How do bears get enough food? Bears are able to find enough food because they have an incredible sense of smell, excellent vision, and they can eat almost anything.
This is a slightly difficult question because there are lots of different types of bears and they are all different sizes. The polar bear is obviously the largest, but we’re not going to look at that because it is primarily a carnivore and I looked at polar bears in a previous question. There are 8 species of bear. The North American Black Bear. The Brown Bear. The Polar Bear. The Asiatic Black Bear. The Andean Bear. The Panda Bear (yes, pandas are bears – which is why it make little sense that they only eat bamboo – something I have also looked at). The Sloth Bear. The Sun Bear. I think, to make things easier, we will just concentrate on the Brown Bear because it is the second largest bear after the polar bear and finding out what it eats will be interesting.
Brown bears are native to North American and northern Eurasia. There used to be a lot more of them and they used to come further south, but their habitats have slowly been built over by us. The largest male brown bears weigh about 600 kg, although some larger ones have been found. They are about 1.5 m at the shoulder, but when they stand up they can reach about 2.5 m. They are not as big as polar bears, but they are massive. They have very long and strong claws on their front and back paws. Bears this size need to find about 20,000 calories a day, up to 50,000 when they are building up to the hibernation period. That is almost ten times more than we need. When humans were hunter gatherers, we spent all the time we were awake trying to find food so that we didn’t die. Imagine having to find ten times as much. So, how do brown bears do it?
Brown Bears have a few advantages to finding food that we don’t have. The first is that they have an incredibly strong sense of smell. A bear’s sense of smell is about 2,100 times better than ours. That makes it seven times better than the sense of smell of a bloodhound. That means they can smell food from a long way away. They can smell things that are under the ground, they can smell insects inside trees, and they can smell animals and dead animals. Humans have to search until the find food, but bears can go directly to the food. The second advantage is their vision. Similar to a cat, bears have a reflective lining at the back of the eyeball that reflects more light into the retina, allowing them to see pretty well in the dark. They can hunt in the daylight and in the dark.
The third advantage is that bears can eat pretty much anything. Humans can as well, but we tend not to eat things like insects or dead animals for fear of getting sick. Bears don’t have this fear. Bears can also digest food that we can’t. The majority of a bear’s calories come from plants. They are omnivores, as we are, so they have a slightly longer digestive tract than a true carnivore, but theirs is even longer than ours is. That means they can digest food for longer and get more calories out of plants than we can. However, they cannot get out as many calories as a herbivore, so they have to eat the youngest plants because they are the most nutritionally dense and easy to digest. Bears can also hunt and kill animals such as deer and moose. A moose is massive, but a bear can kill one if the opportunity arises. They will then eat what they can and bury the rest to be consumed at a later date. Bears can also eat dead animals that they find. A lot of a bear’s food comes from fruits and nuts. These are also energy dense and can provide a lot of calories. They eat insects as well. They will look under rocks and logs for insects, but they will also tear the bark off trees if they smell insects underneath. They can smell ants under the ground as well, and a bear will tear up an ant’s nest, wait for the ants to come out, and then lick them all up. In this way, but eating whatever they can find and spending most of every day looking for food, bears can eat 20,000 calories a day. And this is what I learned today.
Sources
https://www.largecarnivores.fi/species/brown-bear/bears-diet-and-hunting-behaviour.html
https://en.wikipedia.org/wiki/Brown_bear
https://www.nps.gov/articles/yell-wildlife-bear-food-habits.htm
https://www.nps.gov/teachers/classrooms/bear-nose.htm
Photo by Vincent M.A. Janssen: https://www.pexels.com/photo/brown-bear-3048718/