Bears are usually crepuscular or diurnal, meaning they’re active at dawn and dusk or in between, though this depends on both species, seasonality, gender, and human proximity. Some bears, such as the black bear, are diurnal. Males tend to be more nocturnal than females.
The activity pattern of different animals varies depending on their natural adaptations, food sources, and general behavior.
Most animals fit into one of three groups: nocturnal (active at night), diurnal (active at day), or crepuscular (active at dawn and dusk).
Bears fit into all three, depending on their species, as well as other factors.
In this article, we’ll talk more about what species are nocturnal, diurnal, and crepuscular, as well as the different factors that affect this.
When Are Bears Most Active?
Bears are active at dawn and dusk or in between. They may be seen rummaging during any time of day and night, as they’re not exclusively active at dawn and dusk.
There are many different species of bears, hence things are not always straightforward. Most things vary depending on the species.
You can read more about the activity patterns of specific species later in this article.
Other factors also have an effect on a bear’s activity pattern, such as seasonality, gender, and proximity to human development.
Are Bears Nocturnal?
Some bears are nocturnal, or active at night. However, this is not true for all species; there are some that are crepuscular (active during dawn and dusk).
Nocturnal animals are most likely to be seen at night because:
- their prey is active at night
- it’s safer at night
- they’ve developed the tendency over many years
Sloth bears are nocturnal, as they typically stay up at night to feed on termites or other foods.
Are Bears Diurnal?
While most bears are crepuscular, there are some species of bear that are more active during the daytime[1]. Black bears and grizzly bears may be diurnal.
There are a number of factors that can affect a bear’s activity pattern, including season and proximity to humans. In general, female bears are more active during the day than males.
Are Bears Crepuscular?
Most bears are crepuscular, meaning that they are more active at dawn and dusk[2]. This is true for most species of bears in North America.
However, it does depend on the season; during the summer months when food sources are abundant or near hibernation time where there’s not much to eat, this rule may be broken.
Do Bears Come Out at Night?
Yes, bears do occasionally come out at night. Just because they’re most active during the twilight hours, doesn’t mean they can’t be active at night.
While bears do have a preference, when it comes to their activity pattern, their pattern may have exceptions from time to time. A black bear may at times come out at night.
When bears come out at night to search for food, or to avoid human contact.
In general, bears are most active in the early morning or evening, or in between, because that’s when their prey is available in larger amounts. Small mammals, like mice, are abundant under the cover of darkness while larger animals usually sleep until sunrise.
What Bears Are Nocturnal?
The sloth bear is the most nocturnal of all bear species. They primarily eat during the night and are very secretive, rarely seen by people. Ironically, sun bears are also nocturnal.
The two most nocturnal bears are:
- Sloth bears
- Sun bears
Contrary to their name, sun bears are considered to be fairly nocturnal, especially during the summer months.
These bears will typically hunt for food under the darkness of the night, where they won’t be seen as easily.
Grizzly bears are known to be either diurnal or nocturnal, depending on their living conditions. While their activity pattern can be either one, they don’t switch between the two.
It is important to note that not all bears are strictly nocturnal or diurnal. Some species, like the Asiatic black bear, maybe more nocturnal if they live in areas with high human populations.
Factors That Effect Bears’ Sleep Pattern
There are several factors that can affect a bear’s activity pattern. These include proximity to humans, seasonality, and gender.
The three factors can have a great effect on the activity pattern of a bear.[4]
Seasonality may play a role in some bears’ activity pattern – in the summertime when there’s more daylight, bears are typically more active during the day.
Proximity to humans can also make a difference; if there are people around, bears may be more likely to be nocturnal in order to avoid contact.
Gender is another factor that can affect activity patterns. Female bears tend to be more crepuscular than males, while males are more variable in their activities.
Proximity to Human Development
One of the most significant factors that can affect a bear’s sleep pattern is its proximity to human development.
All wild animals, including bears, have an innate fear of humans. They stay away from people, as they’ve learned that people are dangerous.
Bears that are habituated to humans may also be more likely to be active at night, as they’ve learned that people are not likely to be active during that time.
Season
Bears are less active during the winter, where they may be hibernating for up to six months[3]. In the summer, they are more active and may be seen roaming around during the day.
They hibernate due to their natural adaptation to colder climates; in order to conserve energy, bears will sleep throughout the winter when food is scarce. To prepare, they may eat up to 90 pounds (40 kg) of food a day.
While they’re inactive, their body temperature drops and heart rate slows significantly.
Gender
Female bears tend to be more active during the day, while male bears tend to be more active at night. This may be because male bears are polygynous, meaning they are attracted to female bears with whom they can mate.
Species and Activity Patterns
| Species | Activity Pattern |
| Grizzly bear | Diurnal, Nocturnal or Crepuscular |
| Black bear | Diurnal |
| Sun bear | Nocturnal |
| Sloth bear | Nocturnal |
| Polar bear | Neither Nocturnal nor Diurnal |
Are Grizzly Bears Nocturnal or Diurnal?
Grizzly bears can be both nocturnal, diurnal, or crepuscular. Studies show how they may adapt to their environment.
While they can be both nocturnal or diurnal, they won’t change between the two. There’s also a difference among genders, where male grizzly bears tend to be nocturnal or crepuscular, whereas more female grizzly bears are diurnal.
Are Black Bears Nocturnal or Diurnal?
Black bears are active at almost all times of day but are most active during the day, from dawn to dusk.
These bears feed primarily on plants, which make up 90% of their diet. When they hunt, they’ll do so during the day.
Are Polar Bears Nocturnal or Diurnal?
Polar bears are active at all hours of the day. They don’t sleep at night or day, but when they feel the need. They typically also sleep after they’ve eaten.
One study shows the activity pattern of 11 different polar bear families. While it’s clear that activity slows down at night, they were still active at this time of day. Hence, they’re neither nocturnal nor diurnal, but active when needed.[5]
Can Bears See in the Dark?
Bears have great night vision, as they have a reflective layer in their eyes called the tapetum lucidum. This layer reflects light back through the retina, allowing them to see in low-light conditions that are impossible for us.
There are two reasons why bears can see better at night than humans:
- An increase of rod cells
- The tapetum lucidum
Bears are considered dichromatic[6], meaning they have two different types of cones cells in their eyes instead of three like humans do. This means they can detect fewer colors than what we are able to perceive.
Nocturnal animals typically have fewer types of cone cells at the expense of a greater amount of rod cells.
Cone cells are responsible for detecting colors, while rod cells are responsible for detecting light. With more rod cells, bears are better equipped to see at night.
Additionally, they have a reflective layer in their eyes called the tapetum lucidum. This effectively increases the light exposure in their eyes, enhancing their vision in dim light.
When Do Bears Sleep?
Bears take naps during the night, and may also do so in the middle of days, especially very hot days. Bears are known to sleep between 7 and 14 hours per day. The length of time a bear sleeps depends on the species, age, season, and gender.
Related: Where do bears sleep?
Conclusion
Bears can be both nocturnal, diurnal, and crepuscular, depending on their species. Where black bears are diurnal, and sun bears are nocturnal, grizzlies can be both, as well as crepuscular.
The activity pattern for many other bear species depends largely on seasonality, gender, and proximity to human development.
