Driving around the Island recently, one is likely to encounter flocks of American robins. They seem a little more conspicuous at this time of year since, other than starlings, there are few flocks of anything around.

At this time of year the robins are eating fruit and seeds, so places with crab apples, bittersweet berries, juniper berries, etc., are good places to find them. Often they will concentrate in an area until nearly all the food is gone and then move on after a day or two.

This brings me to a phenomenon that seems to happen every year. As is well known, the birds that are here in the spring and summer leave in the fall and are replaced by other robins that nest farther north — much farther north in some cases. The birds we have here in winter probably come from as far as Newfoundland and northern Quebec while the birds we have in summer are now enjoying the relatively balmy weather of the Gulf Coast.

What often happens is that many northern birds begin the winter on Cape Cod. The numbers found there on the Christmas Bird Count can be very large. In one recent year, more than 50,000 were found in one single count area. But by late January, most of the food there is gone so the birds look farther afield.

The Vineyard received relatively little snow this year in comparison to that on the rest of eastern Massachusetts and also less than the Cape. Wintering robin flocks were not particularly large here to start with, so there is plenty of food left.

Thus when food gets scarce on the Cape, birds there make the comparatively short flight to the Island to find more. All of a sudden we get an influx of birds that were not seen before, but from the north, not the south.

The arrival of these birds, unfortunately, does not mean an early spring. If the winter continues cold and severe, the food supply here also may run out. Robins are strong fliers, so it is not a stretch for them to leave here in the morning and be in central Connecticut or on Long Island by the end of the day. In two days, they can be in southern New Jersey.

The American Ornithologists’ Union publishes the bible of bird nomenclature for North America, the union’s Checklist of North American Birds, reflecting the current thinking of professional ornithologists about the correct English and scientific names of our birds. The checklist comes out about every 15 to 20 years or so. The last two editions in 1983 and 1998 treated only the birds at the species level, in part because there was so much disagreement at the time about the taxonomy of the subspecies listed in the 1957 edition. But it has been announced that the next edition will discuss subspecies again.

This is important in the minds of many. Because evolution is a dynamic process, the subspecies of today may be the species of tomorrow. A great deal of work has been done since the 1957 edition using new tools such as DNA and isotope research, and much better distributional information is now available than existed in 1957.

The scientific name of the robin is Turdus migratorius. One of the subspecies of the robin included in the 1957 checklist was Turdus migratorius nigrideus, sometimes known as the black-backed robin. This race spends its summers primarily in Newfoundland and northern Quebec. The backs of males, especially, are nearly jet black from the base of the neck almost to the base of the tail. The breast also tends to be a deeper, richer rusty than our summer birds.

Though this race is seldom seen here, it has been found and is worth looking for among the flocks of robins here in winter or in the northbound flocks that often spread out over open fields in March and April. Even among some of our common birds, there is often something interesting to be aware of if one takes the time.

Bird sightings

Maybe most of the Island’s observers are staying indoors or perhaps still getting over the Christmas Bird Count, but few sightings reported in the last week or so.

By far the most exceptional bird here this month was the juvenile male summer tanager that appeared at a Lambert’s Cove feeder Jan. 17 and remained until Jan. 23 when it still appeared to be in good health. This is the first known winter record of this species ever in Massachusetts, and fortunately was documented by a photograph.

The snowy owl at Cape Pogue was still there Jan. 10 and presumably is still around, as are a couple of small flocks of snow buntings along the beaches there and on Norton Point. Off Wasque Point, the usual show of thousands of long-tailed ducks, common eiders and all three species of scoters continues.

Turkey vultures are patrolling the beaches of Chappaquiddick looking for bird or seal carcasses washed up on the beach. Off Gay Head, there are at least 5,000 common eiders and a combined total of 3,000 or so scoters of all three species, mostly black scoters. King eiders often winter among scoters, so it is worth spending the time to look through the flocks for this rarer sea duck. On Tuesday, nearly 50 razorbills and a single common murre were in the ocean just off the cliffs.

The recent snowstorm forced many small birds back into feeding stations from which they had drifted away during the prior warmer weather. Feeders in Chilmark produced several field sparrows, a chipping sparrow, many dark-eyed juncos, white-throated sparrows, a fox sparrow or two, and a brown-headed cowbird that had not been in the area before. Trudy Carter still has a common redpoll at her feeder in Edgartown, and a merlin cruised through Matt Pelikan’s yard last Sunday.

At Squibnocket, a dozen or so harlequin ducks can be seen from the parking lot and three female common mergansers, in recent years a much scarcer duck than in the past, have been frequenting the cove in company with both hooded and a few red-breasted mergansers.

The usual complement of waterfowl continues at the pond at the Head of the Lagoon. On a recent day there were the same three American coots, a dozen handsome ring-necked ducks, 10 American wigeons, and, sitting on the ice with other gulls, a first winter lesser black-backed gull. Rob Culbert found a northern shoveler in the little cove at Maciel Marine in Vineyard Haven on Jan. 23, the first this year.

At East Chop, several flocks of up to 15 to 20 common goldeneyes have been feeding fairly close to shore. As reported last week, a sub-adult male Barrow’s goldeneye has been found there intermittently and at least one female Barrow’s was there Tuesday. Several hundred long-tailed ducks, surf scoters and common eiders are also often present and easily viewed from this vantage point.

Make sure to put out a little extra feed for the small birds if a snowstorm is predicted. A birdbath filled with water will attract lots of birds at a season when most ponds and many streams are tight with ice; many hardware stores offer heaters that will keep your birdbath from freezing. Be sure to call your observations in to the bird hot line at 508-627-4922 so we all can stay informed about the birds here.