WOOD THRUSH (Hylocichla mustelina) WOTH Sample size: 1,023 |
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This familiar eastern thrush breeds from South Dakota across southern Canada to Nova Scotia, and south to Texas and north Florida [Roth et al. 1996 (BNA)]. Nests are placed on low tree branches or in shrubs in both interior and edges of deciduous and mixed forests. They are normally double-brooded. The breeding habitat is usually moist, mesic forest, but not wetlands or higher altitudes [Roth et al. 1996 (BNA)]. Foraging is below the canopy, usually in leaf litter on the ground, and the diet is largely invertebrates [Holmes and Robinson 1988]. In winter, Wood Thrushes are found from southern Mexico to Panama on both coasts of the mainland of Central America [Howell and Webb 1995]. Their preferred habitat is primary broad-leaved forest or denser layers of older second growth [Blake and Loiselle 1992]; they are probably territorial and feed on invertebrates and fruit [Winker et al. 1990].
Migration is nocturnal, except the end of the northward Gulf of Mexico crossing in April, migrants probably departing from Yucatan to north Veracruz, Mexico [Roth et al. 1996 (BNA)]. New England spring migration peaks in mid-May and fall movements begin from mid-August to mid-September [Laughlin and Kibbe 1985]. Fall migrants probably also cross the Gulf, departing from Texas to Florida [Rappole et al. 1979]. Migration habitat is poorly documented; similar to breeding and winter habitats, but in fall there is more use of scrub, where fruit is abundant [Rappole and Ballard 1987].
Wood Thrush range expanded northwards into New England in the first half of the last century. However, the continent-wide Breeding Bird Survey data show a 1.7% per year decrease from 1966-1994. Holmes and Sherry [1988] showed stable populations at Hubbard Brook, NH from 1969-1979, but declines from 1978-1986. There is general agreement that Wood Thrush is now a severely declining species throughout its range. The causes may be briefly summarized as loss of forest in both breeding and wintering areas, nest predation, brood parasitism by Brown-headed Cowbirds near forest edges, and sporadic loss of migrants over the Gulf of Mexico in storms [Roth et al. 1996 (BNA)].
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Observations
This deciduous forest edge breeding species showed a significant preference for A sites during migration, although B and C sites were also used. In New England, Wood Thrush is close to the northern limit of its range; thus densities in CT and MA were significantly higher than those of NH and VT.
A few Wood Thrushes arrived in period 1 (late April), and peaked at about period 4, earlier in A sites, with densities dropping by the last spring period (period 5). |
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WOTH Map
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