Why are reindeer always headed by females and followed by males?

There are more than 500,000 reindeer living in the west of the Arctic Park, and tens of thousands of females in the huge population are about to give birth every year. Lichen, grass roots and other foods have less nutrients and limited quantities, which can not meet the nutrition needed by pregnant deer. In order to ensure that their children were born in a place with sufficient food, so that their dear children could survive strongly on their way home, the brave pregnant deer did not delay. At the beginning of February, when the sunshine was slightly enhanced, they first embarked on a journey of migration.

It is always headed by the female deer, followed by the male deer. It is vast and March straight ahead, traveling day and night, eating while walking, advancing at a constant speed and orderly.

Reindeer shed their thick winter clothes along the way and grew new thin long hair. The fluff that fell to the ground became a natural road sign. Year after year, I don't know how many centuries have passed

So why do reindeer always start with the female deer, followed by the male deer?

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