The polar bear is one of the largest carnivorous animals on the planet. It is found mainly in the Arctic Circle, and it also holds the record for the biggest extant bear species and predatory carnivore. An adult male polar bear can weigh as much as 700 kilograms, while the female weighs about half of that.
Even though most polar bears are born on land surfaces, they spent practically all their time in the water and on the sea ice. Many have discussed polar bears, but not much is known by many concerning their life cycle. This piece will provide more details on this:
The reproduction cycle for the female polar bears encapsulates the processes of mating, denning, and giving birth. These bears function based on the rhythm of their biological clocks. This cycle rolls on from one season to the other, right from the point of conception to giving birth to the cubs and the period after.
Mating in the Spring
This occurs between the periods lasting from April to the end of June. This is when snow melting commences, and the daytime is longer, and the adult male polar bears spend much of their time searching for virile females to mate with on the sea ice. They track the possible mates by following trails of scent imprinted by the footpads.
Male polar bears become sexually mature around the age of six to ten, while the females achieve sexual maturity by the ages of four and six. Mating is done on the sea ice, but there will be no fertilized eggs implantation until fall arrives.
This is possible only if the mother has been able to consume enough food to have fat deposits that she can use for herself and the cubs’ sustenance. This is particularly important for the denning season, which can be extended. This phenomenon in biology is known as delayed implantation. The adult males spend some days with the female before they move away.
Denning in Fall and Winter
The pregnant female polar bear spends much of summer and fall eating, then proceeds with the construction of a maternity den. Inside this den, she will give birth to the baby cubs and see to nursing them until the spring season.
Gravid polar bears are known for selecting den sites in snowdrifts close to a river or coastal bluffs, banks of snow on iced sea, or rocky outcrops located close to sea ice. In some other cases, mother bears have been spotted digging in raised peat soil or even within proximity of the rivers and lakeshores.
The mother bear excavates a compact snow cave for the construction of her den. This den is spacious enough for her to change body position. They will then wait for the snow to seal up the entrance to the cave.
Birthing in Winter
Observation and studies have shown that the birth of polar bear cubs in the wild often happens in December. Pregnant female bears are known for giving birth mainly to one, two, or even three cubs, but twins are the most common.
The new family will stay in the maternity den until the following March or the beginning of April, depending on the weather and climatic conditions. This means that the mother bear will spend anything between four to eight months in the den and all through this period, she is not going to eat or even drink anything. All she does is just provide for her babies.
Size and Properties of Polar Bear Cubs
Polar bear cubs upon birth measure about 12 to 14 inches in length and weigh up to one pound, around half a kilo. The polar bear cubs are vulnerable as they have no sight, teeth and are covered with soft and short fur. They are dependent on the mother for food and warmth. They feast on the rich milk of the mother and grow swiftly. The nursing by the mother bear continues for a minimum of 20 months.
Leaving the Den in the Spring
The families of polar bears leave their dens around March or April. The cubs are no longer very dependent and have developed enough strength for survival outside the den and can even do the trekking to sea ice. At this point, the mother bears commence the teaching of the young on the tactics of survival in the brutal environment of the Arctic Region.
Growth in the Arctic
Polar bear cubs spend anything for 2.5 to three years with the mother bears. During this period, they learn all that is to learn regarding hunting, swimming, feeding, and survival.