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.
生存环境的缩个原因,更主的它们在地面之间被称为“下空间”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的旅鼠。