All About Hermit Thrush

Here is a recent post from the Union Bay Watch Blog published by Larry Hubbell, long-time local photographer and birder.

Hermit Habits

A Hermit Thrush belongs to the same family as an American Robin. In the fall and winter, similar to a robin, they can act a lot like a frugivore.

If you adjust for size and compare the silhouette of a Hermit Thrush and an American Robin I suspect they would look quite similar. They are both members of the Turdidae or Thrush family. However, there are dramatic differences in plumage, size, and song.

Sadly, this week, I did not get to hear the haunting song of a Hermit Thrush. (Clicking Here will enable you to hear a recording though.) Luckily, I did hear their soft "chuff" call, which is virtually identical to a call made by Varied Thrush.

A Hermit Thrush weighs less than half as much as a Robin. To my eye, it appears even smaller.

I remember seeing one a few years ago crushing a Sorbus berry it found on the ground. It took some time to reduce the fruit to a manageable size. American Robins (and Varied Thrush) have no problem with the size of a 'normal' Sorbus berry. 

This year, I was lucky to find a flock of Hermit Thrush, in the Arboretum, focused on an apparently unique, Asian Sorbus. This particular tree seems to have smaller than average berries, which allow the Hermit Thrush to swallow them whole. 

This is also the first time I remember noticing that the swallowed berry causes a temporary protrusion in the lower throat on its way south.

Sometimes, the Hermit Thrush will sit for a moment while the berry descends into its digestive tract.

At other times, similar to a Robin, after initially swallowing two or three berries it will abandon the fruit tree. They seldom go far. Generally, they sit somewhere nearby while waiting for the urge to consume more fruit. 

An American Robin will often choose an elevated perch in a tree. A Hermit Thrush, on the other hand, is more likely to pick a lower spot in a bush, beneath a small tree, or in the undergrowth. 

Even when sitting, a Hermit Thrush is seldom still. They will often raise their reddish tail and flick their wings. I wonder if this behavior scares insects into moving or silently signals their companions. 

To me, Hermit Thrush appear to be nervous birds. Their behavior looks like I feel when I drink too much coffee. Maybe, they are internally calm - but I doubt it.

Even though we have other spotted Thrush species that breed in Washington state this is the only one that winters here. Lucky, for us.

There are three other small, similar-looking, spotted Thrush species that breed in Western North America e.g. the Veery, the Swainson's Thrush, and the Gray-cheeked Thrush.  The latter is not normally found in Washington state.

Note: There are five other Thrush species in Washington state which are quite distinctively different e.g. without spots in their adult plumage.

Amazingly, Birds of the World (BOW) says that we have 12 subspecies of Hermit Thrush in North America.  However, BOW does not have a map laying out the ranges for all the subspecies. (It makes me wonder if mapping their ranges might be an interesting task for a budding ornithologist.) Locally, Birdweb says we may have four Hermit Thrush subspecies in Washington state. 

Personally, I find this incredible complexity of life keeps me humble while I work to expand my knowledge and understanding.

An interesting, bite-sized, piece of information is learning how to tell a first-year Hermit Thrush from one that is more mature. The tiny buff-colored line across the upper wing, e.g. the tiny pale coloring at the end of the upper coverts, indicates this is a Hermit Thrush who hatched out this year.

This week, as the fruit on the Sorbus tree, disappeared the corresponding number of Hermit Thrush seemed to also decline.

As mentioned above, I have generally assumed the flicking of a bird's wings was to frighten insects. (Inspiring a bug to move makes it easier for a bird to see them.) However, waving your wings above fruit does not make the berries any more obvious, although, I guess the downdraft might make them move.

Notice how the 'fish' hook on the back of the tongue helps to push the fruit down the throat. We might argue whether it is pushing or pulling. However, the tongue runs underneath the berry enabling the hook to apply pressure from the far side.

By the way, the reddish-brown tail, contrasting with the grayish-brown back, is unique to the Hermit Thrush species.

Curiously, a light vertical line on the underside of an upraised wing can be seen in seven out of the eight species of the Thrush family found in Washington State. Can you guess which species does not have a vertical line in the middle on an upraised wing?

Occasionally, a Hermit Thrush will almost hover in the air while harvesting a berry. I wonder if they can detect some variation in color that makes that particular piece of fruit look irresistible?

When they stop and look around before snatching the next piece, I wonder if they are watching for danger?

Maybe, they are just trying to understand that odd clicking noise - coming from my camera.

On the other hand, most of the time...

...I feel positive...

...they are totally focused on the fruit.

Have a great day on Union Bay...where nature lives in the city and Black Birders are welcome!