Polar bears are one of the species that make up the Ursidae family. These are carnivorous animals that occupy the top of the food webs of the arctic area in which they live. The extreme climate of this region has led polar bears to develop a series of adaptations that allow them to live in extreme cold temperatures.
These are the ones that are found both on land and in the ice-covered ocean or in the open waters after the seasonal melting that occurs in some areas. Among the adaptations of these bears are also those that make reproduction possible. In this article on our site we explain how polar bears reproduce and are born
How do polar bears reproduce?
Polar bears are characterized by being polygamous This means that they will have several sexual partners, both males and, eventually, females. The couple will only be together during mating, which usually lasts for about three days A male is capable of traveling long distances in search of a female in order to reproduce. If encounters with other males occur, they may clash for reproductive privilege. Normally, the fights are not usually fatal, but they can leave some wound in the rivals.
Females mature around 4-5 years of age, while males may do so a little earlier. The mating period of female bears is usually long, lasting from late March to early June The highest reproductive rates occur in April and early May.
In polar bears there is a long sequential reproductive process The ovulation of the female is induced by copulation and, although subsequently, fertilization takes place, implantation and development of the embryo take place in a delayed manner, occurring until autumn.
The gestation of the polar bear
Gestation time in polar bears is from 195 to 265 days Implantation is determined by the body conditions of the female, that usually accumulates, before the reproductive season, large reserves of fat to be able to produce optimal breast milk and thus feed the cubs while they remain sheltered during the winter. The female is able to double her weight before starting this process.
Polar bears generally become pregnant in late fall, although it can be a little earlier, specifically between September and October. Once gestation begins, they build burrows in the ice in steep areas near the sea, where they take refuge to continue gestation and breeding.
Birth of the polar bears
The birth of polar bears occurs in the winter, when conditions in the Arctic are much more extreme than normal. The females will find refuge in the burrow they have built and they will have been without feeding for some time. The fast will be kept while they are sheltered. Parturition usually occurs between the end of December and January and the litters are mostly twins To a lesser extent there are single births or triplets.
The newborns are blind, have little hair and are totally dependent on the mother, with whom they will remain sheltered in the burrow until March or April, date in which they will finally come out of the burrow. Puppies at birth have an average weight of 600 grams, however, thanks to high-fat mother's milk, they will quickly grow to 10-15 kg when they surface.
Polar Bear Growth
Polar bear cubs that are most likely to survive are those that achieve the largest size and most fat accumulation while in the den. It is very important because in this species there is a high mortality rate during the first year of life Polar bears are considered to be the mammalian species that can spend the longest time pass without feeding, but for that the reserves of the bears are essential.
During the first year, the cubs completely depend on their mother's care and they stay with the bear for about two years During this time the The mother will be quite aggressive if she perceives any danger to her young. Once the bear and her cubs come out of the den, they go to the seal concentration place. There the bear will feed quickly and teach her little ones how to do it. In this article we explain more about the diet of the polar bear.
Why polar bears are in danger of extinction
The birth of litters with few individuals, the long time that the process lasts, since while the female raises her young she does not reproduce again, which means that she normally goes into heat every three years, and the high probability of death during the first year means that the species in general has a low reproductive success
Although this is similar to that of its ursid relatives and can be compensated with the high chances of life that an adult polar bear has, since, with the exception of the human being, they do not have natural predators in their habitat, the situation of the polar bear is aggravated given the alterations that its habitat is undergoing
Polar bears are a species considered vulnerable by the International Union for Conservation of Nature, mainly due to the effects that the climate change is having on the polar zone of the Arctic, where the unusual increase in temperatures affects the ice cover, necessary for the proper development of these animals, as well as well as for the biodiversity, in general, of these ecosystems. We explain more about their habitat in this article about where polar bears live.
