Swallowtails are large, colorful butterflies which often have the forked tails reminiscent of some swallows. The tails may have evolved as a defensive mechanism: they will tear off if a bird grabs them.
A Pale Swallowtail sips nectar.
A Pale Swallowtail on the wing tucks up its legs to reduce drag
A Pale Swallowtail sips nutrients from the moist ground.
A Western Swallowtail sips from moist ground.
A few of the dozen swallowtail butterflies (Western and Pale) sipping nutrients from moist ground.
A Western Swallowtail sips nectar.
Information from Wikipedia: Swallowtail Butterflies.