But thanks to their ability to survive the cold, 但由于能够适应寒冷环境
Birds had almost been wiped out with the rest of the dinosaurs. 鸟类几乎全都与其它恐龙一起灭绝
a behavior that ensures the survival of the fittest. 这种行为能够确保最优秀者生存下来
were not enough to ensure the future of the birds. 并不足以确保鸟类有一个光明的未来