Speaking of Nature: A new life lister for Bill: Swainson’s thrush

  • Captured in the diffuse golden light of sunrise, this photo shows the gorgeous cinnamon-cream coloration on the face of a Swainson’s thrush. Note the “eyebrow” connected to the ring of light feathers around the eye of this bird. FOR THE GAZETTE/BILL DANIELSON

  • BILL DANIELSON

Published: 9/21/2021 2:35:38 PM

After so many years of writing about birds, it is a rare day indeed that I can write about a species that I’ve never mentioned before. This week, however, I write about something even more rare. On Sunday, Sept. 12, I was sitting in my beloved Thinking Chair and looking for interesting birds that may have arrived during a burst of migratory movement the previous night. At one point I turned my head to the left and saw a thrush of some sort sitting in a sunny spot on a bare branch. I snapped a few photos and only realized later that I had just taken photos of a life bird.

For those of you not fully versed in the vocabulary of birders, a “life bird” is a species that an individual person has just seen for the first time. So let me give you an example of how this might play out. A black-capped chickadee is a species that I probably first saw when I was 3 or 4 years old. I could probably see one every day by just looking out the window. But for a birder from Germany, this common North American species would represent a “rare” and “never before seen” life bird. It just depends on who you are, where you have been and what you’ve seen during your lifetime.

So when I looked at the photos of the bird I had just seen I could immediately see that it was a thrush of some sort. Brown feathers above, white feathers below and a generous splash of black spots on the breast. But when I looked a little closer I noticed some very interesting colors on the face. Specifically, I noticed an “eyebrow” stripe of a delicious-looking cinnamon-cream color. I checked my books, I sought out consultation and I settled on an identification. This was not a wood thrush, a hermit thrush, or even a veery. This was a Swainson’s thrush!

A quick look at my Mass Audubon Checklist of the Birds of Massachusetts may give a hint as to why I’ve failed to see this bird up until now. During the third week of May this species is listed as “common,” but for the rest of the breeding season it is listed as ‘uncommon,” “occasional” and “very infrequent.” This is because the breeding grounds for the Swainson’s thrush are actually located up in Canada and the very northernmost portion of Maine. There is a slight chance that a pair of these birds might breed in the Adirondacks, the Green Mountains and the White Mountains, but they are “never” seen this far south in the breeding season.

Slightly smaller than an American robin, the Swainson’s thrush is a bird of spruce forests, which generally are not seen in our area except for at the tops of very tall mountains. In these forests the birds specialize on insects and other invertebrates, including spiders. Like its thrush cousins, the Swainson’s thrush will do a great deal of its feeding on the ground, but it will also feed up in the forest canopy and even hover in the air to glean insects off of trees. It is also interesting to note that berries account for up to a third of their diet during the summertime, which is unusual for a thrush.

Females build nests in the horizontal branches of spruce trees about 10 feet off the ground. These nests are rather typical in that they are built of coarse twigs and vegetation, but (perhaps as an homage to its relative the robin) it may also incorporate some mud into the inner surface of the cup-shaped nest. Once complete, the female will line the inside of the nest with soft plant fibers, animal hair and even some lichens. Then, over the course of a week, she will lay three to four pale blue eggs into the nest that she built by herself. Sometimes her eggs have dark blotches on them and other times they are solid blue.

While all of this is happening, the male Swainson’s thrush is busy defending the pair’s territory from intruders. This is an extremely important job because the female will need food while she is incubating the eggs for the next two weeks. But a good territory becomes increasingly important when the eggs hatch (after 12-14 days) and chicks must be fed. This is when the male kicks into high gear and helps to feed the chicks while also trying to defend the territory. Not an easy task when you consider the fact that up in Canada the summer days are much longer and there is little time to rest during the brief periods of darkness.

About 10 days after hatching the Swainson’s thrush chicks can fledge. This is where those extra-long days come in handy because the parents can feed the chicks so much more. Once the chicks are flying, the entire rhythm of the family changes. No longer tied to the nest, the birds can fan out across the territory and begin to learn how to find their own food. Initially, hungry chicks may closely follow their parents and pester them for food, but in doing this they are also learning what food is and where it is found.

I was surprised to learn that it is not known if Swainson’s thrushes will have more than one nest per year. I was further surprised to learn that the birds’ winter diet was not well known. The fact that the Swainson’s thrush breeds so far north and winters so far south (Central America and South America in the Andes Mountains) may have resulted in little work done by American ornithologists. What is known is that the spruce forests that are so crucial for breeding are very vulnerable to climate change.

I say this almost every week, but it has just been proven to be true once again: Go outside and keep your eyes open for something new and interesting. You never know what you will find if you are outside and observant and you just might see something for the first time in your life.

Bill Danielson has been a professional writer and nature photographer for 24 years. He has worked for the National Park Service, the US Forest Service, the Nature Conservancy and the Massachusetts State Parks and he currently teaches high school biology and physics. For more in formation visit his website at www.speakingofnature.com, or head over to Speaking of Nature on Facebook.




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