Blue Grosbeak (Passerina caerulea)

[order] PASSERIFORMES | [family] Cardinalidae | [latin] Passerina caerulea | [UK] Blue Grosbeak | [FR] Gros-bec bleu | [DE] Azurbischof | [ES] | [NL] Blauwe Bisschop

Subspecies

Physical charateristics

About 15% larger than Scarlet Rosefinch but with rather similar though stockier form; about 15% smaller than Rose-breasted Grosbeak, with proportionately shorter tail. Rather large, robust but shy Nearctic finch, with two rusty wing-bars in all plumages. male deep blue, with blacker flight- and tail-feathers; female and immature recall lightly marked Carpodacus finch but show some blue on wing and tail.

Listen to the sound of Blue Grosbeak

[audio:http://www.aviflevoland.nl/sounddb/B/Blue Grosbeak.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

North America, Middle America : South USA to Costa Rica

Habitat

A Nearctic forest species, like Rose-breasted Grosbeak, firmly linked with edges between dense woodland and more open lower vegetation, as naturally occurs by streamsides, swamps, or where opened-up patches are undergoing second growth. Human intervention has partly replicated such terrain in roadside plantings, along farm hedgerows and ditches, and in weedy fields, into which range has recently expanded, although attachment to thick cover and to moist places persists and open ground is avoided.

Reproduction

Females most likely build the nest, usually low in small trees, shrubs or tangles of vines, briers and other vegetation. Nests are often built near open areas or even roads. The small, bowl-shaped nest sometimes contains man-made items such as rags, cellophane, string or even newspaper. Females do all the incubating and most of the feeding while young are still in the nest. The male feeds young more actively after they fledge and while the female is building a second nest. These birds are heavily parasitized by the brown-headed
cowbird, and they are also a known host for the bronzed cowbird. Blue grosbeaks have been observed building a nest on top of a parasitized nest and have been documented successfully
raising both cowbirds and their own young. Unlike some of the breeding neotropical migrants of eastern North America, the blue grosbeak has evolved with cowbirds in parts of its range for some time.

Feeding habits

The primary foods of the blue grosbeak are insects, snails, and seeds of wild and cultivated grasses.

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 increasing, 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.
Breeds in southern North America from central California, Nevada, and the Dakotas east to New Jersey, south to central Florida and Gulf of Mexico coast, and through Mexico and Central America to central Costa Rica.
Accidental. Norway: Male, Akershus, June 1970; Male, Rogaland, November 1987. Records from Britain (1970, 1972, 1986) and Sweden (1980, 1983) thought to involve escaped birds.

Migration

Migrant (northern populations) to resident (southern populations). Migrants winter within and slightly south of residents? range: mainly from northern Mexico south to Panama, rarely in southern USA and western Caribbean.

Distribution map