Wild Side : Identifying sparrows is a challenge even for veteran birders
Photo courtesy of USFWS
One of the odd things about birds is that there often isn't much connection between how common a species is and how familiar people are with it. The habits of a bird can keep it largely invisible, even as it nests routinely in yards, parks, and other places frequented by humans. And small birds, especially, are simply too hard for the non-birder to see well to be widely familiar.
A good example would be the chipping sparrow. Small even for a sparrow at about five inches long, this trim little species loves the sort of semi-open habitat that yards and subdivisions represent. It's also found in natural areas, as long as they offer a mix of open space, shrubs, and tall trees. The "chippie," as birders often call it, is a numerous species here through much of the year, and even over-winters in modest numbers (our wintering population seems to be growing as the climate warms and mild winters get more regular). But chipping sparrows spend a good portion of their time concealed in tree canopies. And when they descend to the ground to feed, they are fast, active, and cryptically colored — not easy to get a good look at unless you're alert for birds and handy with binoculars.
One way to appreciate the abundance of this bird is to learn its song. Male chippies give a long, loud, trill on a single note; the sharp attack on each note within the trill gives a percussive effect and accounts for the name of this species. Males prefer to sing from a lofty perch, often the top-most twig of a good-sized oak, and they tend to sing all day long; even so, they can be hard to spot. But this trill is one you can easily pick out from the racket of spring birdsong.
Sparrow identification is never easy; as a group, these are small birds, largely brown with few notable markings, and given to skulking in thick cover. And in the fall and winter, the sheer diversity of sparrows on the Island challenges even a capable birder: almost two dozen species of sparrows grace the Vineyard checklist (if you count juncos and towhees, which are really just fancy sparrows). But the vast majority of these are either species here only during winter or migration, or species that turn up here only as rare vagrants. Come breeding season, the list narrows down to about seven regular nesting sparrow species, several of which associate closely with specific habitats like salt marsh or grassland.
So if you see a sparrow in your yard on the Vineyard during the nesting season, it's most likely either a song sparrow or a chipping sparrow. (House sparrows are common in yards but are not actually sparrows!)
Once you get a look at it, you can recognize the chipping sparrow by its clean underparts, unstriped white with some faint gray shading (song sparrows are heavily streaked on the breast); its rich chestnut cap covering the entire top of the head; and a bold, straight black line through the eye, separated from the cap by a clear white stripe. Males and females look alike; during nesting season, however, the females tend to stick very close to the nest, so most of the chippies one sees in May and June are likely males.
Chipping sparrows are versatile birds, adapting to whatever vegetation they find and therefore showing somewhat different habits in different parts of their range. On the Vineyard, they associate strongly with oaks; in spring, picking insects out of oak catkins is nearly a full-time job for a chippie, and even later in the season, it seems like oaks provide the perfect mix of caterpillars, spiders, and other arthropods for this species to harvest. Chippies are deft enough in the air to catch flying insects, and like other sparrows, they also forage in leaf litter on the ground. Arthropods make up most of their warm-season diet, though this species, like other sparrows, switches largely to a diet of seeds in the fall and winter.
But for nesting, our chippies seem to prefer shrubs offering full dense foliage for full concealment; these birds have a special fondness for red cedars. The dense and prickly foliage of this evergreen deters larger birds and mammalian predators; the nest, often built where a branch joins the trunk, can be difficult to spot until you're right next to it. Chippies build a tidy nest, made of grass and generally lined with fur or animal hair, wound neatly around the inside of the nest cup. Males will often feed their mates as they sit on the nest (and while their primary mate is industriously incubating eggs or hatchlings, the males are not above shopping around for another female to mate with).
Chipping sparrows are at their most active and obvious now, as they court and prepare to nest. Odds are there is pair close to where you live; give a listen for the distinctive song, and you'll be well on your way toward getting acquainted with these genial birds.