Nature Notes: Chipping Sparrow
Looking weary and bedraggled, the tiny bird gathered its remaining strength while staring down its adversary. When it appeared that its aggressive stance and sharp calls were inadequate to drive away the intruder, the sparrow launched another attack. The intruder mirrored the attack and the sparrow dropped back upon the pickup’s tonneau cover to rest and consider its next move.
By now you may have figured out that the battle royale in my driveway involved the small chipping sparrow shown in the photo, almost certainly a male, and his reflection in my truck window. The “fighting” had been going on for a few days and must have left the sparrow exhausted. If nothing else, it distracted him from eating caterpillars and taking some to his mate in the nest overhead in a large white oak tree. I appreciate the sparrows thinning the caterpillar population since the oak can only take so much damage to its foliage each spring.
Over the years I have observed a number of birds engaging in these intense but fruitless battles. American crows, northern cardinals, blue jays, American robins, even wild turkeys have found reason to attack our picture windows, sliding glass doors, and vehicle windows or side mirrors. American goldfinches, northern mockingbirds and ruffed grouse are also known to engage in this behavior. At times the pecking, squawking and fluttering can extend for weeks, from May into August, especially if birds attempt to raise second broods. I recall not so fondly one nasty robin who woke me several days running by starting his aggressions on my glass cabin door at very first light. In desperation I installed a piece of cardboard to keep the robin at bay.
Why would birds spend valuable energy picking fights with their own reflections? It is not because they are stupid, although their actions may appear foolish to us. During breeding seasons, birds become very territorial and surging hormone levels bring on aggression in normally placid birds. Male birds generally arrive early to establish their breeding territories. The early bird gets the best territory considering availability of food, shelter, water and the willingness of a female to set up housekeeping in that particular spot. Other males try to take over attractive territories and they will also try to sneak in to mate with the resident female. Fending off a wide range of competitors is hard work since some birds have territories measured in acres and in some species the females also engage in the behavior, chasing away other females. Much of the bird song you hear in May is from males defining and defending their territories with sound instead of physical battles, since a serious injury could be fatal for a tiny bird. But sometimes a bird just has to fight!
Most of the year the chipping sparrow is a mild-mannered, gregarious bird going about the business of finding food and surviving in a tough environment. When you are only five inches long and weigh less than one ounce, you don’t prosper by picking fights. Finding enough to eat year around and surviving long migration flights is demanding work for these lovely little birds. The chipping sparrows you see in your yard this time of year may have flown from as far south as Mexico just a few weeks ago, arriving in Maine in late April or early May. They will stay in our area until late summer or early autumn, generally leaving by October. It is reported in “Birds of Maine” by Peter Vickery that chipping sparrows were rarely seen here in winter until 1980 but may now be found here even in the coldest months, thanks to climate change and our bird feeders.
The chipping sparrow is one of the smaller sparrows, with muted brown, tan and gray coloring on most of its feathers. The most distinctive feature is a brown cap that is prominent during breeding season when it takes on a reddish-orange tint. The white eyebrow and black streak extending back from the eyes will help you in identification, as will the gray rump, white belly and light gray chest with little of the streaking seen in the more common song sparrows. The bill is short and conical, but powerful enough to crack seeds. While the chipping sparrow is classed as a songbird, Cornell Lab of Ornithology’s Birds of the World considers that a misnomer since the sparrow’s song is a one note trill with none of the musicality of its cousin the song sparrow. The call is a short, sharp “chip,” which clearly led to the name of this bird.
As happens in many bird species, researchers are uncertain as to how many sub-species there are for the chipping sparrow, known scientifically as Spizella passerina. Even though the bird is found in most of the US and Canada below the tundra regions, it has not been studied thoroughly. There are clear physical and behavioral differences among the birds we see in Maine and those you would find living in the central and western states, so it may fall to DNA testing to finally settle the matter.
The favored habitat is open woodlands, grassy clearings, neighboring shrubby cover and the edges of water bodies. Find an overgrown piece of ground, especially if it contains flowering trees that attract insects and you will likely find the chipping sparrow along with many other small birds taking advantage of the shelter and food on offer. Once the female sparrows arrive here there is no messing about – the birds pair up quickly, mate and begin preparing their nests. They may be laying eggs within two weeks since time is valuable for birds like these that commonly attempt two broods per season.
The female typically lays an average of six eggs of her own but their nests are often targeted for what is called “brood parasitism.” The much larger brown-headed cowbird seems to favor chipping sparrow nests for their nefarious deed of depositing eggs and departing. This leaves the tiny sparrow with the choice of trying to raise her own brood with a much larger cowbird chick, or abandoning the nest to start all over. Research has shown on average chipping sparrows are successful in raising just one brood each season.
In researching this bird, I was struck by the speed with which newly hatched chicks develop. In a world where helpless chicks on the nest are highly sought after by a wide range of predators, birds have evolved to take flight in very short order. While the parents are hustling to find enough food to support their young, the growth process takes place quickly. According to Birds of the World, primary feathers begin to show just two days after hatching. Body feathers begin to emerge on the fourth day and by the tenth day the juveniles are covered in unsheathed feathers. Flight is possible by the eighth day if the birds are forced to leave the nest under threat or if they happen to fall out while stretching their new wings. Soon the juveniles are foraging for themselves and building the strength to manage the coming demands of the colder months, with first breeding after one year of life.
Chipping sparrows focus on consuming seeds most of the year, foraging on or near the ground, often under cover to avoid airborne predators. During breeding season, they happily broaden their diet to include a range of insects to gain the benefit of fatty nutrients necessary to raise a family. Later in summer the birds will happily consume berries for their rich carbohydrates. The chipping sparrow has proven to be adept at living in conjunction with human development, since we favor a range of plants around our homes and offices, including conifers that offer shelter along with species that produce flower buds, insects, seeds and fruit.
The Breeding Bird Survey has found that chipping sparrow populations are generally stable across the US but that masks an ongoing decline in the western states. Years of drought has caused a significant loss of seed-producing plants and rapidly falling insect populations. Here in the eastern US, chipping sparrows seem to be doing well thanks to conservation and reforestation efforts, supplemental feeding and a warming climate that allow territorial expansion.
When I returned home from a few days fishing up north, I arrived in the driveway to find the chipping sparrow standing guard in his normal spot. Within minutes he was fluttering a valiant attack at the truck’s chrome bumper. Silly bird, I thought to myself. But the next day the attacks had ended and in the late afternoon I spotted a chunky juvenile sparrow perched on a limb with one of its parents hovering nearby. In his seminal work “Ornithology Biography” famous naturalist John James Audubon described the chipping sparrow as a “gentle and harmless little finch.” But when breeding season comes around, all bets are off!