P/cloudy
57°
P/cloudy
Hi 64° | Lo 46°
Speaking of Nature

Speaking of Nature: The Savannah sparrow

The theme for the past week would certainly have to be rain. It rained a lot last week, then it rained again this weekend, and then — surprise surprise — it rained again. Everything is wet and sticky, there is a tremendous amount of humidity in the morning air and the drive to work has been dominated by morning fogs that are extraordinarily beautiful, but still a little dangerous.

The homeowner/grounds keeper in me is starting to get a little concerned. The grass, fueled by all of this moisture, is starting to resemble a bamboo thicket. Another week of this and I’ll have to be on the lookout for tigers or velociraptors if I even dare venture into the yard. At the very least I will have to make sure Susan is at home so she can send out a search party if I’m late in returning from the more remote corners of my yard.

The bird watcher in me is actually quite pleased with the way things are going. My inability to mow is indicative of a more widespread issue for all mowing in general. Lawns are getting longer everywhere, as are the local hayfields. This sets the stage for a very serendipitous year for some of our local grassland birds.

When I think of huge hayfields, I think not of the hay such fields are meant to produce as much as I think of the habitat that is made available to three particular species of birds. There is the eastern meadowlark, the bobolink and the Savannah sparrow. I have seen all three of these birds this year in the fields that line the margins of the roads I take to and from work. I’ve even seen a bobolink in my own yard for an afternoon, but of the three, I see the Savannah sparrow most reliably.

There is a field at the intersection of my road that has always hosted all three species. This field is actually bisected by the road I live on and when I make the turn, I have to slow down quite a bit. For reasons I cannot explain there is a single wooden stake that was pounded into the ground about 20 feet off the road and on any day that it isn’t actively raining there seems to be a Savannah sparrow perched there.

The Savannah sparrow (Passerculus sandwichensis) is a delicate little denizen of fields and meadows. The bird’s diminutive size obviously made an impression on some taxonomist at some point because the word “Passerculus” is a Latin word that means “Little Sparrow.” As sparrows go, Savannah sparrows are on the small side (sometimes as little as 4.5 inches in length), but since most sparrows are small, it is not a particularly helpful distinction.

The species name is far less helpful. The word “sandwichensis” is the Latinized form of Sandwich … as in Sandwich Bay ... as in the Aleutian Islands … where the first subspecies of the Savannah sparrow was found. The ultimate translation is “the little sparrow from Sandwich.” Perhaps the Latin word for “field” was already used for another species.

The common name of this bird is just as random. You might think that a bird that is so closely tied to grasslands would be named after one. A savanna is a grassland, but it is a name used for African grasslands and there are no Savannah sparrows in Africa. You will also note that (when spelled properly) there is no “h” at the end of African savanna.

The shrewd observer will also notice my persistent capitalization of the “S” in Savannah, suggesting a proper noun of some sort. It just so happens that the famous ornithologist Alexander Wilson named this species after collecting his first specimen in the town of Savannah, Georgia, in 1811. The bird is named for a town rather than for a habitat.

Living in fields presents some challenges for Savannah sparrows. There isn’t really much choice as far as nest placement it concerned, so they build their nests on the ground. The male spends most of their time defending his territory (as most male birds do), which leaves the actual construction of the nest as a chore for the female.

The preferred location is a natural depression in the ground that is covered over by thick grasses. If no natural depression is available, the female may actually scrape one out with her feet. Once this is finished, the actual nest is built, though you might also say that a lining is fashioned. The rim of the nest will be flush with the ground and the interior of the nest will be lined with finer, softer grasses. The nest is usually located next to a tuft of taller grasses that hang over the nest site, offering some concealment from above.

Once her nest is complete the female sparrow will lay an egg per day until she has a clutch of three to five eggs. The basic Savannah sparrow egg is a very light blue or green and is marked with brown spots. But the appearance of each egg can be quite variable from extremely sparse spotting to extremely heavy. Both members of a pair will incubate the eggs, but the female takes the larger portion of the duty.

While on the nest, the female’s back will be flush with the ground and she will be next to impossible to find. The eggs are incubated for 10 to 14 days (a fairly standard period for such small birds), but the babies may leave the nest at only seven days of age. This early fledging age is another adaptation to living out in the open and it requires a lot of food!

This nesting strategy is outstanding protection from natural predators, but it offers no protection from human inventions. The mowing of hay is not a problem, but the spreading of hay to dry and then the raking of hay for baling cause devastation to any animal not able to get out of the way.

If the process of harvesting hay can be delayed just a little while (usually by rain) the sparrows will have a chance to get their chicks fledged. The chicks look quite similar to the adults, but they have the appearance of having been dipped in a solution of yellow dye, which gives their feathers a buttery yellow look. I have only seen baby Savannah sparrows once and I was very lucky to have my camera with me on that day.

So, although I know I am just making my own life a little more difficult in the mowing department, I suppose I hope the wet weather continues for a while. I’m certain to find solace in the continued success of my beloved Boston Bruins as they mow down the Blackhawks. I would normally support a bird over a mammal, but not this time.

Bill Danielson has worked as a naturalist for 16 years. In that time, he has been a national park ranger, a wildlife biologist and a field researcher. He currently works as a high school chemistry and biology teacher. To contact Bill, or to learn more about his writing, visit
www.speakingofnature.com

There are no comments yet. Be the first!
Post a Comment

You must be registered to comment on stories. Click here to register.