Chickens
Chickens are a common barnyard animal. They are successfully raised around farms and even homes in the United States. Although common, they are unique in their own way.
This is very true when it comes to their sleeping habits in the wild.
Sleeping with one eye open is taken very literally by the chicken. They can and do indeed sleep with one eye open and one eye closed if necessary.
But how does this work?
Well, the chicken has two brain hemispheres which they are able to control separately. Their left eye is connected to their left hemisphere while their right eye is connected to their right hemisphere. This allows for differences in control.
In fact, while one eye is closed it is this side of the brain which is in “resting mode” while the side with the eye open remains awake and alert for any potential threats.
Scientifically speaking this is known as “hemispheric slow-wave sleep”. This is a survival mechanism of the chook who may be very vulnerable to predators.
Chickens may not necessarily always sleep with one eye open. Sometimes, they may even take turns in watching over the flock. Or, they may group together with the outside chickens sleeping with one eye open to watch their surroundings.
A very tactical method for a smaller, prey species.