Wild Side: Breeding birds

Nesting grackles, cardinals, chickadees, and sparrows make a home.

A male song sparrow doing what he does best. — Matt Pelikan

As the month of May winds down, the bird breeding season peaks. Here’s a report on the nesting activity in and around our yard in Oak Bluffs.

The yard is a modest one, a scant quarter-acre just off Wing Road in one of the most suburban parts of the Island. Still, it offers resources a lot of birds find attractive. We have tall conifers of three species, a small brush pile, a bird bath, flowers that attract insects, and a meadow-like yard that supports a wealth of arthropod life. Since early winter, I’ve been putting out small quantities of shelled sunflower seeds, which multiple species of birds have been taking advantage of.

A lot of our current bird activity involves common grackles. One pair is nesting high in a red cedar, one of a row of these native trees along our rear lot line. At least two more pairs are nesting, also high up, in a row of white pines on a side lot line. Hidden in clumps of dense foliage, the nests themselves are invisible. But the adult grackles, confident of their ability to defend their nests, are not bashful about coming and going.

As I write this, all the nests appear to have chicks in them. Adults are bringing in a steady supply of food, mostly insects it appears, and carrying out an equally steady supply of what ornithologists call “fecal sacs.” These white objects are an adaptation found in many songbirds to keep a nest clean: Feces produced by the nestlings, which are really just food-processing machines in the early stages of their development, emerge wrapped in a membrane, and adult birds carry these little sacs away for disposal elsewhere. The process keeps the nests reasonably tidy, protecting the health of the nestlings and making the nest less detectable by predators.

Grackles, for some reason, insist on disposing of fecal sacs in water and will, if necessary, fly a considerable distance to do so. In this case, our grackles are lucky to have a bird bath on site, almost directly beneath the nests in the white pines. I change the water several times a day, but after each change, it is just a matter of minutes before the first fecal sac appears, bobbing like a tiny poached egg in the water. This odd behavior is not the most endearing trait of the common grackle.

While the grackles fight among themselves, with the males seemingly intent on copulating with everybody’s mate except their own, they present a unified front when a predator shows up. Crows simply avoid the area, having learned that just passing by attracts a blizzard of irate grackles as all the adults scramble to harass the intruder.

Meanwhile, song sparrows have nested in a round boxwood shrub, one of a pair that frames a walk leading to our front door. The female is sitting on eggs deep inside the bush, emerging periodically to forage and then surreptitiously working her way back into the bush. She sits very tight: I can walk or garden within a few feet of the shrub with no sign that she’s there. The male of the pair, meanwhile, is no help at all. He spends most of his time singing from one of his favored perches.

In an arborvitae right next to our deck, a pair of American robins has built a substantial nest of grass and mud. They, too, have eggs but no nestlings yet. I worry about their prospects for success with this nest, which is in a rather exposed position and is hard for the adults to reach discreetly. A local blue jay has noticed the nest and keeps trying to raid it. So far, it has encountered a brooding bird on the nest at each attempt at robbery, resulting in a horrendous barrage of robin alarm notes and, often, a physical altercation. So far the robins have repelled the invader, but sooner or later the blue jay will likely find the nest unattended and polish off whatever eggs or nestlings it contains. If this happens, the robins will probably try again, hopefully in a better-concealed location.

My little brush pile, meanwhile, a modest assemblage of pruned tree limbs, attracted the attention of a pair of northern cardinals. While a nest so low to the ground seems vulnerable to skunks and cats, the cardinals have successfully hatched two youngsters that are now out of the nest: gawky, tailless chicks constantly begging for food in a high-pitched, juvenile version of the cardinal’s “Chink!” call note. Attentive parents and aggressive in defense of their brood, these birds seem likely to bring at least one chick to maturity.

This is not to mention the chickadees, Carolina wrens, gray catbirds, Baltimore orioles, great crested flycatchers, and mourning doves that are all nesting outside the yard but in the immediate area. It’s a lively part of town, and I regard our local breeding birds as interesting and welcome neighbors.