Adaptation
The grizzly bear has adapted to better live in its environment.
Below are some of the more useful adaptations that play a major
role in the bear’s survival.
Diet
Because of the large size of the bears and the colder climate of their
habitats, grizzlies must eat a lot of food to survive. The proportion of
animals in the diet is positively correlated with latitude (Vulla et al.
2009), which says that the further north the bears are found, the more meat
they consume.
Teeth
To
contribute to the omnivorous diet, the teeth of the grizzly bear must be
able to tear apart meat and grind nuts and other vegetation. The American
grizzly bear is decidedly more carnivorous than previously thought, thus
routinely subjecting its canines to the predation of large prey
(Christiansen 2008). Often the prey will be killed by mauling from the claws
and not the teeth.
Claws
The
claws of a grizzly bear are used for self defense and for collecting food.
When subduing large prey, bears usually attack rather indiscriminately with
both forepaws and teeth (Christiansen 2008). Bears will also dig into the
ground or into tree trunks to scavenge for food.
Hibernation and Sleep Cycle
Due
to long winters in the arctic climate creating a scarcity of food, grizzly
bears will hibernate for four to six months, conserving energy until spring.
During this time a bear will live off of its stored fat and will reduce its
metabolic rate, and they tolerate extremely low heart rates without
ventricular chamber dilation (Nelson and Robbins 2010).
During the rest of the year, grizzlies spend a lot of their time foraging
for food. Due to the seasonal selection of foods, grizzlies adapt their
diets and will require temporal flexibility (Fortin et al. 2013), meaning
they will switch between diurnal and nocturnal activity patterns depending
on when their foods are available.