Friday, May 24, 2024

A hermit thrush is brownish on top with a speckled breast. (Photo: Jeffrey Offermann)

The hermit thrush is a close relative to the American robin and eastern bluebird. Although less colorful than either, the hermit thrush makes up for its lack of color by its flutelike song, for which it is renowned.

Hermit thrushes are migrating north right now (peaking in early May), so we have a good opportunity to see them. Although these birds are noted for their singing, the migrating birds sing only a quiet song early in the morning. Songbirds, including hermit thrushes, migrate at night. The birds you see during daylight hours may be foraging, but they will not continue their northward travels until nightfall.

A hermit thrush flicks its tail in Groton on Jan. 21. (Photo: Tom Murray)

Once they set up their breeding territory in May, these birds begin the singing for which they are best known. Their celebrated song is a series of flutelike notes, that ascend and descend randomly. Like other thrushes, the hermit thrush has a double voice box (called the syrinx). Because of this voice box, the thrush can sing two different notes at once, which blend together. In other words, these birds can harmonize with themselves! If you are lucky, you might hear the male’s sweet song anytime from April to late August.

Hermit thrushes have reddish tails. (Photo: Richard George)

The hermit thrush (Catharus guttatus) is called a hermit because it is so well hidden. These birds nest on the ground, making them easy prey if not well-concealed. Often people hear this bird before they see it. The name Catharus comes from the Greek word katharos meaning “pure,” a reference to its sweet song. Guttatus comes from gutata, meaning “spotted,” a reference to its spotted breast.

Hermit thrushes forage mostly on the ground, overturning leaves to expose insects. In the spring and summer, they eat mostly insects and small invertebrates, including beetles, ants, caterpillars, grasshoppers, snails and worms. In the fall and during its winter migration south, this bird commonly eats pokeberries, raspberries, serviceberries and grapes.

A spring hermit thrush on Strawberry Hill. (Photo: Richard George)

The female hermit thrush builds a well-hidden cup nest of mud and fibers on the ground. The nest is often under a small tree whose branches touch the ground, forming a protective canopy around the nest. Some nests may also be surrounded by ferns or bushes. The female lays about four eggs, which she incubates for 12 days. The male feeds the female while she is incubating the eggs. He also guards the nest by singing, perching some distance away.

A hermit thrush on Coolidge Hill in April 2022. (Photo: Richard George)

The young hatch by breaking open the egg into two pieces near the center. The adult female removes the eggshells from the nest. The chicks are naked — with eyes closed — and hungry. Both the male and female feed the young. At first, the parents give the baby birds small larvae, but as the youngsters grow, the parents bring them larger insects, such as grasshoppers, moths, beetles and spiders.

According to the ornithologist Arthur Cleveland Bent:

The food the first three days consisted of small green larvae. During the first day the larvae were minced in the beak of the adult before they were delivered, and at other times the larvae if large would be divided in two by each of the pair of birds grasping an end of the worm and pulling until it parted. After the third day winged insects, spiders and ants were added to the diet. On the seventh and eighth days, large moths, grasshoppers and beetles were fed to the young without any mincing or tearing apart.

A hermit thrush observes its surroundings in April 2022. (Photo: Richard George)

The chicks open their eyes after three or four days, and feathers emerge at seven days. The chicks learn to fly when they are 12 days old. Thrush parents entice the youngsters to leave the nest by perching at a distance with food in their beaks and calling for the hungry youngsters. The young perch on the edge of the nest, and eventually leap, flutter their wings and hop along the ground to the calling parent, who rewards the youngster with the tasty morsel. This process continues until all the young have left the nest.

As Walt Whitman wrote about hermit thrushes in “When Lilacs Last in the Dooryard Bloom’d,” his elegy mourning the death of Abraham Lincoln but also praising the beauty of the natural world:

Sing on, sing on you gray-brown bird,
Sing from the swamps, the recesses, pour your chant from the bushes,
Limitless out of the dusk, out of the cedars and pines.
Sing on dearest brother, warble your reedy song

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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.

This post was updated April 26, 2023, to correct the spelling of Jeffrey Offermann’s name.