What is the origin of the phrase 'mad as a March hare'?

The phrase was popularised in the late 19th century by Lewis Carroll's inclusion of the character, the March Hare, in Alice's adventures in Wonderland, but it was in existence long before that, having been used by poets such as John Skelton in the 16th century. This phrase first appeared in Lewis Carroll's Alice's Adventures in Wonderland and is now used to describe anyone behaving in an odd or foolish way. Hares tend to be unusually wild in March, during their breeding season, when they leap box, and chase each other around the countryside during courtship.