Why do female reindeer have antlers?

Reindeer (Rangifer tarandus) are unique among all deer species because both males and females grow antlers.123

While male reindeer shed their antlers in late fall following the mating season, females retain theirs throughout the winter. This evolutionary adaptation serves a critical survival purpose: it allows females to defend valuable feeding sites—specifically craters dug in the snow to access reindeer lichen—from other members of the herd, including males who have already shed their own antlers. By securing these food sources during the harsh winter months, females ensure they have the necessary resources to survive and support their offspring.23