Last week, I started a series of columns on sparrows by featuring that species of sparrow that is probably the most ubiquitous in our area — the house sparrow.
This week, I present the second species in my sparrow series — the American tree sparrow (Spizelloides arborea). This is a small species that is only found in our area during the colder portions of the calendar year. In fact, as with some other species that I have mentioned in the past, you could almost set your watch by looking for the arrival of the American tree sparrow in our area.
The Massachusetts Audubon Society has published a checklist of birds that can be found in the state, and the particular edition that I have is a paper folded into a 4-inch by 7-inch pamphlet that opens up accordion style into a 7-inch by 20-inch comprehensive list of species. This is a great resource for any bird enthusiast because it lists all birds that can be seen in the state, but only lists species that breed in the state in boldface type.
If you flip the checklist over to the passerines (the songbirds), you will find the American tree sparrow listed in regular typeface. Next to each species there is a graphic presentation that indicates the species abundance, by month of the year, with bars of varying weight. The absence of bars means that the species itself is absent at that time of year and this is exactly what happens with the tree sparrow.
By mid-April, the species is gone; headed north into Canada for the breeding season. My copy of “The Birders Handbook,” by Paul Ehrlich, et al., describes the prime breeding habitat of the American tree sparrow as, “open areas with scattered trees and brush along the tundra edge.” This is clearly nothing we have to offer here in Massachusetts, and the sparrows are willing to fly more than a thousand miles to find it.
This choice has its drawbacks. The Arctic summer is a short season during which the sun rarely sets. Birds can find enormous tracts of land with a titanic amount of food available, but the season is extremely short-lived and this means that the sparrows really only have enough time to make one attempt at nesting. Successful or not, the weather will dictate the time to flee and that seems to occur like clockwork.
The checklist indicates that American tree sparrows may arrive as early as the last week in October, but then they are only “occasionally” seen. Starting in the first half of November, their status is upgraded to “uncommon,” then “common” in the second half of November and finally “abundant” in December. This abundance lasts until the end of February and then the trend reverses until the species disappears again in mid-April.
I have a list of arrival dates for the tree sparrow, and over the past 10 years, I have personally witnessed an early arrival on Oct. 28, 2011 and a late arrival on Dec. 9, 2009. Seven of the 10 first sightings took place in November, with the average arrival date being Nov. 15. And wouldn’t you know it, the first sighting for this year was actually on Nov. 15!
The American tree sparrow is on the small side of the sparrow spectrum, but it is very easy to identify by looking for three specific “field marks.” First, and easiest, is the cinnamon-brown crown on the head. In our area, this is going to be difficult to confuse with any other species. The second mark, and second easiest to notice, is the small black spot in the center of the light gray breast. No other markings are present on the breast and this is, again, difficult to confuse with any other species.
Finally, the third field mark to look for is the two-colored beak of the species. The upper beak (the maxilla) is a graphite gray while the lower beak (the mandible) is a rich golden yellow. The birds need to be fairly close for you to see this particular feature, so don’t be upset if it takes a while to notice it.
So, as you find your head clearing from your turkey-and-stuffing hangover, consider glancing out a nearby window and searching for signs of American tree sparrows in your yard. The birds are here and I think at this point they are present everywhere in our region. Look for the gray crown of the house sparrow and the brown crown of the tree sparrow. Then, prepare yourself for yet another sparrow species next week.
Bill Danielson has been a professional writer and nature photographer for 21 years. He has worked for the National Park Service, the U.S. Forest Service and Massachusetts State Parks, and currently teaches high school biology and physics. Visit speakingofnature.com for more information, or go to Speaking of Nature on Facebook.