From Wikipedia:
"The hare was a popular motif in medieval church art. In ancient times it was widely believed (as by
Pliny,
Plutarch,
Philostratus and
Aelian) that the hare was
hermaphrodite.
[2][3][4] The idea that a hare could reproduce without loss of
virginity led to an association with the
Virgin Mary, with hares sometimes occurring in
illuminated manuscripts and
Northern European paintings of the Virgin and
Christ Child. It may also have been associated with the
Holy Trinity, as in the
three hares motif,
[2][5] representing the
"One in Three and Three in One" of which the triangle or three interlocking shapes such as rings are common symbols. In England, this motif usually appears in a prominent place in the church, such as the central rib of the
chancel roof, or on a central rib of the
nave. This suggests that the symbol held significance to the church, and casts doubt on the theory that they may have been masons' or carpenters' signature marks.
[6]
Eggs, like rabbits and
hares, are
fertility symbols of
antiquity. Since
birds lay eggs and rabbits and hares give birth to large litters in the early spring, these became symbols of the rising fertility of the earth at the
Vernal Equinox.[
citation needed]
Rabbits and hares are both prolific breeders. Female hares can conceive a second litter of offspring while still pregnant with the first.
[7] This phenomenon is known as
superfetation.
Lagomorphs mature sexually at an early age and can give birth to several litters a year (hence the saying, "to breed like bunnies"). It is therefore not surprising that rabbits and hares should become fertility symbols, or that their springtime mating antics should enter into Easter
folklore."