RIP Alex, the parrot that learnt to count and communicate

Alex the parrot could do a lot of things. He could count to six, and was working on counting to seven. He could name 50 objects, seven colours and five shapes. Scientists who kept him in a lab at Brandeis University near Boston, said he had the emotional maturity of a two-year-old child – they meant that as a compliment – and the intellectual capabilities of a five-year-old. He was, in short, no bird-brain.

But Alex is no more. The 31-year-old African grey, one of the great treasures of US scientific research, has joined the squawking choir invisible. Last Thursday, his chief keeper, avian researcher Irene Pepperberg, said goodnight to him as always. "You be good, I love you," she said. "I'll see you tomorrow." Alex responded: "You'll be in tomorrow."

But next morning he was dead in his 2ft by 3ft cage. A veterinarian who cut short her holiday so she could examine him found nothing obviously wrong.

The news was not released immediately because Dr Pepperberg and her fellow researchers needed to absorb the shock and recover enough equanimity to speak publicly about their loss.

Alex's chief contribution to avian science was to shatter the notion that parrots can only mimic human speech. Over 30 years of research, Dr Pepperberg showed he was capable of understanding and using English on his own initiative. He learnt to use phrases along the lines of, "I want X" or "I wanna go Y", and clearly meant them to express genuine desires. He grasped the concept of certain categories, including bigger and smaller, or same and different, or present and absent.

Brandeis said in a statement marking his passing: "Alex combined his labels to identify, request, refuse, and categorise more than 100 different items, demonstrating a level and scope of cognitive abilities never expected in an avian species."

That's quite an achievement for a bird picked at random from a pet shop in 1977. Dr Pepperberg had trained as a theoretical chemist at Harvard, but became fascinated by advanced forms of communication in animals, be they chimps using sign language, birds singing, or dolphins using sonar.

Gradually, she narrowed her focus to the avian brain and set up a project she called the Avian Learning Experiment, or Alex. So she named her new feathered friend Alex, and started teaching him. She and her research assistants were with him every day, using a method called rival-model technique to spur him to expand his knowledge base little by little. A similar technique has since been used to help children with learning disabilities.

Alex was learning till the end, getting his head around the number seven and forming new words from combinations of sounds he had already mastered. He also enjoyed lording it over two younger African greys in the lab – 12-year-old Griffin and eight-year-old Arthur – telling them to "talk better" when they mumbled their words. "He was so extraordinary in breaking the perceptions of birds as not being intelligent," Dr Pepperberg said. "It's devastating to lose an individual you've worked with every day for 30 years."

Alex's prowess had its precedents. A century ago, the Cheshire Cheese pub on Fleet Street in London had an eccentric parrot called Polly. On Armistice Night 1918, Polly imitated the popping of champagne corks about 400 times then fainted from exhaustion. When she died in 1926, her obituary appeared in 200 newspapers.