From the University of Vienna:
To investigate the play behavior of parrots and crows researchers confronted groups of three crow species as well as a total of nine parrot species with an identical set of wooden toddler toys of different shape and colour categories as well as with a ‘playground’ offering various tubes and holes for insertions and poles for stacking rings. Whereas animals of most species interacted with the toys, complex object-object combinations were largely limited to a subset of the species. The frequency of playfully combining two free toys was highest in New Caledonian crows within crows and in Goffin cockatoos, Black Palm cockatoos and Kea within parrots. Goffins and New Caledonian crows even combined up to three toys. “New Caledonian crows are innate tool users and also the only crow known to regularly use and manufacture different types of foraging tools in the wild”, says Alice Auersperg from the University of Vienna who organized the study: “The Black Palm cockatoos are also habitual tool users, with the males using wooden logs as drum sticks to attack their females to potential breeding sites and to deter competitors. The Goffin cockatoo as well as the kea, although not innate tool users, have both repeatedly demonstrated the capacity for innovative and flexible tool use as well as high-level performances in problem solving tasks involving object manipulations in captivity”.
Again, only the aforementioned species also combined their toys with the tubes and poles of the playground at high rates. “Inserting behaviors occurred most frequently in New Caldonian crows, followed by Palm cockatoos and Goffin cockatoos, again, consistently with their tool use capacities”, says Auguste von Bayern from the University of Oxford. Only parrots stacked rings onto poles and tubes, the Goffin cockatoos notably more often than other species. “Fitting a frame over a fixed shape is likely to occur less frequently in natural situations than fitting a shape into a fixed frame and it may require a higher level of motor control”, adds von Bayern. The cockatoos even stacked the rings onto, or pulled them over, free stick-shaped objects, which is technically more challenging than if either frame or shape are fixed terms of beak foot coordination.
“Our findings parallel previous findings in primates”, says Alice Auersperg: “This further implies that some abilities substrates in large brained birds and primates may have evolved convergently”.
Alice Auersperg, Jayden van Horik, Thomas Bugnyar, Alex Kacelnik, Nathan Emery, Auguste von Bayern: “Combinatory actions during object play in parrots and corvids”. In: Journal of Comparative Psychology). December 2014. http://dx.doi.org/10.1037/a0038314
Remember this when you hear people claiming that primate apes are close kin to humans because they are smarter than other animals. There are good reasons to believe that apes are closer kin to humans but being automatically smarter than all other animals is clearly not one of them.
That fact has a bearing on causes to give apes “human rights.” If the claims are made on the basis of intelligence, should smart crows not also have human rights?
See also: Matching Darwin’s “Tree of Life,” the “Tree of Intelligence” comes crashing down”
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