The samples examined
The large rivers that flow through northern Sweden influence the way brown bears move around their territory. When bears When they reach the riverbank, males and females behave differently. This is demonstrated by a study conducted by researchers at the Swedish University of Agricultural Sciences (SLU). The researchers analyzed DNA in fecal samples from over 500 bears collected in Västerbotten County. By comparing the distance between fecal samples from closely related bears, they were able to estimate the average distance the bears had traveled from their birth areas to establish their territories.
Swimming crossings
The results show clear differences between the sexes. Males settled more than twice as far from their birthplace as females. On average, males lived about 56 kilometers from their close relatives, while the corresponding distance for females was 23 kilometers. When a rushing river appeared to be an obstacle, males were more likely to swim across it. 41% of males crossed at least one river, some even two or three. Only 11% of females crossed a river.
The other large predators
"Females travel shorter distances and have smaller territories than males, but when we simulated how females would move if the direction were random, the percentage of river crossings was significantly higher. This suggests that females actively avoid river crossings." – says Robert Spitzer, researcher and first author. Since males are not limited by rivers and range over large areas, their genes are effectively mixed. The brown bear has gone from being on the brink of extinction to an estimated population of 2.500 in Sweden. The landscape in which they live is influenced by both roads and natural barriers such as rivers. Other large predators can cross rivers on the ice during the winter, but bears hibernate during that time of year. It is therefore important to understand how these barriers affect bears (source: FACE).
You May Also Like ..
