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Song sparrows fear cowbirds, domestic cats

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By Sylvia Brockner

“Zeet, zeet, zeet, buzzy trill.” I stop to listen. Yes, it is the first song sparrow I’ve heard this spring! The three bright, clean starting notes, followed by a rapid jumble of short notes, is a loud announcement by a male song sparrow that he is claiming about an acre of local real estate as his nesting territory.

Even though a few song sparrows actually winter in the area, they sing far less often in winter. We may hear their distinctive call note, “tchip,” but their song is largely reserved for territorial defense and nesting. So it is not until they have returned to their nesting territory that their melodious song once more welcomes spring.

Locally, look for song sparrows along any of the watercourses, for it is here that they find the moisture and thickets they need for their survival. Our ponderosa pine forests are too dry and sparsely vegetated for their liking. They have relatively small territories and may be found at intervals along Bear Creek and Evergreen Lake. There is often a pair near the bridge at the entrance to Evergreen Lake, another pair on the peninsula at the inlet and a pair or two in the Wilmot drainage. Other pairs are found in thickety places along Bear Creek such as along the creek behind the Bradley Gas Station, in the marshy area at Corwina Park, at Lair of the Bear, etc.

Song sparrows are one of the most widely spread species, found across America and from Mexico northward into Canada. In damper parts of the country, such as western New York, they nest along field edges and along fencerows as they did in our backyard when I was a child.

They are relatively common, friendly birds. Alden H. Miller states, “They are one of the best examples of substantial racial diversification” among terrestrial vertebrates on this continent. Ranging from the seashore to desert to mountains, there are 31 subspecies in the United States and Canada, plus three more in Mexico. They range in size and color from the large, dark song sparrows of the Aleutian Islands to the small, pale desert forms about the Salton Sea.

The song sparrow that we see here in Colorado is melospiza melodia montana, or the mountain song sparrow. They are brown-streaked middle-sized birds with a central cluster of streaks forming a large breast spot. They return to their nesting territories by late March or very early April.

Because song sparrows are so common and so friendly, they have been banded in good numbers across the country. This has produced considerable information about these birds, such as that on the average they live to be 8 to 9 years old. They sing through the breeding season, and then singing slows down during their complete annual molt during late August and September, when only a whisper song is heard. Migrating birds may lose as much as 1.41 grams over a single night of migration but regain weight rapidly once they reach their breeding grounds. The same male and female often return to nest in the same area for several years.

However, if one dies, the other will find a new mate.

The male establishes the territory and defends it by scrimmages and singing, six to eight times per minute, during the peak of the season. The female selects the nest site, which is usually on the ground or at most a foot or two up in a shrub. She does all the nest building, but the male occasionally feeds her on the nest. The eggs range from seven to 14 in a clutch (usually four or five) and take 10 to 14 days to hatch. As Forbush said, the song sparrow “male devotes himself more to song than to labor.”

However, he redeems himself by helping to feed the young and then takes over their care when they leave the nest, while she produces another clutch of eggs. They regularly have many broods where the season is long enough, and may have more. The young of the first brood often help with the feeding of the later broods.

Song sparrows’ greatest enemies are cowbirds and domestic cats. They are also subject to some predation by bot flies and other parasites. They are extremely beneficial to man since most of their food consists of injurious insects and noxious weeds.

Song sparrows are easily recognized by their brown-streaked feathers and by the way they pump their long tails in flight, especially just as they land and disappear into some thicket. Look for them and listen for their song at Evergreen Lake.