Great Blue Heron | Life Histories of North American Birds | A.C. Bent
Feather Pic Arthur Cleveland Bent

Life Histories of Familiar North American Birds
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Great Blue Heron
Ardea herodias

[Published in 1927: Smithsonian Institution United States National Museum Bulletin 135:101-114]

The great blue heron, or "blue crane" as it is often called, is the largest, the most widely distributed and the best known of the American herons. Herons probably originated in the warmer climates, where they are certainly better represented in species and in numbers; but this species extends its range across the continent and well up into the cooler climate of Canada. It is a stately bird, dignified in its bearing, graceful in its movements and an artistic feature in the landscape.

In its native solitudes, far from the haunts of man, it may be seen standing motionless, in lonely dignity, on some far distant point that breaks the shore line of a wilderness lake, its artistic outline giving the only touch of life to the broad expanse of water and its background of somber forest. Or on some wide, flat coastal marsh its stately figure looms up in the distance, as with graceful, stealthy tread it wades along in search of its prey. Perhaps you have seen it from afar and think you can gain a closer intimacy, but its eyes and ears are keener than yours; and it is a wise and a wary bird. But even as it takes its departure, you will still stand and admire the slow and dignified strokes of its great, black-tipped wings, until this interesting feature of the landscape fades away into the distance. A bird so grand, so majestic, and so picturesque is surely a fitting subject for the artist's brush.

Courtship.--Throughout the northern portion of its range the great blue heron is migratory, but it returns to its breeding range early in the season. Its spectacular courtship is well described by Audubon (1840) as follows:

The manners of this heron are exceedingly interesting at the approach of the breeding season, when the males begin to look for partners. About sunrise you see a number arrive and alight either on the margin of a broad sand bar or on a savannah. They come from different quarters, one after another, for several hours; and when you see 40 or 50 before you, it is difficult for you to imagine that half the number could have resided in the same district. Yet in the Floridas I have seen hundreds thus collected in the course of a morning. They are now in their full beauty, and no young birds seem to be among them. The males walk about with an air of great dignity, bidding defiance to their rivals, and the females croak to invite the males to pay their addresses to them. The females utter their coaxing notes all at once, and as each male evinces an equal desire to please the object of his affection, he has to encounter the enmity of many an adversary, who, with little attention to politeness, opens his powerful bill, throws out his wings, and rushes with fury on his foe. Each attack is carefully guarded against, blows are exchanged for blows; one would think that a single well-aimed thrust might suffice to inflict death, but the strokes are parried with as much art as an expert swordsman would employ; and, although I have watched these birds for half an hour at a time as they fought on the ground, I never saw one killed on such an occasion; but I have often seen one felled and trampled upon, even after incubation had commenced. These combats over, the males and females leave the place in pairs. They are now mated for the season, at least I am inclined to think so, as I never saw them assemble twice on the same ground, and they become comparatively peaceable after pairing.

Miss Catherine A. Mitchell has sent me the following attractive sketch of the "morning love dance," a more peaceful courtship performance, of this species:

As I turned over in my sleeping bag, a glimpse of a rosy glow in the sky roused me to better appreciation of the world already awake around me. An old pine tree hanging from the mountain of sand back of us, was outlined against a gorgeous reflection in the peaceful waters of Lake Michigan; and in the smooth sands of the shore surrounding us. There! The Japanese picture was complete with a great blue heron in the foreground. But see! A little way farther down the beach are more great blue herons. A group of them together with outspread wings flapping slowly up and down, circling round and round. Eleven birds first, later 14, circling sometimes around each other and sometimes in the one large circle, somewhat as we used to do in dancing-school days. I watched the graceful motions perhaps half an hour, spellbound by the weirdness of the scene.

Nesting.--Many and varied are the nesting sites chosen by this species in the different portions of its wide breeding range, but certain characteristics are common to the species everywhere. It is, as most of the herons are, a sociable species, preferring to nest in closely congested communities, varying in size from a few pairs to several scores or even hundreds. Where trees are available it prefers to nest in trees and usually selects the tallest trees available; but it often nests in low trees, or bushes, or even on the ground. The location of the nesting rookery probably depends more on an available food supply for the young than on the presence of suitable nesting trees. But, as the main object to be gained is security for the eggs and young, a remote and more or less inaccessible locality is always chosen.

My first experience with the nesting habits of the great blue heron was in the Penobscot Bay region on the coast of Maine, where I have examined breeding colonies on the spruce-covered islands near Deer Isle. Bradbury Island, lying northwest of Deer Isle in Penobscot Bay, has long been known as a breeding place for great blue herons. It is a high island with open pasture land in the center, but heavily wooded at both ends with a dense forest of tall spruces and firs, with a few birches. I once counted nine ospreys' nests in the trees around its steep shores and found the bulky nest of a pair of northern ravens in the thickest part of the woods. When I first visited it, on June 10, 1899, the breeding season was well advanced. Most of the nests contained large young, but at least four nests examined held three, four, or five eggs, probably second layings of pairs that had been robbed previously. The nests were placed in or near the tops of the largest spruces or firs, at heights varying from 30 to 40 feet. They were large flat platforms of large sticks and twigs, only slightly hollowed, and smoothly lined with fine twigs; one that I examined was 30 inches in diameter and another was 40 inches. There were not over a dozen pairs of herons in this rookery at that time, but when I visited it again on June 20, 1916, the colony had increased to 30 or 40 pairs. Many of the nests were in dead trees, which probably had died since the nests were built; the damage done by the birds often kills the trees. I had long known of another colony of 25 or 30 pairs on White Island, east of Deer Isle, which I visited on June 25, 1916. Here the herons were nesting from 40 to 50 feet up in the tops of the tall spruces in a dense forest. The trees and the ground under them were completely whitewashed with the excrement of the young birds; but, by picking out and climbing to a nest under which the ground was clean, I succeeded in collecting a set of eggs for my companion.

In Alexander Wilson's (1832) time these herons nested in the primeval cedar swamps of New Jersey, which have long since disappeared as virgin forests; referring to their nesting haunts, he says:

These are generally in the gloomy solitudes of the tallest cedar swamps, where, if unmolested, they continue annually to breed for many years. These swamps are from half a mile to a mile in breadth, and sometimes five or six in length, and appear as if they occupied the former channel of some choked up river, stream, lake, or arm of the sea. The appearance they present to a stranger is singular. A front of tall and perfectly straight trunks, rising to the height of 50 or 60 feet without a limb, and crowded in every direction, their tops so closely woven together as to shut out the day, spreading the gloom of a perpetual twilight below.

More modern conditions in that region are thus described in some notes sent to me by R. P. Sharples:

Down back of Delaware City, near the Delaware & Chesapeake Canal, is a great swamp. It is many hundred acres in extent and is absolutely unfordable and impassable. In places are many trees growing out of the water and down below is a dense thicket shading the mud and ooze. It is such a place as snakes and frogs and slimy things inhabit. Crawfish in immense numbers make their homes in it. But above is a bird paradise, and the thickets and the grasses and the trees are alive with them. In a small patch of maples a colony of great blue herons have built their nests. There were 89 of the nests in the bunch and 35 of them were apparently in use when examined one day, the last of March, 1912. The birds had just begun to lay their eggs and were very wild. Seventeen of the nests were seen in one big tree. These structures are made of small twigs, in a thin layer, so thin that the eggs can be seen from the ground at the foot of the tree. The nests are shallow platforms, and instead of being close to the trunk are generally out on the tops of the higher limbs, often being from 85 to 100 feet from the ground. They are about 3 feet across and are very insecure nesting places.

William B. Crispin wrote me that near Salem, New Jersey, these herons build their nests in the forks of limbs of the largest trees, from 70 to 130 feet from the ground, in swampy, briery places. He said that the largest colony near Salem contained some 80 nests and that he has found nests in pines, pin oaks, white oaks, chestnuts, tulip trees, and swamp maples.

Richard C. Harlow mentions, in the notes he sent me, a colony of about 20 pairs, near Glassbow, New Jersey, nesting in tall pine trees from 70 to 90 feet high. The nests were all repaired from the remains of the preceding years, were made of oak sticks and were "lined with bunches of green pine needles."

Edwin F. Northrup (1885), in describing a large colony on the north shore of Oneida Lake, New York, says:

The timber in the swamp is all black ash and grows very high, branching at the top. The trees are slender, varying from 1 to 3 feet in diameter, and are readily climbed with spurs, that is if one is adept at using them. Several hundreds of these nests, built in crotches of the limbs, are grouped together at one place in the swamp and cover a space nearly or quite half a mile across. Nearly every tree which rises to the general height of the rest and which has favorable crotches, contains from one to four nests. Two, however, is the more usual number in one tree, four being seldom found. The nests are constructed of sticks about one-fourth to half an inch in diameter. A large bundle is laid on a crotch and lined with finer twigs, making a flat nest from 25 to 40 inches in diameter.

Dana G. Gillett (1896) says that in Tonawanda Swamp in western New York:

The great blue heron also nests in large elm trees, selecting one with a very large trunk, and nearly always building at the extremity of a limb, generally a horizontal one, and many are not strong enough to bear the weight of a man, thereby making it exceedingly dangerous to try to approach the nest.

I have seen as many as eight nests in the top of one large spreading elm, and the old herons sitting on their nests, which would swing to and fro with every breeze. The nests are very large, usually about 4 feet across, and sometimes larger, being composed of sticks, some of them larger than a man's thumb, firmly stuck together, and lined with fine bark or moss, but sometimes composed only of sticks.

Perhaps the most interesting of all are the colonies in Michigan, where the herons build their nests in giant sycamores at heights varying from 50 to 90 feet above the ground. Eugene Pericles (1895) gives a thrilling account of egg collecting in such a rookery in Van Buren County. The smallest sycamore was only 7 feet in circumference, but it was 40 feet to the first limb and there were 12 nests in it, distributed over five large straggling limbs and either at or near their extremities. The largest sycamore in the heronry was over 10 feet in girth and held 16 occupied nests, as well as several old nests; the lowest nest was about 70 feet up and the highest was over 80 feet. Climbing the smooth trunks of these big trees and going out on the slippery limbs must test the nerve and strength of the best climber.

Walter E. Hastings has sent me some fine photographs and some interesting notes, including a map showing the locations of 18 Michigan rookeries of great blue herons. In the colonies that he has visited, the nests were usually placed in high elm trees, from 40 to 110 feet from the ground, near the tops of the trees or the ends of the branches; often the trees or branches are dead, making it dangerous to climb them. In building their nests the birds often break the twigs off the trees rather than pick them up off the ground. New nests of the year are often so frail that the eggs can be seen through them from below. The older nests, which have been added to each year, are much larger, thicker, and firmer; the accumulated filth helps to cement the material together. Mr. Hastings once sat in one of these nests, 110 feet from the ground, for a number of hours while photographing the birds.

On the plains and prairies of the interior the great blue herons have to be contented with the largest trees they can find, cottonwoods, poplars, and box elders, in the timber belts along the streams. We found a colony of about 15 or 20 nests on Skull Creek, near Crane Lake, Saskatchewan, on June 5, 1905. The nests were from 15 to 25 feet up in the tops of the largest box elders. At that date most of the nests contained young of various ages, but two nests held six eggs each and several others 4 or 5 each. We visited this colony the following year and found that it had been shot out; the dead bodies of the herons were lying on the ground under the trees and the nests were deserted.

A. D. Henderson writes me that there has been a small colony near Belvedere, Alberta, since 1920. He saw "two of the nests on an island in tall poplar trees in the fall of 1920." In the fall of 1922, he "saw six nests in a solitary spruce on another island about a mile distant." On May 15, 1923, he "visited this island and found five occupied nests and took one set of five eggs and one of six. The nests were all on the same spruce tree and those occupied had been newly built, the old nests being easily distinguished by the liberal coat of whitewash on them. The nests were large structures of dead sticks, lined with green alder twigs and weed stalks and a very little dry grass." This is the most northern colony of which I have any record.

Eggs.--Four eggs is probably the commonest number laid by the great blue heron, though full sets of three are not uncommon, sets of five are common, sets of six are frequently found, and sets of seven have been reported. The shape varies from ovate, or (rarely) oval to elliptical ovate, or (rarely) fusiform. The shell is smooth or slightly rough. The color varies from "pale Niagara green" to "lichen green " or "pale olivine." The measurements of 50 eggs average 64.5 by 45.2 millimeters; the eggs showing the four extremes measure 70.4 by 47.6; 67.9 by 49.2; 56.9 by 42.7; and 59.2 by 42.2 millimeters.

Young.--The period of incubation is about 28 days. Mr. Hastings says that both sexes incubate. He once saw a bird with broken wing feathers leave a nest and very shortly another, with perfect wings, took its place. Also he has seen a great commotion around a heronry early in the morning, again about 10 a.m., and at about 2 p.m., and again just before dark, which he believes is due to the birds changing on the nests.

Young herons are far from attractive, either in appearance or behavior, at any age; at first they are feeble and helpless, but later on they are awkward, ungainly, and pugnacious. If undisturbed, they remain in the nest until as large as their parents and fully fledged; but when nearly grown they are easily frightened and leave the nest to climb awkwardly over the surrounding branches and perhaps fall to the ground or water below, which often results in death, as their parents do not seem to have sense enough to rescue or even feed them.

In the nest they are fed by both parents, at first on soft regurgitated food, later on whole fresh fish. With the youngest birds the soft soup-like food is passed from the bill of the parent into that of the young bird; but later on the more solid food is deposited in the nest and picked up by the young. The young birds usually lie quietly in the nest, crouched down out of sight, between feedings; but as soon as the parent is seen or heard returning (the senses of the young are very keen) there is great excitement, as they stand up to clamor and wrestle for their food. The old bird approaches with deliberate dignity and may stand on the nest for a few minutes with her head high in the air. Then with crest and plumes erected and with a pumping motion, she lowers her head and one of the youngsters grabs her bill in his, crosswise; the wrestling match then follows until the food passes into the young bird's mouth or onto the nest. The young are usually fed in rotation, but often the most aggressive youngster gets more than his share.

The young instinctively try to void their excrement by squirting it over the edge of the nest, but they are not eminently successful at it and the nest, the tree, and the ground under it are usually completely whitewashed with their profuse ordure before they are fully grown. This and the decaying fish which fall from the nests make a heronry far from pleasant and one has to expect an occasional shower bath from one or both ends of a frightened young heron.

Young herons are particularly noisy at feeding times and, as this is an almost continuous performance in a large rookery, there is always more or less chattering to be heard, which sounds like the barking of small puppies or the squealing of young pigs. E. S. Cameron (1906) thus describes an interesting squabble caused by a young heron climbing into a nest where he did not belong:

Several times it seemed likely to fall into the water but managed to regain its balance with violent flapping of wings. Later, when all was quiet again, the four real owners of this nest stood erect indignantly protesting at this outrage on their rights, and one bolder than the rest endeavored to eject the intruder. The newcomer as valiantly resisted, and, being of the same size, a protracted and most extraordinary battle ensued which I witnessed through my binoculars. The birds would feint, and spar for a hold, until one was able to seize the other by the neck when, exerting all its strength, it endeavored to drag its antagonist over the side of the nest. Both in turn had the advantage and swayed backwards and forwards, while the three noncombatants crouched down in characteristic fashion, so that the battle was waged partly on their bodies and partly on the edge of the nest. The fight was continued until an old bird arrived with fish, when the five nestlings again stood erect, and, in the general scramble for food, the parent fed all without discrimination. As it became too dark for binoculars I saw no more that evening, but next morning the duel was renewed until the interloper became exhausted, and, being driven from the nest, scrambled down the branch to its rightful abode. As far as I could see, all the other young birds lived in perfect harmony.

Plumages.--In the downy, young, great blue heron, the top and sides of the head are thickly covered with long whitish and grayish plumes, one inch or more long, "light olive gray" to "pale olive gray," grayer, basally and whiter terminally; the back is thickly covered with long, soft down, "light mouse gray" basally to "pallid mouse gray" terminally; the flanks and belly are more scantily covered with soft, white down; and the throat is naked. The young bird begins to acquire its plumage at an early age; before it is one-third grown its head, neck, and body is well feathered and its flight feathers are growing, but the downy plumes persist on the crown, and the rump remains downy until the young bird is nearly fully grown.

In this first, or juvenal, plumage the crown is "dark mouse gray"; the cheeks, chin, and throat are white; the neck is variegated with grays and browns, and spotted with black and pale russet; the upper parts, back, and wing coverts are plain gray, "deep mouse gray" to "deep Quaker drab," without any signs of plumes anywhere; the feathers of the greater, median and lesser wing coverts are broadly edged with "russet" or "pinkish cinnamon" and there is at first a white spot on the tip of each greater covert feather; these spots and edgings gradually fade and wear off; the breast is streaked with dusky, and the thighs are "light pinkish cinnamon." All of the colors named above vary somewhat, as in the adults of the various subspecies.

The above plumage is worn through the first fall and winter without much change before February, when the first spring plumage begins to show advance toward maturity; at this season one or two occipital plumes may appear, but the crown remains black; rudimentary plumes appear on the breast and back; the buff edgings have worn away and some new feathers have replaced the old in the mantle; and the under parts are more like the adult.

At the first postnuptial molt, which is complete, the following summer and fall, further advance toward maturity is made; the forehead becomes partially white, some occipital plumes are acquired; the black shoulder tufts appear, somewhat mixed with white; many long, narrow plume-like feathers appear in the back and breast; the thighs are purer cinnamon; and the neck and under parts are more like those of the adult. This is the second winter plumage, which becomes nearly adult at the next prenuptial molt, when the young bird is ready to breed. After the next complete postnuptial molt, when the young bird is over two years old, the plumage becomes fully adult, though signs of immaturity are still to be seen, such as dusky markings in the white crown and white markings in the black shoulder tufts; these may not wholly disappear for another year or two.

Adults have a complete postnuptial molt in late summer and fall and a partial prenuptial molt of the contour feathers in late winter and early spring. There is little seasonal change in adults except that in spring the plumes of the head, breast, and back are more fully developed and perhaps the showy colors are a little more brilliant. The adult is a handsome bird at all seasons.

Food.--The principal food of the great blue heron is fishes of various kinds and it seems to be willing to accept whatever kind of fish is most easily available. Ora W. Knight (1908) says:

Frogs, eels, horn-pouts, pickerel occasionally, suckers, shiners, chubs, black bass, herrings, water puppies, salamanders, and tadpoles, are the items I have discovered among their rations. They do not frequent as feeding grounds the spots where trout usually congregate, and I have very strong doubts that they eat trout, except very rarely, let alone consuming them in the vast quantities certain persons have affirmed.

It fishes by night as well as by day and employs two very different methods, still hunting and stalking. The former is the best known and probably the commonest method. Standing as still as a graven image in shallow water, where fish are moving about, it waits patiently until one comes within reach, when a swift and unerring stroke of its well trained bill either kills or secures the fish. Usually the fish is seized crosswise between the mandibles; if it is a small one, it is tossed in the air and swallowed head first, so that it will slip down easily; but if the fish is a large one, the heron may walk ashore with it and beat it on the ground to kill it or may kill it by striking it in the water. I have never had the patience to watch a heron long enough to learn how long it would stand and wait for a fish to come to it. I have found it more interesting to watch it stalking its prey, a more active operation. Slowly and carefully, with stately tread, it walks along in water knee deep, its long neck stretched upward and forward; its keen eyes are scanning the surface and an occasional quick turn of the head indicates a glimpse of a fish; suddenly it stops, as if it had seen a fish, but it moves on again; at last comes its chance, as in a crouching attitude the long neck darts downward, quick as a flash; the stroke is not always successful, but sooner or later the heron secures a meal. Sometimes, in its eagerness, the heron may step beyond its depth and lose its balance, but a few flaps of its wings restores its equilibrium and its dignity.

Audubon (1840) says:

The principal food of the great blue heron is fish of all kinds; but it also devours frogs, lizards, snakes, and birds, as well as small quadrupeds, such as shrews, meadow mice, and young rats, all of which I have found in its stomach. Aquatic insects are equally welcome to it, and it is an expert flycatcher, striking at moths, butterflies, and libellulae, whether on the wing or when alighted. It destroys a great number of young marsh-hens, rails, and other birds; but I never saw one catch a fiddler or a crab; and the only seeds that I have found in its stomach were those of the great water lily of the southern states. It always strikes its prey through the body, and as near the head as possible. Now and then it strikes at a fish so large and strong as to endanger its own life; and I once saw one on the Florida coast, that, after striking a fish, when standing in the water to the full length of its legs, was dragged along for several yards, now on the surface and again beneath. When, after a severe struggle, the heron disengaged itself, it appeared quite overcome, and stood still near the shore, his head turned from the sea, as if afraid to try another such experiment.

Wilson (1832) includes in its food grasshoppers, dragon-flies and the seeds of splatter docks. Mr. Hastings says that it eats great quantities of insects and mice. When the grasshoppers have been thick he has seen it feeding in the open meadow on these insects entirely, often for two hours at a time; it does not chase them but stands very still, allowing the insects to come within reach of its quick beak. Arthur H. Howell (1911) adds crustaceans to the list. Bartlett E. Bassett wrote me that a bird he shot for me was carrying a large black snake in its bill. Altogether the food habits of this species are decidedly beneficial. It may occasionally take a few trout, but it does not ordinarily frequent the streams where trout are found.

Behavior.--When forced to make a hurried departure, as when frightened, this heron makes an awkward start, as it scrambles up into the air with vigorous strokes of its big wings, with its long legs dangling and its long neck outstretched. When undisturbed it starts more gracefully; leaning forward, with extended neck, it takes a few steps and with a few long wing strokes it mounts into the air. When well under way its flight is strong and majestic, sustained by long, slow strokes of its great wings; its neck is folded back between its shoulders and its long legs are extended backwards, to act as a rudder in place of its tail, which is too short for this purpose. When about to alight the neck and legs are extended, a few flaps of the wings check the bird's momentum and it drops lightly to its perch.

The great blue heron is quite at home on dry land where it moves about with dignified ease and grace. M. P. Skinner writes to me that in Yellowstone Park it often walks "across the meadows from one pool to the next, with long, stately strides." It must spend considerable time on land in pursuit of such prey as field mice, shrews, grasshoppers, and other insects. It can also alight on the water or swim, if necessary. P. A. Taverner (1922) says that, while watching some of these herons flying across a lake, he "saw them drop to the lake level, hesitate a moment and then drop softly into the water. They remained perhaps half a minute there, and then, with an easy flap of wings, rose and continued their way." There was no shoal there and "nothing but deep water anywhere in the vicinity." Dr. John B. May has twice noticed a similar occurrence, about which he writes me, as follows:

On the first occasion the bird was flying over the middle of Little Squam Lake, at Holderness, New Hampshire, where the lake is about 400 yards wide. It sailed down to the water, then flew to a raft of logs and was seen to swallow some object. Two years later, at the same spot, a similar event was witnessed more carefully this time. The bird closed its wings for about eight seconds, opened them slowly once and closed them again, then raising them flew away with a slender eel-like object dangling from its bill. The water was at least 25 feet deep at this place and the bird 150 to 200 yards from shore.

Dr. Charles W. Townsend, Dr. Daniel S. Gage, and Mr. Josselyn Van Tyne have told me of similar observations.

Illustrating the wariness and the sagacity of this species Wilfred A. Bretherton (1891) writes:

A mill pond some three-quarters of a mile from my home is a favorite feeding place for these birds. This pond, being just outside of the corporation in a very pleasant locality, is often visited, and hence the herons are often interrupted in their fishing. Past experience has made them very sagacious. One or two sentinels are always posted upon tall trees, usually at the upper end of the pond--if two, about 30 rods apart--and in such a manner that no one can approach the pond from any direction without being observed by one or the other sentinel, who will immediately give the alarm. The pond is so situated that the herons fishing cannot be seen until the border is reached, and the sentinels, being high above the water, can see a man long before he gets to where he can see the fishers, unless he approach through the woods on the south side.

One day I thoroughly tested their sagacity, and found it greater than I had suspected. Stealthily moving through the woods south of the pond, I came near the steep bank of the pond, partly hidden from the pond, by dense shrubbery. However, the nearest sentinel, some 30 rods away, caught sight of my head above the bushes and uttered a harsh cry of alarm, which was repeated by the second sentinel, who was posted so far up that I would not have seen him had he not repeated the cry. Immediately four or five herons flew from the water between me and the nearest sentinel, one of them having been but a few rods from me, but invisible except from the water's edge. As they flew to the woods north of the pond they uttered hoarse cries, and soon all had disappeared save the two sentinels.

Moving back and eastward I crept up to a clump of bushes about 6 feet in height growing upon the very top of the bank. Lying close to the ground I kept silent for some time. The bushes entirely hid me from the watchful sentinels and they evidently supposed I had gone. Soon the one nearest me began to utter low and peculiar cries which the upper sentinel quickly answered. This style of conversation was kept up for several moments. This was shortly followed by the return of all the fishers, one coming quite near my locality. As soon as fishing had again gotten well under way I rose upon my feet. The instant my head appeared above the bushes the nearest sentinel uttered the harsh cry of alarm, immediately followed by the tumultuous flight of the fishers, most of which had been invisible from my hiding place.

The attitude of the great blue heron towards other species of herons with which it is associated on its breeding grounds or its feeding grounds is usually one of dignified indifference or haughty disdain. It never seems to molest the smaller herons, but apparently picks an occasional quarrel with other species. Dr. Charles W. Townsend (1920) once saw "a fine adult great blue heron flying high in the air pursued by a screaming common tern who darted at it from behind and from above. The heron screamed hoarsely, stretched out and around its long neck and partly dropped its legs. The feathers of its head were erected. The tern attacked again and again and the scene was repeated. It reminded one of an old hawking picture."

Audubon (1840) says he has--

seen the blue heron giving chase to a fish hawk, whilst the latter was pursuing its way through the air towards a place where it could feed on the fish which it bore in its talons. The heron soon overtook the hawk, and at the very first lounge made by it, the latter dropped its quarry, when the heron sailed slowly towards the ground, where it no doubt found the fish. On one occasion of this kind, the hawk dropped the fish in the water, when the heron, as if vexed that it was lost to him, continued to harass the hawk, and forced it into the woods.

Enemies.--There are very few birds or animals that dare to attack such a large and formidable antagonist as an adult great blue heron, for it is a courageous bird, armed with a powerful sharp bill that can inflict serious wounds. Even men must approach it with caution, when it is wounded and at bay. But great damage is done to the eggs, and probably also to the very young birds, by crows, ravens, vultures, and probably gulls. Once on Bradbury Island, referred to above, we flushed a heron from its nest and, on returning to it a few moments later, we found three eggs on the ground under it, which had evidently just been broken and sucked by a pair of ravens that were flying around and croaking. Crows and ravens often live in or near the rookeries and, as soon as the herons are frightened away from their nests, these black marauders pounce down on the nests and devour the eggs. R. P. Sharples, in his notes, relates the following incident:

Once a red-shouldered hawk sailed over at great height. Presently he espied the unprotected heron eggs, and folding his wings he dropped down like a bullet right into the treetops amid the heron nests. Then the parent birds saw him and all came piling home in a hurry, no longer afraid of their human enemies. The hawk missed his dinner for the herons with their long daggerlike bills are well able to defend their nests.

In this connection it is interesting to note that both the red-shouldered hawk and the red-tailed hawk have been recorded as nesting in or near heron rookeries. In southern rookeries nests of turkey or black vultures are often found. Mr. Hastings once found a pair of great horned owls raising a brood in an old nest in the middle of a colony.

Fall.--Throughout the northern part of its range the great blue heron is migratory. Its fall migration is particularly well marked. Many individuals migrate singly, as solitary birds are often seen, but flocks of a dozen or 20 birds are not uncommon. I have several times seen such flocks in the fall, but none in the spring. Doctor Townsend (1920) says that "at Ipswich, on October 28, 1917, at 5 p.m. a flock of 20 of these great birds flew south high up over the marshes in a loose V or U formation." In some notes, sent to me by Harry S. Hathaway, from Miss Elizabeth Dickens, she writes that on November 12, 1910, a flock of 12 appeared about 8:30 a.m. on Block Island:

After circling awhile like gulls playing in air they dropped down on the edge of the bluff. I had never seen more than nine in a flock before. Of course, the gunners got after them and they had to depart, but that was only the beginning. All the forenoon they came from the west in flocks of from 2 to 60. I counted 40 in one flock and 60 in another that were in sight at one time. The life savers said these were all one flock until their shooting divided them.

I believe that there is a regular coastwise flight, over the water as well as over land, for we often saw them when off shore "coot" shooting.

Winter.--The great blue herons of the North mingle in winter with their near relatives of the southern Atlantic and Gulf states, adding materially to the heron populations of these congenial shores. There they live in peace and harmony with their neighbors, sharing with them the bounteous supply of fish and other foods. Many linger as far north as the central portions of the United States and stragglers are occasionally seen as far north as New England and Michigan. W. J. Erichsen (1921) says of their winter habits on the coast of Georgia:

The greater portion of its food is secured from the salt marshes and the banks and shallows of the numerous creeks that wind their way through them. It is often seen in company of the smaller herons, particularly the little blue species. At such times it is the first to take wing at the approach of danger, and usually is far away before the intruder has arrived within 100 yards of the spot where it stood. Upon stationing itself in a shallow creek to secure passing fish, if the latter are scarce the bird will remain motionless in one spot for a long period of time, apparently sluggish, and in an indifferent attitude; but when the fish are plentiful it becomes very active, spearing them right and left in rapid succession.

At sundown, or a little before, numbers of these stately birds can be seen slowly winging their way toward the forested portions of the islands, there to spend the night. They become much attached to these roosting places and will not desert them as long as their aspect remains unchanged and the birds are not greatly persecuted.

Great Blue Heron* Ardea herodias

*Original Source: Bent, Arthur Cleveland. 1927. Smithsonian Institution United States National Museum Bulletin 135: 101-114. United States Government Printing Office