We’re jiggling all the parts of their life history at the same time. We’re probably changing seal abundance, we’re affecting primary productivity, we’re asking the bears to walk farther, we’re asking them to fast for longer periods, we’re cutting into the best times of year for feeding.
Collectively, the problem is that these effects accumulate in bears in poor body condition. That translates into lower reproductive rates and lower rates of survival. And once you put those two together, it’s just a matter of time before the population abundance declines.
Does the decline of sea ice also affect where female bears make their dens?
Polar bears do den offshore, on ice that has to be relatively thick and have snow on top of it. So that tends to be ice that’s more than one year old. Multiyear ice is already disappearing, and if you look at the projections, it will continue to disappear. So there’s been this big shift from multiyear-ice denning to terrestrial denning.
The pregnant bears look for a place with enough snow. On land, usually those are on the lee side of a prevailing wind — on the bank of a lake or on small creek where the snow has accumulated.
When they are in their den, basically they are in slowdown mode. Their cubs are born somewhere around December. The mothers raise them from a tiny one-and-a-half-pound critter to an animal that is about 20 pounds over three to four months, and then they take them out on the ice to hunt.
What do scientists know about the impact of oil and gas exploration and production on polar bears?
One of the things that’s pretty cool about bears in general and polar bears in particular is each bear has an individual behavior pattern, or personality, if you want to call it that. Some bears just don’t seem to care — they are just not worried by people, not worried by snow machines or all-terrain vehicles or trucks going by. Yet others are extremely wary, don’t like it and will move away quickly from disturbance.
By and large, I think polar bears are fairly robust to disturbance, but once they have small cubs they tend to be quite timid.
Source : Nytimes
