Contributed by Charles Wendell Townsend
[Published in 1927: Smithsonian Institution United States National Museum Bulletin 135: 185-194]
Familiarity with the habits of this well-known little heron explains its common or vulgar names such as "fly-up-the-creek," "chalk-line," "shite-poke," and "skeow." These names are of long standing and very expressive, for the bird is a familiar one to the country boy and to the fisherman by stream or pond, where the tameness or stupidity of this bird often brings it within close range.
I have observed their return in early spring, when arriving in flocks of from 20 to 50 individuals. They would plunge downwards from their elevated line of march, cutting various zigzags, until they would all simultaneously alight on the tops of the trees or bushes of some swampy place, or on the borders of miry ponds. These halts took place pretty regularly about an hour after sunrise. The day was occupied by them, as well as by some other species especially the blue, the yellow-crowned, and night herons, all of which at this period traveled eastward, in resting, cleansing their bodies, and searching for food. When the sun approached the western horizon, they would at once ascend in the air, arrange their lines and commence their flight, which I have no doubt continued all night.
During the love season they exhibit many curious gestures, erecting all the feathers of their neck, swelling their throat, and uttering a rough guttural note like 'qua, qua,' several times repeated by the male as he struts before the female.
Mrs. Irene G. Wheelock (1906) describes the dance or "hornpipe of a solitary green heron" in June, "although," as she says, "possibly his mate may have been an unseen witness. Backward and forward, with queer little hops, he pranced first on one foot and then on the other. . . . The effect is as ludicrous as though a long legged, dignified D. D. were to pause in his learned discourse and execute a double shuffle."
Nesting.--The green heron nests singly or in colonies. Although it generally prefers for its nesting locality a region close to the water, it may choose dry woods or an orchard in the midst of cultivated ground. The height of the nest is also very variable, and although most nests are placed from 10 to 20 feet from the ground, they may be found in the tops of high trees, or, on the other hand, on low bushes or even on the ground. Hatch (1892) says: "Instances have occurred under my observation, where in the entire absence of trees or bushes of any size, they have placed the nest, composed of coarse dry weeds and reeds and cat-tails, on a tussock in a reed-hidden quagmire." And he mentions one that was built on the top of a muskrat house. Maynard (1896) says that in Florida, "among the keys, they often place their domiciles on the roots of the mangroves, frequently not over 6 inches above high-water mark." W. J. Erichsen (1921) in his observations in Chatham County, Georgia, says:
These birds breed in considerable numbers on Sylvans Island on the Herb River, some 3 miles from the town of Thunderbolt, placing their nests in the extreme tops of tall pine saplings. Probably the most populous colony in the county is near Lazaretto station on Tybee Island. Here the birds breed in a jungle of oaks difficult to penetrate. So numerous are they that every available nesting site is occupied, many new nests being built on the foundation of old ones.
In Massachusetts, I have generally found single nests, but on several occasions, small colonies. One at Magnolia, many years ago between the beach and a fresh water marsh, consisted of 20 or 30 pairs nesting in pitch pines about 20 feet from the ground. Another colony was on an island in the salt marsh at Ipswich in trees of gray birch, red oak, and hickory about 15 feet from the ground. A colony of about 20 nests at Westport on a salt marsh island was in cedars, sassafras, and hickories. In this case the nests varied from 3 to 20 feet from the ground.
The nest itself is a simple affair from 10 to 12 inches in diameter, ill-adapted, it would seem to hold eggs when the tree branches wave in the wind, for it is a flat platform of sticks, destitute of any sort of lining and not cup shaped. Some at least of the twigs composing the nest are green. The nest is so thin and flimsy that one can sometimes look through it from below and see the eggs. In making the nest the herons must weave the twigs in and out to a certain extent, for if they merely laid the sticks one on top of the other, the nest would fall to pieces at the least disturbance. The nests on the ground made of course weeds, reeds, and cat-tails already mentioned are very unusual both in site and material.
The green heron does not nest with other species as a rule, but is occasionally found nesting in the same grove with little blue, Louisiana, black-crowned, and other herons. The boat-tailed grackle and the bronze grackle have also been found nesting in the same group of trees. Mrs. Wheelock (1906) says of the association with the latter birds:
The grackles were quarrelsome, thieving, noisy, and the only possible advantage the herons could hope to derive from them would be the loud alarm always given by them at the approach of danger.
Eggs.--[Author's note: Green herons have been known to lay from three to nine eggs, but the ordinary sets consist of four or five eggs; the larger sets are probably the product to two females. The eggs are ovate or oval in shape. The shell is smooth without gloss and the color varies from "pale glaucous green" to "pale olivine."
The measurements of 43 eggs average 38 by 29.5 millimeters; the eggs showing the four extremes measure 41 by 28, 40.5 by 30.5, 36 by 27.5 millimeters.]
Young.--The incubation according to Burns (1915) is 17 days. The young at an early age are expert climbers among the branches of the nesting tree, long before they are able to fly and while the natal down still adheres to the juvenal feathers and forms a halo around their heads. In climbing they make use of their feet, wings and bill, or, rather of the neck, hooking their bills and chins over the branches and pulling themselves up. The bastard wing is extended during the climbing process, suggesting an ancestral, reptilian use, but whatever power it may have had in the past, this was long since lost. I have never seen any attempt to use the bastard wing in grasping. If the ornithologist climbs the tree in order to observe the half-grown young in the nest, these almost always leave in haste and scatter to the outermost tips of the branches.
Another ancestral trait, which is suggested in the adult by the persistence of a distinct web between the middle and outer toes, is an ability on the part of the young to swim, an inheritance which must be of distinct value in many cases where the young fall from the nesting tree or bush into the water below. I once placed a vigorous half-grown young green heron in the water below its nest and was delighted to see it sit erect like a little swan and paddle gracefully off, using its feet alternately. It seemed perfectly at ease, dabbed at the water occasionally with its bill, swam a creek 20 yards broad, and threaded its way among the grass stalks until it disappeared from sight. The grace and ease with which it swam contrasted forcibly with its movements on land. The adult also is able to swim.
When the young are approached too closely, they regurgitate the contents of their crops to the discomfort of the seeker after knowledge, although this action gives the latter an opportunity to learn the character of their food. Mrs. Irene G. Wheelock (1906), who has made some interesting and valuable studies of several families of these birds in southern Wisconsin says:
As soon as the little ones were fairly out of the shells and before the down was dry on their heads we had taken several pictures of them. One of these revealed a remarkable heron trait, for the brand new baby, who had never been fed, and who had scarcely opened his eyes on this queer world, yet attempted to protest against our meddling by the characteristic heron method of defense. In his case the action was merely a nervous "gagging" and would seem to indicate that this act is involuntary rather than intentional on the part of all herons. . . . When first hatched the herons stretched up to a height of 3 1/4 inches, and when 7 days old, 11 inches.
She found that they "gained one-half ounce in weight every day for 6 days, weighing three-fourths of an ounce at the beginning and 3 3/4 of an ounce on the seventh day." These young were fed only in the early morning and in the late afternoon, and the periods of greatest activity were from 4 to 6 in the morning, and from 5 to 7 in the evening. One record taken when the young were a week old, showed that they were fed 7 times in the morning and 7 times in the afternoon. The food was given by regurgitation but was not predigested.
Plumages.--[Author's note: The downy young green heron is scantily covered with "drab" down, thickest on the back and longest on the crown; the color varies to light gray on the under parts and to "hair brown" on the crown. The juvenal plumage is acquired in the usual heron sequence and is complete before the young bird reaches the flight stage, when fully grown.
The sexes are distinguishable even in the juvenal plumage. In the young male, in August, the crown is solid, glossy, greenish black; the sides of the head and neck are solid "chestnut"; the chin, throat, and neck stripe are yellowish white, spotted with black; the back is solid, glossy, dark green; the wing coverts are the same color as the back, but the lesser coverts are edged with chestnut and the median and greater coverts are rounded (not pointed, as in the adult), edged with pale buff and have a triangular buffy white spot at the tip of each feather; these spots soon fade out to white and then wear away; the remiges and retrices are glossy, greenish black; the secondaries and primaries are tipped with white in decreasing amounts from the inner to the outer; the under parts are buffy white, streaked with dusky. The young female differs from the juvenal male in having chestnut streaks in the crown and having the sides of the head and neck streaked with chestnut, buff, and dusky.
The juvenal plumage is worn during the fall and early winter, without much change until the partial prenuptial molt begins in February; this involves mainly the head, neck, and body plumage, which, by May, is much like the adult plumage, except that there is more white in the chin, throat, and under parts, with more broad, dusky stripes in the fresh plumage of the lower neck and upper breast than in the adult; some new, fresh back plumes, scapulars, and wing coverts, similar to those of the adult, are acquired at this molt; but the flight feathers are old and worn and some of the juvenal wing coverts are retained. The complete postnuptial molt begins earlier in young birds than in adults; I have seen a young bird molting its primaries as early as April first; at this molt, when the young bird is but little over a year old, the adult plumage is assumed. The adult wing is easily recognized by the coverts; the lesser coverts are narrowly edged with rufous buff and the median and greater coverts are pointed (not rounded as in the juvenal) and narrowly edged with pale buff; only the inner primaries and the secondaries are very narrowly tipped with white.
Adults apparently have a partial prenuptial molt in late winter and early spring and a complete postnuptial molt from July to November. I have seen an adult male molting its primaries as late as January 16, which suggests the possibility of a complete prenuptial molt, but this may be only a case of delayed molt. There is very little seasonal difference in adult plumages.]
Food.--The food of the green heron varies somewhat with the locality. In birds taken in salt marshes, I have found the stomach contents to consist of the minnows common in the little creeks together with a variable amount of sand. Live stomach worms are also common, a fact mentioned by other observers. In regions of fresh water, tadpoles, water insects and their larvae, crayfish, and small bony fishes are common articles of diet. Food is also gathered in the uplands by these birds and their stomachs have been found to contain earth worms, crickets, grasshoppers, snakes, and small mammals. Grasshoppers in very large numbers have sometimes been found. B. S. Bowdish (1902) says the food of the green heron in Porto Rico: "Several stomachs examined contained respectively, remains of lizards and crabs, and one whole fish about 6 inches long; a kind of water beetle about three quarters of an inch long, many entire; crawfish and grasshoppers; 11 crawfish; small live worms." Oscar E. Baynard (1912) reports that the stomach of an adult green heron taken in Florida contained 6 small crayfish, 16 grasshoppers, 2 cut worms and the remains of small frogs.
Like the crow and black duck, it is at once a wary and venturesome bird, endowed with sufficient intelligence to discriminate between real and imaginary dangers and often making itself quite at home in noisy, thickly settled neighborhoods where food is abundant and where it is not too much molested.
The green heron is equally at home in the salt water marshes and in the regions of fresh water. It is a day feeder but prefers the early morning and late afternoon, often taking a nap at midday. One of the familiar sounds and sights by salt creek or by river or pond is the frightened cry of this bird and its awkward flight over the water. The names "skeow" and "fly-up-the-creek" are expressive of these attributes. The classic names "chalk-line" and "shite-poke" express the commonly observed physiological effect of fright. This effect must incidentally serve a useful purpose in blinding the stealthily creeping pursuer, be it carnivore or savage.
The length of the neck of the green heron in life is a most variable one and this bird well deserves to be called "rubber neck." Early one May morning I watched unseen one of these birds with its neck drawn in creeping along the branches of a spruce. In the dim light it looked more like a mammal than a bird. Suddenly it elongated its neck and seized with its bill a twig of a near-by elm, but was unable to break it off. It tried another and another and finally succeeded in tearing the green twig off from its base. I watched another bird as it awoke from its morning nap and, as it stretched its neck to an equal length with its body and shook out its feathers, the general form and appearance of the bird went through a marvelous change. In short flights this heron may retain the elongated pose of the neck, but in longer ones it folds up and retracts that member.
When walking about, especially if it knows it is watched, the green heron nervously twitches its tail downward and erects and depresses its crest. It is also able to remain perfectly still, especially when on the watch for game. A common posture assumed on the margin of the pond or sand flats at low tide is with the back and neck horizontal and the tarsi so nearly flat on the ground that the body is close to the same. The bird under these circumstances is easily mistaken for a log of wood. In this position it waits patiently, ready to pounce on the little fish that swim its way and it rarely misses its aim. At other times it approaches stealthily, putting down each foot with care and secures its prey with a quick stroke. That this stroke must be quick and accurate is evident when we consider the nature of some of its food, frogs, fish, and grasshoppers.
That green herons in some cases jump or even dive into the water after their prey, is shown in the following account by Samuel H. Barker (1901) who saw an individual plunge from a plank after fish into a pond 3 to 6 feet deep.
Although he missed his aim, the effort was well meant and, to judge by appearances, not the first of its kind. Turning about in the water, he rose from it with little difficulty and with a few flaps was back on the plank. . . . That this one instance of an individual green heron plunging into deep water after food proves such to be a natural habit of the species can hardly be said. I would add, however, that further study of the feeding habits of the green heron, with a view to settling this question, convinces me that a quite usual method of fishing is for it to watch from a stand a few inches above the water and from there to jump quickly down upon its prey.
W. Sprague Brooks (1923) watched a green heron walking stealthily along the stone rim of the Public Garden pond in Boston.
After a while it turned cautiously until facing the water, toes at the rim of the stone, its neck stretched out full length, and suddenly, as a swimmer in a race plunges from the marble rim of a tank, it plunged into the water, completely submerged, came to the surface with a goldfish which it immediately swallowed, and raising its wings, flew back, only a matter of two wing strokes, to the stone border. Twice I watched it do this.
The note commonly emitted by this bird as it flies from the intruder can, perhaps, best be represented by the syllables peu-ah. It generally resembles very closely the sound made by blowing a blade of grass stretched tightly between the thumbs side by side. When much startled the green heron croaks hoarsely but soon returns to the usual peu-ah. Sometimes, especially about the nesting tree, it may be heard to give a short cackle or cluck. Early one morning, when I was lying concealed in a grove of trees, a green heron alighted among them nearly over my head. Thereupon it emitted a series of low double groans at irregular intervals. If I had not seen the bird, I should have been puzzled as to the source of the sounds.
The small size of this heron, somewhat smaller than a crow, its short cut-off tail, its general greenish-black color with a chestnut-colored throat and bluish-gray primaries make its recognition in the field easy.
The green heron is too interesting a bird to be used for a pot hunter's target as is often the case. He who is so fortunate as to have a breeding place for this bird near him should zealously guard it and he will learn many interesting and amusing traits and will be well rewarded.
Green Heron* Butorides virescens
*Original Source: Bent, Arthur Cleveland. 1927. Smithsonian Institution United States National Museum Bulletin 135: 185-194. United States Government Printing Office