OF all the nearly eight hundred species of North American birds, the robin is without question the one most generally known. Its great commonness and wide distribution have something to do with this fact, but can hardly be said to account for it altogether. The red-eyed vireo has almost as extensive a range, and at least in New England is possibly more numerous; but except among ornithologists it remains a stranger, even to country-bred people. The robin owes its universal recognition partly to its size and perfectly distinctive dress, partly to its early arrival in the spring, but especially to the nature of its nesting and feeding habits, which bring it constantly under every one’s eye.

It would seem impossible, at this late day, to say anything new about so familiar a bird; but the robin has one interesting and remarkable habit, to which there is no allusion in any of our systematic ornithological treatises, so far as I am aware, although many individual observers must have taken notice of it. I mean the habit of roosting at night in large flocks, while still on its breeding grounds, and long before the close of the breeding season.¹

Toward the end of summer, two years ago, I saw what looked like a daily passage back and forth of small companies of robins. A friend, living in another town, had noticed similar occurrences, and more than once we discussed the subject; agreeing that such movements were probably not connected in any way with the grand southward migration, which, so far as we could judge, had not yet commenced, but that the birds must be flying to and from some nightly resort. The flocks were small, however, and neither of us suspected the full significance of what we had seen.

On the 19th of July, 1889, the same friend informed me that one of our Cambridge ornithologists had found a robin roosts in that city, — a wood in which great numbers of birds congregated every night. This led me to keep a sharper eye upon my own robins, whom I had already noticed repeating their previous year’s manoeuvres. Every evening, shortly before and after sunset, they were to be seen flying, now singly, now by twos and threes, or even by the half dozen, evidently on their way to some rendezvous. I was suspicious of a rather distant hill-top covered with pine-trees; but before I could make it convenient to visit the place at the proper hour, I discovered, quite unexpectedly, chat the roost was close by the very road up and down which I had been walking; an isolate piece of swampy wood, a few acres in extent, mostly a dense growth of gray birches and swamp white oaks, but with a sprinkling of maples and other deciduous trees. It is bounded on the further side by a wet meadow, and at the eastern end by a little ice-pond, with a dwelling-house and other buildings beside it, all within a stone’s throw of the wood.

This discovery was made on the evening of July 25th, and I at once crossed a narrow field between the wood and the highway, and pushed in after the birds. It was too dark for me to see what was going on, but as I brushed against the close branches the robins set up a lively cackling, and presently commenced flying from tree to tree before me as I advanced, though plainly with no intention of deserting their quarters. The place was full of them, but I could form no estimate of their number.

On the following evening I took my stand upon a little knoll commanding the western end of the wood. According to my notes, the birds began to arrive about sunset, — but this was pretty certainly an error, — and though I did not undertake an exact counts until the flight was mainly over, it seemed likely that at least three hundred passed in at that point.. This would have made the total number twelve hundred, or thereabout, on the assumption that my outlook had covered a quarter of the circuit. After the flight ceased I went into the wood, and from the commotion overhead it was impossible not to believe that such a calculation must be well within the truth.

The next day was rainy, but on the evening of the 28th I stood by the shore of the pond, on the eastern side of the wood, and made as accurate a count as possible of the arrivals at that point. Unfortunately I was too late; the robins were already coming. But in fifty minutes, between 6.40 and 7.30, I counted 1072 birds. They appeared singly and in small flocks, and it was out of the question for me to make sure of them all; while I was busy with a flock on the right, there was no telling how many might be passing in on the left. If my observations comprehended a quarter of the circle, and if the influx was equally great on the other sides (an assumption afterward disproved), then it was safe to set the whole number of birds at five thousand or more. Of the 1072 actually seen, 797 came before the sunset gun was fired, — a proportion somewhat larger than it would have been had the sky been clear.

On the afternoon of the 29th I again counted the arrivals at the eastern end; but though I set out, as I thought, in good season, I found myself once more behind time. At 6.30 robins were already dropping in, notwithstanding the sky was cloudless. In the first five minutes eighteen birds appeared; at sunset 818 had been counted; and at 7.30, when I came away, the figures stood at 1267. “The robins came more rapidly than last night,” I wrote in my notebook, “and for much of the time I could keep watch of the southeastern corner only. My vision then covered much less than a quarter of the circuit; so that if the birds came as freely from other directions, at least five thousand must have entered the wood between 6.30 and 7.30. As long as it was light they avoided passing directly by me, going generally to the left, and slipping into the roost behind some low outlying trees; though, fortunately, in doing this they were compelled to cross a narrow patch of the illuminated western sky. I suspect that the number increases from night to night. Between 6.40 and 7.30, 1235 birds came, as compared with 1072 last evening.”

Two days afterward (July 31st) I went to the western end of the wood, and found the influx there much smaller than on the opposite side; but I arrived late, and made a partial count only. After sunset 186 birds were seen, whereas there had been 455 entries at the eastern end, two nights before, during the same time.

Thus far I had always been too late to witness the beginning of the flight. On the evening of August 1st I resolved to be in season. I reached the border of the pond at 5.15, and at that very moment a single robin flew into the wood. No others were seen for eighteen minutes, when three arrived together. From this time stragglers continued to appear, and at 6.30 I had counted 176. In the next ten minutes 180 arrived; in the next five minutes, 138. Between 6.45 and 7, I counted 549; then, in six minutes, 217 appeared. At 7.25, when I concluded, the figures stood at 1533 birds. For about twenty minutes, as will be noticed, the arrivals were at the rate of thirty-six a minute. Throughout the thickest of the flight I could keep a lookout upon only one side of me, and, moreover, the gathering darkness was by that time making it more and more difficult to see any birds except such as passed above the dark tree line; and from what went on just about me, it was evident that the number of arrivals was increasing rather than diminishing as my count fell off. There seemed to be no good reason for doubting that at least two thousand robins entered the wood at the eastern end.

Two nights later I stationed myself in the meadow southwest of the roost. Here I counted but 935 entries. The movement appeared to be fully as steady as on the opposite side, but as darkness came on I found myself at a great disadvantage; a hill occupied the background, giving me no illuminated sky to bring the birds into relief, so that I could see only such as passed close at hand. Of the 935 birds, 761 came before seven o’clock, but it was reasonably certain that the flight afterward was nearly or quite as great, only that I wanted light wherewith to see it.

On the evening of August 4th I went back to the eastern end, and as the sky was perfectly clear I hoped to make a gain upon all my previous figures. But the fair weather was perhaps a hindrance rather than a help; for the robins came later than before, and more in a body, and continued to arrive long after it was impossible to see them. I counted 1480, — 53 less than on the 1st.

I attempted no further enumeration until the 18th. Then, in an hour and ten minutes, 1203 birds were seen to enter the roost at the eastern end. But they arrived more than ever in flocks, and so late that for much of the time I missed all except the comparatively small number that passed in my immediate vicinity. Many were flying at a great height, — having come from a long distance, as I inferred, — and sometimes I knew nothing of their approach till they dropped out of the sky directly over the wood. On this occasion, as well as on many others, — but chiefly during the latter part of the season, — it was noticeable that some of the robins appeared to be ignorant of the precise whereabouts of the roost; they flew past it at first, and then, after more or less circling about, with loud cackling, dived hurriedly into the wood. I took special note of one fellow, who came from the south at a great altitude, and went directly over the wood. When he was well past it he suddenly pulled himself up, as if fancying he had caught a signal. After a moment of hesitation he proceeded on his northerly course, but had not gone far before he met half a dozen birds flying south. Perhaps he asked them the way. At all events, he wheeled about and joined them, and in half a minute was safe in port. He had heard of the roost, apparently (how and where?), but had not before visited it.

This count of August 18th was the last for nearly a month, but I find a minute of August 27th stating that, while walking along the highway on the westerly side of the roost, — the side that had always been the least populous, —I saw within less than two minutes (as I calculated the time) more than eighty robins flying toward the wood. Up to this date, then, there could not have been any considerable falling off in the size of the gathering. Indeed, from my friend’s observations upon the Belmont roost, to be mentioned later, it seems well-nigh certain that it was still upon the increase.

Toward the close of August I became interested in the late singing of several whippoorwills, and so was taken away from the robins’ haunt at the hour of sunset. Then, from the 5th to the 13th of September, I was absent from home. On the night of my return I went to the shore of the pond, where, on the 1st of August, I had counted 1533 entries. The weather was favorable, and I arrived in good season and remained till the stars came out, but I counted only 137 robins! It was plain that the great majority of the congregation had departed.

As I have said, there was little to be learned by going into the wood after the robins were assembled. Nevertheless I used frequently to intrude upon them, especially as friends or neighbors, who had heard of my “discovery,” were desirous to see the show. The prodigious cackling and rustling overhead seemed to make a deep impression upon all such visitors, while, for myself, I should have had no difficulty in crediting the statement had I been told that ten thousand robins were in the treetops. One night I took two friends to the place after it was really dark. All was silent as we felt our way among the trees, till, suddenly, one of the trio struck a match and kindled a blaze of dry twigs. The smoke and flame speedily waked the sleepers; but even then they manifested no disposition to be driven out.

For curiosity’s sake, I paid one early morning visit to the roost, on the 30th of July. It would be worth while, I thought, to see how much music so large a chorus would make, as well as to note the manner of its dispersion. To tell the truth, I hoped for something spectacular, — a grand burst of melody, and then a pouring forth of a dense, uncountable army of robins. I arrived about 3.40 (it was still hardly light enough to show the face of the watch), and found everything quiet. Pretty soon the robins commenced cackling. At 3.45 a song sparrow sang, and at the same moment I saw a robin fly out of the wood. Five minutes later a robin sang; at 3.55 another one flew past me; at four o’clock a few of the birds were in song, but the effect was not in any way peculiar, — very much as if two or three had been singing in the ordinary manner. They dispersed precisely as I had seen them gather: now a single bird, now two or three, now six, or even ten. A casual passer along the road would have remarked nothing out of the common course. They flew low, — not as if they were starting upon any prolonged flight, — and a goodly number alighted for a little in the field where I was standing. Shortly before sunrise I went into the wood and found it deserted. The robin is one of our noisiest birds. Who would have believed that an assembly of thousands could break up so quietly? Their behavior in this regard may possibly have been influenced by prudential considerations. I have said that many of them seemingly took pains to approach the roost indirectly and under cover. On the westerly side, for example, they almost invariably followed a line of bushes and trees which runs toward the roost along the edge of the meadow, even though they were obliged sharply to alter their course in so doing.

All this time I had been in correspondence with my friend before referred to, who was studying a similar roost,² — in Belmont, — which proved to be more populous than mine, as was to be expected, perhaps, the surrounding country being less generally wooded. It was a mile or more from his house, which was so situated that he could sit upon his piazza in the evening and watch the birds streaming past. On the 11th of August he counted here 556 robins, of which 336 passed within five minutes. On the 28th he counted 1180, of which 456 passed within five minutes, — ninety-one a minute! On the 2d of September, from a knoll nearer the roost, he counted 1883 entries.

This gathering, like the one in Melrose, was greatly depleted by the middle of September. “Only 109 robins flew over the place to-night,” my correspondent wrote on the 25th, “against 538 September 4th, 838 August 30th, and 1180 August 28th.” Two evenings later (September 27th) he went to the neighborhood of the roost, and counted 251 birds, — instead of 1883 on the 2d. Even so late as October 9th, however, the wood was not entirely deserted. During the last month or so of its occupancy, the number of the birds was apparently subject to sudden and wide fluctuations, and it seemed not unlikely that travelers from the north were making a temporary use of the well-known resort. It would not be surprising if the same were found to be true in the spring. In April, 1890, I saw some things which pointed, as I thought, in this direction, but I was then too closely occupied to follow the matter.

How early in the season does this nightly flocking begin? This question often presented itself. It was only the middle of July when the Cambridge roost was found in full operation, though at that time many robins must still have had family duties, and some were probably building new nests. Next summer, we said, we would try to mark the beginnings of the congregation.

My own plans to this end came near being thwarted. In December I was dismayed to see the owner of the wood cutting it down. Happily some kind power stayed his hand when not more than a third of the mischief was done, and on the 29th of June, 1890, while strolling homeward along the highway, listening to the distant song of a veery, I noticed within five or ten minutes seventeen robins making toward the old rendezvous.

On the following evening I stood beside the ice-pond and saw one hundred and ninety-two robins enter the wood. The flight had begun before my arrival, and was not entirely over when I came away. Evidently several hundreds of the birds were already passing their nights in company. In my ignorance, I was surprised at the early date; but when I communicated my discovery to the Belmont observer, he replied at once that he had noticed a movement of the same kind on the 11th of June. The birds, about a dozen, were seen passing his house.

Thinking over the matter, I began to ask myself — though I hesitate about making such a confession — whether it might not be the adult males who thus unseasonably went off to bed in a crowd, leaving their mates to care for eggs and little ones. At this very moment, as it happened, I was watching with lively sympathy the incessant activities of a female humming-bird, who appeared to be bringing up a family (two very hungry nestlings), with no husband to lift a finger for her assistance; and the sight, as I fear, put me into a cynical mood. Male robins were probably like males in general, — lovers of clubs and shirkers of home duties. Indeed, a friend who went into the roost with me, one evening, remarked upon the continual cackling in the treetops as “a very social sound;” and upon my saying something about a sewing circle, he answered, quite seriously, “No, it is rather like a gentleman’s club.” But it would have been unscientific, as well as unchristian, to entertain an hypothesis like this without putting its soundness to some kind of test. I adopted the only plan that occurred to me, — short of rising at half past two o’clock in the morning to see the birds disperse. I entered the wood just before the assemblage was due (this was on the 9th of July), and took a sheltered position on the eastern edge, where, as the robins flew by me, or alighted temporarily in the trees just across the brook, they would have the sunlight upon their breasts. Here, as often as one came sufficiently near and in a sufficiently favorable light, I noted whether it was an adult, or a streaked, spotted bird of the present season. As a matter of course, the number concerning which this point could be positively determined under such conditions was very small, — only fifty-seven altogether. Of these, forty-nine were surely birds of the present summer, and only eight unmistakable adult males. If any adult females came in, they passed among the unidentified and uncounted.³ I was glad I had made the test. As a kind-hearted cynic (I confess to being nothing worse than this), I was relieved to find my misanthropic, or, to speak more exactly, my misornithic, notions ill founded. As for the sprinkling of adult males, they may have been, as a “friend and fellow woodlander” suggests, birds which, for one reason or another, had taken up with the detestable opinion that “marriage is a failure.”

During the month of July, 1890, I made frequent counts of the entries at the eastern end of the roost, thinking thus to ascertain in a general way the rate at which its population increased. On the whole, the growth proved to be fairly steady, in spite of some mysterious fluctuations, as will be seen by the following table: —

After July 6th all the enumerations were made with the help of another man, though we stood side by side, and covered no more ground than I had hitherto attempted to compass alone. The figures of the 27th were far in excess of any obtained in 1889, and for a day I was disposed to take seriously the suggestion of a friend that some other roost must have been broken up and its members turned into the Melrose gathering. But on the evening of the 28th I tried a count by myself, and made only 1517 birds! The conditions were favorable, and the robins came, as they had come the night before, in flocks, almost in continuous streams. The figures had fallen off, not because there were fewer birds, but because I was unable to count them. They were literally too many for me. The difficulties of the work, it should be explained, are greatly enhanced by the fact that at the very corner where the influx is largest none of the low-flying birds can be seen except for a second or two, as they dart across a bit of sky between the roost and an outlying wood. To secure anything like a complete census, this point must be watched continuously; and meantime birds are streaming in at the other corner and shooting over the distracted enumerator’s head, and perhaps dropping out of the sky. I conclude, therefore, not that the roost had increased in population, but that my last year’s reckoning was even more inadequate than I then supposed. Even with two pairs of eyes, it is inevitable that multitudes of birds should pass in unnoticed, especially during the latter half of the flight. I have never had an assistant or a looker-on to whom this was not perfectly apparent.

As I stood night after night watching the robins stream into this little wood,-- no better, surely, than many they had passed on their way, — I asked myself again and again what could be the motive that drew them together. The flocking of birds for a long journey, or in the winter season, is less mysterious. In times of danger and distress there is no doubt a feeling of safety in a crowd. But robins cannot be afraid of the dark. Why, then, should not each sleep upon its own feeding grounds, alone, or with a few neighbors for company, instead of flying two or three miles, more or less, twice a day, simply for the sake of passing the night in a general roost?

Such questions we must perhaps be content to ask without expecting an answer. By nature the robin is strongly gregarious, and though his present mode of existence does not permit him to live during the summer in close communities, — as marsh wrens do, for example, and some of our swallows, — his ancestral passion for society still asserts itself at nightfall. Ten or twelve years ago, when I was bird-gazing in Boston, there were sometimes a hundred robins at once about the Common and Garden, in the time of the vernal migration. By day they were scattered over the lawns; but at sunset they gathered habitually in two or three contiguous trees, not far from the Frog Pond and the Beacon Street Mall (I wonder whether the same trees are still in use for the same purpose), where, after much noise and some singing, they retired to rest, — if going to sleep in a leafless treetop can be called retiring.

Whatever the origin and reason of this roosting habit, I have no doubt that it is universal. Middlesex County birds cannot be in any respect peculiar. Whoever will keep a close eye upon the robins in his neighborhood, in July and August, will find them at sunset flocking to some general sleeping-place.

It would be interesting to know how far they travel at such times. The fact that so many hundreds were to be seen at a point more than a mile away from the Belmont roost is significant; but I am not aware that any one has yet made a study of this part of the subject. My own birds seemed to come, as a rule, by easy stages. In the long narrow valley east of the roost, where I oftenest watched their approach, they followed habitually — not invariably — a zigzag route, crossing the meadow diagonally, and for the most part alighting for a little upon a certain wooded hill, whence they took a final flight to their nightly haven, perhaps a quarter of a mile beyond. Farther down the valley, a mile or more from the roost, birds were to be seen flying toward it, but I found no place at which a general movement could be observed and large numbers counted.

As to the size of these nightly gatherings, it seems wisest not to guess; though, treating the subject in this narrative manner, I have not scrupled to mention, simply as a part of the story, some of my temporary surmises. What I am told of the Belmont wood is true also of the one in Melrose: its shape and situation are such as to make an accurate census impossible, no matter how many “enumerators” might be employed. It could be surrounded easily enough, but it would be out of the question to divide the space among the different men so that no two of them should count the same birds. At present it can only be said that the robins are numbered by thousands; in some cases, perhaps, by tens of thousands.
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¹ Mr. William Brewster has been aware of this habit for twenty-five years, but, like myself, has never seen it mentioned in print. He devotes to it a paper in The Auk for October, 1890, to which I am happy to refer readers who may wish a more thorough discussion of the matter than I have been able to give. My own paper was printed at the same time, in The Atlantic Monthly, and had been accepted by the editor before I knew of Mr. Brewster’s intention to write. References to a roost in Belmont, Mass., discovered by Mr. Brewster six years before, are frequent in the following pages.

² This roost was discovered by Mr. William Brewster, in August, 1884, as already mentioned.

³ A week later, my correspondent reported a similar state of things at the Belmont roost. “A very large proportion of the birds are spotted-breasted young of the year, but occasionally I have detected an adult male.” He examined the birds at near range, and at rest, after they had come into the roost in the earlier part of the evening.