[B]road claims for animal intelligence that go well beyond problem-solving abilities are often questionable.
Consider, for example, the mirror test (“ravens recognise themselves in the mirror”). It wasn’t until a fish, the cleaner wrasse, passed the test that a number of researchers began to voice questions.
Suzana Herculano-Houzel writes at Science,
The term “birdbrain” used to be derogatory. But humans, with their limited brain size, should have known better than to use the meager proportions of the bird brain as an insult. Part of the cause for derision is that the mantle, or pallium, of the bird brain lacks the obvious layering that earned the mammalian pallium its “cerebral cortex” label. However, birds, and particularly corvids (such as ravens), are as cognitively capable as monkeys and even great apes.
Just a minute. Few people familiar with corvids have supposed that they can’t think at all. And if they really are as “cognitively capable as monkeys and even great apes,” that only makes humans much more exceptional than previous supposed. Apparently, there is no “ladder of intelligence.”
Generally, we are the only life form that writes great novels or great equations, invents philosophies or religions, or sends probes into space just to find out what is up there. So we really are just unique.
In the end, crows, ravens and various other birds are proving to be as smart as our ancestors thought they were.