Bell's vireo

Vireo bellii

Photo by Paul L'Etoile (Mango Verde)

Common name:
Bell's vireo (en); juruviara-de-Bell (pt): viréo de Bell (fr); vireo de Bell (es); braunaugenvireo (de)

Taxonomy:
Order Passeriformes
Family Vireonidae

Range:
This species is found breeding in the central and southern United States, from North Dakota to Ohio, south to Louisiana and Texas and also in southern Arizona, New Mexico and California, and into northern Mexico. They migrate south to winter along the Pacific coast of Mexico, Guatemala and Honduras.

Size:
These birds are 11-13 cm long and have a wingspan of 18 cm. They weigh 7-10 g.

Habitat:
The Bell's vireo is mostly found in low dense scrublands and woodlands, especially in riparian vegetation along rivers and streams, but also in dry scrublands, coastal chaparral and forest edges, from sea level up to an altitude of 2.000 m.

Diet:
They forage on low vegetation, mainly taking insects such as caterpillars, stink bugs, wasps, bees, beetles, grasshoppers and weevils, and also some spiders and a few berries.

Breeding:
Bell's vireos breed in April-July. They are monogamous, but may switch mates between successive nesting attempts within the same season and between years. The nest is an open cup made of stems, plant fibres, leaves, paper and strips of bark fastened with spider silk. The outside may be ornamented with spider cocoons and the inside is lined with fine grass. The nest is suspended from a low branch of a small tree or scrub. The female lays 3-5 white eggs with brown or black spots, which are incubated by both parents for 13-15 days. The chicks are fed by both parents and fledge 10-13 days after hatching, but only become independent 2 weeks later. They raise 1-2 broods per season.

Conservation:
IUCN status - NT (Near-Threatened)
This species has a relatively large breeding range and a global population estimated at 1,5 million individuals. The population has undergone a large decrease of 24% per decade over the last 4 decades, main caused by the loss of riparian habitats through agricultural, logging and housing developments.

Hutton's vireo

Vireo huttoni

Photo by Greg Gillson (Pacific NW Birder)

Common name:
Hutton's vireo (en); juruviara-de-Hutton (pt); viréo de Hutton (fr); vireo de Hutton (es); Hutton-vireo (de)

Taxonomy:
Order Passeriformes
Family Vireonidae

Range:
This species is found in western North America, in two distinct populations. One is found along the Pacific coast from British Columbia, Canada, to Baja California in north-western Mexico. The other population is found from northern Mexico, Arizona and Texas to Guatemala, being separated from the former by the Mojave and Sonoran deserts.

Size:
These birds are 12-13 cm long and weigh 9-15 g.

Habitat:
Hutton's vireos are mainly found in evergreen forests, preferring oak or pine-oak forests and tall chaparral, at altitudes of 900-3.500 m.

Diet:
They mainly glean caterpillars, beetles, crickets and spiders from the forest canopy, but will also take berries, small fruits and plant galls.

Breeding:

The Hutton's vireo nests in an open cup woven of lichens, spider webs, plant down, bark shreds, fine grasses, small green leaves, and moss, lined with grasses and placed in a fork in a branch, 2-8 m above the ground. There the female lays 3-5 white eggs with a few brown speckles, which are incubated by both parents for 14 days. The chicks are fed by both parents and fledge 14-17 days after hatching.

Conservation:

IUCN status - LC (Least Concern)

This species has a very large breeding range and the population has undergone a large increase of 17% per decade over the last 4 decades.

Black-capped vireo

Vireo atricapillus

Photo by Cody Conway (Flickr)

Common name:
black-capped vireo (en); juruviara-de-barrete-preto (pt); viréo à tête noire (fr); vireo cabecinegro (es); schwarzkopfvireo (de)


Taxonomy:
Order Passeriformes
Family Vireonidae


Range:
This species is only found breeding in Texas and Oklahoma, in the southern United States, and across the border into northern Mexico. They migrate south to winter along the western coast of Mexico.


Size:
These birds are 11-12 cm long and have a wingspan of 18 cm. They weigh 8-10 g.


Habitat:
Black-capped vireos are found in sparse dry scrubland and open woodlands, in areas of rocky or eroded soils.


Diet:
These birds are insectivorous, taking adult and larval insects and sometimes also spiders.


Breeding:
Black-capped vireos breed in March-June. Both sexes help build the nest, a cup made of leaves, grasses, plant fibers and animal silk, lined with fine grass. The nest is placed in a fork in a branch up to 2 m above the ground. The female lays 2-5 white eggs, which are incubated by both parents for 14-17 days. The chicks are fed insects by both parents and fledge 10-12 days after hatching.


Conservation:
IUCN status - VU (Vulnerable)
This species has a relatively restricted breeding range and the global population is estimated at just 8.000 individuals. The population is undergoing a rapid decline caused by habitat loss and degradation through fire suppression, urban development, agricultural conversion and intensive grazing. The increase in the numbers of brown-headed cowbirds Molothrus ater has resulted in high rates of brood-parasitism and the rates of nest predation are high, primarily from snakes, fire ants and mammals.