Common Tern

The Common Tern is a medium tern which in breeding plumage has pale gray upperparts, white underparts, gray primaries, a black cap, a forked tail, red legs, and a red bill with a black tip.  Length: 12 in.  Wingspan: 30 in.

Photograph © Glenn Bartley.

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The sexes are similar.

Winter adults have a dark carpal bar, a white forehead, a black bill, dark outer primaries, and dark edges to the outer webs of the outer tail feathers.

Immature birds have brownish backs.

Common Terns inhabit inland lakes as well as coastal areas.

Common Terns eat fish, and sometimes crustaceans as well.

Common Terns forage by plunging into the water after fish.

In North America, Common Terns breed across much of southern Canada and parts of the northern and eastern U.S. They winter along coastal areas of Central and South America, and can be seen in migration across much of the U.S. The population is not well measured, but appears to be declining or stable.

More information:

Bent Life History

Visit the Bent Life History for extensive additional information on the Common Tern.

Wing Shape

The shape of a bird’s wing is often an indication of its habits and behavior. Fast flying birds have long, pointed wings. Soaring birds have long, broad wings. Different songbirds will have a slightly different wing shape. Some species look so much alike (Empidonax flycatchers) that scientists sometimes use the length of specific feathers to confirm a species’ identification.

• Adult, Washington, Aug.
• From below
• Juvenile, Washington, Sept.
• From below

Wing images from the University of Puget Sound, Slater Museum of Natural History

Male Common Terns present the female with a fish as part of a courtship ritual that also includes display flights.

Common Terns were slaughtered in the late 1800s because their feathers were used to decorate women’s hats

Common calls include a “keeyur” or a sharp “kik”.

The Common Tern’s nest is a scrape on the ground lined with plant material.

Number: Usually lay 1-3 eggs.
Color: Buffy with darker markings.

Incubation and fledging:
The young hatch at about 21-25 days, and leave the nest after several days, though they associate with the adults for some time.

Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.

Bent Life History for the Common Tern – the common name and sub-species reflect the nomenclature in use at the time the description was written.

One of the most charming features of our eastern seacoast is this graceful little “sea swallow.” The most attractive combination of summer sea, sky, and sandy beach would be but an empty, lifeless scene without the little “mackerel gull,” such a fitting accompaniment of its gentle surroundings and so suggestive of summer sunshine and cooling sea breezes. One can not help admiring such an elegant and dainty creature, its spotless and delicate plumage and its buoyant, graceful flight, as it flies listlessly up the beach until the discovery of some school of small fry, on which it feeds, causes it to pause, hover for an instant, and plunge headlong into the water for some tiny minnow.

We came near losing this beautiful bird a few years ago, because its exquisite plumage was so much in demand for feminine decoration that, before we realized it, collectors for the millinery trade had alarmingly reduced its numbers. Stringent laws, however, were passed for its protection and it has now practically regained its former abundance. The most important breeding colony in Massachusetts is on Muskeget Island, between Nantucket and Martha’s Vineyard, which has been rigidly protected for a number of years and contains the largest sea-bird colonies on the New England coast south of Maine. Mr. George H. Mackay kept very close watch over it during its most critical period, and the keeper of the life-saving station has guarded it ever since. That the terns prospered under protection is clearly shown by Mr. Mackay’s records, covering a period of five years from 1894 to 1898, inclusive, during which time they nearly doubled in number.

When Mr. ‘William Brewster first visited Muskeget in 1870 the terns were astonishingly abundant though he was told by the fishermen that they had been diminishing for years. Four years later he found their numbers sadly depleted by the depredations of fishermen who landed there regularly to collect their eggs, through June, July, and August, keeping the poor terns laying like hens, so that very few of them succeeded in raising broods. I made five visits to Muskeget in 1885, 1889, 1890, 1892, and 1903. Between my first two visits they continued to decrease in spite of the new laws enacted for their protection, but between 1890 and 1902 they increased again and are now probably as abundant as they ever were within my memory. Mr. Mackay’s record show a very satisfactory increase between 1894 and 1898. Egging operations and shooting for millinery purposes have been effectively stopped.

Muskeget Island is the largest of a group of small, low sandy islands forming a part of the southern boundary of Nantucket Sound. It is a little more than an elevated sand bar raised above the level of the numerous sand shoals so dreaded by sailors in that region, which are usually invisible at high tide, but in rough weather are white with combing breakers. A life-saving station has been established there for the rescue of unfortunate mariners. A few fishermen’s and gunners’ shanties are the only other buildings on the island. It is approximately crescent shaped, though its outline changes frequently, and is about 3 miles long and a mile wide. Several small islands near it are practically a part of it. In the central portion of the island are low rolling sand hills and small sand dunes; the beaches are mostly flat and sandy, though in some places stony. Vegetation is scarce over most of the island, consisting of a sparse growth of beach grass (Ammophila arundinaca) and a low-growing poison ivy (Rhus radicans) , with scattering patches, some of them quite extensive, of bayberry (Myrica carolinensis) and beach plum (Prunus maritima) bushes. In some places the beach grass grows tall and thick or in dense clumps or tufts. The isolation of this island, the variety of nesting sites offered, and the abundant food supply to be obtained in the adjacent shoals and tide rips make Muskeget an ideal breeding ground for common and roseate terns and laughing gulls. I know of no more extensive or interesting colony of these two terns on the American coast. A visit to Muskeget Island in June or July, the height of the breeding season, is an experience never to be forgotten. As we approach it in our little sailboat a cloud of minute white specks is seen hovering over it and the air is full of birds coming and going, for not all of this vast multitude can find food enough in the immediate vicinity; hence they wander far to the shores of Martha’s Vineyard and Cape Cod.

As we land and walk out among the sand hills the terns rise from the ground on all sides and circle about us overhead in an ever-increasing cloud. Some are darting down at our heads with harsh and grating cries of protest, others are drifting around us closely at hand. If we look up into the air we are made fairly dizzy; for as far as we can see, extending up into the deep blue sky, is a bewildering maze of whirling birds, flying in every direction and at varying heights in countless thousands. Their plaintive notes when heard singly are nearly musical, but the combined din of such a multitude of voices is almost deafening in its effect, and for days afterwards we can hear the rhythmic chorus ringing in our ears. If we shoot down one of them every voice is hushed; the silence is appalling as they come gliding in from every side in sympathetic horror to hover over their fallen companion and try to encourage him to rise again. Some observers have attributed this action to another motive – the desire to kill and remove a useless member of their society – but I have never seen any evidence to support this theory. Now is the greedy murderer’s chance, as the plume hunters have learned to their advantage, for as fast as the terns are shot down others will hurry in, and, as if at a given signal, all will burst out again into an excited chorus of angry cries of protest, hovering over and darting down at their dead companions in confusion and despair; but if no more are shot they seem soon to forget, the crowd gradually disperses and all goes on as if nothing had happened. Perhaps a marsh hawk may appear upon the scene quartering over the low ground in search of mice. The din suddenly ceases, every voice is still; the silence is so striking that we look up to see the cause, as thousands of white wings are diving after him in an angry mob, and he is forced to beat a hasty retreat, leaving the terns free to renew their attacks on us.

Spring: The terns arrive at Muskeget usually about the 8th or 10th of May, but sometimes as early as the 1st, their time of arrival depending somewhat on the weather conditions prevailing at the time, mild weather with strong southwest wind being favorable for their migration, and cold northerly winds retarding it. When first seen they are usually flying high in the air in small numbers, but they soon settle down onto the island as their numbers increase. Courtship: Soon after their arrival they may be seen indulging in their simple courtship performances. Gathered in a small party on the beach, resting and sunning themselves, the male begins strutting about before and around the females. His neck is stretched upwards to its fullest extent with his bill pointing to the sky, his chest is thrown out, and his tail is held at a steep angle as he waddles about on his short legs. Soon he flies away and brings his lady love a peace offering, a sand eel, curving in a circle around his bill like an engagement ring. As he struts around her with it she seems to beg for it with open mouth, waddling up to him with half raised wings. Finally he offers it to her and she accepts it; perhaps they pass it back and forth again before she swallows it; but at length the conjugal pack seems sealed and they fly away. Sometimes this little ceremony is interrupted by the arrival of a second male with another sand eel which he offers to the same female. She seems willing to accept the offering from either suitor until a fight ensues and one of the males is driven away.

Nesting: Nest building for the common tern is not an elaborate operation, for many of them build no nest at all, merely excavating a slight hollow in the sand or on a pebbly beach. The windrows of seaweed or dry eelgrass, just above high-water mark, are favorite nesting sites, and here the bird makes a small cavity by beating down the soft mass with a circular movement of its body. On Muskeget Island nests are scattered every where over the sand hills, among the beach grass or ivy, along the higher portions of the beaches, about pieces of driftwood and in entirely open situations. Generally some nesting material is brought in – seaweed, grasses, bits of twigs, and other rubbish. These the bird molds into a circular hollow with its body, and in this way elaborate nests are sometimes built, but they always harmonize with their surroundings.

The first eggs are laid on Muskeget between the middle and end of May, the date of laying being more dependent on the weather than on the date of the arrival of the terns. Comparatively few eggs are laid in May, the greater portion being laid during the first two weeks in June and plenty of fresh eggs may be found up to the Fourth of July. Formerly, when much disturbed, egg laying was prolonged through August, but now only a few belated sets are to be found in that month. One egg is laid each day until the set is complete, which normally consists of three eggs, often four, sometimes five, and very rarely six. Frequently, sets of four, and usually the larger sets, show evidence of having been laid by two birds, either by marked difference in color, shape, or size, or by different degrees of incubation. Many eggs are dropped indiscriminately anywhere, probably by birds unable to reach their nests in time, and left to bleach in the sun. Such eggs are often broken, as if dropped by birds in the air.

On the islands near Penobscot Bay, Maine, which are mostly high and rocky or covered with grass, I have examined a number of small breeding colonies of common terns. The nests were on the higher portions of the islands in open situations, either on bare rocky or stony ground or in the short grass, frequently near or even on pieces of driftwood or bunches of seaweed. They were merely slight hollows in the ground, carelessly lined with bits of straw, grass, or rubbish. Once I saw a broken sea-urchin’s shell half inclosing one of the eggs. There are numerous small and several large breeding colonies scattered along the New England coast where the terns adapt their nest building to the conditions existing. These are almost invariably on islands, and generally on small islands, which are inaccessible to predatory animals. Notable among these are Penikese and Weepecket Islands, south of Buzzards Bay, Massachusetts, where both the common and roseate terns breed in large numbers, nesting among the stones and rocks on the beaches or on the grassy uplands. Occasionally a nest is found lined with small stones, as if collected for that purpose. On Cobb’s Island, Virginia, and on the adjacent islands, we found a few small colonies of common terns, nesting on the beaches with the gull-billed terns and black skimmers, and on drift seaweed in the marshes. Mr. B. S. Bowdish (1910) mentions a colony of 250 common terns breeding on Royal Shoals, a low sand spit on the coast of North Carolina, together with least terns, black skimmers, and laughing gulls. The most southern breeding colony I have ever seen was in the Breton Island reservation off the coast of Louisiana, a small colony of about 25 pairs on Battledore Island scattered among the large breeding colonies of laughing gulls and black skimmers.

In Lake Winnipegosis we found a number of large colonies, on small rocky or stony islands, breeding in company with ring-billed gulls, double-crested cormorants, and white pelicans. Some of these colonies contained over 1,000 pairs of terns, nesting in dense groups on the pebbly beaches. Often the nests were not over 2 or 3 feet apart and often within that distance of the gulls’ nests.

Eggs: The eggs of the common tern vary in shape from ovate or short ovate to elongate ovate. The ground color varies from “pale buff” or “olive buff” in the lightest eggs to shades of “wood brown,” “cinnamon,” or “Isabella color” in the darkest eggs. I have one egg in my collection which is ” pale turquoise green ~~óa rare type of coloration. There is a great diversity of color patterns in the markings, but most of the eggs are quite heavily spotted with various shades of dark brown and drab, “hair brown,” “Vandyke brown,” “seal brown,” or “clove brown.” Some eggs are sparingly spotted and others quite densely covered with small spots or dots; some are boldly marked with large blotches of dark colors or heavily splashed with lighter shades; many have underlying splashes or blotches of” olive gray” or ” lilac gray,” producing handsome effects. The measurements of 82 eggs, in the United States National Museum, average 41.5 by 30 millimeters; the eggs showing the four extremes measure 45 by 31.5, 44 by 32.5, 35.5 by 28.5 and 41 by 27.5 millimeters.

Young: I believe that only one brood is normally raised in a season, although it frequently happens that the first set of eggs or young is destroyed, making a second attempt necessary; but Prof. Lynds Jones (1906), who has made a careful study of this species, has produced some evidence to indicate that two broods are often raised. It does not seem to me, however, that his evidence is conclusive. He has worked out the period of incubation as 21 days and has given a very accurate account of the development of the embryo. I can hardly spare the space to quote from his excellent paper on the subject as freely as it deserves, but the following two passages are well worth repeating:

Both male and female take regular turns sitting, but my observations Indicate that the female spends more time on the nest than the male. In the cases studied, a bird, later found to be the female, approached the nest abruptly and settled upon the eggs without any preliminaries. She remained quiet 40 minutes, when she uttered a peculiar call, which was repeated at short intervals, until a bird separated Itself from the hovering cloud or company at the water’s edge, when she stood up, took a few steps, and flew away. The male alighted on the sand several rods to leeward of the nest and approached it gradually, simulated feeding, and called loudly at intervals. When he reached the nest he merely stood over the eggs to protect them from the scorching rays of the sun and kept calling at intervals. In 20 minutes he became more restless, called more frequently, and soon ran some distance to windward of the nest and took wing. Within a few minutes the female alighted on the sand near the nest and went abruptly to It and settled upon the eggs. This maneuver was repeated many times, with slight modifications.

How do the old birds recognize their own young among the multitude of young birds congregated on the beach 7 was a question which occupied a good deal of say attention and interest. After the young leave the nest and its vicinity they wander about aimlessly and may be at widely different places at two visits of the old birds. Hence It is often a serious question on the part of the parent how to find its offspring. Abundant opportunity was afforded for studying this question. Old birds with young which had left the nest, when coming in with a fish, stooped to examine each group of young in turn until a young bird, apparently its own, was found, when the old bird alighted. Immediately the youngster began to dance and call vociferously, but not until the old one mid touched the young one with its forehead was the question decided. Often this minute inspection was immediately followed by the departure of the old bird without delivering the fish, the quest for its own young being renewed. It thus became clear that sight alone was not depended upon for recognition, but that the final decision rested upon the sense of smell. Sometimes the quest resulted in failure, when the old bird swallowed the fish. The evidence seemed to Indicate that these ferns feed only their own young.

By the 1st of July on Muskeget probably the majority of the young terns have hatched in nests which have not been disturbed. Under favorable weather conditions the eggs are often left uncovered, the sun and the warm sand supplying the proper amount of beat; but the birds seem to be able to judge these conditions quite accurately, for in cold, cloudy, or rainy weather, when the eggs might become chilled, or, on the other hand, when the sun is too hot for them, I have always found the birds anxious to return to their nests and protect their eggs. I think they always incubate at night. Terns are seldom seen on their nests because they are timid and restless, but they will soon return to them if the intruder remains quietly concealed at a safe distance. The hatching process is often slow and laborious, a day or more intervening between the time when the horny tip of the bill makes a small hole near the larger end of the egg and the actual hatching time, when the weak, wet little chick emerges from the shell. It dries off within a few hours and remains in the nest for two or three days. Its eyes are open at birth, but it is not fed until the second day. It is fed on small fish from the very first, which it swallows head first. When three or four days old the young chick becomes very lively, running about rapidly, hiding in the grass or between stones, or even lying flat on the sand, where its protective coloring helps to conceal it. It seems to realize this fact, for I have often seen one remain perfectly motionless until it felt sure it was discovered, after which its capture was far from easy. Parents must experience considerable difficulty in finding their own young, and still more trouble in protecting them against inclement weather. On July 4. 1903, 1 noticed evidences of great mortality among the very young chicks on Muskeget; I found hundreds of their little dead bodies scattered over the island, drying in the sun, sometimes two or three in one nest, and once I saw the dead body of an adult tern covering the bodies of two young in the nest. Captain Gibbs, of the life-saving station, thought that they were killed by exposure to pro-~ longed, cold, easterly rainstorms which prevailed during the previous month. Probably the older young were able to run to shelter under the ivy vines, bushes, and thick grass, and thus survived. (in certain portions of the island, where the grass grew tall and thick, the mortality was much less noticeable.

The young are fed by their parents until they are fully grown and well able to fly and have been taught to fish for themselves. I have seen young birds fully as large as their parents and in the first winter plumage fed in this way while standing on a sand bar or sitting on the water. As the old bird approaches with a small fish held crosswise in its bill the youngster shows its excitement by fluttering its wings rapidly, screaming and throwing back its head, with open mouth ready to receive the coveted morsel, while the parent hovers over it and feeds it. I have never seen the feeding process performed on the wing.

Dr. Charles W. Townsend contributes the following notes on the feeding of the young:

The full-grown young appear to be always hungry and call in a monotonous, beseeching way whenever an adult appears with a fish. There are three methods of receiving the fish from the parent – either in the air, on the sand, or on the water. There can be no doubt that the hungry and clamorous young ~vill take food from any adult. Whether the adults feed any but their own young an~l whether they are able to recognize their own is of course a question. I am Inclined to think that, although an adult may occasionally feed a clamorous youngster not its own, as a rule It refuses to feed any but its own legitimate offspring, which it is perfectly able to recognize. As the sexes of the adults are alike in plumage It is difficult to tell whether Only one or both parents feed the young.

In the air the feeding of the young is often a graceful and interesting performance. By a series of aerial evolutions the adult and young reach a point where the transference of the fish directly from bill to bill is made so quickly that one often can not be sure whether the fish was thrown or dropped or actually passed from mouth to mouth. I am inclined to think all methods are used.

On the sand the young sometimes collect in numbers while the adults fish for them. Although the young, easily recognized by their white foreheads and black bills, generally stand motionless, they sometimes walk about, often more rapidly than adults are in the habit of doing. When an adult flies toward a group with food the young all clamor at once, opening their black bills and displaying their crimson gapes, and crowding up toward the food-bearing adult. On one occasion at Ipswich I saw an adult with a fish in its bill alight on the beach near two immature birds, who both clamored loudly to be fed. Disregarding their cries it flew to a third imature bird, but was soon off and alighted near an adult, to whom it delivered the fish, which was swallowed. The young either swallow the fish at once on the beach or sometimes rise in the air and fly about until the fish disappears down the throat. If the fish is large the swallowing may he a slow process. One young bird after swallowing the fish alighted on the water a moment and appeared to take a drink before rejoining Its companions on the beach.

The process of feeding the young bird on the surface of the water is perhaps the most interesting, end points to the former more aquatic ancestry of the terns. An adult flies screaming with a fish in its bill; the young responds by a beseeching call and flight toward the parent, and alights on the water still calling. The old one flies down and delivers the fish without alighting, or doing so but for a brief moment. The thing is done so quickly that It is often impossible to know what happens. The young one as soon as it receives the fish flies up into the air.

Plumages : Several very distinct color phases may be found in the downy young of the common tern, each having numerous variations. The commonest type is “cream buff,” “ochraceous buff,” or “clay colored” above, irregularly mottled with “sepia” or “seal brown;” the throat is sometimes “smoke gray,” but more often “drab” or “sepia;” and the under parts are pure white. There is a. gray phase in which the back is “pale neutral gray” and the crown “cartridge buff” or “pale olive buff;” it is spotted with black on the upper parts; and the throat is” bone brown.” A much rarer type is plainly colored and entirely unspotted. In this type the color of the upper parts varies from “clay color” to “pinkish cinnamon” or “cinnamon buff,” shading off to paler tints on the sides and to white on the breast. This type intergrades with the common type, and there is much individual variation in the extent of the dusky throat and its color, which varies from “smoke gray” to “brownish black.”:

Dr. Jonathan Dwight (1901) describes the molts and plumages of the first year as follows:

Juvenal plumage acquired by a complete post-natal moult shortly after leaving the egg. Dusky markings and buff edgings are conspicuous above, the lower parts being a clear white. The forehead Is pale brown, blending Into a dull black occiput. Buffs and browns later become dull white by fading and the blacks become brownish. The forking of the tall is much less than that of adults, and the rectrices are more rounded, darker, and tipped with dusky or buff markings which become largely lost by wear. A couple of rows of lesser coverts along the cubital border of the wing form a dull black band. The flesh-colored bill and feet, after first brightening, begin to darken.

First winter plumage acquired by a partial post-Juvenal moult, limited to the body feathers, and sometimes a few of the lesser wing coverts. The new mantle is gray except for the dusky cubital bands. The forehead Is white and the occiput black, with some tendency to streaking on the crown. The bill and feet become wholly black. Save for the less forked, darker tall, and traces of buff on the retained wing coverts, young birds closely resemble adults. The change to this plumage is not apt to begin before the end of September on the Atlantic coast.

First nuptial plumage acquired by a complete first prenuptial moult, which explains the freshness of all the feathers of breeding birds. The lateness of this moult in some birds is indicated by over 50 specimens (some ,~ which appear to be adults) taken in Florida between May 28 and June 3, which vary from birds with the first primary barely grown to those still retaining two or three of the old primaries and a number of old rectrices and body feathers. The black cap is now assumed, the dusky cubital bands disappear, and the bill and feet become chiefly coral red.

Occasionally in young birds the first nuptial plumage, described above, is not assumed, but instead a plumage like the adult winter plumage is acquired by a late prenuptial or an early postnuptial molt. This plumage is worn throughout the spring and summer, probably by the less vigorous birds which do not breed. It is the plumage which was once described as a species under the name Sterna portlandica.

Adults have two complete molts each year, a prenuptial early in the spring, before their arrival on their breeding grounds, and a postnuptial in September or later. The adult winter plumage is similar to the first winter except for the wings and tail; the latter is shorter than in spring.

Food: The food of the common tern consists almost wholly of small fish, not over 3 or 4 inches long, such as the sand launce (Ammodytes americanus) and the pipe fish (Siphonostoma fuscum), and probably the young fry of larger species. Shrimp and aquatic insects are eaten to some extent. Mr. Ora W. Knight (1908) speaks of seeing a tern chase, catch, and devour a yellow swallow-tail butterfly (Papilio turnus). The fishermen about Nantucket find the terns very useful in helping them to locate a school of bluefish, for a hovering, diving flock of terns is almost sure to indicate the presence of the fish. The small fry on which the bluefish feed are driven to the surface in dense schools to escape from their enemies below only to be pounced upon by their enemies in the air. It is remarkable to see how quickly the terns will gather, from far and near, as soon as one of their number has discovered such a school. It is an exciting scene, for the water fairly boils with rushing, plunging fish, and the air is full of screaming, fluttering, diving birds; but for the poor fry it is a strenuous struggle for existence.

Doctor Townsend describes its feeding habits as follows:

The plunge of the common tern resembles in miniature that of the gannet. Down they drop like winged arrows, folding their wings as their bodies enter the water. Often they disappear entirely under the water to emerge victorious, with the fish in the bill, or prepared to try again. They scream their triumph or failure, for they can scream even with a fish In the bill. Sometimes a fish Is difficult to swallow, and it is dropped to be caught again before It strikes the water. As the turns leave the water they generally shiver violently, probably to shake off the water. At times they fly down at the beach for a small crustacean or a sea worm. Off the southern Labrador coast I have seen flocks of turns follow small whales and dart down screaming at the water, after the whale had broached and gone down. It is probable that the whale and tern both relish the same small fry.

During the month of August one of this tern’s favorite food fishes, the sand eel or sand launce (Ammodvtes americanus), abounds in the shallow waters about the beaches and inlets at Ipswich, Massachusetts, and thither the terns flock in large numbers from distant breeding places. These fish are 3 or 4 inches long and swim in compact schools of many hundreds. Where they abound the terns congregate and busily bombard the water, disappearing completely below the surface in order to capture their prey. As the bird rises from the water, with the fish hanging from its bill, it occasionally throws It Into the air either from pure fun or to get a better hold on the fish. Sometimes a bird drops a fish, but catches It again before It has fallen more than a yard or two. The presence of the fish In the mouth never interferes with the capacity of the bird to scream or cry out, In fact, the fish bearer generally screams constantly, as if to announce Its success in the chase or the fact of food to Its young.

Behavior: The flight of the common tern, like that of all of its congeners, is light, airy, and graceful. At times it seems listless and desultory, as it flits along the shore looking for its prey, the slow beats of its long wings lifting its light body at every stroke; but again it is swift and direct when traveling high in the air or when hurrying to join a bevy of its fellows hovering over a school of fish; but always the bird has better control of its movements than it appears to have. Its diving habits have been described above. It seldom indulges in swimming, though it can do so if necessary. On hot days large numbers may sometimes be seen swimming and bathing.

In life the common tern can not be easily distinguished from the Forster’s tern, and it still more closely resembles the Arctic tern; the movements of all three are almost exactly alike, and the common tern is intermediate in color between the other two. Its voice will distinguish it from the former, but not from the latter. Its somewhat harsh rolling call, “tee ar-r-r-r-r,~’ is almost musical at times and has a decidedly pleasing cadence, a tinge of wildness, associated with the poetry of summer seas. There is a delightful variety in its notes, with the repetition of the same theme, varying in rapidity and tone, expressive of its various moods. Doctor Townsend writes to me in regard to it:

I have had them fly directly at my head to within a few feet, when they suddenly swerve upward. As they dart down they emit in their rage a rapidly repeated and vibratory tut tut or kik kik kik, followed by a piercing, screaming tear. These sharp rapidly repeated notes are sometimes followed by a loud rattling sound, as if the mandibles were vibrated in anger.

The Muskeget terns have suffered seriously at times by the introduction of cats, kept by the life-saving people, which also nearly exterminated a local species of field mouse (Microtus brewed). Perhaps their worst enemy, next to man, has been the short-eared owl. A colony of these owls lived on the island, making their home on some high grassy knolls, about which hundreds of dead terns lay, partly eaten and drying in the sun. Mr. ‘William Brewster (1879) has thus described their destructive work:

Every day at a certain time these owls sallied forth in search of fresh prey. We used regularly to see them about sunset, sailing in circles over the Island or beating along the crests of the sand bills. They were invariably followed by vast mobs of enraged terns, which dived angrily down over the spot where the owl had alighted, or strung out in the wake of his flight like the tail of a comet. The owl commonly paid little attention to this unbidden following, apparently never tried to seize his persecutors while on the wing, but on several occasions we saw a sitting bird pounced upon and borne off. Sometimes in the middle of the night a great outcry among the terns told where a tragedy was being enacted.

Fortunately for the terns, but unfortunately for the cause of science – for the owls were supposed to be approaching subspecific distinction – this little colony of interesting owls was entirely wiped out during the summer of 1896, through the misdirected ardor of a bird protectionist. Furthermore, as the owls destroyed large numbers of the mice, which probably destroyed many of the eggs of the terns, perhaps it would have been better to have left nature’s balance undisturbed.

A very large colony of terns at Chatham, Massachusetts, was practically exterminated by a colony of skunks in 191’1 and 1918.

Dr. Townsend writes:

The common tern appears to be one of the favorite victims of jaegers, but the worm sometimes turns and chases the jaeger in return. Once in mid-August, on the Maine coast, I found a common tern chasing a male sharp-shinned hawk. The latter twisted and turned, but was unable to escape his adversary until he took refuge in an alder thicket, around which the tern flew screaming in anger.

Dr. Louis B. Bishop sends me the following interesting notes on the behavior of terns on an island in Stump Lake, North Dakota. He says:

On the third island we found the terns killing the young ring-billed gulls by chasing them till they took to the water, then descending on their heads in a perfect shower, striking at the back of their heads until they had pierced their brains. We saw three killed in this manner in less than half an hour, two more before we left, and many bodies of those killed before. The old gulls seemed to pay no attention to them.

I remember it as if it were yesterday. Eastgate and I had seated ourselves on the bank of the high island, and the adult gulls had gone offshore. Suddenly we noticed the terns screaming loudly and diving at something in the high weeds. Wondering what was the matter we watched, and soon saw a young gull make its way to the water with the terns diving at it. When it swam from shore the terns simply rained on it. The gull was, I think, just out of down. As the terns descended, the little gull tried to strike back, but presently a tern struck it on the back of the head, and its head fell to one side. Soon it came to life again, when the terns again descended until its head fell to rise no more. Then the terns left it to chase up others. We tried to save some of these young gulls by shooting the terns that were attacking them, but to no avail; the other terns paid no attention to those who were killed, or to the reports of the gun. They were more anxious to kill the young gulls than to save their own lives. We picked up several of the young gulls thus killed, and the backs of their heads, where merely a membrane covers the brain at this age, looked like pincushions. The only explanation I could think of was that the adult gulls ate the terns’ eggs and young, and the later were taking their first chance to retaliate. This theory was strengthened by the fact that we did not find nearly as many young terns as there ought to have been with a colony as large as this.

Fall: As soon as the young are able to fly, usually in August, many of the terns desert their breeding grounds and wander about the shores in loose scattering flocks, free from the arduous cares of reproduction, to spend the remainder of the season in rest and recreation. They are still largely gregarious and may be seen resting on the sand bars or sandy beaches in large compact flocks, all facing the wind. Some may be bathing in the shallow waters or preening their immaculate plumage, while others stand and sleep with bills buried under the scapulars. As the rising tide encroaches on their roosting ground those nearest the water are forced to rise, and flying over their fellows, to alight above them on the sand. Birds are constantly coming and going, making an animated scene of lively interest. Their summer wanderings are often extended over long distances in search of food. Large numbers of terns are seen daily, flying high in the air over Cape Cod to their favorite feeding grounds in Massachusetts Bay, spending the day on the sandy beaches near Plymouth and returning each night to their breeding grounds south of Cape Cod, 25 or 30 miles distant. The fall migration begins on the coast of Maine by the middle or last of September. In Massachusetts there are a few scattering winter records, but as a rule they begin to leave early in October, and by the end of that month nearly all of the common terns are gone. Winter records along the Atlantic coast seem to be scarce north of Florida, and probably most of the common terns spend the winter from the Gulf of Mexico southward.

DISTRIBUTION
Breeding range: Along the Atlantic coast of North America from northern Nova Scotia (Cape Breton) south to North Carolina (Pamlico Sound); and in the interior, south to the Gulf of St. Lawrence, the St. Lawrence River, northern Ohio (Oberlin and islands in western Lake Erie), southeastern Michigan (St. Clair Flats), southern Minnesota (Heron Lake), northern North Dakota (Devil’s Lake region), and southwestern Saskatchewan (Crane Lake region). West to southeastern Alberta (Many Island Lake) and central Alberta (near Edmonton). North nearly, if not quite, to the Arctic coast of Mackenzie, certainly to Great Slave Lake (Fort Providence) and the west coast of Hudson Bay. A few birds breed in Bermuda. the Bahamas, and the Florida keys, on the coast of Venezuela (Aruba and Bonaire Islands) and on the coasts of Alabama, Louisiana, and Texas (Matagorda). In Europe, from Norway to the Mediterranean, Black, and Caspian Seas, in the Azores. Canary, and Madeira Islands; in northern Africa and in temperate Asia, from Turkestan to Lake Baikal.

Winter range: A few birds winter as far north as Florida (St. Johns River), but the main winter range is in South America, all along both coasts, as far south as the Straits of Magellan. In the Eastern Hemisphere, Africa, ranging to the Cape, and southern Asia.

Spring migration: Early dates of arrival: Masaschusetts, April 20 to 25; St. Lawrence River, May 20; Pennsylvania, Erie, April 26; Ohio, Columbus, April 4; South Dakota, April 20; Colorado, New Windsor, May 14; California, Point Pinos, April 29. Late dates of departure: Brazil, Barra, May 1; Chile, Valparaiso, April 23; Peru, Ancon, May 10.

Fall migration: Early dates of arrival: Argentina, Mar del Plata, September 18; Chile, Valparaiso, September 17; Straits of Magellan, Punta Arenas, November 19. Late dates of departure: Massachusetts, Barnstable, November 14, and Woods Hole, December 2; Pennsylvania, Erie, September 26; Ohio, Cincinnati, November 11; British Columbia, Comox, September 24; California, Point Pinos, October 17; Lower California, San J05~ del Cabo, September 30.

Egg dates: North Dakota, Saskatchewan, and Manitoba: Thirtysix records, May 31 to July 15; eighteen records, June 11 to 21. Virginia: Thirty-five records, May 27 to July 19; eighteen records, June 11 to 27. Maine: Twenty-one records, May 29 to July 26; eleven records. June 14 to July 4.