they will have to return to their dens to hibernate, 他们就要回自己的窝里冬眠

137. Itches satisfactorily scratched,
     痒痒挠满意之后
138. it's time to eat.
     是时候该进食了
139. In a couple of months,
     几个月后
140. they will have to return to their dens to hibernate,
     他们就要回自己的窝里冬眠
141. so now they must put on as much weight as they can.
     所以现在必须尽可能地增重
142. Winter in the mountains returns fast and hits hard.
     山里的冬天来得迅猛
143. Temperatures in the Rockies will drop to -54 degrees,
     落基山脉地区的温度会降至零下五十四度

来自《行星地球 第二季 第二集 Planet Earth S02E02 山脉》第 140 行