The avian brain doesn't have to deal with a sense of smell.... birds can't smell at all.
This does free up a lot of brain runtime for visual processing.... birds have a far superiour and faster image processing rate than humans and other mammals.
For instance an average Hawk processes images, from the eye, at over 25 frames per second. By comparison, we process at 4 per second. A Hawk can see the flicker in a TV screen or cinema projection, a Human sees no such flicker.
Also the Human eye cannot see a common Hover Fly (the world's fastest life form) move or even its 127 beats per second wings moving. To a Human eye, the Hover Fly appears to disapear and reappear from one place to another. To a bird it is visible throughout its movement.
The other sense that birds have that we lack is the inbuilt Earth magnetic field anmaly sense. Our pet Crow, "B;lackie", is blind (detached retinas and catarachs). Despite this he manages to navigate his way with uncanny precission around the large back garden, cache food in precisely the same spot and orientate when placed anywhere in the garden. However, if taken out of the garden he is completely lost and waits for help.
Also, when a large number of the Human population can't figure out their left from right, "Blackie" the Crow definately knows his left from right as he responds to directions from me when he has a supervised flyi around. He isn't a strong flyer as he spends 99.9% of his time on the ground, but occasionally lets it be known that he wants to have a go.
He also understands tha the phrase,t "Do you want...." is offering him a choice of something and a question. Crows, being fussy and fincky eatters, will eat something one day and refuse to eat it another. Blackie recognises the association of the names with various foods and if I reel through the list he'll stretch his neck up with the beak upwards with a look of interest to acknowledge that's what he wants to eat.
There are times that I appear to be talking to a petulant child when I'mtelling the bird, "What's wrong with that.... you were quite happy to eat that earlier today / yesterday".
Blackie has also devised a mime system to ask for things, which at present, is to have his head, neck and throat vigorously rubbed with a finger as he is in malt and can't scratch there himself properly.
Watching a Crow throwing a tantrum is quite amusing. Crows bellow like a rutting Stag when angry, pick up things and throw them around and look ready to pick a fight. Watching a Cat being chased by a blind Crow around the garden is even more amusing though Cats do have an instictive recognision of which birds not to mess with.