Bear Model Reveals All
Polar bear families shrinking with the ice through lack of food | The Times
The latest study, published today in the journal Nature Communications, predicts that up to 73 per cent of pregnant females will lose their offspring if the spring sea ice break-up occurs a month earlier than during the 1990s and up to 100 per cent if it occurs two months earlier.
"If climate change continues unabated the viability of the species across much of the Arctic will be in question," said Péter Molnár, a biologist at the University of Alberta in Canada, and lead author of the paper.
Predicting climate change impacts on polar bear litter size : Nature Communications : Nature Publishing Group
We used multinomial logistic regression models30 on data from 28 pregnant females with known litter sizes to test whether litter size at den emergence can be predicted from maternal age (A), storage energy29 at den entry (E), energy density29 at den entry (E/LBM), or certain combinations of these variables (see Table 1 and Methods for details). The model with only energy density was an excellent predictor of litter size at den emergence (likelihood ratio test, P=0.0004), and the regression probabilities of having one, two or three cubs (Fig. 1) are
28 mummy bears and a computer model, add a couple of scenarios and press the panic button.