from
The Collaborative International Dictionary of English v.0.48
Wagtail \Wag"tail`\, n. (Zool.)
Any one of many species of Old World singing birds belonging
to {Motacilla} and several allied genera of the family
{Motacillidae}. They have the habit of constantly jerking
their long tails up and down, whence the name.
[1913 Webster]
{Field wagtail}, any one of several species of wagtails of
the genus {Budytes} having the tail shorter, the legs
longer, and the hind claw longer and straighter, than do
the water wagtails. Most of the species are yellow
beneath. Called also {yellow wagtail}.
{Garden wagtail}, the Indian black-breasted wagtail
({Nemoricola Indica}).
{Pied wagtail}, the common European water wagtail ({Motacilla
lugubris}). It is variegated with black and white. The
name is applied also to other allied species having
similar colors. Called also {pied dishwasher}.
{Wagtail flycatcher}, a true flycatcher ({Sauloprocta
motacilloides}) common in Southern Australia, where it is
very tame, and frequents stock yards and gardens and often
builds its nest about houses; -- called also {black
fantail}.
{Water wagtail}.
(a) Any one of several species of wagtails of the restricted
genus {Motacilla}. They live chiefly on the shores of
ponds and streams.
(b) The American water thrush. See {Water thrush}.
{Wood wagtail}, an Asiatic wagtail; ({Calobates sulphurea})
having a slender bill and short legs.
[1913 Webster]