Photo credit: Laura Gooch (CC BY-NC-SA)

For the relative abundance of the Hermit Thrush, a medium sized olive-brown backed thrush with a contrasting warm brown to reddish tail, it is far easier to hear this forest-dwelling bird than see it. Cornell’s website Birds of the World states that the “Song has a ventriloqual quality, often making it difficult to determine the direction and distance from which the bird is singing.” Even the recordist, David Kazdan, who captured this week’s featured recording for our project, did not see the Hermit Thrush while recording it along the Alder Trail in the Schoodic Peninsula. Yet, the song is so distinctive it can be ID’d with certainty without seeing it.

Similar to other thrushes, like the Wood Thrush or Swainson’s Thrush, the song is often described as ethereal. Cornell’s description in Birds of the World uses the phrase: “a richly melodious, haunting, fluty warble.” But, it is the Hermit Thrush’s introductory note, a steady whistled note at the beginning of its many songs, that you can listen for to help you differentiate among the thrushes. Listen below to a small portion of David Kazdan’s 16+ minute recording:

Excerpted from ML105829431 with Kazdan’s permission.

A common menomic for the song of the Hermit Thrush is Oh, holy holy,-ah, purity purity,-eeh, sweetly sweetly, which hints at the echo-like qualities of the bird’s song. When you listen closely, you can hear the bird’s two voice boxes (syrinxes). Yes, birds have two voice boxes (humans have one). The left is used for lower frequencies and the right for higher frequencies, and they can use them individually or at the same time — that is how they are able to make that “fluty warble” sound you hear.

you can almost “hear” the fluty-warble by looking at the spectrogram

You can hear it best when we manipulate the recording, reducing it to 1/4 speed, which scientists note also helps our ears resolve the intricacies of song similar to how the birds themselves are able to hear the complexity (nb: in this 1/4 speed recording spaces between the Hermit Thrush’s song, normally about 1.5 – 2 seconds, were significantly shortened). Do you also think of Native American flute songs when you hear it?

1/4 speed manipulation of excerpt from Kazdan’s ML105829431

In sharp contrast to last week’s featured bird/recordings of the Common Yellowthroat, whose songs are greatly influenced by learning their neighbor’s songs– sometimes throughout an entire region– Hermit Thrushes have unique songs; no two sing the same songs! In fact, Hermit Thrushes usually have a repertoire of about 9-14 songs, that they sing. Once completed, they sing the repertoire again. A nice long recording like a couple we have in our project — David Kazdan’s 16+ minute recording, and his 5+ minute recording (of same bird recorded with different equipment) — allows you to listen and find how many songs this particular Hermit Thrush sings before re-starting his “playlist” again. Donald Kroodsma in his new book, Birdsong for the Curious Naturalist, suggests listening for the highest frequency song, and then finding it again, to count the number of songs in that birds repertoire.

Beautiful and fascinating. Data is too, and can help you find and understand the bird in its place. Toward that Seth Benz, Director of the Bird Ecology Program at Schoodic Institute, had provided analysis below of the Hermit Thrush in context of the Schoodic Peninsula in Acadia National Park.

By executing a data dive into eBird through the Explore portal’s Species Map function the distribution of checklists that reported at least one Hermit Thrush looks like this:

The map is a compressed depiction of where 249 different observers reported at least one Hermit Thrush on a cumulative total of 527 checklists submitted since 1971 through May 4, 2020.

When the aggregate of thrush-reporting checklist dates are plotted along a calendar year to create a phenological model (or timing of species observations) , it shows that the very best time to experience Hermit Thrush on the Schoodic Peninsula is during the breeding season in June and July.  And the best place to look and listen for them is along the Alder Trail (and happens to be where the featured recording was made. Also, note the interactive map of the Peninsula on the sidebar to the right).

Interestingly, while the species has been seen in every month of the year in Maine, it is noteworthy that not a single Hermit Thrush has been seen from late fall through the winter months on the Schoodic Peninsula south of Frazer Point according to eBird checklists.  Here is a stacked line graph that depicts the phenology of occurrence:

The first Hermit Thrush of a typical year is observed on the Schoodic Peninsula in early to mid-April. The number of observations build in May (spring migration), peak in June (nesting), diminish a bit from mid to late July (post nesting dispersal), then decline in August through October as birds undertake fall migration, and haven’t been found throughout the winter months.

“Ever since I entered the woods, even while listening to the lesser songsters, or contemplating the silent forms about me, a strain has reached my ears from out of the depths of the forest that to me is the finest sound in nature –the song of the hermit thrush.” 

  ~In the Catskills by John Burroughs, 1910