugar hit.

Doctoral candidate Amalia Bastos, from the School of Psychology at the University of Auckland, had a hunch that the quick-witted New Zealand Kea parrot (Nestor notabilis), known for its ability to make snowballs and raid wheelie bins, might have similar smarts.

To find out, she and supervisor Alex Taylor trained Blofeld and five other Keas to learn that black tokens meant a food reward and orange tokens meant no food.

Read the full story in Cosmos magazine here