Cowbirds are

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s belonging to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial no ...

''Molothrus'' in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

Icteridae Icterids () or New World blackbirds make up a family, the Icteridae (), of small to medium-sized, often colorful, New World passerine birds. Most species have black as a predominant plumage color, often enlivened by yellow, orange, or red. The ...

. They are of

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...

origin, and are obligate

brood parasite Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its ow ...

s, laying their eggs in the nests of other species. The genus was introduced by English naturalist

William John Swainson William John Swainson FLS, FRS (8 October 1789 – 6 December 1855), was an English ornithologist, malacologist, conchologist, entomologist and artist. Life Swainson was born in Dover Place, St Mary Newington, London, the eldest son of ...

in 1832 with the

brown-headed cowbird The brown-headed cowbird (''Molothrus ater'') is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the souther ...

(''Molothrus ater'') as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

. The genus name combines the Ancient Greek , meaning "struggle" or "battle", with , meaning "to sire" or "to impregnate".

Species

The genus contains six species: One

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species, the Talara cowbird (''Molothrus resinosus''), is known from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

remains recovered from the Talara Tar Seeps of northwestern

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

, and likely went extinct during the late Quaternary. It may have been a close associate of

Pleistocene megafauna Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of hu ...

communities, and may have gone extinct following their collapse in populations. The nonparasitic

baywing The baywings are two species of birds in the genus ''Agelaioides'', which were described in the early 19th century. These species are found in Brazil and in the case of ''A. badius'', also Argentina, Bolivia, Uruguay, and Paraguay Paraguay ...

s were formerly placed in this genus; they are now classified as ''Agelaioides''.

Behavior

Cowbirds are

insectivores A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

. The birds in this genus are infamous for laying their eggs in other birds' nests. The female cowbird notes when a potential host bird lays its eggs, and when the nest is left momentarily unattended, the cowbird lays its own egg in it. The female cowbird may continue to observe this nest after laying eggs. Some bird species have evolved the ability to detect such parasitic eggs, and may reject them by pushing them out of their nests, but the female cowbird has been observed to attack and destroy the remaining eggs of such birds as a consequence, dissuading further removals. Widespread predatory behaviors in cowbirds could slow the evolution of rejection behaviors and further threaten populations of some of the greater than 100 species of regular cowbird hosts, favoring host acceptance of parasitic eggs in a mafia-like contest between cowbirds and other species.

References

* Jaramillo and Burke, ''New World Blackbirds''

External links

Audubon Society: Cowbirds and Conservation
{{Authority control Brood parasites * *