Figure 1: The relationship between maternal energy density and litter size.
From: Predicting climate change impacts on polar bear litter size
(a) Estimated probabilities for a pregnant female polar bear to have one (p1, dashed line), two (p2, solid line) or three cubs (p3, dotted line) at den emergence as a function of maternal energy density (defined as storage energy relative to lean body mass) at den entry, as determined by multinomial logistic regression. (b) Expected mean litter size at den emergence as a function of maternal energy density at den entry (solid line), calculated as X(E/LBM)=p1(E/LBM)+2p2(E/LBM)+3p3(E/LBM). Data are observed litter sizes at den emergence as a function of maternal energy density at den entry (N=28).
