Don't ever mess with crows. Why? Because apart from just being incredibly intelligent, the corvids will remember your face for the rest of their life, and they and their friends will attack any time they ever see you.
So why in the world are crows so good with human faces? Researchers from the same department that were involved with first discovering just how good the crows are with faces have been imaging the bird's brains.
The team captured 12 adult, male crows while wearing one face mask, and then housed them and fed them wearing another — which helpfully meant that when the crows were released they wouldn't actually recognize the researchers, and make the rest of their time in Seattle a living hell.
After four weeks in captivity, the authors imaged the crow's brains using FDG-PET, which tracks the uptake of labeled glucose to measure brain activity, and they found that like us humans, the birds have sophisticated systems to recognize people, tied to their experiences.
When shown the face of their captors, the threatening face "activated circuitry including amygdalar, thalamic, and brainstem regions, known in humans and other vertebrates to be related to emotion, motivation, and conditioned fear learning", and the crows froze and fixed their gaze on the face. In contrast, when they saw the caretaker face, it activated areas of the brain tied to associative learning, motivation, and hunger.
In other words, much like humans, the crows recognize faces, and link them to emotions and memory, across diverse areas of the brain.
The question now is if the regions that are active in the crows' brains are analogous to those in humans, and if so, how much of a link is there between the learning and memory parts of the brains between birds and mammals? And is that substantially different because corvids have such fantastic memories?