Utah is blessed with many melodious songbirds, but which one sings most beautifully of all? I vote for the haunting, achingly beautiful melodies of our two common thrushes, Swainson’s Thrush and Hermit Thrush. These birds have been leisurely migrating northward from the tropics since early spring. By June, males are singing on their forested territories.
Thrushes are a bit secretive, but if you re lucky, you ll see a bird a tad smaller than a robin clothed in rich brown back feathers that contrast with a pale breast sporting descending lines of fat brown spots the size of raindrops. Both thrush species look much the same, however. To distinguish them, you need to listen. Their haunting melodies arise deep in their chests, in the syrinx. Their syrinx works something like our larynx, using vibrating membranes that can be stretched taut or relaxed to produce different notes. Unlike our larynx, the bird’s syrinx sits where it’s two tracheae meet the windpipe. The most skilled songsters, like these thrushes, can work the two sides of their syrinx independently to produce two simultaneous notes.
The song of the Swainson’s Thrush always ends in a spiral of ascending notes.
[Audio: Swainson’s Thrush #61 Songbirds of Yellowstone and the High Rockies]
Now listen to the song of the Hermit Thrush. It ends with a warbling flourish that alternately rises or falls in pitch.
[Audio: Hermit Thrush #27 Songbirds of the Rocky Mountains]
It helps me to remember the song of the Hermit Thrush as being a lonely hermit talking to himself in two different voices, one ending high, the other low.
The glorious songs of thrushes grace our woodlands all through the weeks of early summer. So listen carefully and see if you too can now distinguish the song of Swainson’s Thrush from that of the Hermit.
This is Linda Kervin for Bridgerland Audubon Society.
Photos: Courtesy Fish and Wildlife Service Online Digital Media Library
Audio: Dr. Kevin Colver, www.wildsanctuary.com
Text: Jim Cane & Jason Pietrzak, Bridgerland Audubon Society