For the North American musk oxen, this is rutting season.

对北美麝牛来说，这正是求偶的季节。

At summer's end, male bison help to move the sun-baked soil as the rutting season starts.

夏末，随着发情期的开始，雄性公牛也开始帮助翻动太阳晒过的土壤。