Close this search box.

Our Blog

Owl Eyes: Nature’s Night Vision Goggles


by Holly Hastings

In the mystical realm of night, where shadows dance and humans sleep, there exists an animal with eyes that pierce through the darkest abysses. Imagine a world where sight is an art form and vision is a symphony of precision. Let us go on an enchanting journey to understand the nocturnal magic in owls’ eyes. 

An owl’s diet consists mainly of mice, voles, and other rodents, often active at night.1 Therefore, most owls are nocturnal, and night is where the hunt begins.2 Not only are owls’ eyes specialized for darkness, but they also have other evolutionary characteristics that enhance their vision:3

  1. They account for 1-5% of their body weight!4

  2. Owls have binocular vision (can see objects with both eyes simultaneously) compared to birds with monocular vision (eyes on each side of the head).5

  3. Binocular vision gives the owl (and other predatory birds such as hawks and eagles) superb depth perception.6

  4. The owl’s field of view is about 110 degrees, with 70 degrees being binocular vision. By comparison, the human field of view is about 180 degrees, with 140 degrees being binocular. This means that owls can judge distances similar to humans.
Short-eared owl recieving an exam while in care at AIWC (2024).

Similar to ours, light enters the owls’ “pupil through the cornea and passes through the lens.”9 Two types of photoreceptors exist in the retina: cone-shaped and rod-shaped.10 Cones are responsible for “color vision and spatial acuteness,” whereas rods are used for low light levels.11 Owl retinas have 30 times more rods than cones, meaning they have excellent night-time vision but can’t see much colour.

One common misconception is that because owls can see so well at night, they can’t see in the day.13 In fact, their specialized eyes are able to adjust to “allow less light in, unlike some other nocturnal animals” that can truly only see in the dark.14

Curiously, if you see an owl in daylight that you believe is sleeping, it could actually be awake but closing part of its eyelids to block out the daylight.15 All birds of prey have three eyelids: the upper eyelid closes completely downwards when blinking, and the lower eyelid closes upwards when the owl sleeps.16 The third eyelid is called the “nictitating membrane,” and it moves horizontally from one corner to the other.17 Most interestingly, this eyelid is translucent (meaning the owl can still see when it is closed) and helps to keep the eye moist.18


Great horned owl skull. CC BY-SA 4.0 by David J. Stang.
Fun fact – owl eyes aren’t actually spherical at all; they are so specially adapted that they are elongated tubes instead.20 In the image above, we see something called sclerotic rings; these rings are the bony structures of an owl’s skull that hold these tubes in place.21 Because they are so large and tubular, owls “can’t turn or roll their eyes to follow an object, and can only look straight ahead.”22 This is the reason for owls’ amusing neck rotations that can reach up to 270 degrees!23 The one drawback to these fantastic tubes is that they are very long-sighted.24 Owls can’t focus well on objects close by, so to compensate, they have adapted specialized “bristle-like feathers” around their beaks called crines.25 Crines have many functions, such as:
  • Locating dead prey once caught
  • Finding food brought by its parents
  • Removing blood from the beak to prevent sickness.26 But remember, not all owls are nocturnal.
Do you know which owls are diurnal (awake during the day)?
A wild snowy owl, one of several diurnal owl species. Photo by Vicki Hale (2019).

Leave a Comment

Your email address will not be published. Required fields are marked *

Ospreys and their recovery

by Courtney Collins Ospreys (Pandion haliaetus) can be found across Canada during the summer breeding season. Ospreys are migratory and can travel over 250,000 km

Read More

Swallows in Alberta

by Marissa Hansen Alberta is home to a diverse array of wildlife. Among the many avian residents of this province, swallows stand out as fascinating

Read More