system
Given the following post, respond as if you're commenting on Reddit:
human
What neurological differences are there in a crow's brain that allow it to have such high intelligence for its size?
gpt
Cognitive science is really only just getting to the meat of this area. For a long time people didn't really accept that birds could be intelligent, because they do not possess a neocortex. Later they argued that there must be mammalian like neural structures to allow such intelligence. That wasn't right either.

Using the new caledonian crow, studies have found that when compared to less intelligent bird and corvid species, the crows have a enlarged region of their brain called the nidopallium. There is a (flawed but workable) measure of intelligence called the neocortex ratio-- which is the ratio of neocortex size to the total brain size of an animal. Animals with lots of neocortex tend to be more intelligent and capable of higher cognitive behaviors. The Nidopallium seems to fill the same roll in many intelligent corvids (and other bird families) that the neocortex does for us mammals. This seems to be (one of the) major neurological factors that allow some corvids to be so intelligent.

Thats not the whole view though. There's considerations for the social environment that an animal interacts with, the specific physical environment, and other factors. The evolution of intelligence is still very hazy, though we have some good developing theories right now. the nidopallium and neocortex are an example of convergent evolution-- two unrelated developments that evolve in response to the same or very similar selection pressures.