“Before Pepperberg’s work with Alex, it was widely believed in the scientific community that birds were not intelligent and could only use words by mimicking, but Alex’s accomplishments indicated that birds may be able to reason on a basic level and use words creatively. Pepperberg wrote that Alex’s intelligence was on a par with that of dolphins and great apes. She also reported that Alex had the intelligence of a five-year-old human and had not even reached his full potential by the time he died. She said that the bird had the emotional level of a human two-year-old at the time of his death.” <wiki>
“… studies have found that some corvids are not only superior in intelligence to birds of other avian species (perhaps with the exception of some parrots), but also rival many nonhuman primates.” <Crows as Clever as Great Apes, Study Says – National Geographic
“Savage-Rumbaugh claims that in addition to the symbols Kanzi uses, he knows the meaning of up to 3,000 spoken English words. She tests his comprehension in part by having someone in another room pronounce words that Kanzi hears through a set of headphones. Kanzi then points to the appropriate symbol on his keyboard. But Savage-Rumbaugh says Kanzi also understands words that aren’t a part of his keyboard vocabulary; she says he can respond appropriately to commands such as ‘put the soap in the water’ or ‘carry the TV outdoors.'” <Speaking Bonobo – Smithsonian.com>
INSIDE THE ANIMAL MIND – three-part NATURE mini-series.