Cowbird

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Cowbird
Brown headed cowbird female in JBWR (25487).jpg
Female brown-headed cowbird
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Icteridae
Genus: Molothrus
Swainson, 1832
Type species
Fringilla pecoris [1]
Gmelin, JF, 1789
Species

Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin, but some species not native to North America are invasive there, and are obligate brood parasites, laying their eggs in the nests of other species.

Contents

The genus was introduced by English naturalist William Swainson in 1832 with the brown-headed cowbird (Molothrus ater) as the type species. [2] [3] The genus name combines the Ancient Greek mōlos, meaning "struggle" or "battle", with thrōskō, meaning "to sire" or "to impregnate". [4] The English name "cowbird", first recorded in 1839, refers to this species often being seen near cattle. [5]

Species

The genus contains six species: [6]

Genus Molothrus Swainson, 1832 – six species
Common nameScientific name and subspeciesRangeSize and ecologyIUCN status and estimated population
Screaming cowbird

Screaming Cowbird (Molothrus rufoaxillaris).jpg

Molothrus rufoaxillaris
Cassin, 1866
Northeast and central Argentina, southeast Bolivia, central Brazil and throughout Paraguay and Uruguay
Molothrus rufoaxillaris map.svg
Size:

Habitat:

Diet:
 LC 


Giant cowbird

Giant Cowbird - Pantanal - Brazil H8O0545 (23593619780).jpg

Molothrus oryzivorus
(Gmelin, JF, 1788)

Two subspecies
Southern Mexico south to northern Argentina, and on Trinidad and Tobago
Molothrus oryzivorus map.svg
Size:

Habitat:

Diet:
 LC 


Shiny cowbird

Shiny cowbird (Molothrus bonariensis) male.JPG
Male
Molothrus bonariensis Chamon comun Shiny Cowbird (female) (8348449535).jpg
Female

Molothrus bonariensis
(Gmelin, JF, 1789)

Seven subspecies
South America, the Caribbean, and Florida
Molothrus bonariensis map.svg
Size:

Habitat:

Diet:
 LC 


Bronzed cowbird

Bronzed Cowbird (Molothrus aeneus) (7223072934).jpg

Molothrus aeneus
(Wagler, 1829)

Three subspecies
  • M. a. loyeiParkes & Blake, 1965
  • M. a. assimilis(Nelson, 1900)
  • M. a. aeneus(Wagler, 1829)
Southern U.S. states of California, Arizona, New Mexico, Texas, and Louisiana south through Central America to Panama
Molothrus aeneus map.svg
Size:

Habitat:

Diet:
 LC 


Bronze-brown cowbird


Molothrus armenti
(Cabanis, 1851)
Colombia
Molothrus armenti map.svg
Size:

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 NT 


Brown-headed cowbird

Molothrus ater 2.jpg
Male
Brown headed cowbird female in JBWR (25490).jpg
Female

Molothrus ater
(Boddaert, 1783)

Three subspecies
Southern Canada, United States, and Mexico
Molothus ater Map.svg
Size:

Habitat:

Diet:
 LC 


One extinct species, Molothrus resinosus , is known from fossil remains recovered from the Talara Tar Seeps of northwestern Peru, and likely went extinct during the late Quaternary. It may have been a close associate of Pleistocene megafauna communities, and may have gone extinct following their collapse in populations. [7] The convex-billed cowbird (Pandanaris convexa) is another extinct species that likely co-evolved with the megafauna, though it is placed in its own genus.

The nonparasitic baywings were formerly placed in this genus; they are now classified as Agelaioides.

Behavior

Cowbirds eat mostly insects and seeds. Some species follow ungulates to catch insects stirred up by the larger animals' grazing.

Cowbirds reproduce by laying their eggs in other birds' nests. Female cowbirds observe a potential host bird laying 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 female cowbirds have been observed to attack and destroy the remaining eggs of such birds in retaliation, as suggested by the Mafia hypothesis. [8]

References

  1. "Icteridae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-07-16.
  2. Swainson, William; Richardson, J. (1831). Fauna boreali-americana, or, The zoology of the northern parts of British America. Vol. Part 2. The Birds. London: J. Murray. p. 277. The title page bears the year 1831 but the volume did not appear until 1832.
  3. Paynter, Raymond A. Jr, ed. (1968). Check-list of Birds of the World. Vol. 14. Cambridge, Massachusetts: Museum of Comparative Zoology. p. 195.
  4. Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names . London: Christopher Helm. p.  258. ISBN   978-1-4081-2501-4.
  5. "Cowbird" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
  6. Gill, F.; Donsker, D.; Rasmussen, P. (July 2020). "IOC World Bird List (v 10.2)" . Retrieved July 15, 2020.
  7. Steadman, David W.; Oswald, Jessica A. (July 2020). "New species of troupial (Icterus) and cowbird (Molothrus) from ice-age Peru" . The Wilson Journal of Ornithology. 132 (1): 91–103. doi:10.1676/1559-4491-132.1.91. S2CID   220714575.
  8. Jeffrey P. Hoover; Scott K. Robinson (13 March 2007). "Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs". Proceedings of the National Academy of Sciences. 104 (11): 4479–4483. Bibcode:2007PNAS..104.4479H. doi: 10.1073/pnas.0609710104 . PMC   1838626 . PMID   17360549.

Further reading