How Polar Bears Mate & Give Birth [Reproductive Cycle]

There's no tinder for polar bears, so how do they find a partner? Hi, I'm Nate from PolarGuideBook.com, and in this video, we'll look at the breeding cycle of polar bears, from finding a mate to giving birth. Polar bears have fewer offspring than most mammals. A female will have just two to four litters in their lifetime, with up to three cubs in each. This is in line with other bears, such as pandas, which have around seven offspring in total. Although way behind other mammals, such as lemmings, with 192 offspring, and European rabbits with over 300, the reproductive cycle of polar bears can be broken down into four parts. Mating, Denning, Birth, and Emerging from the Den. Mating takes place on the sea ice during spring. As polygynous mammals, they will rarely mate with the same bear more than once. Male polar bears do not raise the offspring. They only stay with the females for a few days after mating before moving on. This means that males are looking to mate every year, whereas females only mate every three years once their young cubs have grown up. With a 3 to 1 ratio, competition is high among males, and fighting is common, often resulting in serious wounds. Larger males have an advantage in these battles, which explains how male polar bears have evolved to be much larger than females over time. They use their excellent sense of smell to track potential partners and can follow them for many miles, often attempting to herd them away from other males. The females are induced ovulators. This means that the act of mating releases the egg. This can take several attempts, so they can mate for many days before success. They have a reproductive strategy called delayed implantation. Once the egg is fertilized, it won't immediately enter the uterus. Instead, it remains dormant until the fall. This gives the female time to build up her fat reserves, ready for the pregnancy. However, female polar bears often mate with several males in the same year. If another egg is fertilized, it can result in giving birth to offspring from different fathers at the same time. The next part of the cycle is denning. Pregnant females build a small cave by digging into snow drifts or peat soil. They will remain in this den until they have given birth and the cubs have grown enough to leave. During this time, they will enter a hibernation-like state, where they will not eat, drink, urinate, or poop until they leave. After entering the den in the fall, they will give birth around 60 days later, between November and January. They will give birth to between one to three cubs, which will usually be about 30 centimeters long and weigh around 500 grams. Cubs will only have a thin covering of fur when they are first born and cannot keep themselves warm, so they remain in the den for several months. Finally, in the spring, the cubs will emerge from the den once they have learned to walk. Emergence usually occurs between February and May. On average, cubs leaving the den will weigh around 10 kilograms. They will stay in the area around the den for up to a month, depending on the progress of the cubs. After this, they will start to move across the sea ice where the mother will teach them all of the skills to survive, including hunting for food. If you're interested to find out more about polar bears, check out this next video with 12 fun facts such as how they have built-in snow goggles and how they can swim for 9 days straight. Thanks for watching.