Have you noticed any change in the birds at your feeders? Many of our summer residents have migrated south, while winter visitors are now arriving and will fill the now available niches. My favorite example of this can be seen with two sparrows: Chipping Sparrow and American Tree Sparrow.
Here is a chart, generated using the Explore features in eBird, showing Chipping and American Tree Sparrow frequency throughout the year. Using citizen science data, we can see that Chipping Sparrows are present in the summer (April through November) and are essentially replaced by American Tree Sparrows in the winter (October through May).
Most sparrow species are hard to identify, especially for beginners, but this is a good pair to begin with because they are common at your feeders and not likely to be confused with each other when you factor in the date. Here are a few important field marks to look for:
Chipping Sparrow is the perfect example of a spizella sparrow. Don’t roll your eyes at latin names, they are a very helpful tool in learning families (actually genera, in this case) of birds. Spizella sparrows all tend to be long and thin, making them smaller than the other sparrows we see. They also all have clear, unstreaked breasts. Other features are more variable: Chipping tend to show very rich red caps, especially in summer, but other species (Swamp Sparrow) can show this as well.
American Tree Sparrows are superficially similar to Chipping Sparrows, and are currently considered spizella sparrows (though this is probably changing soon following recent genetic work), but have some key differences: they are slightly heftier – hopefully, since they are arctic breeders (a loose example of Bergmann’s Rule). They also look much grayer in the face. But my favorite field mark is their bicolored bill. Their mandible is yellow, and maxilla is very dark, almost black. American Tree Sparrows do show dark spots on their chest, while Chipping tend to be clear, but ALL SPARROWS CAN SHOW A DARK SPOT ON THEIR CHEST. A very important thing to remember with sparrows.
Keep an eye out for these birds at your feeders!
A Maine native, Doug grew up in Hollis and graduated from the University of Maine in 2011. Throughout college Doug worked at Scarborough Marsh Audubon Center and was hired as Maine Audubon’s staff naturalist in the summer of 2013, a long time “dream job.” In his free time, Doug volunteers as one of Maine’s eBird reviewers, is the owner and moderator of the ‘Maine-birds’ listserv and serves as York County Audubon board member and Secretary of the Maine Bird Records Committee.