Most bears are naturally crepuscular animals, meaning they are most active at dawn and dusk. They can be awake both during the day and night, but usually nap in the middle of the night and in the middle of very hot days.
However, due to human activity, many bears have increasingly adapted to nocturnal habits to avoid any human contact during the day.
Campers may come across bears at night. Bears will avoid the area during the day and may head into campgrounds at night when they think they’re safe from humans.
Are Bears Nocturnal or Diurnal?
Research into bear sleeping behaviors has found that both black and grizzly bears tend to nap at midday and midnight. Both species can also be active day or night, depending on a range of factors.
Therefore, most bears are neither nocturnal or diurnal. Rather, they are crepuscular, meaning they are active at dawn and dusk.
There are many factors that influence bear sleeping patterns, including predator threats, threats from humans, and gender.
Factors Influencing Bear Sleep Patterns
| # | Factor | Explanation |
|---|---|---|
| 1. | Proximity to Human Development | Roads, houses and campsites nearby lead bears to be more night-active to avoid human contact. |
| 2. | Hunting Season | Bears will be more active at night during hunting season (in hunting areas only) to avoid hunters. |
| 3. | Gender | Studies have found female grizzlies are more day-active while male grizzlies are more night-active. |
| 4. | Inter-Species Interactions | In areas where black and brown bears are both active, studies have found black bears are more active during the day and grizzly bears are more active at night. Presumably, this is so black bears can avoid being attacked by grizzly bears. |
| 5. | Hunger and Time of Year | Bears tend to eat more in Spring (following hibernation) and Fall (preceding hibernation) in order to put on weight. At these times, bears will be more active around the clock. |
Are Black Bears Nocturnal?
The black bear is usually very busy at dawn and dusk. However, this does not mean it’s not possible to see a bear at other times of day. They can be active at any time of day.
In the months leading up to winter hibernation when a black bear is putting on weight in preparation for his lengthy slumber, he will be much more active around the clock.
A black bear may eat for up to twenty hours each day during this period, consuming more than 20,000 calories.
Because the black bear eats for up to twenty hours a day and has sporadic sleep patterns, it’s hard to classify it as either nocturnal or diurnal. Their sleeping habits have as much to do with the time of year and their environment as it does with when the sun rises and sets.
Are Brown Bears Nocturnal?
Like black bears, brown bears are crepuscular, meaning they’re most active at dawn and dusk. However, their sleep habits are heavily impacted by proximity to hunters and human settlements.
During the salmon spawning season, the mother brown bear eats during the day with her cubs. Adult male brown bears, on the other hand, are more likely to be active at night. They hunt both during the day and at night.
But, when hunters are nearby, grizzlies will choose to be more active at night to avoid hunters.
Here, it’s evident that grizzly bears can be active at any time of the day, depending on their environment, proximity of food, and proximity of humans.
Are Polar Bears Nocturnal?
In the arctic, polar bears have to endure months of darkness and months of sunshine, depending on the time of the year. Polar bears would starve for months if they solely hunted for food at night or day.
So, polar bears are neither diurnal or nocturnal. They sleep when they feel the need.
One study found that polar bears sleep 7-8 hours a day, and more often during darker hours. However, a main influencer on polar bear sleep patterns is feeding time. They will usually sleep about 2 hours after feeding.
Mother polar bears will also take her cubs far from other bears when sleeping to avoid attacks from male polar bears.
Are Bears More Nocturnal Near Human Developments?
Studies have found bears are more active at night when humans are nearby, presumably to avoid human contact. But, they become used to humans and more bold with increased contact.
Therefore, you can come across bears at any time of day or night. Be extra careful when in bear habitats during dawn and dusk and store camping food in bear boxes away from campsites to avoid potential interactions at night.
Bears who become acclimatized to human, such as those where new developments have encroached on bear habitats, will become more bold around human beings. They will still be more nocturnal, but at night will be more bold about approaching human-dominated areas.
Therefore, many rangers will have to relocate or euthenaise a bear who is too curious around humans. This is a last resort, though, because rangers know we are in bears’ territory, where they have a right to roam.
Do Bears Change Sleep Behaviors to Avoid Hunters?
Most people hunt bears during the day, between dawn and dusk. There are many laws in parts of North America outlawing nighttime hunting.
Bear behaviors have been observed to change their sleeping habits in response to the presence of hunters.
This study found that bears will choose to cross roads at night time when hunters are not around. Male bears are hunted more than female bears, and the study found male bears consequently changed their sleep behaviors more than female bears to avoid hunters.
Conclusion
Bears are neither nocturnal or diurnal. They are considered to be crepuscular, meaning they are most active at dawn and dusk. They are most likely to sleep in the middle of the day and middle of the night, but a range of factors will influence their sleep patterns. Primarily, they are prone to act out of fear and sleep when they feel most safe from attacks form other bears or humans.
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