It is more factual and accurate to evaluate and admire an animal's intelligence by looking at its own innate biological abilities than by how much human language it can learn. In fact, the way humans and animals can bond and connect without language makes it all the more remarkable.
What About the Claims That Birds Can Learn Languages?
The way that parrots and other birds can imitate human language words is an impressive feat. So, what is really going on when birds seem to say words? Well, for one thing, and for the most part, talking birds’ utterances don’t mean anything. Bird-owning readers may agree that a bird might say “hello,” over and over and over, in a way that a person over the age of two never would, or, say “hello” when someone is leaving instead of arriving. Unlike when people say words, birds that say words are doing something more like playing a game.
People, again, choose what we want to say and when, as opposed to producing language inadvertently. When people are hungry, we can choose to tell this fact to someone, or we can choose to stay quiet about it. When someone arrives, we are free to greet the person, or ignore the person, and when someone leaves, we are very unlikely to part ways with a “hello.” These birds are brilliant imitators, but true human language is generated by choice and intention, not by imitation.
Humans can break words down into separate sounds.
Talking birds also can’t generate new sentences by combining words they have learned, nor can they segment the words they have learned. The utterances of birds can’t be broken down into discrete units. Think of a bird who has learned to say “Polly wanna cracker.” We could ask an English-speaking child to say the same sentence, and then say, “Now say ‘Polly.’ Now, say ‘want.’ Say ‘cracker,’” with great success, and without any crackers or Pollys nearby for visual cues. I’m sure you can see how asking the parrot to do the same would be an exercise in frustration. In addition, we could ask the child to make the “p” sound, or the “ah” sound in Polly, or the “l” sound, because human language speakers produce words by combining discrete sounds. Good luck asking a parrot to isolate each sound in a word or sentence it has learned!
But What about the African Grey?
A quick YouTube search will reveal remarkable abilities in certain African Grey birds, who seemingly illustrate the ability to answer questions about shapes and colors, and to have meaning attached to the words they have learned. Although the intelligence of these birds is truly astounding, and it is a step beyond the simple imitations of a Parakeet, it is simple to explain how unlike human language these feats are. Just compare this to the words that a dog can comprehend/associate with certain actions, like “sit,” “heel,” etc. Associating a word with its meaning is not the same as being a speaker of the language.
Further, while the African Grey can answer questions, you would be hard-pressed to find a bird who could ask a fully-formed question due to a desire to find out the answer! Also, one could argue that the way dogs know a walk is coming when they hear the sound of a leash jingle is no different from knowing what the sound “sit” means, after repeated exposure to the sound and the event co-occurring. In other words, animals can associate non-linguistic sounds with meaning, too, not only linguistic sounds.