Although polar bears' locomotion is similarly inefficient, polar bearcubs walk along with their mother.
尽管北极熊的运动能力同样低下，北极熊幼崽还是和妈妈一起前行。
2
Collectively these factors probably selected against tree-climbing as a defensive strategy for sloth bearcubs.
总的来说，这些因素可能选择不爬树作为懒熊幼崽的防御策略。
3
Black bearcubs use trees for defense, whereas brown bears and polar bears, which regularly inhabit treeless environments, rely on aggression to protect their cubs.