Survival and reproductive rates for polar bears at Svalbard

Polar bears (Ursus maritimus) were captured near Svalbard north of the Norwegian mainland between 1988 and 1993. Only one female older than 15 years was caught. A constant relationship between the number of sampled female bears in consecutive age classes was estimated for females between 2 and 15 years of age at phi = 0.96. If growth rate of the Svalbard population is between 1.00 and 1.03, the age structure estimate of annual female survival rate between ages 2 and 15 years is 0.96-0.99. The lack of females older than 15 years in the catch sample is difficult to explain. Based on data sampled by satellite transmitters on females between 4 and 17 years of age, dates for maternity den entry was between 7 September and 12 December and emergence dates were between 2 March and 27 April. Mean denning duration was 153 days. Reproductive class of females were assessed in 115 cases. The youngest females that had cubs were 5 years old, and mean annual rate of litter production for females between 7 and 17 years was 0.41. Birth success for the same range was 0.82. Annual first year cub survival was 0.55, assuming the mother survived. Survival rate from birth to 2 years was 0.35 and from emergence to weaning was 0.38, assuming the mother survived.