In the UK the Cowbird refers to the yellow WAGTAIL, but in North America the name applied to two very distinct birds.
The first of these is the Yellow billed cuckoo
(Coccyzus americanus), an attractive little bird around 26 to 31
cm in length. The lower part of its gently curved beak is a yellow
color, giving this bird its name, with black coloration on the upper parts
of the beak Its plumage is grayish brown on top, with white underparts.
It has a long dark tail with white spots on the tail's underside.
Picture of a female Shiny Cowbird (Molothrus bonariensis)
The second and far more common usage of the name
Cowbird in the USA is for birds of the genus Molothrus.
These are not cuckoos but are part of the icteridae family (cuckoos,
on the other, hand being the cuculidae family). However, they share
one particularly interesting habit with many of the cuckoos - the females
of the Moluthrus genus lay their eggs in other birds' nests for an apdoptive
parent to incubate and raise. This habit was first recorded
in 1810 by Alexander Wilson (Amer. Orn. ii. pp. 145-160), though,
as he was careful to say, they had "long been known to people of observation
resident in the country", and indeed he cites an instructive series of
observations by Dr. Potter of Baltimore; showing that that gentleman had
for some time made the bird his study. The species who are the victims
of the Cow-bird's intruding its eggs into their nests are hardly less numerous
than the dupes of the Cuckoo, and like the cuckoo, the adoptive parent's
own progeny are displaced from the nest by some species of cowbird.
In a South American species of Molothrus,
W. H. Hudson (Argent. Ornithol. i, pages 72-97) observed that the
old Cowbirds, both male and female, destroy many of the eggs in the nests
which they visit.
The name Cowbird is an abbreviation of Cowpen-bird
according to Catesby (N. H. Carolina,
i. p. 34), who says:-"They
delight much to feed in the pens of cattle, which has given them their
name" These birds are also spoken of as Cow-Blackbird, Cow-Bunting,
The word Moluthrus was originally a misprinting
of Molobrus. Although Swainson (Faun. Bor.-Am.
p. 277) was at the pains to explain this meaning of it, "qui non vocatus
alienas aedes intrat", showing that
Molobrus must have been intended,
the majority of ornithologists preferred to follow the error. Thus
the name of the genus continues even now in the 21st Century to be known