Masters of the air but unable to walk or swim, Magnificent Frigatebirds are known for their occasional acts of aerial piracy in which they chase down and force other birds to drop recently captured food. Magnificent Frigatebirds are also known to be able to survive a hurricane by riding it out in flight.
It is thought that Magnificent Frigatebirds do not breed until they reach the age of five to seven years. Females that are successful at nesting probably do not breed the following year. While it is not known how long Magnificent Frigatebirds can live, a related frigatebird species has been known to live 34 years in the wild.
Length: 40 inches
Wingspan: 90 inches
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Description of the Magnificent Frigatebird
The Magnificent Frigatebird is a dark seabird with long, narrow wings and a long, forked tail. Orange or red throat pouch.
White belly patch.
Seasonal change in appearance
Juveniles resemble adult females but have white heads.
Coastlines and islands of warm oceans.
Fish, squid, and crustaceans.
Forages by taking food from the surface of the water while flying.
Breeds on islands off Mexico and in the Caribbean, and occurs from the Dry Tortugas of Florida south to South America.
Eggs and young birds are never left unguarded by parents, because other members of the colony will eat them if given the chance.
Female Magnificent Frigatebirds are considerably larger than males.
Usually silent, although chicks give begging calls.
- Not likely to be confused with other species.
The nest is a platform of sticks placed in a small tree or on the ground.
Incubation and fledging:
– Young hatch at 40-50 days.
– Young fledge (leave the nest) in 20-24 weeks after hatching but remain with the female for some time.
Bent Life History of the Magnificent Frigatebird
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 Magnificent Frigatebird – the common name and sub-species reflect the nomenclature in use at the time the description was written.
FREGATA MAGNIFICENS ROTHSCHILDI Mathews
Now Magnificent FrigatebirdHABITS
This well-known buccaneer is widely distributed over the warmer waters and tropical coasts of both hemispheres, where several species and subspecies have been recognized by recent investigators, all of which are closely related. Its popular names, man-o’-war-bird, frigate bird, or frigate pelican, reflect its well-known character as a pirate and a tyrannical freebooter. But, with all its faults, it is a picturesque character and one can not help admiring its wonderful aerial evolutions, for which it is so highly specialized, and which make it such a noticeable and an interesting feature in the bird life of tropical seas.
Courtship: One of the most curious traits of this species is the inflation of the great red pouch of the male, which plays such a conspicuous part in his courtship. Dr. Walter K. Fisher (1906) gives a very good account of it as follows:
The man-o’-war-bird proved scarcely less entertaining than the albatrossee. The curious and excessively bizarre appearance of the male at this season of the year compels attention. His antics are as extraordinary as his looks, and when engrossed in the task of making himself attractive his self-absorption and nl)parent vanity are highly diverting. During the courting period the gular pouch of the male is enlarged, and before the brooding cares have begun he inflates It to a large size, and at the same time it becomes a bright red color. The bird looks as if there were a balloon, such as children dangle on a string, fastened to Its throat.
The pouch is apparently a large air-sac, connected only indirectly with the lungs, which can not be emptied readily nor inflated instantly. It varies In the intensity of its carmine or crimson, and catching on its surface the sheen of the sky, shows at times bluish hues, or, becoming somewhat collapsed, turns a translucent orange about the sides. It is no uncommon occurrence to see a male bird sitting on the nest with the sac blown out, obscuring the whole front of the creature, only the bill and eyes appearing over the top. For hours he sits on a newly-made nest without once leaving, or scarcely altering this position. But if the female appears somewhere overhead, sailing to and fro, he suddenly arouses himself from the lethargy, and as she passes he rises partially from a sitting posture, throws hack his head, spreads his wings, and protruding the brilliant pouch, shakes his head from side to side, uttering a hoarse cackle. Occasionally, when the femnie alights near, he waves his pouch from side to side, the head being thrown well back and the wings partially spread. At the same time the long, greenish, iridescent, scapular feathers are fluffed up and the creature presents a most unusual and absurd appearance. In this posture he chuckles again and again, and rubs his pouch against his mate, who usually Ignores him completely and flies away. These performances take place before the egg is laid; afterwards the male ceases to inflate his sac.
Nesting: Prof. Homer IR. Dill (1912) estimated that the number of man-o’-war-birds nesting on Laysan Island was about 12,500, and says: “They nest in colonies in the tops of low bushes which, if placed near together, would cover about 6 acres. As it is, however, they appear to cover many times that amount of space.” This seems like a large colony, but it looks very small beside the immense colonies of other sea birds on this wonderful island.
Of their nesting habits on this island Doctor Fisher (1906) says:
At Laysan the birds live in colonies varying from a few pairs to many, and the nests are always built on the tops of low bushes, sometimes very close together. The species has congregated almost entirely on the eastern half of the island, and their villages are spread over the inner slope of the old atoll basin. The nests, which are sometimes so old that they have become mere masses of filth, are scarcely more than platforms of sticks, not entirely devoid of leaves, woven together loosely with morning-glory (Ipomaea insalari.s) vines.
Both parents take turns in covering the egg, which is a necessity, for if the nest were left without an occupant other frigate birds would quickly appropriate its material, especially if the nest were new. Consequently, even before the egg is laid, either bird holds down the property, as it were, against marauding neighbors. After the nestling is out this vigilance is all the more necessary, for if left unprotected a young bird would very likely serve as food for some watchful reprobate of the vicinity. Mr. Snyder saw an old frigate bird snatch up and fly away with a young of the same species, whose parent had been frightened off the nest. According to Henry Palmer, who visited the island a few weeks later in 1891, this is a very common occurrence, but the young were so scarce we considered the accidental demonstration mentioned above as sufficient evidence of the heartless trait.
On the west coast of Mexico, Mr. H. H. Bailey (1906) found them nesting on Isabella Island, of which he writes:
The nests on the island were placed on the top of the bushes or on crotches of limbs, the nests being a loosely made platform of sticks and twigs, with generally a few straws or grasses on the inner surface. In some cases the nests were not more than from eighteen inches to two feet above the ground, as on the west side of the island where the bushes are low and stunted, while on the south and eastern sides they were sometimes placed as high as twelve and fifteen feet above ground, the bushes and scrubby trees here permitting of it. At the time of my visit the majority of these birds had eggs, one being a complete set. A few young birds were, however, found on the western side of the island, and it did not take the hot sun long to kill any small young that the parents left unsheltered for even a few moments. The majority of these birds were very tame, allowing one to approach within a few feet of them.
Great numbers of dead birds, hanging from the bushes by wings, feet, or heads, were scattered over the island, the cause of which I discovered when flushing one from its nest. Their short legs and extremely long wings make it a hard matter for the birds to rise from their nests, especially so when the nest is placed on the top of the bushes, and their wings come in contact with other branches in their effort to rise. A number of times as I watched them in their attempts to alight on or depart from their nest I saw them become entangled in the foliage, from which position they were unable to rise. The odor from the dead birds, with that given out by the birds themselves, was far from agreeable.
On the Galapagos Islands the man-o ‘-war birds nest in colonies on the ground or on the rocks, as well as on low bushes. But on the islands off the coast of British Honduras, Capt. D. P. ]Ingraham writes, in his notes sent to Major Bendire, that ha found them nesting in the high mangrove trees, 60 or 70 feet from the ground, several nests in a tree.
Referring to some of the breeding colonies in the Bahamas, Dr. Henry Bryant (1861) writes:
I found a few man-of-war birds breeding at the Biminis. Their nests were placed upon the mangroves, amidst those of the brown pelican and Florida cormorant. As these birds are much disturbed by the inhabitants, their breeding places will probably be given up in a few years. On the central and highest part of Booby Key a colony of about 200 pairs was breeding. The nests here were on the bare rock and closely grouped together, the whole not occupying a space more than 40 feet square. There were no boobies amongst them, though thousands were breeding on the key. The latgest breeding place visited by me is situated on Seal Island, one of the Ragged Island keys, and is 5 or 6 acres in extent. The nests, thickly crowded together, were placed on the tops of prickly pear, which covered the ground with an almost impenetrable thicket. On the 8th of April the young were hatched in half of the nests, the largest about one-third grown; the other nests contained eggs more or less hatched. Out of many hundreds, I procured only 7 that were freshly laid.
I have visited the breeding places of many sea birds before, and some well worth the trouble, but none so interesting to me as this. It was a most singular spectacle. Thousands and thousands of these great and ordinarily wild birds covered the whole surface of the prickly pears as they sat on their nests or darkened the air as they hovered over them, so tame that they would hardly move on being touched; indeed, the specimens that I procured were all taken alive with my own hands. When I had penetrated as far among them as possible, I fired my gun; the whole colony rose at once, and the noise made by their long and powerful wings striking against each other was almost deafening. In a moment they commenced settling upon their nests and were soon as quiet as before.
From Dr. Frank M. Chapman’s (1908a) contribution to the life history of this species, in the Bahamas, I quote as follows:
The luxuriant growth of cactus among the sea grapes in which the man-o~-war birds nested added to the difficulty with which these thickly branched, shrubby trees were penetrated, and we did not attempt to make a census of the numbet of birds of this species which were breeding on Cay Verde. We estimated, however, that there were between 200 and 300 pairs.
The man-o’-war birds awoke at about the same tIme as the boobies and at 5.30 a. m. were sailing over their rookery. From this time until they retired, considerably before the boobies, and while it was yet light, a flock of birds was constantly over the sea grapes. The birds may be said to have perched in the air above their homes. Only one bird is in attendance on the young at the same time. Both sexes assumed this duty, as well as the task of Incubation; but there appeared to be no regularity as to when male or female should be on guard.
The nests are frail, open-worked, slightly hollowed platforms, composed of smau sticks and twigs placed in the tops of the sea grapes, at a height of 6 or 7 feet, or among the cactuses within 2 feet of the ground. Several nests are often placed in one bush within reaching distance of one another. They become matted with filth as the young Increase in size. One adult was seen carrying nest-building material in Its bill.
Eggs: The man-o’-war bird lays but one egg, which is approximately “elliptical ovate” in shape and pure dead white in color. The shell is very thin for an egg of its size, smooth and lusterless. The measurements of 50 eggs, in several collections, average 68.4 by 46.5 millimeters; the eggs showing the four extremes measures 74 by 48.5, 72.5 by 50, 64.5 by 46, and 66.5 by 43.5 millimeters.
Young: Doctor Chapman (1908a) says of the development of the young:
The man-o’-war bird lays but one egg, and in a number of nests fresh eggs were found. The young are born naked and are brooded by the parents. As they increase in size and become covered with white down, their wings seem to he much too large for them to hold close to the body, and relaxing are permitted to rest on the nest. Their whole attitude suggests extreme dejection; not only do the wings droop, but the head often hangs over the edge of the nest. When approached they utter a squealing, chippering call, and snap their hills with a rattling sound, both the note and action strongly suggesting similar habits of the young brown pelican.
The black feathers of the interscapular region appear mimediately after the down on this portion has pushed through the skin, and “before there is any evidence of the remiges and rectrices they cover the back like a mantle * * * Not only are the wing feathers late in appearing, but the secondaries precede the primaries, the former averaging 2 inches in length, with the greater and median coverts showing, when the latter are just observable.” This seems remarkable and contrary to the rule with birds of great wing and tail development.
Plumages: The sequence of molts and plumages in this species are puzzling and their study is complicated by the prolonged and variable breeding season, which makes it difficult to estimate the age even approximately. In the juvenal or first-year plumage, the head, neck and under parts are white, in both sexes, with dusky flanks and, sometimes more or less brownish mottling on the head and neck; the lesser wing coverts are brownish and the upper parts are dull, dark brown, without any luster; the tail is comparatively short and the lateral rectrices are not much longer than the others. I have seen birds in this plumage in January, May, July, and October, from which I infer that it is worn for one year, but the date of the molt into the next plumage is very variable, depending, I suppose, on the date at which the young bird was hatched. An interesting phase of this first year plumage of the male which I have seen in nearly every Pacific specimen that I have examined and have never found in any Atlantic specimen, is the rich “cinnamon” suffusion which partially or largely covers the breast, neck, and head. Mr. Edward W. Gifford (1913) says of the birds collected for the California Academy of Sciences, in the Galapagos Islands: “Birds in juvenal plumage, have the entire head and neck a rich cinnamonrufous. No exception to this is found in the academy series.” I have also seen cinnamon-headed birds from Lower California, Necker Island, Madagascar, Laysan Island, and the Phillipines. That this character should hold constant in the large series of birds that I have examined from both oceans is confirming evidence that they are distinct species. This plumage is also probably worn throughout the first year, as I have seen it in January, March, May, September, and October birds.
After the first year the sexes become dissimilar in plumage. The male becomes much darker on the upper parts, almost black, but still lacks the glossy tints of the adult; the lateral rectrices become more elongated; and the head, neck, and under parts become mottled with dusky and white. The female acquires more dusky on the head and neck, as well as on the belly, but the breast and sides still remain white. During the third year, probably at the second postnuptial molt, when the birds are a little over two years old, the adult plumages of the male and female are assumed. The plumage of the male is then entirely black, with its beautiful metallic luster and lanceolate feathers on the upper parts; and the flight feathers have reached their fullest development; the bright red gular sac of the male is an adornment of the nuptial season only. The female in full plumage has the head and neck clear blackish brown and the breast and sides pure white; she is less glossy above than the male, there is more or less brownish in the wing-coverts, and the feathers of the upper parts are less lanceolate.
Food: The food of the man-o’-war bird consists largely of fish, but it includes much of the varied bills of fare indulged in by the various species of boobies, pelicans, cormorants, gulls, and terns on which it makes its piratical raids. It is not wholly predatory in its feeding habits and obtains much of its food by its own efforts from the surface of the sea at which it is very skillful. Doctor Fisher (1904b) says:
Frigate birds glean a portion of their livelihood from the host of creatures which live at the surface of the ocean: flying fishes, ctenophores, jelly fishes, vellela. janthina, anti in fact anything that may attract their fancy. I even observed one bird aimlessly carrying a splinter of wood, uncertain of its utility, yet unwilling to release It. As they never alight on the water they seize such bits of food by swooping down in a broad curve. They are able to measure distance so accurately that no disturbance is created when the object is grasped.
Prof. William A. Bryan (1903) has given us an excellent account of the frigate bird’s attacks on the boobies of Marcus Island, as follows:
I have before referred to the large colonies of common brown boobies about the north point of the Island. It was in the vicinity of this colony that the man-o’-war birds were most abundant. Here they would lie in ambush for the old boobies and tropic birds as they returned from the sea heavily laden with fresh food for their young. Sitting quietly on the tree tops, or more often wheeling high overhead industriously patrolling the island, out where the surf broke on the reef, these birds would keep a sharp lookout to sea for a sight of the returning fishing fleet of boobies. Sighting one (sometimes consisting of one, sometimes of several individuals), as many as half a dozen haxvks would make for them under full sail, and without a moment’s warning would engage a helpless bird in battle. Swooping down upon it from every side, buffeting it with their wings, snapping at it with their long hooked bills, flying now above, now before, now beloxv it, the hawks would so confuse their victims that eventually, feeling that the only safety for its life lay in letting go part of Its store of supplies as a sop for its assailauts to quarrel over, the booby would on a sudden drop one of Its fish, whereat a hawk would swoop down, more rapidly than the eye could follow, and catch the food before it had touched the wave, then taking It securely in Its bill would fly majestically off to feed Its own everexpectant offspring. The unfortunate booby meanwhile was farther pursued by the less fortunate hawks until, ref t of her quarry, she was allowed to return to her young.
Audubon (1840) gives the following graphic account of its fishing prowess:
Yonder, over the waves, leaps the brilliant dolphin, as he pursues the flyingfishes, which he expects to seize the moment they drop Into the water. The frigate-bird, who has marked them, closes his wings, dives toward them, and now ascending, holds one of the tiny things across his bill. Already fifty yards above the sea, he spies a porpoise in full chase, launches toward the spot, and in passing seizes the mullet that had escaped from its dreaded foe; but now, having obtained a fish too large for his gullet, he rises, munching it all the while, as if bound for the skies. Three or four of his own tribe have watched him and observed his success. They shoot toward him on broadly extended pinions, rise in wide circles, smoothly, yet as swiftly as himself. They are now all at the same height, and each as it overtakes him, lashes him with its wings, and tugs at his prey. See! one has fairly robbed him, but before he can secure the contested fish it drops. One of the other birds has caught it, but he is pursued by all. From bill to bill, and through the air, rapidly falls the fish, until it drops quite dead on the waters, and sinks into the deep. Whatever disappointment the hungry birds feel, they seem to deserve it all.
Behavior: The flight of the man-o’-war-bird is an inspiration; the admiring observer is spellbound with wonder as he beholds it and longs for the eloquence to describe it; but words are powerless to convey the impression that it creates. It is the most marvelous and most perfect flying machine that has ever been produced, with 7 or 8 feet of alar expanse, supporting a 4-pound body, steered by a long scissor-like tail. It is not to be wondered at that such an aeroplane can float indefinitely in the lightest breeze. I shall never forget an exhibition I once saw among the Florida keys. We had anchored for the night near a small mangrove key, a famous roostang place for this species, and saw that it was black with hundreds of the birds sitting on the low trees. As we rowed toward it they all arose into the air and hung over it in a dense cloud, as thick as a swarm of insects. Gradually they spread out, floating without the slightest effort on motionless wings, separating into three great flocks and then into five flocks. By counting and carefully estimating the flocks, we concluded that there were between 1,000 and 1,200 birds in all. For over an hour we watched them as they floated out over us in a leisurely, dignified manner and slowly drifted away. At times they seemed to be almost stationary and never once did we detect a flap of the long, half-flexed wings, though it was almost calm. Like painted birds upon a painted sky they faded into the shadows of the night.
The active flight of the frigate-bird and its control of its powers is fully as wonderful as its passive sailings. While floating high in the air, almost out of sight, its keen eye detects some morsel of food in the water below it; with wings half closed it shoots downward like a meteor, and so accurately does it gauge its speed and distance that, just as it seems as if it must plunge like a falling arrow into the water, it checks its momentum with a marvelous twist of its great wings and lightly picks up the morsel from the surface with its bill without wetting a feather. It indulges in some startling, playful antics in the air, performs much of its courtship on the wing, and caresses its mate as gracefully in mid-air as on the ground. It strikes terror into its victim by darting at him at such speed that it is useless for him to attempt to escape; over, under, and around him at will, as if playing with his powers of flight; it is mere sport for the man-o’-war, the swift frigate, to overtake the fastest flier, and when the poor victim drops its fish, the frigate bird quickly catches it and, perhaps, tosses it in the air, drops and catches it again as if it enjoyed the game.
While soaring, either in a calm or in the teeth of a howling gale, the long tail feathers are held parallel and close together, and are moved only slightly to steer or balance the bird, but when fighting in the air, as the males often do, or when courting or playing they are frequently opened and closed like a pair of scissors. The man-o’war-birds’ wings have been developed at the expense of its feet, which are very small and weak; it can hardly stand upon them, and can hardly walk; it never dives and is a very poor swimmer; it becomes wet and helpless in the water. But in the air it is a past master.
Harsh grating cries indulged in by fighting males, a clucking note heard during the mating season, and a rough croak are about the only sounds made by these birds as they are usually silent. The young birds are often quite noisy in the rookeries.
Enough has already been said above about the behavior of the man-o’-war-bird toward other species, by whom it is justly dreaded and cordially hated. But it is apparently sometimes moved by unselfish motives toward birds of its own species, as the following incident, related by Mr. A. W. Anthony (1898a) seems to illustrate:
At a considerable distance from the colony a bird was found that was unable to fly, and thinking that it had been recently Injured, and must necessarily starve, where food was not easily obtained by even the best of flyers, I kiUed the cripple and made an examination of Its injuries. One wing was withered and useless; evidently the bird had never enjoyed its use, though It was fat and its stomach was well filled with flying fish. Those who know the feeding habits of Fregata need not be told that all their food is obtained on the wing, and a bird deprived of the use of its wings would speedily starve if not fed by its fellows. The precipitous sides of San Benedicte also made it impossible for a ma~-o’-war-bird to gain the top of the island If deprived of its wings. So It was quite evident that the pensioner had never left the island, but had been dependent on the bounty of Its fellows all of its life. From its excellent condItion it was evident that even In that busy community of thousands some of them found time to feed the unfortunate. This remarkable exhibition of altruistic unselfishness hardly seems to be in keeping with its well-known habit of eating its neighbors’ young.
Winter: The man-‘o-war-bird is not a migratory species and is practically a resident throughout the year in the general vi6inity of its breeding range. But between nesting seasons it is apt to wander far from home and has often been noted or taken in most unexpected places, even in the interior of the continent. During the summer, fall, and winter it is often as gregarious as during the breeding season, especially in its roosts at night, where it gathers in enormous rookeries, frequenting the same roost regularly. Large flocks of man-o’-war-birds may often be seen resting on the mangroves during the daytime, in company with pelicans, cormorants, and other water birds. It is also a common sight to see them perched in flocks on sand bars, coral reefs, old wrecks, or abandoned structures, lazily digesting their food or waiting for an other meal.
Since the above life history was compiled and long since most of the above observations were made, the species then known as Fregata ce/U iia has been split into various species and subspecies, some of which are undoubtedly worthy of recognition. But rather than attempt to discuss or separate them, the author prefers to let the life history stand as it is, for the habits of all of them must be practically the same.
Breeding range: The North American form breeds on some of the Bahama Islands (Cay Verde, Biminis, Seal Key, Atwood’s Key, etc.), Cuba (Puerto Escondido), Isle of Pines, Porto Rico (Mona and Desecheo Islands), sonic of the Lesser Antilles (Guadeloupe, Battowia. Carriacou, etc.), on islands off the coast of Venezuela (Marrarita. Los etc. Los Hermanos, Testigos, ) and in the Caribbean Sea as far xvest as honduras (Little Cayman and Swan Islands). The birds breeding on islands in the tropical Atlantic, and in the Pacific and Indian Oceans are now regarded by some authorities as distinct species or subspecies, but others regard the birds which breed on islands off the west coast of Mexico (as far north as Santa Margarita Island) as identical with the birds of the West Indies. Breeding grounds protected in Porto Rico, Desecheo Island Reservation.
Winter range: Includes the breeding range and adjacent seas, extending northward, more or less regularly, to northern Florida and the coast of Louisiana. Birds which wander to the coast of California, a~ far north as Humboldt Bay, may be referable to one, 5 perhaps more, of the Pacific forms.
Casual records: Accidental in Bermuda (four records). Has wandered as far east as Nova Scotia (Halifax, October 16, 1876), as far north as Quebec (Manicouagan, August 14, 1884) and Wisconsin (Humboldt, August, 1880), and as far west as Kansas (Osborne County, August 16, 1880).
Egg dates: Bahama Islands: Twenty-one records, February 3 to May 11; eleven records, March 3 to April 16. Off west coast of Mexico: Eighteen records, January 15 to June 1.