The Science of Bear Vision | Do bears have good eyesight?

Ajouté : 2026-05-05

[00:00:00]There is a long-held belief that bears have poor eyesight. I've questioned that myself for a long time, but finally science has given us the proof that black bears actually have very good eyesight. And we're going to get into that today. We're also going to talk a little bit about what colors they can see, how well they can see at night, and some of the fallacies that we have long believed about bears' eyesight. So, first of all, we got to talk about where did this myth come from that bears have poor vision? And I think there's two primary factors to it. Number one is that they have these beady little eyes, and you would think, "Well, maybe they don't have very good vision because they have these really small eyes." Well, it turns out that they actually don't have small eyes. Their eyeball is actually quite large. It's about the same size as a deer's eyeball. And we can find that out by measuring the eye socket in the skull of a deer versus the eye socket in the skull of a bear. And we learn that the eyeballs are about the same size.

[00:01:06]The difference is the opening for the eye in a bear is much smaller, even though the eye is about the same size.

[00:01:14]And that is, of course, a function of the fact that their heads are lower to the ground, and they live in thick cover, and they're always moving through a lot of brush, and they need the protection. So, while their eyes are not small, just the opening for their eyes make it look like they have these beady little eyes. And another thing, a side interest here is that they actually have a third eyelid. And some other animals have it, like a cat has it, beavers have it. The third eyelid can actually cover up the eye to protect it when it's in thick cover. Another reason I think this myth of poor eyesight came about is because so many people have had an experience where they said, "Well, the bear looked right at me, and he didn't even react. He wasn't scared." Um I was in a tree stand or whatever, and the bear just looked right at me and did not react. So, he must not have seen me. The reality is it's not that he didn't see you. We often compare the behaviors of animals to what we know when we're out there in the wild. And when you see a deer, for example, that's what most people compare it to cuz they're hunting, they're in a tree stand, they see a deer, the deer sees them, the deer takes off, but the bear doesn't. And he doesn't have the same fears, and his demeanor is different. And when he sees you, deer live basically in a edge of panic all the time. And so, when they see you, they take off, but a bear doesn't have to. He's a predator. And the other component to this is, especially if you were in a tree stand, what does a small bear do when a big bear comes along? The small bear runs up a tree. That's his escape. So, being in a tree is actually being in a subordinate position. So, that adds also to the confidence of a predator, the bear, who sees you and doesn't feel afraid of you at all. So, those are, I think, where the ideas that bears have poor eyesight came from. But let's talk about the science, and let's dive into what the bears can actually see based on what a couple of universities have learned over the past few years when they actually dissected a bear's eye.

[00:03:22]I'mma tell you a quick story here that really illustrates the way bears value other senses over their eyes, which also might lead people to believe that they had poor eyesight.

[00:03:35]There were a couple of biologists that were observing this bear that was working its way just feeding up this hillside, and they had were in a position where they could see it very well. And it was a sow working her way up this hillside. And then along came a boar. And he hit the trail of that sow, and this was in the spring. It was during breeding season, and she was in heat. And when he hit the trail of that sow, he just turned and started following her scent trail. Well, she was quite a ways up the hillside. And when she got towards the top of the hillside, she kind of made this U-turn and started to come back down. While he was following her, and pretty soon he was going up the hillside, and she was coming back down. Well, he heard her, he looks over, and he sees her over there.

[00:04:18]It's only maybe 20 yd away. And he can see her. Well, there she is. But he put his nose back to the ground, and then kept following that scent trail.

[00:04:30]And he went up around and eventually caught up to her. But the point of this is that he prioritized his ability to smell over his vision. That kind of encapsulates what a bear's life is like.

[00:04:43]They can see well, but they prioritize their other senses like smell and hearing. Okay, let's dive into the actual physiology of a bear's eye, and we know what they can see and how well they can see and what colors they see and everything like that from dissecting multiple bears' eyes. It's been done at a couple of universities here recently.

[00:05:09]And so, we know a lot more now than we ever did before. So, let's start out with a basic science lesson here, and that is how the eye is designed. It has a lens, and it has a cornea. Imagine the back of an eye as like a screen, and it has rods and cones. And rods collect light, and cones interpret color. So, the the number of rods and cones and the placement of them tell us how much light the eye can collect. It tells us what colors the bear can see.

[00:05:38]By dissecting the eye and looking at the rods and cones through a microscope, we can learn that the bears' eyes are highly sensitive to blues and greens and that part of the spectrum, to a lesser degree yellow. But they're not sensitive to reds and oranges. So, they don't see reds and oranges well at all. They see blues and greens much better, actually, than we do. Also, humans have a UV protector on their eyes, which most animals do not have because their lifespans are much shorter, and the damage of UV rays to the eye isn't as much of a concern in animals that only live. Bears live, you know, 8 to 10 years, maybe 15 to 20 in extreme cases.

[00:06:20]But they don't have the degradation in the eyes like humans do for living 80 years or so from the UV rays. Okay, we also have learned, which we already knew, that their eyes are highly sensitive to any kind of motion. They have about the same field of view as far as peripheral vision go as humans do because their eyes are placed towards the front of their head rather than on the side like a prey species. Like many other animals that you see the eye shine at night where the light reflects in their eyes, that is a membrane behind the retina. It's called the tapetum lucidum, which is a reflective substance. And so, when light enters the eye, it is reflected back across the eye. So, it effectively doubles the amount of light that a bear's eye can take in. So, they don't need a full moon, they don't need a lot of stars.

[00:07:10]They can actually see very well even when it's an overcast night. Their eyes can take in about 50 times as much light as a human's can. So, they can see very well at night with no problem at all. Of course, they probably can't see colors as well, but their night vision is spectacular. Other than the night vision, bears' eyes are surprisingly similar to a human's. Their visual acuity is very similar to a human's.

[00:07:36]It's actually quite a bit better than a deer's eyes that don't have great visual acuity. But the deer's eyes are optimized in other ways. There's a video on this channel. If you want to learn more about how a deer's eye works and what they can see in colors and all that, there's another video on this channel. You should watch that because a deer's eyes are optimized for survival just like a bear's and like a human's.

[00:08:01]So, once and for all, we can put away this myth that bears have poor eyesight.

[00:08:05]They actually have very good vision. And we know that because the science tells us that. If you want to watch a really interesting video about why the black bear population is exploding across North America, there's a video right there.

[00:08:19]Thank you for being a subscriber. Thank you for watching this channel, and we'll see you in the next video.

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