Movement patterns and space use of maternal grizzly bears influence cub survival in Interior Alaska

Abstract

Abstract Foraging decisions and movement strategies by animals often involve a trade-off between meeting nutritional demands and minimizing risk of predation. We evaluated the influence of space use and movement patterns of maternal female grizzly bears (Ursus arctos) on cub (defined as first year of life) survival in eastern Interior Alaska, USA, during 2008–2012. We monitored 9 GPS radiocollared females that produced 28 cubs in 12 litters (x¯ litter size = 2.3, range = 2–3). The estimated annual cub survival rate was 0.39 (95% CI = 0.20–0.57). In all cases the entire litter survived or died prior to den entrance. All cubs in a litter died either concurrently or within 14 days in 5 of 7 litters lost. Sixty-nine percent of cub mortality occurred between 31 May and 16 June. We did not document cub mortality before 31 May. Females with surviving cubs remained within 1 km of the den for a longer period following emergence than those that lost cubs. Between den emergence and the onset of vegetation gree...