Just like our eyes, parrots have a pupil in the middle of the eye, as well as an iris that surrounds it. The color and patterning of the iris differs a lot between different species. Parrots also have eyelids. Unlike us, but like many other animals, parrots have a nictitating membrane - a translucent memebrane that is sometimes called the third eyelid. Some bird species will "blink" with only their nictitating membrane, but parrots rarely do this in a visible way which can make it hard to spot. If you do start noticing the nictitating membrane in a parrot more than usual, it is a sign that you should contact and avian veterinarian. Many parrots also have very visible "eyelashes" - these are tiny feathers that likely have the same function as our lashes do.
What parrots do with their eyes can often give us a lot of information. In a resting bird you will often notice that the eye is slightly almond- or tear drop shaped due to the eye lids being relaxed. When something sudden happens or the parrot is very interested in something - situations where the bird might tense up a bit - the eyes will often be wide open and almost completely round, often with the pupil situated in the middle of the eye.
Parrots irises are not controlled in the same way as ours, that expand or contract depending on the light conditions, among other things. Parrot irises can contract and expand in many other situations, making the pupil bigger or smaller. Sometimes you will see parrots do something called eye pinning where the iris contracts, making the pupil look smaller. Sometimes it's just a slight change. Other times, the iris almost looks like it's pulsating, rapidly changing the size of the pupil back and forth.
We usually see this behavior:
• When parrots are eating something they really like
• During play
• Before bites and during aggressive displays
• During courtship
• ...and a lot more! As you can tell, that is quite a range of contexts!
Eye pinning doesn't tell us much on it's own, but it does give us information about a parrot's level of arousal; something we will get back to in a later chapter. The iris is sometimes difficult to see in parrots that have dark eyes, such as cockatoos or very young birds, but in for example amazons, macaws, poicephalus and grey parrots eye pinning is easy to spot. Also keep in mind that parrots will have a more contracted iris in very bright light, and a more dialated pupil in lower light conditions. It's not necessarily the size of the pupil that is important to spot, but the change in size.
Gaze and focus
Where or what the parrot a parrot is looking at can also give us useful information together with other body language. Parrots will look directly at something they might want to get closer to, or to keep track of something they are unsure about and might want to keep at a distance. They might also look away or quickly dart their head and eyes looking for the best escape route if they don't feel comfortable in a situation. You will sometimes notice parrots tilting their heads to look at things, or turning the side of their head towards you. This is often a way for the parrot to get a better look at something. One reason why they might do this is that they, unlike us, have two foveas in each eye. The fovea is the spot in the retinas in our eyes that has the most light-receptor cells and it's what helps us get that very sharp image in the middle of our visual field, like when you are reading this. You can still see a lot of other things than this text in your visual field, it's just not as sharp as what you are focusing on. Most parrots have one fovea in the front of the eye and one in the middle, which means they can focus both on what's in front of them and what's to the side. The two foveas are useful in different ways. One is better for looking at things far away, and one is better for focusing on things nearby. You'll often notice a parrot switching to looking at something that caught their attention with one eye - like when they spot a bird of prey outside, or drop a toy off a table.