When Times Get Tough,
the Tough Get Vicious:
Polar Bear Infanticide
Marisol Lauffer, Aashis Thapa, Gustavo Lopez
Biology 342 Fall 2012
Ursus Maritimus: Some Background Information
"The Sea Bear"
Polar Bears are the largest members of the Ursidae (bear) family. They are actually considered marine mammals because they take 100 percent of their sustenance from the sea, mainly feeding on seals (Oregon Zoo 2011). They live between twenty-five and thirty years, grow to around seven or eight feet long, and weigh anywhere between 900 and 1600 pounds (National Geographic 2011). They live on the ice sheets of the Arctic Circle, ranging over one million miles (Oregon Zoo 2011).
Figure 1. A map of the Polar bears' habitat, and a size comparison of an average Polar bear to an average, human male.
They spend their time swimming, with partially-webbed front paws to aid them, and using their black skin (underneath all their white fur) to soak in the sun's rays to stay warm. They also have fur covers insulating a layer of fat on their paws to protect against the cold and improve their grip. Female polar bears tend to give birth to twin cubs in the winter, who stay with their mother for the first 28 months of their lives. Females protect their cubs aggresively. Male Polar bears do not care for cubs at all, and even slaughter them (which is the focus of this webpage and will be defined later on this page) (National Geographic 2011).
Figure 2. Polar bears living in captivity at a zoo.
There are only about 20-25 thousand polar bears left on the Earth, and that population continues to decline. They are likely to vanish within the next forty years, if no action is taken to protect their Arctic habitats. Polar bears do notoriously badly in captivity, so their survival really depends on an improvement of their natural habitat through a dedicated effort to reduce climate change and global warming by humans (Oregon Zoo 2011).
Figure 3. An adult, male Polar bear enjoying a freshly slaughtered cub.
What is Infanticide?
Infanticide is defined as the intentional killing of babies. In Polar bears, specifically, it refers to the behavior of adult, male Polar bears slaughtering, and sometimes consuming, other Polar bear cubs. This website aims at examining the possible causes of infanticide in Polar bears by using Niko Tinbergen's four questions concerning proximate and ultimate causes of a behavior. These four questions relate to: mechanism, ontogeny, phylogeny, and survival value.