Saturday, July 23, 2016

Wood Thrushes

On our hikes around Sandy Lake, in northeastern Ohio, this week, I have encountered the usual mix of permanent and summer residents.  Of note has been a fair number of wood thrushes, more common than I would have expected in the limited, lakeside forest.

Indeed, a steady decline of wood thrush populations has been documented over the past half Century, perhaps due to fragmentation of forests by agricultural and suburban development.  Though still fairly common in the eastern U.S. and southeastern Canada, these eloquent songsters are known to be common targets of brown-headed cowbirds, which parasitize their nests; forest fragmentation likely increases their exposure to the cowbirds as well as to avian predators.  Wood thrushes typically place their nests in saplings and shrubs of the understory and may produce two broods during the spring-summer season.

Feasting on a wide variety of ground-dwelling invertebrates and an assortment of berries, these reclusive summer residents may be mistaken for immature robins by the casual naturalist.  Like their red-breasted cousins, they sing early and late in the day but their tune, often characterized by self-harmony, is far more impressive.  Before autumn chill envelops their breeding ground, wood thrushes head for Central America to winter in tropical forests.