• Version
• Download 8
• File Size 327.40 KB
• Create Date 1 January 1998
• Download

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 φ = 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.