Wild Side: Spring brings the red-winged blackbird.

It’s about two weeks earlier than previously, and always welcome.

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Female red-winged blackbird. — Jim Hudgins/USFWS

The approach of spring is signaled by a host of changes: longer days, stronger sun, the onset of bird song, plants breaking dormancy. But if I had to pick only one thing that says “spring” to me, it’d be the sight of the season’s first arriving red-winged blackbird.

This is a common breeding species, and it won’t take long for me to start taking it for granted. Moreover, the thrill of the first red-wing has been tempered somewhat in recent years by the fact that the species is wintering in small numbers on the Vineyard with increasing regularity, often in association with birdfeeding stations.

But incoming migrants behave differently than overwintering individuals, singing more, perching higher, and often turning up in natural habitat. They’ve got a chip on their brightly colored shoulders that wintering birds haven’t yet acquired.

Following the first arrival, which might consist of either single birds or small flocks, and takes place sometime in February, a steady and predictable sequence of other arrivals takes place. At first, we get flocks consisting solely of males, and they’re clearly transients; they may stick around for a few days, but the first hint of warmer air or southerly winds sends them on their way.

A couple of weeks later, the first females filter in, smaller than the males and dramatically different in appearance (streaked brown birds, sparrow-like, in contrast with the glossy black adult males). These birds, too, are transients, and while they may roost in Island wetlands that will later host breeding birds, they also head northward as soon as conditions strike them as favorable.

In late March or early April, our own breeding red-wings filter in. In contrast to the migrants, which congregate happily in flocks, breeders rapidly grow pugnacious, noisily defending a territory against all comers. (If you captured and dissected a transient male and a locally breeding male, you’d find that the testes in the former are much smaller than those in the latter. Hormonally, they’re less far along with seasonal changes.)

Finally, the local nesting females arrive, appearing rather surreptitiously in breeding habitat: wetlands, especially grass and sedge meadow and cattail marsh, but also (surprisingly, for a bird one often thinks of as a swamp dweller) pasture and grassland. Females, in this species, seem to choose their mates based on the female’s opinion of territory quality. Early-arriving males get first choice of territory, and if they exercise this opportunity shrewdly, they increase their chances of being selected by a female.

Females also build the nests, while the males look on proudly, act important, and contribute nothing at all. While these birds are mainly monogamous, neither sex will pass up a chance to mate outside the pair; nature, after all, is all about hedging your bets and passing along your genes.

The nests themselves are well-constructed, deep cups woven from grasses and other fibers that are tightly bound to sedge, grass, or cattail stems. As is the case with many songbirds, a female may start multiple nests and even complete several. This habit may help confuse potential nest predators like raccoons and crows, and it may also reflect the fact birds can’t really predict how a nest will work out until they’ve nearly finished it.

Because of the vegetation types they nest in, red-winged blackbirds rarely nest far off the ground; in the case of birds breeding in pasture, the nest may be touching the ground, but it’s still firmly tied to the stems that surround it.

As I write this, we’re well along with the process. I had my first red-wing in mid-February. By the last week in the month, I was encountering small flocks here and there. And this past weekend, the swamp upstream from Sunset Lake in Oak Bluffs, adjacent to Dukes County Avenue, housed a robust gang of transients, giving the species’ distinctive “Conk-a-ree!” song and contemplating the next stage of their northward journey.

Red-wings are the quintessential omnivores, eating nearly anything they can find. Wintering birds, especially, seem to do just fine on seed. Breeding birds, which need extra protein either to produce eggs (if they are females) or to raise their fast-growing young, rely extensively on invertebrates, including snails, moths, and beetles. While they don’t do it often, I’ve seen them flap up off a perch to snag a flying insect in midair. And red-wings will happily eat small invertebrates, such as salamanders and spring peepers.

Breeding widely across North America, including most of Canada, these abundant birds are familiar to nearly everyone. As the climate warms, birds wintering at our latitude (and farther north) are getting steadily more common. And the arrival of the spring vanguard grows steadily earlier (in my 50 years birding in Massachusetts, I’d say the arrival date of this species has advanced about two weeks, on average).

Still, the pattern of arriving red-wings — advance guard, transient males, transient females, and finally our breeders — remains the same. But as familiar and predictable as this phenomenon is to me, it still somehow always catches me as a pleasant surprise.