audubon's "sweet little creatures"

Any day now, American Tree Sparrows (Spizella arborea) will arrive to spend the winter.  They share honors with Red-bellied Woodpeckers and Ring-necked Ducks in being comically misnamed. American Tree Sparrows (tree sparrows for short, although they should not be confused with Eurasian Tree Sparrows, Passer montanus) breed across great expanses of northern Canada (click on Cornell map below), often north of the treeline, where they nest on or near the ground.  In winter, they are also most often seen on the ground, frequently underneath backyard feeders, or balancing daintily on the dried seed heads of wildflowers and grasses.

They are, using an old-fashioned term once applied to birds deemed beneficial to humans, "good neighbors," consuming seeds of some of the weediest weeds: ragweed, lamb's quarters, crab grass, knotweed, pigweed, and even Phragmites.  One very old account estimated that American Tree Sparrows consumed 875 tons of weed seeds over the course of a winter in Iowa alone.  In the early part of the twentieth century, much was made of the value of tree sparrows to farmers because of the "vast quantities of obnoxious weed seeds" the bird consumed.  The contributor to the American Tree Sparrow section in Bent's Life Histories series went into some detail on this point, then concluded, "In the summer the tree sparrow is of no economic significance, as it nests beyond the reaches of civilization."  She quickly redeems herself by adding, "But whether or not we can evaluate the species in cold dollars and cents, it will always be welcome as a gentle, cheerful little creature in our winter fields and gardens."

With their chestnut caps, tree sparrows resemble Chipping Sparrows (S. passerina), and are sometimes called "winter chippies," but at least here in Michigan it is not too often that these two species are in the same place at the same time. Chipping Sparrows depart south for winter as tree sparrows arrive, and return north as tree sparrows are heading back to Canada.

American Tree Sparrows are fairly well known for their fidelity to wintering sites, but much of the literature on the subject is old, and studies were in less-developed areas, which could be more appealing to the birds.  How faithful might they be to an urban bird feeder, especially given the option of many other feeders in the vicinity?

I started banding this species in my back yard the winter of 1997-98.  This is admittedly not a very high-volume effort -- we are able to attempt to catch birds only on weekends with decent weather. Still, I've banded over a hundred tree sparrows, and 17% have returned in subsequent years, some for three to five years in a row.  Considering that the majority of small songbirds, in particular migratory species, don't live two years, that seems pretty remarkable.  I think the rate would be higher, except the last few years my husband and I have had less time to band in the yard, and there have been fewer tree sparrows around.

Some authors have hinted populations of tree sparrows may be slipping. Due to the remoteness of their nesting areas, population trends can be difficult to accurately discern, and are based primarily on winter bird counts here in the U.S.  One of those counts is Cornell's Project FeederWatch, which noted a shift in the areas where tree sparrows spent the winter, (as shown in this series of maps) as opposed to a true decline.  My own long-term winter surveys show a 95% decline from 1993-2004, but habitat at my site has been maturing, so it may not be as attractive to tree sparrows as it used to be.  I've also done analyses on a couple of local Christmas Bird Counts; they also show declines. But over the 30 years of those counts, the count circles have undergone extensive development, and there is less sparrow habitat available.

Which of these factors -- shifts in distribution, habitat change, or habitat destruction -- is causing the apparent declines in tree sparrow numbers?  Or is climate change playing a role, causing them to stay further north in winter, or impacting food resources on the nesting grounds?  Is it a combination of these factors? Or are populations actually stable?

Audubon knew these birds as "Canada Buntings," and referred to them as "sweet little creatures." I look forward to the return of these hardy souls, so charming and unassuming, such heroic exterminators of malicious weeds. 

calls like clear sweet bells
flock of graceful tree sparrows
enlivens winter

Comments

[Clare]

Wonderful post about a wonderful bird. Sure wished they bred just a little farther north, "beyond the reaches of civilization"

[Tom Andersen]

Very nice essay. I've never had tree sparrows at my feeder here in NY, even though we have a small amount of field and transitional field habitat, and in fact I rarely see them elsewhere either. But their relative rarity makes it a treat when I do.

Add Connecticut warbler to the list of misnamed birds...

[Cindy]

Fantastic account of one of my fav. sparrows- I find it amazing that you've banded them for 3-5 years in a row.. long live the American Tree Sparrow!

[Rurality]

Several years ago (when we had more time on our hands) one visited a golf course in north Alabama, and we drove up to see it. It's still the only one I've ever seen!

[green LA girl]

This is so cute! My fave bird's the puffin -- Too bad I've never seen them in their natural habitat :(

[Michael]

American Tree Sparrows arrived at our feeder here in southern Ontario on October 21. Among the granivores they joined were a trio of lingering White-throated Sparrows and several dozen juncos. After reading your notes on the impact of Tree Sparrows of seed mast, I wondered about seed consumption by juncos, a species I've enjoyed observing on breeding territories across the boreal forest in Canada.

Last winter, I had the chance to observe wintering flocks of juncos in the Chihuahuan desert of New Mexico. Daily, I watched wind-buffeted flocks of hundreds pausing to forage on fallen seeds along rocky slopes spanning hundreds of metres of elevation. Two things surprised me. The first was their relative abundance; they easily outnumbered all resident and wintering passerines combined. The second was the degree to which these birds seemed so "at home" in a desert habitat so different from that they breed in.

I'm aware of studies on seed predation and plant recruitment as mediated by desert rodents and ants. I wonder how these compare to that caused by sparrows/juncos...

[Tiffany Walter]

I am almost positive that yesterday while walking from the bus stop I found a tree sparrow on the ground. When looking closer I found that it's eye was all bloody and woozing. I quickly came back with a kleenex box and some tissue and picked it up. I called the local animal services and when they came to pick it up they said they would put it down... which I thought it had a pretty good chance of surviving and so i declined for them to take it.

Now I have been giving it water through a bottle dropper and was told to feed it worms, as it is still fairly little, but it nolonger had all its baby feathers. The animal services said it was roughly an adolescent.

I am just curious as to what i can do to help it along, as it looks as if its probably lost an eye, and will not be able to survive in the wild again, I am happy to keep it and take care of it. When looking at it closer though I realized that it has a bald rim around its neck and wondered if this is normal.

Do you have any suggestions for feeding it? Someone told me to mush up worms and peanut butter and feed it through a bottle dropper.
Also is there anything I can do about the eye? I don't want it to get infected.

Thank you

[Nuthatch]

This species is now nesting in the tundra, so it is not what you found on the street. There is a good reason animal services told you they would put it down -- it is going to die and you are currently prolonging its suffering by feeding it an incorrect diet, to say the least. Further, unless it's a house sparrow, which is not native, it is illegal for you to possess it. Sorry to sound harsh, but I answer DOZENS of letters like yours every year, and every single person manages to kill birds, however well-intentioned. Let the bird be humanely euthanized rather than killed with kindness.