The Wood Thrush's loud, flute-clear ee-oh-lay song rings through the deciduous forests of the eastern U.S. in summer. This reclusive bird's cinnamon brown upperparts are good camouflage as it scrabbles for leaf-litter invertebrates deep in the forest, though it pops upright frequently to peer about, revealing a boldly spotted white breast. Though still numerous, its rapidly declining numbers may be due in part to cowbird nest parasitism at the edges of fragmenting habitat and to acid rain's depletion of its invertebrate prey.
This was one of best finds. It was photographed at Elizabethtown college. Me and Susanne heard this amazing song and spent 30 minutes in silence waiting for this bird to show itself. It finally did and I was able to take this photo.
A songbird like the Wood Thrush requires 10 to 15 times as much calcium to lay a clutch of eggs as a similar size mammal needs to nurture its young. That makes calcium-rich food supplements like snail shells crucial to successful breeding. These are rare in soils subject to acid rain, which may help explain patterns of population decline in the Wood Thrush. Wood Thrushes are vulnerable to nest parasitism by Brown-headed Cowbirds, which lay their eggs in other birds’ nests. Some species refuse to raise these eggs, but Wood Thrushes accept them as their own. In some Midwest forest edge habitats, virtually every Wood Thrush nest contains at least one cowbird egg. The Wood Thrush is a consummate songster and it can sing “internal duets” with itself. In the final trilling phrase of its three-part song, it sings pairs of notes simultaneously, one in each branch of its y-shaped syrinx, or voicebox. The two parts harmonize with each other to produce a haunting, ventriloquial sound. The male Wood Thrush does more feeding of the chicks than the female, freeing her up to start a second brood. After that next brood fledges, the pair divides them up and feeds them at separate sites in the territory.
A songbird like the Wood Thrush requires 10 to 15 times as much calcium to lay a clutch of eggs as a similar size mammal needs to nurture its young. That makes calcium-rich food supplements like snail shells crucial to successful breeding. These are rare in soils subject to acid rain, which may help explain patterns of population decline in the Wood Thrush. Wood Thrushes are vulnerable to nest parasitism by Brown-headed Cowbirds, which lay their eggs in other birds’ nests. Some species refuse to raise these eggs, but Wood Thrushes accept them as their own. In some Midwest forest edge habitats, virtually every Wood Thrush nest contains at least one cowbird egg. The Wood Thrush is a consummate songster and it can sing “internal duets” with itself. In the final trilling phrase of its three-part song, it sings pairs of notes simultaneously, one in each branch of its y-shaped syrinx, or voicebox. The two parts harmonize with each other to produce a haunting, ventriloquial sound. The male Wood Thrush does more feeding of the chicks than the female, freeing her up to start a second brood. After that next brood fledges, the pair divides them up and feeds them at separate sites in the territory.
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