Social and Individual Behavior and Intraspecific Interactions

Scandinavian brown bears are solitary animals that live individually, rather than in groups. However, that does not mean that the Scandinavian bear population does not have an underlying social organization or that bears never interact. Indeed, bears in Scandinavia interact with other bears in various ways during their active period and have a complex matrilineal social structure, i.e., a structure based on the multiple generations of related females (1). They also display a wide array of behaviors that can vary between individuals, at least some of which is driven by social learning (2). Individuality is important as the variation in individual behaviors is ultimately what underlies the ‘average’ patterns we see in nature. Furthermore, species that show a lot of variation in behavior between individuals are thought to be more robust in terms of adapting to anthropogenic disturbances or changes in food base, for example incurred by future climate shifts.

Social organization

Female brown bears in Scandinavia have a complex matrilineal social organization, i.e., their social organization is based on multiple generations of related females with overlapping home ranges. Two types of female group formations have been reported in the Scandinavian system: 1) some females form multigenerational groups where related females occupy exclusive areas and 2) other matrilines are more dispersed and females establish among nonrelated females or between other matrilinear groups (1). In general, females settle home ranges that overlap or are close to their mother’s home range, while males often disperse and move farther away from their mother’s home range in order to seek out unrelated potential mates (3-5). This ‘sex-biased’ dispersal pattern means that females are generally geographically located closer to their relatives, while males are more randomly distributed across the landscape (1). The short dispersal distance of females means the home range a newly independent female is more likely to overlap with that of her mother and with other female relatives, e.g., sisters and aunts. (1). Female bears have also shown a preference for establishing a home range where they overlap ‘familiar’ but unrelated individuals, where familiarity with the individual was gained during the natal period (6). Within matrilines, competition for space occurs in areas with higher density. Newly independent females appear to be in competition with both their mother and female siblings for space use following family breakup (7). Dispersal behavior may be related to bear density, the ongoing expansion of the bear population, and habitat limitations. For example, areas with high bear density and less turn over may host the more established matrilineal groups, while female bears may disperse to lower bear density areas or within the expansion front where there is less competition, and they can establish more easily among other females (1). High harvest rates increase male turnover and relatedness in matrilineal groups decreases (8). It can be advantageous for a young female to establish near her mother and there appears to be competition between sisters to do so; the larger sister is more likely to establish close to home (3, 9). However, this does also come with some cost in the form of reproductive suppression; on average, females that establish near their mother wait an extra year before they begin having cubs (4).

Bear individuality

Understanding variation in the behavior of individual animals is an up-and-coming topic within ecology. Recognizing and appreciating this variation in individual behavior is essential for understanding the underlying mechanisms behind the broadscale patterns we see in nature. Furthermore, behavioral diversity among individual brown bears contributes to their overall adaptability, genetic resilience, and ecological roles within their ecosystem.

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Bears in Scandinavia exhibit a wide range of different behaviors including how far they travel, what routes they use, the times of day they are active, and their diet preferences (2, 10, 11). For example, bear diet varies quite a lot between individuals, and dietary specialization is shown to be primarily driven by maternal effects, social and experiential learning, and habitat characteristics rather than genetic relatedness (2). Meaning, bears learn and because they learn, they behave in different ways, including utilizing different food sources (2). Individuals also use their habitat differently from one another. For example, on average, younger bears and those living in areas with higher density of bears and roads tend to be more nocturnal, mostly moving at night. However, older bears and bears who have good foraging habitat in their home ranges tend to move more during the day (12). Likewise, the movement patterns and habitat preferences of older, resident male bears and younger, dispersing males show that older males show clear preference and avoidance patterns while younger males do not. Even within groups, there is a great deal of individual variability in for example risky movement behavior or proximity to human settlements (13).

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Yet, even within these broader patterns we see variation in behaviors between individuals. Some bears are seemingly more bold and explorative and willing to take greater risks than others (14) and some are more consistent in their behavior while others are less consistent (10). For example, bears that are more active, especially during the daytime, tend to be less consistent in their behavior (or behave in a more random way) while bears that are less active are more stable in their behavior, especially when they are active at nighttime (10). How stable or random bears  behave, is important, as bears that are more random in their behavior may be better adapted to random events, and it may be an adaptive response to reduce risk (either with humans or risk from interspecific interactions) (10).

Interactions with other bears

General bear characteristics and behavior, brown bears both communicate indirectly via visual and scent marking as well as interact directly with one another. Brown bears interact most often during mating season, when males and females in estrous actively search for one another (15). Furthermore, brown bears appear to tolerate related individuals more than non-kin (1). Bears may also interact when scavenging for meat, either when a bear approaches another bears kill, or when they are both scavenging carrion, e.g., either from hunter harvest remains or wolf-killed prey. It is possible that bears may interact more at scavenge sites where they overlap with wolves, as wolves provide more sources of carrion on the landscape (16), although whether this increases bear-bear interactions in Scandinavia remains unknown. Bears do also kill one another (17, 18). This most commonly occurs when males kill cubs of the year to induce a female to mate and reproduce sooner than she otherwise would, or sexually selected infanticide, which is discussed in detail in Mating, reproduction, and fitness. However, adult bears do occasionally kill other adult bears (17).