About how many polar bears die every year? How do the scientists know if more or fewer polar bears are surviving each year? Is the reasons for polar bear deaths changing. How do scientists know?

Amanda, Daurghter of Polartrec teacher Gary Wesche

Cristina Galvan

Hi Amanda,
Great questions! Let's start with how scientist get an idea of how many polar bears are surviving each year. Studies, like the one that I get to be part of, capture and recapture bears. The data from these bears is used to make generalizations about the density and stability of the population of the bears.
Here's an example, in one year 108 bears were captured. However in that group of 108, there were no two year old bears and only a handful of bears age 3-5. They can infer that the amount of 2-5 year old bears decreased in the population.
Here are some basic statistics - the average survival rate for cubs at one year is 65% and at two years is about 85%. However, this has been changing recently.
One of the reasons for this change could be decreases in the amount of sea ice. Sea ice is so important to the bears because they are dependent on it for the hunting habitats. Polar bears hunt seals and capture them when they come up to breath through the ice.
Hope that helps!
Thanks, Ms Galvan

Dameon (not verified)

what is a polar bears death rate

Maria (not verified)

Hi there the polar bears death rate is increasing each year. I like to keep it simple and straight to the answer and explanation

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Submitted by Anonymous (not verified) on Wed, 09/30/2009 - 17:04