The Blue Grosbeak is often mistaken for its relative, the Indigo Bunting. Indigo Buntings are smaller overall, have a smaller bill, and the adult male lacks the wing bars present in the Blue Grosbeak. Both male and female Blue Grosbeaks have the habit of spreading and flicking their tails, and occasionally raising the feathers on the crown, giving the head a shaggy appearance.

Length: 15.8 - 19cm
Physical characteristics: The male of this species is a brilliant blue, with black wings and reddish-brown wing bars. The female is brownish overall, with buff wing bars. Both sexes have the large, thick, conical bill common to grosbeaks and cardinals.
Voice: Song is a melodic series of warbles without pauses.

Breeding habitat:
This bird is found in forest edges, overgrown fields, thickets, orchards and hedgerows.

Mating system:
Monogamous; a pair usually raises two broods in each nesting season.

Nest:
The nest is a deep, compact cup of twigs, rootlets and bark strips, lined with fine rootlets, grass and hair. Snakeskin, dried leaves or paper is commonly woven into the exterior. The nest is located in a low tree, bush or vine tangle at the edge of an open area or roadside. It is most likely built by the female.

Eggs:
There are 3 to 5 eggs in a clutch, with the typical number being four. The eggs are white or pale blue in color and unmarked. 22mm (0.9″).

Chick development:
Incubation by the female only takes 11-12 days. The chicks are altricial at hatching. The female also does most of the feeding of the nestlings. The young fledge in 9-10 days. The male takes over the primary care of the fledglings in the first brood while the female starts on a second nest.

Diet:
The diet of the Blue Grosbeak includes insects (especially grasshoppers and crickets), snails and seeds, gleaned from the ground or low foliage.

Conservation Biology:
The Blue Grosbeak biology is poorly known. However, its numbers do seem to be stable or even slightly increasing. And the breeding range of this bird has been expanding northward.

It is frequently parasitized by the Brown-headed Cowbird and is also a host for the Bronzed Cowbird. It may rebuild a nest over the parasitized nest, or raise both the cowbird chicks and its own successfully.

Breeding: the Blue Grosbeak occurs from New Jersey west to California and south through Mexico and Central America. In the United States its range includes North and South Dakota, but excludes most of the Gulf Coast.
Winter: This species is a neotropical migrant and winters in Mexico and Central America, the Bahamas and Cuba. It forms large flocks after the nesting season, descending on fields of grain or weeds to feed before migration.

The Blue Grosbeak is an uncommon breeding bird species in the Park. Blue Grosbeaks prefer open and shrubby areas so observations of this species are generally restricted to the Cades Cover area of the Park. This species may occasionally be observed in the Park during migration. In a survey of breeding birds in the Park, performed from 1996-1999, eleven individual Blue Grosbeaks were observed, all in Cades Cove.

References:

Committee on Classification and Nomenclature of the American Ornithologists' Union. 2000. Forty-second supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 117: 847-858.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 2002. Forty-third supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 119: 897-906.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 1998. Check-list of North American Birds: the Species of Birds of North America from the Arctic through Panama, including the West Indies and Hawaiian Islands, 7th ed

Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The Birder's Handbook: a Field Guide to the Natural History of North American Birds. Simon and Schuster, Inc., New York.

Elphick, C., J. B. Dunning, Jr., and D. A. Sibley, eds. 2001. The Sibley Guide to Bird Life and Behavior. Alfred A. Knopf, New York.

Gough, G. A., Sauer, J. R., Iliff, M. Patuxent Bird Identification Infocenter. 1998. Version 97.1. Patuxent Wildlife Research Center, Laurel, MD.

Ingold, J. L. 1993. Blue Grosbeak (Guiraca caerulea). In The Birds of North America, No. 79 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union.

Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

Stupka, A. 1963. Notes on the Birds of the Great Smoky Mountains National Park. University of Tennessee Press.