The typical range of an average temperature in polar bears is around 36.5 – 38.8 °C (97.7 – 101.8 °F). They are thought to use numerous physiological and behavioral mechanisms to normalize temperature. However recent findings indicate that the ice bears find it difficult to slow down their metabolism during summer when the food is scarce. The pregnant female bear appears to show a progressive form of behavioral thermoregulation which is mainly described by a cyclic establishment of microclimate. Let’s study polar bear metabolism in detail.
They rarely adapt to surviving in warmer months because dormancy (sort of hibernation) doesn’t seem to last long. Due to rapid climate change many ice bears are forced to live on land. The ashore bears appear to lose a reasonable amount of body heat as well as they reduce their activity in summer. However scientists made the same discovery of behavior in bears that are living on the sea ice. ‘The polar bears acted more like fasting humans than like hibernating brown or black bears’, said John Whiteman.
Polar Bear Metabolism
- The increasing global warming has hit polar bears the hardest. It has not only forced the bear to leave its habitat but reduces its foraging opportunities. As it turns out bears spend more time on land in summer.
- Earlier scientists thought that ice bears were able to adjust to summer months by gradually slowing their metabolism—reducing the risk of energy loss. Scientists refer to this adaptation or behavioral change as walking hibernation.
- Findings suggest that walking hibernation is not an innovative change in polar bear’s behavior instead it is typical fasting behavior in mammals. Thus the recent studies oppose the early hypothesis of scientists. It
- also implies that ice bears do not possess any action reserve specifically for summer food scarcity. Instead she might starve to death if climate continues to change at the current pace.
Read More: Polar Bear Digestive System
Polar Bear Temperature
- The average temperature in adult bears range from 37.5 to 38.3 °C (99.6 to 101.0 °F). In captivity the temperature averages range 37.2 – 38.4 °C (99 – 101 °F). The temperature of a polar bear wandering in the Arctic is about 36.5 °C.
- Scientists measure the deep body temperature in bears that fall asleep in cloudy weather at 36.8o C whereas individuals that become inactive in a bright sunny day shows the temperature of 38.8o C.
- Research also shows that there is a slight variation in temperature when the bear is busy in certain activities. For instance if a polar bear digs den or eat snow the body temperature goes high (especially with the increasing pulse rate). Ice bears usually eat snow minutes after copulation.
- Biologists observed areas of a polar bear’s skin that are almost always exposed to the sunlight. The temperature of these unprotected areas found to be higher than the core temperature.
- The arctic temperature mostly ranges from +7.5 to -29.5 °C but the central body temperature of a bear is estimated at 36.9 +/- 0.5 °C. The resting polar bears have central body temperature of about 36.9o C.
- During fall when the sea ice melts and the bear couldn’t prey seals, the metabolic rate is reduced to 33.5o C. By so doing polar bears can cope with the fasting months.
- The temperature in adult females during denning averages 35.4 – 37.2 °C. When female bears enter into dormancy state (hibernation) the estimated temperature significantly drops by about 73%. They have got the ability to reduce metabolic rate by half.
Metabolic Rate in the Maternity Den
- Female polar bears are blessed with unique ability to diminish their metabolic rate during maternity den which ultimately increases the likelihood of her survival on available fats. The reduction in metabolic rate doubles the survival time of a female bear. (See in detail: Polar Bear Den)
- Scientists however believe that the given energy-saving technique doesn’t always increase the chances of her survival for there are numerous other factors that can make her to consume energy. These factors include lactation, quality of the den site, pregnancy, and looking after the cubs.
- Sometimes it happens that females take more time than usual to dig dens in winter. The unusually extensive digging is likely to check metabolic reductions. If she chooses an unsuitable denning site then she probably starves which can adversely affect the survival of her cubs.