Richard R. Knight Harold D. Picton 1986 A 5-year double-bind test was conducted to test the predictive capability of a previously published (Picton 1978) regression (Y= 2.01 + 0.042<i>x</i>), which described the relationship between the littler size of grizzly bears (<i>Ursus arctos horribilis</i>) and an index of climate plus carrion availability (climate-carrion index). This regression showed an efficient in excess of 99% in predicting the observed grizzly bear littler size. The predictions made using the climate-carrion index had a mean absolute error of less than 25% of forecasts using other methods. The updated climate-carrion index regression, which includes all of the 16 years for which data are available, is Y= 2.009 + 0.042</i>x</i> (<i>r</i> = 0.078; <i>P</i> < 0.01; <i>N</i> = 16). We concluded that the climate-carrion index can be a helpful tool in predicting grizzly bear littler size. The relation of this information to the effects of the closure of Yellowstone Park garbage dumps is discussed. application/pdf 10.2307/3872804 en International Association for Bear Research and Management Using climate data to predict grizzly bear litter size article