Polar bear picture

Description: 1.Once mated, females begin depositing fat in preparation for cubbing. Females need to gain at least 200 kg (441 lb.) for a successful pregnancy (Stirling, 1988). 2.Some females may seek out maternity dens as early as late August, but most enter dens in mid to late October. Dens protect newborn cubs from winter's temperature extremes. ... ( +expand to view full text )

Description: 1.Once mated, females begin depositing fat in preparation for cubbing. Females need to gain at least 200 kg (441 lb.) for a successful pregnancy (Stirling, 1988). 2.Some females may seek out maternity dens as early as late August, but most enter dens in mid to late October. Dens protect newborn cubs from winter's temperature extremes. 3.Females usually dig dens in snowdrifts on southerly facing slopes. Some dig earthen dens that later become covered by snow. 4.Most dens are on land, within 16 km (10 mi.) of the coast. In some areas, dens are more than 100 km (62 mi.) from the coast. A few polar bears make dens on the sea ice (Harington, 1968). 5.Den elevations range from sea ice level to 548.6 m (1,800 ft.) above sea level (Harington, 1968). 6.Most dens consist of a single chamber slightly elevated from a short entrance tunnel. On average, the chamber is 2 m (6.6 ft.) long, 1.5 m (4.9 ft.) wide, and 1 m (3.3 ft.) high. Polar bears maintain a ventilation hole through the chamber ceiling to provide fresh air (Stirling, 1988). 7.Because of body heat and snow insulation, the den stays warmer than the outside air temperature.