Snail Kite

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 Snail Kite – the common name and sub-species reflect the nomenclature in use at the time the description was written.

The Tamiami Trail runs due west from Miami for 35 miles straight through the southern half of the Everglades. For most of this distance one sees only a broad expanse of marsh, mainly covered with long grasses as far as one can see, but dotted here and there with little clumps of small trees or bushes, with an occasional island of larger trees and bushes, amphibian willow, alligator apple, waxmyrtle, swamp bay, silver-leaved magnolia, and cocoa plum. Toward the western border the grassy glades are dotted with very small isolated cypresses, 8 to 10 feet high, so scattered that the broad view is not obstructed. Farther west the cypress becomes thicker and taller, often forming dense cypress clumps. During wet seasons these glades are covered with clear, fresh water 1 or 2 feet deep; but since the drainage operations in dry seasons the glades are mainly dry and the abundant bird life disappears. The winter of 1929 and 1930 was unusually rainy, the glades were full of water, and we were favored with many interesting views of water birds. Little blue herons, in both blue and white plumages, were the most abundant birds, feeding in the shallow water or flying away in immense flocks to their evening roosts; with them were many American and snowy egrets and Louisiana herons; and frequently a stately Ward’s heron stood and calmly watched us as we drove by. This was the former home of the everglade kite, and here it was that we saw a lone individual in March 1930. After many days of careful scrutiny of every hawk, crow, or other suspicious bird, we finally discovered one sitting on a tiny cypress in the western part of the glades. Its slaty-gray appearance attracted our attention, but when it spread its broad wings and circled over the marsh, showing the white base of its tail, both above and below, and we caught a glimpse of its reddish legs as it wheeled, all doubt was dispelled. Twice we saw it dart down into the grassy marsh, pick up something, and alight on a small cypress to eat it. This was probably a snail and we thought we could see it extract the meat with its long, hooked beak.

When I first visited southern Florida, in 1904, everglade kites were breeding commonly all through the southern Everglades, west of Palm Beach and back of Miami and Homestead; there was even said to be a breeding colony of them near Paradise Key, now Royal Palm State Park. But the draining of the Everglades has changed all this; most of their former haunts are so dry, except during especially wet seasons, that the great marsh snails (Ampullaria dep’ressa), their principal food, have died and their pearl-like egg clusters are no longer seen on the marsh vegetation; during temporary wet spells the snails do not become established again and the kites must look elsewhere for their food supply. What few everglade kites still remain to breed in Florida may be found only where there are permanently wet marshes and where the snails still survive, such as still exist in some portions of the upper St. Johns River region. Further drainage operations may dry up these marshes, and these interesting birds will disappear permanently from the North American fauna. On March 20, 1930, we visited one of the localities in Brevard County, where the evergiade kites were still breeding in some vast marshes near the river. These marshes were very difficult to explore, as the water was from knee deep to waist deep; the vegetation was so thick and high that in many places a man disappeared from sight while wading; and it was infested with plenty of deadly moccasins. The deeper and more open spaces were full of floating “lettuce” and “bonnets”, with yellow flowers in bloom; and among them were a few large white pond lilies. There were many large and small clumps of sawgrass and large areas of lower growth of Sagittaria and Pontederia; in some places were patches of blue Iris in bloom and some extensive tracts of cattails (Typ/ia). There were large islands, small clumps, and isolated bushes of myrtle and willow, a few scattered small cypresses, and occasional tangles of morning-glory vines. Here also we saw the usual Florida marsh birds, both gallinules, limpkins, herons, white ibises, bitterns, grackles, and blackbirds. Such was the setting in which we located five or six pairs of kites, but we found only one empty nest.

Courtship: I did not see anything at the above locality that I thought was a courtship performance, but one of my companions on that trip, John H. Baker, told me that he saw a group of three kites soaring at a height of about 500 feet above the marsh; they were seen repeatedly folding their wings for sudden dips of short duration, much as do kingfishers and terns when plunging.” After some 5 minutes spent in these evolutions they set their wings and sailed away out of sight. Such behavior in March looked like part of a courtship display, but it may have been caused by the presence of two men in the marsh hunting for nests. Dr. Charles W. Townsend (1927) witnessed a somewhat similar performance, which he describes as follows:

In the marshes of the upper waters of the St. John River, Florida, on March 4, 1926, I watched three of these birds flying together. Presently one departed and the other two circled about, darting at each other from time to time.

Occasionally one would turn on its side and stretch out Its legs as If to grapple. After playing in this way for a short time, one of the Kites circled upwards and, reaching a considerable elevation, dove swiftly downwards with wings curved back, and then turned completely over, end to end. This maneuver was repeated several times, the bird crying out at the same moment In a bleating fashion very much like a sheep.

Nesting: While I was collecting near Miami, Fla., in 1903, a guide brought me a set of three evergiade kite eggs, together with the parent bird, taken near there on April 28. He described the nest as located 7 feet up in a solitary “custard apple tree” about 9 feet high, in a sawgrass slough; it was made of sticks and leafbearing twigs, with both dry and green leaves, and was lined with fine twigs and bay leaves.

C. J. Maynard (1896) seems to have been the first to discover the nest of this species. His first nest “was small, flat in form, composed of sticks somewhat carelessly arranged, and was placed on the top of the grass [sawgrass] which supported it and which grew so luxuriantly at this point that it bore” him up as he “was endeavoring to reach the nest.” About three weeks later, on March 24, he found another nest in a magnolia bush; “it was placed about four feet from the water, was quite flat, about a foot in diameter, was composed of sticks quite carelessly arranged, lined with a few dry heads of sawgrass and contained one egg.”

Bendire (1892) quotes J. F. Menge as writing to him: “According to my observations the female does not assist in the building of the nest. I have watched these birds for hours. She sits in the immediate vicinity of the nest and watches while the male, builds it. The male will bring a few twigs and alternate this work at the same time by supplying his mate with snails, until the structure is completed.”

Bendire continues:

A nest of this species now before me, taken by Mr. Menge, and kindly forwarded, measures 16 by 13 inches in diameter, and Is about 8 inches thick. It is not an artistic looking structure, but rather carelessly put together. The base consists of dry willow twigs, some of them half an inch In diameter; the greater portion are, however, smaller. The Inner cavity is about 7 Inches wide by 1′,~ Inches deep. This Is lined with small stems of a vine and a few willow leaves. The latter look as If the twigs, to which some of them are still attached, might have been broken off by the birds while green; the first mentioned material predominates in the lining.

Donald J. Nicholson (1926), who has had considerable experience with this kite, has found as many as 10 nests in one day; these were in two separate colonies about 150 yards apart. Three of the nests were in sawgrass clumps, but all the others were built in dead or partly dead myrtles, 3 to 71/2 feet above water. He says of one nest: “The nest was a fairly compact structure, about one foot deep, and fifteen inches across, with a hollow for the eggs, three and one-half inches deep. Upon nearing the nest the female flew towards me with a cackling note similar to that of an Osprey, but finer in tone, and not so loud. Soon the male appeared, scolding with notes exactly like those of the female. At times they both circled around together, again only one flew around while the other sat perched on a myrtle nearby.”

A set of four eggs in my collection is said to have been taken from a “nest of sticks and grasses on the ground in a dense marshy growth.” In Argentina the South American subspecies often nests in colonies. Major Bendire (1892) quotes Mr. Gibson, as saying: “In the year 1878, I was so fortunate as to find a breeding colony in one of our largest and deepest swamps. There were probably twenty or thirty nests placed a few yards apart in the deepest and most lonely part of the whole ‘cafiadon.’ They were slightly built platforms, supported on the rushes and 2 or 3 feet above the water, with the cup-shaped hollow lined with pieces of grass and water rush.”

Eggs: The evergiade kite usually lays three or four eggs, but sometimes only two. These are mostly oval in shape, with an elliptical tendency in some; the shell is smooth but without gloss. The ground color is dull white or rarely creamy white, but is usually mostly concealed by profuse markings. Some eggs are heavily and boldly blotched, some irregularly spotted or blotched, some finely sprinkled with minute dots, and some washed with light browns, “hazel” or “ochraceous-tawny”, so completely as to conceal the ground color. The markings are usually in shades of “chestnut”, “auburn”, or “chocolate”, but sometimes lighter browns, “hazel” or “tawny”; rarely the browns are combined with “fawn color” or “cinnamondrab” in a pretty pattern. An occasional egg is largely white with only a few scrawls or small spots of dull light browns. The measurements of 65 eggs average 44.2 by 36.2 millimeters; the eggs showing the four extremes measure 59.4 by 37.9, 47.4 by 38.3, 40.1 by 34.8, and 43.9 by 33 millimeters.

Young: The period of incubation seems to be unknown. Both sexes incubate and assist in the care of the young. Mr. Nicholson (1926) says: “When a nest was found with young, the little fellows would remain perfectly quiet and still; sometimes one would squat in the nest as if to hide. The note of the young birds is hard to describe but is much different from that of the adult. On April 27, young kites six days old were in the downy stage, and upon our return May 12 they were practically fully feathered and would have likely been able to fly by May 20. They showed a remarkable growth in sixteen days’ time.”

Mr. Menge wrote to Major Bendire (1892): “They feed and care for their young longer than any other birds I know of, until you can scarcely distinguish them from adults.”

Plumages: A small downy young everglade kite, recently hatched, is sparsely covered with short down, “cartridge buff” in color, tinged with “cinnamon” on the crown, with “cinnamon” and “snuff brown” on the rump, and with “warm sepia” on the wings. On an older downy young this first buff down is being replaced by short thick down of a much darker color, “dark grayish brown.” The bill in both cases is long and decidedly hooked.

In fresh juvenal plumage the young bird is quite richly colored. The crown and occiput vary from “sayal brown” to “ocliraceoustawny”, heavily streaked, especia1ly on the occiput, with “mummy brown”; the under parts are “ocliraceous-tawny” to “tawny”, heavily marked with “mummy brown”, in the form of narrow streaks on the throat and involving large central portions of the breast feathers; the flank feathers are “mummy brown”, notched with “tawny”; the tibiae are unmarked “tawny”; the primaries are nearly black, tipped with ”cinnamon”; the tail above is ”mummy brown” to nearly black, broadly tipped with “cinnamon-buff”; the upper tail coverts are “warm buff” to “light buff”; the rest of the upper parts are “mummy brown”, broadly tipped with “cinnamon~~ or “cinnamonbuff” on the back and wings, except that the lesser coverts are very broadly edged with “tawny” or “russet.” The sexes are about alike in this plumage, but they can be distinguished by the tails, which show the same differences as in adults.

The juvenal plumage is worn through the first winter, subject to much wear and fading, the lighter edgings disappearing by wear and the bright colors fading to pale buff or nearly white; I have seen this faded plumage in March, April, and May birds. But usually an extensive molt takes place in spring, at which the sexes begin to differentiate. This molt involves much of the body plumage, the wing coverts, and the tail. Young males acquire much slate-colored plumage on the upper parts and some on the breaK; but, in both sexes, much of the new plumage of the under parts is broadly edged or notched with “tawny” or “cinnamon.” Whether this plumage is worn throughout the second year the material does not show. An adult male that we collected, and another that we saw closely, in March, were molting the primaries, so it may be that the complete annual molt begins in spring and that the young birds referred to above were undergoing a molt into a second-year plumage. Summer and fall material is needed to settle the question.

Some of the manuals imply that the sexes are alike, in adult plumage, or fail to make the difference clear. They are easily recognized in life. The female is somewhat larger than the male; her general color is “mummy brown” or “bister”, instead of bluish slatecolor, mixed with whitish or pale buff below, with much whitish streaking on forehead and throat and with duller colors on the soft parts; the under side of the tail is different, the dark portion being browner and more restricted and the subterminal light portion more extensive.

Dr. Alexander Wetmore (1926) has described the colors of the soft parts as follows: “The immature female taken October 28, when fresh, had the bill, anterior to the cere, black; base of bill, including the mandibular rami, the skin back as far as the eye and a narrow external rim on the eyelids zinc orange; iris liver brown; tarsus and toes dull yellow ocher; claws black. The male in adult plumage secured on October 31 had the bill mainly black; cere, bare skin in front of eye, gape, and mandibular rami flame scarlet; iris carmine; tarsus and toes apricot orange; claws black. The adult thus was much brighter in color.”

Food: The everglade kite has been well named “snail hawk”, for it feeds exclusively on the meat of a large fresh-water snail (Ampullaria depressa), which formerly abounded all over the Everglades and is still abundant in some other fresh-water marshes and sluggish streams in Florida and in many places in South America. It is useless to look for this kite where these snails have been killed off by drainage or drought, as in southern Florida. Their presence can be detected by their pearly egg clusters on the sawgrass or reeds. The kites search for the snails in the open places in the marshes or in shallow ponds, beating slowly back and forth, low over the ground, after the manner of marsh hawks, or hovering over the water like a gull. When the snail is located the kite plunges down to secure it and flies with it in its claws to some favorite perch on a stump, post, low tree, or bush; often an old deserted nest is used as a feeding station. Here the snail is neatly extracted with the aid of the kite’s long hooked beak, admirably suited for the purpose, and the shell is dropped unbroken. That the birds use the same perch regularly is shown by the large number of empty shells often found in such places, sometimes as many as 200 or 300. There is no evidence to indicate that this kite ever eats anything but these mollusks.

Dr. John B. May (1935) quotes Herbert Lang (1924) as follows, regarding its methods of feeding, as observed at Georgetown, British Guiana:

The snails remain in the water during the hotter part of the day, but In the early morning and late afternoon are found at the surface or creeping about on the marsh vegetation. The kite quarters back and forth low over the water, suggesting a sea gull at a distance. Often it hovers over one spot for a considerable interval, then dives down to pick up a snail which It carries In its talons to some favorite perching place In a bush or low tree. Here It stands for several seconds motionless, on one leg, holding the snail In the long claws of the other foot. Soon the snail, which had withdrawn Into Its shell when picked up, closing tightly its operculum, begin~ slowly to extrude Its slimy body. Suddenly, like a flash the Kite grasps the body of the snail, between the operculum and the shell, in its blunt-edged hut deeply hooked beak. The muscular contraction of the snail’s body apparently detaches It from Its attachment within the shell, and a moment later, with a shake of the Kite’s head, the shell is tossed aside and the body swallowed, Including the operculum.

Behavior: Although it has a broad expanse of wing, this kite flies with a slow, desultory flight; it seemed to me rather floppy and heronlike, as if lacking the muscular power to move its great wings vigorously. Its flight has been compared to that of the marsh hawk, as it flies low over the marshes while hunting. But it often soars to great heights, gliding along easily and gracefully; its slender body is easily supported on its broad wings and tail. Bendire (1892) quotes Selater and Hudson: “When soaring, which is their favorite pastime, the flight is singularly slow, the bird frequently remaining motionless for long intervals in one place, but the expanded tail is all the time twisted about in the most singular manner, moved from side to side, and turned up, until its edge is nearly at a right angle with the plane of the body.”

It is a gentle, harmless species and lives so peacefully with its neighbors that even the small song birds do not seem to fear it at all. It is not particularly shy and sometimes even shows some curiosity; one that we were watching from the Tamiami Trail twice flew out over the road near us, as if to look us over. About its nest it is mildly solicitous, but not bold enough to attack the intruder.

Voice: Mr. Nicholson (1926) heard, upon nearing the nest, “a cackling note similar to that of an osprey, hut finer in tone and not so loud.” Dr. Wetmore (1926) found them rather noisy; they “emitted a rasping chattering call that was audible at no great distance.” Bendire (1892) gives it as “a peculiar cry, resembling the shrill neighing of a horse.”

Field marks: The eveeglade kite can be easily recognized at a great distance by its dark color, its broad rounded wings and square tail, and by its slow flight. When nearer, the white upper and under tail coverts are quite distinctive and the brilliant orange-colored feet and cere are very conspicuous, especially in the male.

DISTRIBUTION
Range: Florida, Cuba, eastern Central America, and South America.

The everglade kite breeds north to northwestern Florida (probably rarely Waukeenah and near Crescent City). East to Florida (near Crescent City, Lake Norris, St. Johns Marsh, probably Micco, Fellsmere Marsh, Loxahatchee Marsh, Lake Hiepochee, Miami, and probably Cuthhert Lake); Cuba (Isle of Pines); British Guiana (Demerara River, Mahaica River, Abary River) ; southeastern Brazil (Iguape) ; and Argentina (Buenos Aires, Barracas al Sud, and Cape San Antonio). South to Argentina (Cape San Antonio, Espartilla, Conchitas, and Tucuman). West to northwestern Argentina (Tucuman and Jujuy); Ecuador (Babahoyo); Colombia (Remedios. l3onde, and Barranquilla); Nicaragua (Los Sabalos and Ometepe Island in Lake Nicaragua); Guatemala (probably Lake Peten); Veracruz (Catemaco, Cosamaloapan, and Mirador); and northwestern Florida (Wakulla Springs, and probably rarely Waukeenah).

The range as outlined is for the entire species. The North American form, R. s. plumbeus, is probably confined to the peninsula of Florida, Cuba, eastern Mexico, and Central America.

Migration: It appears likely that the everglade kite withdraws slightly from the northern and southern limits of its range during the winter seasons, but the extent of the movement is not known. The species has been observed to arrive in the vicinity of Waukeenab, Fla., on May 9, while in the Province of Buenos Aires, Argentina, Dr. Wetmore found them fairly common on October 28 and judged that they had only recently returned from the north.

Egg dates: Florida.: 68 records, February 15 to July 20; 34 records, March 13 to April 28.