;Loss of habitat is to blame, specifically, the lack of the pocket of air between snow and ground called the “subnivean space.” There lemmings winter and give birth to prodigious litters of young.
生存
缩小是一个原因，更主
是它们在冰雪和地
被称为“雪下空”里得不到保护，有些旅鼠会在冬天生下数量惊人却无法存活小旅鼠。
