Joann Merritt's Essays

Bird Of The Month - Catharus Ustulatus
July, 1996

If you think the title is confusing you should have been with Don and me as we tried to identify the Swainson’s Thrush, Catharus Ustulatus, by its song. To our ears none of the five thrush songs we listened to on tape sounded identical to what we were hearing but we could rule out the Veery and Gray-cheeked Thrushes. Could it be the Wood Thrush, or was it the Hermit or Swainson’s Thrush? We heard this flutelike song June 3rd but were unable to identify it by sound alone. We finally got a good look at the bird: gray-brown in color, lightly spotted breast, big buffy eye-ring, pale buffy cheeks and breast and dark streaks along each side of its throat. These details confirmed it as a Swainson’s Thrush.

Those of you who have read my articles know my fondness for the old-fashioned style of writing in Birds of America edited by T. Gilbert Pearson. Regarding the songs of thrushes, it states, “The listener whose ear recognizes and whose heart responds to such utterances is thrilled by it.” It goes on to say “Ocular identification of the bird may be a puzzling operation for the unpracticed or careless observer since Gray-cheeked, Swainson’s, Veery, Wood and Hermit Thrushes have considerable resemblance.” The more recent Reader’s Digest publication states “Though they (the 5 brownish thrushes) appear confusingly similar to us, each species is distinct. Each species also has an acoustic “signature”, a distinctive song and call.” The Swainson’s Thrush sings much during migration and almost continuously day and night in its northern breeding grounds, but just as some written signatures are hard to decipher so was this thrush’s acoustical signature.

Catharus, its genus name, alludes to the purity of its flutelike song and ustulatus, its species name, comes from “having been singed” referring to the ash-colored plumage. Its common name commemorates the English naturalist William Swainson, as do the Swainson’s Hawk and Swainson’s Warbler.

Swainson’s Thrushes winter in Central and South America. While migrating northward at night during April into June many are killed by striking TV towers and tall buildings. They breed from Alaska across Canada, south into New England, the West Virginia mountains, Michigan, northern New Mexico and east-central California. The one which was here the first week of June can surely travel to New Mexico and arrive for the nesting season which is from April to July I in its western range. There is nothing unusual about its cup-shaped nest which is built from four to twenty feet high in a tree by the female who also incubates the eggs for 11-14 days and is then helped by the male for 10-14 days until the young fledge.

While here the Swainson’s Thrush fed in Mulberry trees where Rose Marie, Don and I observed it eat a big juicy mulberry, but its diet consists of insects and worms as well as fruit. Since quite a few Midnats came to see and hear the thrush, maybe he’ll return next migration for an encore. The Chestnut-sided Warbler did!