Catharus
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 Gray-cheeked Thrush
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Catharus is a genus of birds in the thrush family Turdidae. It contains the small, mostly insectivorous or omnivorous migrant thrushes of North America and the nightingale-thrushes of Central and South America. Its closest relative is the Wood Thrush of the monotypic genus Hylocichla (Winker & Pruett, 2006) which is sometimes merged into Catharus.
These are mainly forest birds with large eyes, straight slim bills and fluty voices.
This is a typical New World thrush genus, although representatives of other genera, such as the true thrushes (Turdus) also occur in the region, especially in Central and South America.
[edit] Systematics
The Catharus species are either long-distance migrants or fairly resident birds. They were sometimes split according to this and morphological characters, the migrant group occasionally including the Wood Thrush also. Comparison of mtDNA cytochrome b and NADH dehydrogenase subunit 2 as well as nuclear β-fibrinogen intron 7 sequence data indicates that this is incorrect (Winker & Pruett, 2006).
Due to the adaptational requirements of the independently-acquired long-distance migrant lifestyle, several apparent morphological similarities between supposedly related species are actually due to convergent evolution. It seems that the genus originated in tropical or subtropical forest ecosystems of northern Central America, and that ever so often species diverged to settle more northernly regions, subsequently finding themselves forced to migrate south in winter into more food-rich habitat. The most ancient of these northward divergences was probably Swainson's Thrush, and the most recent one the fuscescens-minimus-bicknelli cryptic species complex.
The nightingale-thrushes are also paraphyletic. Whereas the aurantiirostris-fuscater/mexicanus-dryas group indeed forms a distinct lineage - probably living close to the genus' center of origin -, the Russet Nightingale-thrush is closest to the Hermit Thrush. The Ruddy-capped Nightingale-thrush is close to the Gray-cheeked species complex, while the Black-billed Nightingale-thrush is also fairly close to both of the nightingale-thrush/migrant lineages. Swainson's Thrush has no close living relatives.
The species are:
- Veery, Catharus fuscescens
- Gray-cheeked Thrush, Catharus minimus
- Bicknell's Thrush, Catharus bicknelli
- Ruddy-capped Nightingale-thrush, Catharus frantzii
- Black-billed Nightingale-thrush, Catharus gracilirostris
- Hermit Thrush, Catharus guttatus
- Russet Nightingale-thrush, Catharus occidentalis
- Swainson's Thrush, Catharus ustulatus
- Orange-billed Nightingale-thrush, Catharus aurantiirostris
- Slaty-backed Nightingale-thrush, Catharus fuscater
- Black-headed Nightingale-thrush, Catharus mexicanus
- Spotted Nightingale-thrush, Catharus dryas
[edit] References
- American Ornithologists' Union (AOU) (1998): Check-list of North American Birds (7th ed.). American Ornithologists' Union, Washington, D.C.
- Stiles, F. Gary & Skutch, Alexander Frank (1989): A guide to the birds of Costa Rica. Comistock, Ithaca. ISBN 0-8014-9600-4
- Winker, Kevin & Pruett, Christin L. (2006): Seasonal migration, speciation, and morphological convergence in the avian genus Catharus (Turdidae). Auk 123(4): 1052-1068. [Article in English with Spanish abstract] DOI: 10.1642/0004-8038(2006)123[1052:SMSAMC]2.0.CO;2 HTML abstract
