At the first sign of danger 当发现危险信号时

67. It has developed special techniques for hunting amongst the cacti.
    它练就了在仙人掌林捕食的特殊技能
68. Ground squirrels.
    这是地松鼠
69. Prey.
    栗翅鹰的猎物
70. At the first sign of danger
    当发现危险信号时
71. they bolt for the safety of the thorns.
    地松鼠们迅速躲进刺丛中避险
72. But the hawks have a tactic to flush them out.
    但栗翅鹰有法子逼它们出来
73. These are the only birds of prey that hunt in packs.
    栗翅鹰是唯一成群捕食的猛禽

来自《行星地球 第二季 第四集 Planet Earth S02E04 沙漠》第 70 行