Giant Cowbird (Molothrus oryzivorus)

[order] Passeriformes | [family] Icteridae | [latin] Molothrus oryzivorus | [UK] Giant Cowbird | [FR] Vacher geant | [DE] Riesenkuhstarling | [ES] Vaquero Pirata | [IT] Molotro gigante | [NL] Grote Koevogel

Subspecies

Physical charateristics

The Giant Cowbird male is almost entirely purplish-black with a ruff on the neck and a noticeably darker head. The iris varies in colour from red to yellow. The female, is smaller and a duller black and lacks the ruff.

Listen to the sound of Giant Cowbird

[audio:http://www.aviflevoland.nl/sounddb/G/Giant Cowbird.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

From Veracruz, northern Oaxaca, Tabasco, Chiapas and southern Quintana Roo (Peters 1913) south on Gulf-Caribbean slope of Central America to Honduras, in Nicaragua (both slopes), Costa Rica (Caribbean slope, central plateau, and Pacific slope in Golfo Dulce region) and Panama (both slopes but more widespread on Caribbean slope); and in South America from Colombia, Venezuela, Trinidad and Tobago and the Guianas south, west of Andes to western Ecuador and east of Andes to eastern Peru, Bolivia, eastern Paraguay, extreme northeastern. Argentina, and central and eastern Brazil

Habitat

Molothrus oryzivorus
Giant CowbirdOrder: Passeriformes Family: Icteridae Polytypic 2 Subspecies
Authors: Lowther, Peter E.
Overview

Identification

Distribution

Life History

Conservation

Future Research

References

Acknowledgments

Distribution
The Americas
From Veracruz, northern Oaxaca, Tabasco, Chiapas and southern Quintana Roo (Peters 1913) south on Gulf-Caribbean slope of Central America to Honduras, in Nicaragua (both slopes), Costa Rica (Caribbean slope, central plateau, and Pacific slope in Golfo Dulce region) and Panama (both slopes but more widespread on Caribbean slope); and in South America from Colombia, Venezuela, Trinidad and Tobago and the Guianas south, west of Andes to western Ecuador and east of Andes to eastern Peru, Bolivia, eastern Paraguay, extreme northeastern. Argentina, and central and eastern Brazil (Peters 1913, American Ornithologists’ Union 1998, Stiles and Skutch 1989, Howell and Webb 1995).

The elevational distribution of the Giant Cowbird varies across its range. In Mexico, it occurs up to 750 m (Howell and Webb 1995); in Costa Rica, up to 1700 m (Stiles and Skutch 1989, Skutch 1996); up to 2200 m in Colombia (Hilty and Brown 1986, Skutch 1996); to 1700 m in Venezuela (Hilty 2003); to 2000 m in Ecuador (Ridgely and Greenfield 2001); and to 1200 m (locally) in Peru (Schulenberg et al. 2007).

Outside the Americas
Endemic to the Americas.

Habitat
Partly open situations with scattered trees, cultivated lands, second growth, open fields and plantations, usually in vicinity of colonies of oropendolas or caciques; tropical and lower subtropical zones (American Ornithologists’ Union 1998). Found to 1675 m in Costa Rica and 2135 m in Colombia (Skutch 1996). In Ecuador, was not found above 914 m; present at banana plantations but not seen in the forest (Goodfellow 1901). Frequent canefields, savannas, cultivated lands and golf courses; sometimes considered “rare” but evident around colonies of oropendolas.

Reproduction

Giant Cowbirds are brood parasites. Nests, incubation and parental care of young provided by host species. List of known hosts totals 10 species, mostly caciques and oropendolas. Does not build nest; see discussion of hosts above. Regular host species are colonial icterids that build pendulous nests. Characteristics of either host birds, host nest, host nest site, host habitat, host eggs, or some combination of host characters may influence selection by female cowbird of which particular host nest for parasitism. Young altricial (nearly naked and helpless) and nidicolous (confined to nest). Recently hatched (“2 or 3 days old”) cowbirds have white skin, well covered with long, dark gray down; beak white and gape wide and yellowish; would gape “eagerly” when nest disturbed.

Feeding habits

Fruit (Ficus trigona and Coussapoa sp.), nectar (chiefly Combretum sp. and Quararibea sp.), and arthropods (Robinson 1988). One bird collected had been eating rice (Wetmore et al. 1984); stomach of young male had seeds
Giant CowbirdOrder: Passeriformes Family: Icteridae Polytypic 2 Subspecies
Authors: Lowther, Peter E.
Overview

Identification

Distribution

Life History

Conservation

Future Research

References

Acknowledgments

Life History
Food
Fruit (Ficus trigona and Coussapoa sp.), nectar (chiefly Combretum sp. and Quararibea sp.), and arthropods (Robinson 1988). One bird collected had been eating rice (Wetmore et al. 1984); stomach of young male had seeds

Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Migration

Sedentary throughout range.

Distribution map