Screaming cowbird

Molothrus rufoaxillaris

Photo by Jorge Vicente (Reserva Ecológica Costanera Sur)

Common name:
screaming cowbird (en); vira-bosta-picumã (pt); vacher criard (fr); tordo chillón (es); rotachsel-kuhstärling (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species is found from south-eastern Bolivia and Goiás in central Brazil, through Paraguay and Uruguay and into Argentina as far south as Río Negro and north-eastern Chubut.

Size:
These birds are 18-21 cm long and weigh 45-60 g.

Habitat:
The screaming cowbird was originally associated with grasslands and open woodlands, but is now mostly found in arable land and man-made pastures. They occur from sea level up to an altitude of 1.000 m.

Diet:
They feed mainly on insects and other arthopods, particularly beetles and ants, but also eat seeds.

Breeding:
These birds are apparently monogamous and breed in October-March. They are obligate brood parasites, meaning they never build their own nests, always laying their eggs on the nests of other birds. Most often they parasitize bay-winged cowbirds Agelaioides badius, but can also lay eggs on the nests of chopi blackbirds Gnorimopsar chopi and brown-and-yellow marshbirds Pseudoleistes virescens. Each female lays 2 eggs which are incubated by the host for 12-14 days. The chicks are fed by the host and fledge 12-16 days after hatching.

Conservation:
IUCN status - LC (Least Concern)
This species has a very large breeding range and is described as fairly common. The screaming cowbird has more than doubled the extent of its range in the last 50 years, probably due to conversion of natural vegetation into pastures and arable land.

Montezuma oropendola

Psarocolius montezuma

(Photo from Ecos del Bosque)

Common name:
Montezuma oropendola (en); japu-de-Montezuma (pt); cassique de Montezuma (fr); cacique de Moctezuma (es); Montezumastirnvogel (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species is found from southern Mexico south to western Panama, mainly on the lowlands bordering the Carribean Sea.

Size:
This species is sexually dimorphic. Males are 46-51 cm long and weigh about 520 g, while the females are smaller at 38-39 cm long and weighing 230-250 g.

Habitat:
The Montezuma oropendola is mostly found in moist tropical forests, particularly in forest clearing, forest edges and areas near water. They also use banana plantations and bamboo thickets. They occur from sea level up to an altitude of 800 m.

Diet:
They feed mainly on fruits, but also take nectar, flowers and other plant material, as well as large insects and other arthropods, frogs and other small vertebrates.

Breeding:
Montezuma oropendolas breed in January-August. They are polygynous, with males defending harems, and nest in colonies of 20-150 nests. Females build the nests, which consist of large, elaborate, pear-shaped structures made of plant fibres and twigs that hang from tree branches. Each female lays 1-2 white or buff-coloured eggs with dark spots, which she incubates alone for 15 days. The chicks fledge about 30 days after hatching.

Conservation:
IUCN status - LC (Least Concern)
This species has a large breeding range and the global population is estimated at 50.000-500.000 individuals. The population is suspected to be stable in the absence of evidence for any declines or substantial threats. Their rainforest habitats are being reduced by moderate deforestation, but they can adapt to open country with scattered trees.

Yellow-headed blackbird

Xanthocephalus xanthocephalus

Photo by Mike Ross (Internet Bird Collection)

Common name:
yellow-headed blackbird (en); graúna-de-cabeça-amarela (pt); carouge à tête jaune (fr); tordo cabeciamarillo (es); brillenstärling (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species breeds in south-western Canada, in eastern British Columbia, Alberta, southern Saskatchewan, southern Manitoba and marginally in south-western Ontario, and in the United States, mainly east of the Cascades, from Washington to Michigan and south-westwards into to north-western Texas, northern New Mexico, northern Arizona and some areas in southern California. Also marginally into Baja California, in Mexico. They migrate south to winter from southern Arizona and Texas to central Mexico as far south as Puebla.

Size:
These birds are 21-26,5 cm long and have a wingspan of 42-44 cm. Females are smaller than males, weighing 44-60 g while males can weigh up to 100 g.

Habitat:
the yellow-headed blackbird is mostly found breeding in wetlands with abundant emergent vegetation, such as marshes, swamps and bogs, but also use grasslands and parks located near wetlands. Outside the breeding season they also use arable land and pastures. They are present from sea level up to an altitude of 1.000 m.

Diet:
During the breeding season they feed mainly on aquatic insects, but also other insects, including beetles, grasshoppers, dragonflies, caterpillars, flies and ants, as well as spiders. Outside the breeding season they feed on grains and weed seeds.

Breeding:
Yellow-headed blackbirds breed in May-June. They are polygynous, with males defending harems of up to 16 females. Each female builds one nest, a cup made of woven strands of wet vegetation, attached to the leaves of aquatic plants and always located above water. There she lays 2-5 greyish to greenish-white eggs with brown, rufous and grey blotches, which she incubates alone for 11-13 days. The chicks are fed by both parents, although the more females the male has in its harem the less it is involved in feeding the young. They fledge 9-14 days after hatching.

Conservation:
IUCN status - LC (Least Concern)
This species has a very large breeding range and the global population is estimated at 11 million individuals. The population has undergone a small increase over the last 4 decades, possibly due to the increase in food supply for the birds outside of the breeding season caused by the expansion of corn, sunflower and small grain production. They may be affected by wetland drainage and their diet and habitat choice can expose them to herbicides and pesticides. In some areas, farmers consider yellow-headed blackbirds a pest and use toxic baits or sprays against them, beside trapping and shooting.

Jamaican blackbird

Nesopsar nigerrimus

Photo by Jaremy Gatten (Flickr)

Common name:
Jamaican blackbird (en); iratauá-da-Jamaica (pt); carouge de Jamaïque (fr); turpial de Jamaica (es); bromelienstärling (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species is endemic to Jamaica, being found in Cockpit Country, the central hills the Blue and John Crow Mountains.

Size:
These birds are 18 cm long and weigh about 40 g.


Habitat:
The Jamaican blackbird is found in mountain rainforests, including elfin and limestone forests and forest edges, favouring areas with heavy epiphytic growth of bromeliads or Phyllogonium moss. They are present at altitudes of 500-2.200 m.

Diet: 
They forage among epiphytes, moss-covered trunks and dead leaves, picking various insects.

Breeding:
Jamaican blackbirds are monogamous and breed in May-August. The nest is a cup made of plant material and placed against the trunk of a tree in the lower canopy. The female lays 2 eggs, which she incubates alone for bout 14 days. The chicks are fed by both parents, but there is no information on the length of the fledgling period.

Conservation:
IUCN status - EN (Endangered)
This species has a relatively small and fragmented breeding range. The global population is estimated at just 1.500-7.000 individuals and is likely to be slowly decreasing as a result of habitat loss. Habitat loss has been caused primarily by afforestation, mainly with Caribbean pine Pinus caribaea, coffee plantations, removal of trees for charcoal-burning, deliberate fires, small-scale farming and development, and ongoing habitat degradation leds to an increase in parasitism by shiny cowbird Molothrus bonariensis. The removal of mature trees reduces the availability of large tank bromeliads in which it forages. However, the most significant current threat is bauxite mining in its stronghold in Cockpit Country.

Scott's oriole

Icterus parisorum

Photo by Brian Small (Larkwire)

Common name:
Scott's oriole (en); corrupião-de-Scott (pt); oriole jaune-verdâtre (fr); turpial de Scott (es); Scott-trupial (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species breeds in Mexico an the south-western United States, as far north as Nevada, Utah and Colorado. The more northern population migrate south to winter in western and southern Mexico.

Size:
These birds are 22-24 cm long and have a wingspan of 29-32 cm. They weigh 32-41 g.

Habitat:
The Scott's oriole is found in hot deserts and dry scrublands, especially in areas populated by yuccas. they are present from sea level up to an altitude of 3.000 m.

Diet:
They feed mainly on insects, such as grasshoppers, beetles, ants, bees, butterflies, caterpillars and other insect larvae. They also eat berries, cactus fruits and nectar.

Breeding:
Scott's orioles breed in April-July. They are monogamous and the nest is a slightly hanging basket of woven plant fibres stripped from dead leaves, lined with soft grasses and other plant fibres. It is placed in a small trees or scrub, mainly yuccas, usually hanging from the leaves at the crown of the tree. There the female lays 3-5 pale blue eggs with dark spots and streaks, which she incubates for 12-14 days. The chicks are fed by both parents and fledge 14 days after hatching. Each pair raises 1-2 broods per year.

Conservation:
IUCN status - LC (Least Concern)
This species has a large breeding range and the global population is estimated at 1,6 million individuals. In the United States the population has undergone a small decline over the last 4 decades.

Bobolink

Dolichonyx oryzivorus

Photo by Guy Poisson (Internet Bird Collection)

Common name:
bobolink (en); triste-pia (pt); goglu des prés (fr); charlatán (es); reisstärling (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species breeds in southern Canada and the northern United States as far south as Oregon, Colorado, Illinois and Virginia. They migrate south to winter in eastern Bolivia, Paraguay and marginally into south-western Brazil and northern Argentina.

Size:
These birds are 15-21 cm long and have a wingspan of 27 cm. They weigh 30-55 g.

Habitat:
The bobolink breeds mostly in tall grasslands, also using arable land. Outside the breeding season they temperate and tropical dry grasslands, moist savannas and arable land.

Diet:
They feed on various wild seed, as well as larval and adult insects, and spiders. At the wintering grounds and during migration they also feed on domestic crops such as rice, oats and other small grains.

Breeding:
Bobolinks breed in May-August. They are polygynous, with male forming pairs with up to 4 females, but usually only helping raise the brood produced by the first female with which he mates. The nest is a cup made of dead grass and lined with fine grasses or sedges, placed on the ground among dense vegetation. The female lays 3-7 bluish-grey or pale reddish-brown eggs with dark spots and blotches. The eggs are incubated for 11-14 days and the chicks fledge 10-14 days after hatching.

Conservation:
IUCN status - LC (Least Concern)
This species has a large breeding range and the global population is estimated at 11 million individuals. The population is declining over most of its range, mainly due to agricultural intensification, but they are also shot as an agricultural pest on the wintering areas. The bobolink is not considered threatened at present.

Baltimore oriole

Icterus galbula

Photo by Henry Domke (Health Care Fine Art)

Common name:
Baltimore oriole (en); corrupião-de-Baltimore (pt); oriole de Baltimore (fr); turpial de Baltimore (es); Baltimoretrupial (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species breeds throughout the eastern United States, south-eastern Canada and north-eastern Mexico, and migrate south to winter in Florida, from Mexico to western Colombia and northern Venezuela and throughout the Caribbean.

Size:
These birds are 17-20 cm long and have a wingspan of 23-30 cm. They weigh 30-40 g.

Habitat:
The Baltimore oriole breeds in open deciduous forests, forest edges, rural areas and urban parks. Outside the breeding season they also use grasslands and tropical moist forests.

Diet:
They mainly eat insects and other invertebrates, berries and nectar, especially caterpillars,
beetles, crickets, grasshoppers, moths, and flies, spiders, snails, mulberries, cherries and grapes.

Breeding:
Baltimore orioles are mostly monogamous, although extra-pair paternity is known to happen. They breed in May-June and nest on a tightly woven pouch located on the end of a branch, which the female builds using any any plant or animal materials available. It is usually placed 7-9 m above the ground. The female lays 3-7 pale greyish or bluish white eggs with brown and black blotches and streaks. She incubates the eggs alone for 11-14 days. The chicks are fed by both parents and fledge 11-14 days after hatching, becoming independent shortly after.

Conservation:
IUCN status -LC (Least Concern)
This species has a very large breeding range and a global population estimated at 6 million individuals. The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Crested oropendola

Psarocolius decumanus

Photo by Dominic Sherony (Wikipedia)

Common name:
crested oropendola (en); japu-preto (pt); cassique huppé (fr); oropéndola crestada (es); krähenstirnvogel (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species is found from southern Costa Rica and Panama down to Bolivia, Paraguay, southern Brazil and northern Argentina. It is only found east of the Andes mountain range.

Size:
These birds are sexually dimorphic. The females are 36-38 cm long while the males are 46-48 cm long. They weigh 155-360 g.

Habitat:
The crested oropendola is found in various forested habitats, including rainforests, swamp forests, savannas and dry forests. They are present from sea level up to an altitude of 2.600 m.

Diet:
They feed on fruits, seeds and insects, namely bananas, tangerines and papayas.

Breeding:
Crested oropendolas are colonial breeders and polygynous, with a dominant male than mates with most of the females. Each colony will have 3-4 males and 15-30 females.  They build large hanging nests woven from dry grasses and twigs. The nests are placed hanging from a high branch in a tree, usually along forests edges and clearings. The female lays 1-2 green or bluish-green eggs with dark blotches, which are incubated for 15-19 days. The chicks fledge 24-36 days after hatching. Each female can raise 3 broods per year.

Conservation:
IUCN status - LC (Least Concern)
This species has an extremely large breeding range and described as common but patchily distributed. The population is suspected to decline moderately based on current models of Amazonian deforestation.

Red-bellied grackle

Hypopyrrhus pyrohypogaster

Photo by Juan Ochoa (Internet Bird Collection)

Common name:
red-bellied grackle (en); iraúna-de-ventre-vermelho (pt); quiscale à ventre rouge (fr); cacique candela (es); rotbauchstärling (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
This species is endemic to Colombia, being found in isolated patches along the Andes.

Size:
These birds are 27-32 cm long and weigh 80-90 g.

Habitat:
The red-bellied grackle is mostly found in mountain rainforests, but can also use cleared areas such as pastures and along roads. They are present at altitudes of 800-2.400 m.

Diet:
They forage on the forest canopy, eating fruits, flowers, arthropods and some small vertebrates. They are known to take the fruits and flowers of melastome Tibouchina lepidota, various arthropods, frogs ans Anolis lizards.

Breeding:
Red-bellied grackles breed in January-August. They form family groups of 3-7 individuals, including the breeding pair and several helpers who are usually immatures from previous years. The nest is an ovoid open cup, made of sticks and roots and lined with dry leaves. The nest is placed in a fork in a tree, 2-15 m above the ground. The female lays 2-4 pale blue eggs with purplish-brown spots and stripes, which are incubated by both the mother and female helpers for 15-17 days while the males provide them with food. The chicks are mainly fed by immature helpers and females, and fledge 16-18 days after hatching.

Conservation:
IUCN status - VU (Vulnerable)
This species has a small and highly fragmented breeding range. The global population is currently estimated at 2.500-10.000 individuals and is believed to be declining at a slow rate. The main threat affecting the red-bellied grackle is habitat destruction and fragmentation  through extensive forests clearance for timber extraction and agricultural development. Within their native range, the area covered by primary rainforests has reduced by over 90%. Further threats include human disturbance, brood parasitism by the giant cowbird Molothrus oryzivorus, persecution as a maize crop-pest, and illegal trapping for the cage-bird trade.

Yellow-rumped cacique

Cacicus cela

Photo by Dave Nunez (Flickr)

Common name:
yellow-rumped cacique (en); xexéu (pt); cassique cul-jaune (fr); cacique lomiamarilo (es); gelbrücken-stirnvogel (de)

Taxonomy:
Order Passeriformes
Family Icteridae

Range:
These birds are found in northern South America, from Bolivia and south-eastern Brazil to Venezuela, Colombia and Panama.

Size:
The males are 27-29 cm long, while the smaller females are 23-25 cm long. The males weigh 100-115 g and the females weigh 65-75 g.

Habitat:
These birds are found along the edges of rainforests and swamp forests. Originally they were found along rivers and oxbow lakes, but now also along roads, pastures, and other human-created edge habitats. They may sometimes be found in dry forests and savannas. The yellow-rumped cacique occurs from sea level up to an altitude of 1.100 m.

Diet:
They mainly eat arthropods, such caterpillars, grasshoppers, crickets, katydids and spiders, but will also eat fruits, namely chupa-chupa Quararubea cordata and figs Ficus trigona. They are also known to raid the nests of other birds for eggs and nestlings.

Breeding:
The yellow-rumped cacique breeds in July-February. The males are polygynous, sequentially matting with several females during the course of the breeding season, but guarding each female until egg laying. They nest in colonies of 20-100 nests, each nest being built by the female and consisting of a long, hanging bag made of palm fronds, twigs and grasses. The nests are placed hanging from a branch in a low tree, often over water and near wasp nests, which may protect them from predators. There the female lays 2 pale blue or white eggs with dark blotches, which she incubates alone for 13-15 days. The chicks fledge around 25 days after hatching. Each female may raise 2-3 clutches per season.

Conservation:
IUCN status - LC (Least Concern)
This species has a very large breeding range and is described as common throughout most of its range. Models of deforestation in the Amazon basin suggest the yellow-rumped cacique is loosing suitable habitat at a moderate rate, which may be causing population declines. However, since this species occupies edge habitats, it will probably benefit, at least in the short term, from human activities such as road construction or clearing of forests that create more edge habitats, as long as some large trees and patches of forest remain. Overall, this species is not considered threatened at present.

Eastern meadowlark

Sturnella magna

Photo by William Hull (Mango Verde)

Common name:
eastern meadowlark (en); peito-amarelo-ceroulo (pt); sturnelle des prés (fr); turpial oriental (es); lerchenstärling (de)


Taxonomy:
Order Passeriformes
Family Icteridae


Range:
This species if found from south-eastern Canada, across the eastern United States, through Mexico and Central America and into Colombia, Venezuela, the Guyanas and northern Brazil.


Size:
These birds are 19-28 cm long and have a wingspan of 35-40 cm. They weigh 75-150 g.


Habitat:
Eastern meadowlarks are mostly found in dry grasslands and pastures, but also in arable land, dry scrublands and rural gardens. They occur from sea level up to an altitude of 3.500 m.


Diet:
They forage on the ground taking various invertebrates, namely crickets, grasshoppers, caterpillars and grubs. They also eat seeds and berries.


Breeding:
Eastern meadowlarks breed in March-August. The female builds the nest on the ground out of grasses woven into surrounding vegetation. There she lays 2-6 eggs white eggs with reddish-brown speckles, which she incubates alone for 13-15 days. The chicks are mostly fed by the female and fledge 10-12 days after hatching, but continue to rely on the adult birds for food for a another 2 weeks.


Conservation:
IUCN status - LC (Least Concern)
This species has a very large breeding range ans a global population estimated at 10 million individuals. The population has undergone a large decline of -26.9% per decade over the last 4 decades, but overall it is not considered threatened at present.

Boat-tailed grackle

Quiscalus major

Photo by Connie Denyes (Wikipedia)

Common name:
boat-tailed grackle (en); iraúna-dos-paúis (pt); quiscale des marais (fr); zanate marismeño (es); bootschwanzgrackel (de)


Taxonomy:
Order Passeriformes
Family Icteridae


Range:
This species is found breeding along the eastern coast of North America, from New York to Florida, and along the Gulf of Mexico coast to Texas. Some populations migrate south and may reach northern Mexico.


Size:
These birds are 26-37 cm long and have a wingspan of 39-50 cm. They weigh 90-240 g.


Habitat:
The boat-tailed grackle is mostly found in coastal saltwater marshes, but also in inland wetlands near the coast, in agricultural fields and even in urban areas.


Diet:
They mostly eat small crabs, shrimps and other aquatic invertebrates, but also insects, earthworms, seeds and fruits. Rice is an important part of their diet in autumn and they are also known to eat small lizards, frogs, turtles, eggs and even garbage.


Breeding:
Boat-billed grackles nest in colonies. Both males and females are often promiscuous and the females are responsible for building the nest, a bulky cup of twigs, grass, weeds and bulrushes placed in a tree or bush near water. The female lays 2-5 light blue eggs with dark spots, which she incubates alone for 13-15 days. The chicks are fed only by the female and fledge 20-23 days after hatching. This species produces 2-3 clutches per year.


Conservation:
IUCN status - LC (Least concern)
This species has a relatively large breeding range and a global population estimated at 4 million individuals. The population has undergone a large increase of 16% per decade over the last 40 years.

Yellow-tailed oriole

Icterus mesomelas

Photo by Bill Lynch (Neotropical Birds)

Common name:

yellow-tailed oriole (en); corrupião-de-cauda-amarela (pt); oriole à queue jaune (fr); turpial de cola amarilla (es); gelbschwanztrupial (de)

Taxonomy:

Order Passeriformes

Family Icteridae

Range:

These birds are found from southern Mexico down to western Peru and north-western Venezuela.

Size:

Yellow-tailed orioles are 20-24 cm long and weigh around 70 g.

Habitat:

These birds are found in tropical lowland areas, generally in woodlands, forest clearings and scrublands. They are also common in agricultural areas, namely Heliconia stands, Manila hemp, and banana plantations. They are present from sea level up to an altitude of 500 m.

Diet:

Yellow-tailed orioles mostly eat insects and spiders, but will also consume nectar and certain fruits such as gumbo-limbo Bursera simaruba.

Breeding:

They breed in April-November. The female builds a deep, basket-shaped nest made of plant fibres, which hangs from a thorny scrub about to 2 m above the ground. There she lays 2-3 light blue eggs with brown spots, which are incubated for 14 days. The chicks fledge 13 days after hatching.

Conservation:

IUCN status - LC (Least Concern)

The yellow-tailed oriole has a large breeding range and a global population of 500.000-5.000.000 individuals. The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Bullock's oriole

Icterus bullockii

Photo by Kevin Cole (Encyclopedia of Life)

Common name:

Bullock's oriole (en); corrupião-de-Bullock (pt); oriole de Bullock (fr); bolsero calandria (es); Bullock trupial (de)

Taxonomy:

Order Passeriformes

Family Icteridae

Range:

This American species breeds in western North America, from British Columbia, in Canada, down to northern Mexico. They migrate south to winter from central Mexico sown to Guatemala.

Size:

These birds are 17-19 cm long and have a wingspan of 31 cm. They weigh 29-43 g.

Habitat:

They mostly breed in riparian corridors, open woodland, and scrub forest. In winter they are found in riparian woodlands and woodland edge, typically in pine, pine-oak, or fir forests.

Diet:

The Bullock's oriole feeds primarily on insects, namely butterflies and their larvae, beetles, weevils and scale insects. They also eat fruits, berries, seeds and nectar. Ocasionally, they may also eat molluscs, small lizards and even hummingbirds.

Breeding:

These birds breed in May-July. They are monogamous and both sexes build the nest, a deep, pensile structure, made of of plant fibre, especially flax fibre, oat stalks, and the interior bark of willow and juniper trees. The nest is usually placed on the outer branches of a tree. The female lays 3-6 pale bluish or grey eggs, which she incubates alone for about 11 days. The chicks are fed by both parents and fledge 14 days after hatching. The family groups typically stay together after the young fledge, and may join with other families in post-breeding flocks.

Conservation:

IUCN status - LC (Least Concern)

This species has a very large breeding range and a global population estimated at 3,8 million individuals. The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Tricoloured blackbird

Agelaius tricolor

(Photo from Animal Photo Album)

Common name:

tricoloured blackbird (en); iratauá-tricolor (pt): carouge de Californie (fr); turpial capitán (es); dreifarbenstärling (de)

Taxonomy:

Order Passeriformes

Family Icteridae

Range:

This species is found along the Pacific coast of North America, from southern Oregon to California and Nevada, in the United States, and into Baja California and El Rosario in Mexico.

Size:

Tricoloured blackbirds are 18-24 cm long and have a wingspan of 30-35 cm. They weigh 59-68 g.

Habitat:

These birds breed in freshwater marshes with tall emergent vegetation, in upland habitats and in silage fields. They forage in agricultural areas, particularly where livestock are present and grass is short, and show a preference for roosting in marshes. They are found from sea level up to an altitude of 1.300 m.

Diet:

An opportunistic forager, the tricoloured blackbird takes any locally abundant insect including grasshoppers, beetles and weevils, caddis fly larvae, moth and butterfly larvae, dragonfly larvae, and lake shore midges, as well as grains, snails, and small clams.

Breeding:

These birds breed in April-July. They are polygynous with 1-4 females per male. Each females build the nests alone, a shallow, open cup made with dry leaves which are dipped in water and woven around strong, upright plant stems, usually around 1 m above the ground. The nest is lined with mud and softer materials. There the female lays 3-5 eggs which she incubates alone for 11-12 days. The chicks are fed by both parents and fledge 10-14 days after hatching.

Conservation:

IUCN status - EN (Endangered)

This species has a relatively small breeding range and the global population of 250.000 individuals is believed to be undergoing very rapid declines owing to loss of nesting habitat, low reproductive success in native habitats and complete breeding failure in harvested agricultural fields. Additionally, herbicide spraying and contaminated water are suspected to have caused complete breeding failure in several colonies. Because breeding success is so poor in native wetlands, protection of these habitats will not reverse population declines in the species, so conservation measures must focus on agricultural land and upland habitats as well.

Brown-headed cowbird

Molothrus ater

Common name:

brown-headed cowbird (en); vira-bosta-de-cabeça-castanha (pt); vacher à tête brune (fr); tordo cabecicafé (es); braunkopf-kuhstärling (de)

Taxonomy:

Order Passeriformes

Family Icteridae

Range:

This North American species is found in western and southern Canada, throughout the United States and in Mexico. The northern populations are migratory, moving south to Mexico in winter.

Size:

Males tend to be larger than females in this species. The males are 19-22 cm long, have a wingspan of 36 cm and weigh 42-50 g. The females are 16-20 cm long, have a wingspan of 28-32 cm and weigh 38-45 g.

Habitat:

Brown-headed Cowbirds occur in grasslands with low and scattered trees as well as woodland edges, brushy thickets, prairies, fields, pastures, orchards, and residential areas. They generally avoid forests.

Diet:

They feed mostly on seeds from grasses and weeds, with some crop grains. Grasshopper and beetles are also taken, often been caught as cows and horses stir them into movement. The females also eat snails and even the eggs of other birds in order to supply the extraordinary calcium demand of laying so many eggs.

Breeding:

Brown-headed cowbirds are brood-parasites, so the females lay their eggs in the nests of other birds. Over 140 host species of the brown-headed cowbird have been described, from birds as small as kinglets to as large as meadowlarks. Common hosts include the yellow warbler (Dendroica petechia), song and chipping sparrows (Melospiza melodia and Spizella passerina), Red-eyed Vireo (Vireo olivaceus), Eastern and spotted towhees (Pipilo erythrophthalmus and P. maculatus), and red-winged blackbird (Agelaius phoeniceus). A female can lay up to 36 eggs in a season, usually 1-7 per nest. The eggs hatch after 10-12 days of incubation by their hosts. Cowbird chicks tend to grow faster than their nestmates, allowing them to get more attention and food from their foster parents, and will fledge 8-13 days after hatching.

Conservation:

IUCN status - LC (Least Concern)

Originally a bison-following bird of the Great Plains, the brown-headed cowbird spread eastward in the 1800s as forests were cleared. This species greatly benefited from the human caused changes to the landscapes of North America and its population is now 56 million strong and believed to be mostly stable or slightly increasing. Its habit of nest parasitism can threaten species with small populations, such as the endangered Kirtland's warbler (Dendroica kirtlandii) and black-capped vireo (Vireo atricapillus).