Bicknell's Thrush

Bicknell's Thrush

Catharus bicknelli

Zorzal de Bicknell

Photo: C. Rimmer*

IDENTIFICATION: BicknellÆs Thrush (illustrated at a banding station) is gray above with rufous-tinged wing feathers and tail. The underparts are white with black breast spots. Length: 16-17 cm.; weight: 26-30 g. Taxonomists recently split Bicknell's Thrush from the more common and widespread Gray-cheeked Thrush (Catharus minimus). The Gray-cheeked Thrush is slightly larger, has less yellow on the lower bill, and has a grayer, less rufous tail and back.

VOICE: BicknellÆs Thrush sings infrequently on the winter grounds, but it sometimes calls at dawn and dusk. The call note is often described as a "whee-ah" or "quee-ah."

HABITAT: Dense understory in high mountain forests.

HABITS: A secretive, forest interior species whose behavior away from its northern breeding grounds is only now being explored. It feeds on berries, ants, caterpillars, wasps, beetles and flies. It nests in stunted, mountaintop forests above 3,000 feet in eastern Canada and New England. The nest is a well-hidden, bulky mass of moss, twigs and roots, placed 3-12 feet up in a birch or conifer tree. The female lays 3-4 bluish-green eggs with faint brown spots. She incubates the eggs for about 13-14 days, and both male and female feed the nestlings.

STATUS AND CONSERVATION: There are very few records of Bicknell's Thrush in Puerto Rico, e.g. El Yunque and Sierra de Cayey. The worldwide population of BicknellÆs Thrush is probably only 50,000 birds. Although most are thought to winter on Hispaniola, Bicknell's Thrush may be more common in the western mountains of Puerto Rico than currently suspected. It will respond to tape playback of its call. The population of this species may be declining due to destruction of mountain forests in its northern breeding grounds.

RANGE: Breeds in southern Quebec, New Brunswick and Nova Scotia, and the mountains of New England and New York State. It winters primarily in Hispaniola, but has been reported from Puerto Rico, St. Croix, Jamaica, and Cuba.

TAXONOMY: PASSERIFORMES; TURDIDAE

References

Arendt, W.J. 1992. Status of North American migrant landbirds in the Caribbean region: a summary. Pp. 143-171 in Ecology and conservation of neotropical migrant landbirds (J.M. Hagan III and D.W. Johnston, eds.) Smithsonian Instit. Press, Washington, D.C.

Bent, A.C. 1949. Life histories of North American thrushes, kinglets, and their allies. Smithsonian Instit. U.S. National Museum Bull. 196. (Reprinted by Dover Press, NY, 1964).

BirdLife International. 2000. Threatened birds of the world. Lynx Edicions and BirdLife International, Barcelona and Cambridge, UK.

Clement, P. 2001. Thrushes. Princeton University Press.

Evans, W.R. 1994. Nocturnal flight calls of BicknellÆs Thrush. Wilson Bull. 106:55-61.

Hobson, K. A., K. P. McFarland, L. I. Wassenaar, C. C. Rimmer, and J. E. Goetz. 2001. Linking breeding and wintering grounds of Bicknell's Thrushes using stable isotope analysis of feathers. Auk 118(1):16-23.

Lane, D. and A. Jaramillo. 2000. Identification of Hylocichla/Catharus thrushes: Part 1: Molt and aging of spotted thrushes and field ID of Wood Thrush and Hermit Thrush. 32:120-135.

Lane, D. and A. Jaramillo. 2000. Identification of Hylocichla/Catharus thrushes: Part III: Gray-cheeked and Bicknell's Thrushes. 32:318-331; with commentary, 2001. Birding 33(1):12-13.

Marshall, J. T. 2001. The Gray-cheeked Thrush Catharus minimus, and its New England subpecies, Bicknell's Thrush, Catharus minimus bicknelli. Nuttall Ornith. Club, Cambridge, MA.

McLaren, I. 1995. Field identification and taxonomy of Bicknell's Thrush. Birding 27(5):358-366. Corrigenda: 1996. Birding 28(1):16.

Ouellet, H. 1993. BicknellÆs Thrush: taxonomic status and distribution. Wilson Bull. 105:545-574.

Ouellet, H. 1993. BicknellÆs Thrush in Ontario. Ontario Birds 11:41-45.

Raffaele, H.A. 1989. A guide to the birds of Puerto Rico and the Virgin Islands. Princeton.

Raffaele, H.A. 1989. Una guía a las aves de Puerto Rico y las Islas Vírgenes. Publishing Resources, Inc., Santurce, PR.

Raffaele, H.A., J.W. Wiley, O.H. Garrido, A.R. Keith, and J.I. Raffaele. 1998. Guide to the birds of the West Indies. Princeton.

Rimmer, C.C. and K.P. McFarland. 1999. Sky island songbirds. Natural History 108(7):34-39.

Rimmer, C. C., K. P. McFarland, W. G. Ellison, and J. E. Goetz. 2001. Bicknell's Thrush (Catharus bicknelli). No. 592 in The birds of North America (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Bicknell's Thrush, Spanish text

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