Savannah sparrow: It's everywhere, but worth a second look – The Chesapeake Bay Journal


With its mostly brown, black and white coloration, the Savannah sparrow is not easy to distinguish from other sparrows, except for the distinctive yellow eyebrow. (Rejean J. Deschenes/CC BY-NC 2.0

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Sitting in the parked car, idly staring out the windshield, I suddenly realized there was a sparrow poking about in the grass right in front of me. I reached for my binoculars (we had been birding at Blackwater National Wildlife Refuge). The sparrow kept moving, walking methodically, as it snatched insects from the ground and off blades of grass.
With its mostly brown, black and white coloration, the Savannah sparrow is not easy to distinguish from other sparrows, except for the distinctive yellow eyebrow. (Rejean J. Deschenes/CC BY-NC 2.0
With the binoculars I could see the bird in detail. I had registered “sparrow” without thinking about it. But which one? Maryland routinely has 10 different species. A diagnostic yellow eyebrow quickly answered my question: It was a Savannah sparrow (Passerculus sandwichensis).
Other than the eye stripe, the Savannah looks like most common sparrows. Primarily, it is brown with a white belly and a strongly striped breast. Sometimes the breast contains a central black spot, mimicking the song sparrow’s coloring. Seen from above, the Savannah is a cryptic blend of brown and black. The short tail is a uniform brown and slightly forked. The top of the upper bill is black. The remainder is a pinkish bone color, the same color as the lower bill.
I saw this bird on Maryland’s Eastern Shore. Years earlier, I saw my first one in California. They get around! (“Savannah” doesn’t derive from the word meaning a grassy plain. The early U.S. naturalist who named it found his bird in Savannah, GA.)
The breeding season — early June to early August — finds Savannahs throughout Canada and Alaska. They also breed in the northern tier of the lower 48 states, from New England down to New York and Pennsylvania and west to the Pacific Ocean. In the East, the breeding range dips down the Appalachian Mountains, including all of West Virginia through to Georgia.
During the nonbreeding season, most of these middle-distance migrants take up residence below the Mason-Dixon line, including the Chesapeake Bay watershed and on through the Gulf states to the western Caribbean. Nonbreeding Savannah sparrows also overwinter in the U.S. Southwest, all of Mexico, inching into Central America. Both Mexico and California have small year-round ranges.
The fall migration starts in mid-September, peaks in October and ends in early November. Which raises the question: How do these birds, whether from Anchorage or Atlantic City, find their way to winter habitat?
In part because of their relative ubiquity, Savannahs have been studied for decades by scores of Canadian and U.S. scientists. Research has shown that these sparrows use a combination of internal solar, stellar and magnetic compasses. They are nocturnal migrants but use the setting sun to help with initial orientation. At night, they set their course by the stars and, if clouds interfere, the earth’s magnetic poles help to keep them on course. It is a remarkable feat, repeated millions of times every spring and fall.
Numbering an estimated 170 million, Savannahs are among the most common songbirds in North America, with 20 or more subspecies. Regardless of where they breed or spend the winter, these sparrows can always be found in the grasses.
They survive on insects, larvae, spiders, grasshoppers, millipedes and other small creeping, crawling and hopping creatures. In winter, they eat tiny seeds that drop from grasses or glean the seeds directly from the source.
The female selects a well-hidden nesting site, close to the ground. Both sexes build the nest, which typically holds four eggs. Only the female has a brood patch, and she will spend every night on her eggs. During the day, the male provides some relief at the nest, but most of the time it is the female’s responsibility.
After 12–13 days the eggs hatch. The chicks are helpless but mature quickly. Just 8–13 days later, the nestlings are ready for their first tentative steps. They are not yet able to fly but immediately begin learning to find the insects that will sustain them for life. The parents, which look alike, help feed the young birds for another two weeks. Then it’s time for the parents to start a second brood and for the youngsters to fend for themselves.
There may be a third or fourth brood, depending on weather, latitude and other factors.
It is during these early days that young males learn the high, thin, buzzy song that characterizes the species. Their fathers’ songs aren’t the only source of learning. Hearing other nearby males sing is also formative.
The Savannah sparrows’ songs come in three recognizable parts: a few opening notes, then the buzzy part, ending in a brief trill. Each young male will come up with a unique combination of notes that first summer, all based on this common pattern. They will sing that song for the rest of their lives.
Savannah sparrows are easy to overlook. They fall into that unfortunate category of LBBs: little brown birds. Today, we like lots of color more than unremarkable browns. The everyday gets overlooked in favor of the odd or different. We see these trends throughout society, from fashion to entertainment.
Maybe these preferences are hard-wired in humans just as the Savannah’s navigation systems are. Or perhaps it is more akin to learned behavior like the song-learning among the sparrow’s young males. Either way, it suggests that we share more in common with these overlooked birds than meets the eye. Don’t they deserve a second look?
Mike Burke, a Bay Journal columnist, is an amateur naturalist based in Maryland, having retired from a career that toggled between Capitol Hill and the U.S. Environmental Protection Agency.
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