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.
生存环境的缩小是一个原因，更主要的是它们
冰
和地面之间被称
“
空间”里得不到
护，有些旅鼠会
生数量惊人却无法存活的小旅鼠。
