SWAINSON’S THRUSH
(Catharus ustlatus)
eBird gives this description for the Swainson’s Thrush: Uniform medium-brown above from head to tail. Distinctive pale, buffy eyering and face separates Swainson’s from other thrushes. Spots are concentrated and clearly defined on upper breast, becoming smudgier towards belly. Breeds in the boreal forest. Migrates to South America for winter; very rare in the U.S. after October, unlike Hermit Thrush. Its song is flute-like, ascending spiral like Veery in reverse.
All About Birds gives more descriptive information about the Swainson’s Thrush: More likely to be heard than seen, Swainson’s Thrushes enliven summer mornings and evenings with their upward-spiraling, flutelike songs. During fall and spring migration, their soft, bell-like overhead “peeps” may be mistaken for the calls of frogs. These largely arboreal foragers pluck berries, glean bugs from leaves, or perch on branches and stumps. They also bound across the forest floor to catch insect prey. They breed in the north and the mountainous West, but they become very widespread during migration.
I saw my first Swainson’s Thrush on the morning of May 18, 2020, at Warbler Pond in Warbler Woods. I am grateful more experienced birders were present, because I probably would not have identified this bird without their help!
“Cool Facts” About the Swainson’s Thrush From All About Birds…
- The “russet-backed” Pacific population has more reddish plumage and a slightly different song than the “olive-backed” birds in the rest of the range. The russet-backed birds winter in Central America while the olive-backed ones winter in South America.
- The Swainson’s Thrush’s whirling song has a ventriloqual quality that can make it difficult to track. This may happen as the singer moves quickly from one perch to another between songs. It may also have to do with the sounds’ reverberation in dense foliage. Swainson’s Thrushes also sometimes sing quiet songs that create the illusion that its song emanates from a more distant location.
- Territorial disputes between males often take the form of singing duels, with song volume and frequency escalating until the combatants’ physical exertions are clearly evident. During these contests, rivals very occasionally invert their customary melody so that it spirals downward in pitch. A sing-off can lead to a chase and even occasionally to physical attack.
- Swainson’s Thrushes have been called “mosquito thrushes” for their flycatching habit of going after flying insects while feeding on their breeding grounds.
- In New England spruce-fir forests, the nests of Swainson’s Thrushes are often lined with root-like cords of horsehair fungus. The fungal filaments can have antibiotic effects and may help deter nest pathogens.
- The longest-lived Swainson’s Thrush on record was at least 12 years, 1 month old when it was recaught and rereleased during banding operations in Montana in 2006.