In 1977, animal psychologist Irene Pepperberg went into a pet shop to purchase a parrot. The one-year-old African grey, randomly chosen by the store clerk, was named Alex—or more specifically ALEx—the acronym for Avian Learning Experiment.

For the next 30 years until his death in 2007, Alex helped Dr. Pepperberg show the scientific community—and eventually the general public—that parrots possessed the potential to reason and understand complex abstract ideas.

User moonsprite shared an article about Alex’s accomplishments on Reddit’s Today I Learned community, highlighting that his handlers believed he possessed the intellectual abilities on par with a five-year-old human:

“At the time of his death, he could identify 50 different objects and recognize quantities up to six and could distinguish seven colors and five shapes. He understood the concepts of ‘bigger,’ ‘smaller,’ ‘same,’ and ‘different,’ and was learning ‘over’ and ‘under.’”

He had a strong vocabulary spanning over 100 words and even came up with his own word for an apple, when he saw one for the first time, naming it “banerry”—a combination of “banana” and “cherry,” two fruits he was already familiar with. Alex could also count and was able to communicate what he wanted.

Once, when Alex told researchers he wanted a banana, he was instead given a nut. He responded by chucking the nut back at the researcher and asking for a banana again.

Alex was making incredible progress—and had made headlines and been in television features—when he died suddenly. He was only 31-years-old, just half of his expected lifespan, but the researchers said he suffered from heart disease.

His last words, which he spoke to Pepperberg every night before bed, were, “You be good, see you tomorrow, I love you.”

Alex’s legacy lives on in Pepperberg’s research, which she has continued under The Alex Foundation: A nonprofit organization dedicated to supporting research that will increase understanding about the extent of parrots’ cognitive abilities.

According to their mission statement, the foundation seeks to secure the future for parrots, both through preservation efforts and by educating owners on how to handle their smart feathered friends:

“Through these efforts, The Alex Foundation, and the memory of Alex, will live on and will accomplish its mission to improve the lives of all parrots worldwide.”