The March hare is the informal name sometimes given to the common European hare, Lepus europaeus. Normally nocturnal and timid, these hares become conspicuously active during their springtime mating season. They are especially known for the behavior called boxing, when two hares rear up on their hind legs and strike each other with their paws.

The European hare is one of the largest members of the hare family. Its body length can exceed 30 inches, and it can weigh over 15 pounds. Since they are herbivorous and do not hibernate, they must spend all winter foraging for food. Capable of bursts of speed approaching 45 miles per hour, they are the fastest European land mammal.

The expression "mad as a March hare" goes back as far as the 16th century, and it is based upon the behavior of the animals during mating season. Despite the nickname, the hare's mating season extends well beyond the month of March, from January to August in some places. The characteristic boxing behavior was long assumed to be a competition between two males. In fact, it is usually a female hare fending off a male either to show that she is not ready to mate or to test his determination.