因为树懒的体型比棕熊和北极熊要小，而且面临着更大的来自危险动物的威胁，所以它们可能会带着幼仔采取额外的预防措施。
Because sloth bears are smaller than brown and polar bears and are under greater threat from dangerous animals, they may have adopted the extra precaution of carrying their cubs.
除非有足够的雄性来繁衍新生代，否则长久以往，动物的数目将面临真正的威胁。
Unless enough males contribute to the next generation there is a real threat to animal populations in the long term.
虽然长江豚的灭绝主要是因为水源污染，但对海洋哺乳动物来说，面临的最大威胁是深陷鱼网或被渔船捕获。
The greatest threats to Marine mammals are being caught in fishing nets or being struck by shipping vessels, although for the Yangtze river dolphin, pollution is a major contributor.
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