Parturition and Postnatal Development in the Captive Hokkaido Brown Bear Ursus arctos yesoensis

概要

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This study was carried out to clarify the developmental biology of Hokkaido brown bears Ursus arctos yesoensis from birth to approximately 90-day-old. Though the birth date of 107 litters ranged from 11 January to 1 March, 91% of the cubs were born between 17 January and 5 February. The body weight of 40 neonates was 419±40 g (mean±SE) and did not differ significantly between the sexes (p>0.05). Mean litter size was 1.82±0.70 (SE). Mean body weight gain per day, an indicator of bear development, was calculated for 192 cubs from the date and body weight at birth and at about 90-day-old. The body weight gain varied greatly among individuals (range: 0.018-0.130 kg/day) and tended to be smaller as litter size increased. The body weight gain differed significantly (p<0.01) between the sexes when there was only one cub, but not when there were two or more cubs. The mean intake of calories per unit body weight gain from birth to 68 days after birth, was calculated at 4,000 kcal/kg for the hand-reared cubs.
日本哺乳類学会の論文