Valentine's Day equals blackbird's return
The middle of February on Martha's Vineyard is the time for the return of flock after flock of red-winged blackbirds (Agelaius phoeniceus). This widespread species nests in virtually every wet, brushy or marshy area within its extensive range. This includes most of North America and all of Martha's Vineyard. They are abundant here during the warmer months in a diverse selection of habitats, ranging from swamps to shrubby grasslands. With such a large range and impressive population, this species is one of the best-known land birds on the continent.
A small and variable number of red-wings remain to spend the winter on the Vineyard. They are inconspicuous and reclusive as they try to survive the winter months. The last ten days of this month bring about a real and noticeable change in these birds. When, invariably utilizing southwest winds, northbound flocks of male birds arrive; the over-winterers immediately come out of their shell, so to speak. They break into song and go from hiding in the bushes to singing from the tops of trees.
Red-wings form large flocks in the winter months, sometimes made up exclusively of their own species but more often mixed with other blackbirds. Some of these flocks are staggering in size, numbering in the millions of birds. These massive flocks are found in wintering areas in the south and central U.S., usually around farms and farmland. The birds feed and roost en masse. Security in numbers seems to be the reasoning.
While these huge flocks attract predators, the chances of an individual bird getting picked off are remote, as there are millions of other choices for the raptors to make. So the survival advantage for an individual to join a flock is real and compelling. Virtually all blackbirds form flocks except during the breeding season when they partition up available habitat and protect an area from others of their kind.
Beginning next week, roving flocks of these birds can be expected to arrive on the Island every time the wind blows from the southwest quarter. The birds' biological clocks are finely honed and lengthening days trigger their northward movement. Look for these striking birds at bird feeders or around wetlands any day now.
While winter is still in charge here, it is quickly giving up control as spring approaches. The red-wings, soon followed by the larger common grackles, stand out dramatically against a leafless background. They are obvious, noisy, hungry and affirming of the seasonal nature of life at this latitude. They are proof that spring is coming.
Red-winged blackbirds are dimorphic: the males look quite different from the females. Males are a shiny black with brilliant red and yellow shoulders, females a drab, streaked brown, looking nothing like what people think red-winged blackbirds should look like.
Many people confuse them for a sparrow. A close look at both males and females at one's bird feeder will point out the similarities in size, shape, bill structure and design. Plumage characters and differences can be studied and noted at leisure at this season. The birds are hungry and tame at this season.
The reasons for dimorphism are many. Males have to hold and defend territories from other males as well as attract a mate. The bold markings help the males stand out against the background and visually identify occupied areas. Presumably the coloring and markings are attractive to females. Constant and loud song reinforces this visual cue.
Females have much more to do with nest building, egg laying and raising young than the males. They are tied to a nest and need to be as inconspicuous as possible. They are well camouflaged, in fact near invisible, when sitting on their extraordinarily well-constructed and concealed nests. If they resembled the male they would stick out and be much more easily detected by the scores of predators that target nesting birds.
Flocks of these attractive birds are about to descend upon us. They are eagerly anticipated and offer visual and audible proof that the end of winter is coming soon. They feed on a variety of seeds and will come to almost any feeder, especially if a storm hits. If you want to attract flocks, they are especially fond of millet and finely cracked corn, spread in a visible location on the ground. Get ready, here they come.
Right on the heels and sometimes arriving with red-wings are common grackles and brown-headed cowbirds. In a little over a month, the first ospreys will be returning for another breeding season. The days are getting longer fast.
Lastly, Genevieve Jacobs reports that aside from the usual suspects at her Head of the Lagoon feeder, including tufted titmice, she was visited by a large flock of common redpolls this past weekend. The birds arrived and were seemingly everywhere on the ground and feeders, and abruptly disappeared ten minutes later. She was delighted to see these handsome little Arctic-nesting land birds that occasionally grace our latitude with their presence.
Until next week - keep your eyes to the sky!
To contribute news about birding activities or sightings, call The Times Birdline, 508-693-6100, extension 33, or e-mail vernlaux@comcast.net.
