Reproduction
Polar bears reproduce sexually. Males typically start looking for mating partners from around late spring into early summer. The males follow the female that they want to mate with by following their scent. Males usually fight with other males over the female that they want to mate with. The strongest male gets the female to mate with. Strong and dominant males may mate with several females in a single season.Females begin mating when they are around the age of 4 or 5, but the males take longer to mature. They start mating when they are older, about 10 years old. The polar bear breeding season takes place from March to June of the sea ice, and males and females find each other during the breeding season by congregating together in the best seal-hunting habitats. Since polar bears reproduce sexually, the act of mating causes the males and females to release sex cells. The sperm is released from the male and combines with the egg released from the female, and they combine to form a fertilized egg. This causes the female to become pregnant. Polar bears go through several days of mating in order to stimulate ovulation and guarantee that the female becomes pregnant.
Females are usually pregnant with their cubs for about 8 months. The fertilized egg divides into a blastocyst which is a hollow ball of cells one layer thick. The blastocyst stops growing and lies in the uterus without growing for about 4 months. It then implants in the uterine wall of the female polar bear and develops for another 4 months. Once the cub is fully developed, the mother is ready to give birth. According to scientists, delayed implantation assures that the cub is born in the best time of the year, and that the mother has time to get in good physical shape in order to take care of the cub when it is born.