Male and female reindeer can be distinguished by the shape of the white patch on their booty—heart-shaped for males and rectangular for females.
Reindeer cyclones are formed to make it hard for predators to target the weaker reindeer
Reindeer cyclone’s have been documented as far back as the Viking period with reindeer forming cyclones to make it harder for hunters to target any of the reindeer. The cyclones form around weaker members of the herd as a way to protect them. Many animal species have a similar defense strategy.