Double-crested Cormorant

The Double-crested Cormorant is a large, black swimming bird with a long neck, long tail, and an orange throat pouch. Breeding birds have short plumes on the back of the head.  Length: 33 in.  Wingspan: 51 in.

Photograph © Greg Lavaty.

Sexes similar.

Breeding plumes behind the eye develop during the breeding season.

Juveniles resemble adults, but have a pale brownish neck and breast.

Double-crested Cormorants inhabit coasts, bays, rivers, and lakes.

Double-crested Cormorants primarily eat fish, but also many other aquatic animals.

Photograph © Greg Lavaty.

Double-crested Cormorants swim, and dive in pursuit of prey, propelling themselves with their feet.  Captured fish are taken to the surface and maneuvered so they can be swallowed head first.

Double-crested Cormorants breed along the Atlantic and Pacific Coasts, as well as inland locations in the north central and western U.S., the northeastern U.S., and south central Canada. Their population is increasing.

More information:

Bent Life History

Visit the Bent Life History for extensive additional information on the Double-crested Cormorant.

Wing Shape

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

• Male, Washington, Mar.
• From below
• Female, immature, Washington, Apr.
• From below

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

Because cormorants swallow their prey whole, they periodically regurgitate pellets containing fish bones and other indigestible materials.

Double-crested Cormorants nest colonially, sometimes in large numbers, and often with other species such as seabirds or herons.

Double-crested Cormorant populations declined due to toxins such as DDT and PCBs, but following the bans of these substances, populations have recovered.  Cormorants occasionally cause problems for fish farms.

Double-crested Cormorants  are usually silent, but they occasionally make soft grunts.

The nest is a platform of sticks and other materials placed in a tree, on the ground, or on a cliff ledge, but always near water.

Number: Usually lay 3-4 eggs.
Color: Bluish-white and often stained by nest material.

Incubation and fledging:
The young hatch at about 30 days.  Young leave the nest after about three weeks for ground nests, but later for tree or cliff nests.  Fledged young are tended for another 4-6 weeks.

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 Double-crested Cormorant – the common name and sub-species reflect the nomenclature in use at the time the description was written.

Among the passing flocks of wild fowl which migrate along the New England coast, one occasionally sees a flock of large black birds flying high in the air in a regular V-shaped formation like geese, or in single file, or rarely in an irregular bunch. At first he may mistake them for geese or brant on account of their size and manner of flight, which is heavy and strong, with rather slow wing strokes, but if he watches them carefully he will see them set their wings and scale along at occasional intervals, by which he recognizes them at once as cormorants or “shags.’~ There are two species of “shags” found on this coast, the double-crested and the common cormorant, of which the former is much the commoner.

Courtship: 0n the flat top of PercA Rock, which stands only a few rods from the shore of Perc~, Quebec, is a large breeding colony of double-crested cormorants and herring gulls, and the top of the rock is about level with the heights of Cape Cannon, the nearest point. On June 19, 1920, while watching this colony from that point through a powerful telescope, I had a good opportunity to study the courtship or nuptial greeting of this species. Many birds were standing by their mates on the nests; others were constantly coming or going. The incoming bird, presumably the male, bows to his mate and walks around her with his neck upstretched and swollen, opening and closing his bill. Then approaching his mate he begins caressing her with his bill; she steps off the nest; then both begin a series of snakelike movements of heads and necks, almost intertwining them. Finally he passes his head over, under, and around his mate, apparently caressing her from head to tail, and he or she settles down on the nest.

Nesting: Many of the birds must reach their breeding grounds on the south coast of Labrador by the middle of May or earlier, for we found their nesting operations well under way during the last week in May, and they are said to begin nest building before the snows of winter have passed away. They must be very common all along this coast, for in a 75-mile cruise from Esquimaux Point to Natashquan, Doctor Townsend and I saw three breeding colonies in 1909. These were all on low, bare, rocky islets well off the coast. The first colony visited, on May 26, was on Seal Rock, off St. Genevieve Island, a lowlying rock of less than an acre in area. From a distance we could see the large black birds sitting all over it, but as we approached it in a small boat they all flew off, and after circling about us a few times, to satisfy their curiosity, they settled down on the water to watch us.

We counted 204 nests in various stages of construction, closely grouped together on the higher portions of the rock, which was thickly covered with excrement, making the rocks quite slippery and filling the small water puddles with a putrid, vile-smelling mix ture. Some of the nests had well-made foundations of sticks, but most of them were made wholly or largely of seaweed, kelp, rock weed, grasses, feathers, and bark; they were generally lined with grasses or seaweed, and many were decorated with green sprigs of fir, spruce, cedar, or laurel; a few were still further ornamented with gull’s feathers, birch bark, or dead crabs, and one had a long curly shaving in it. A typical nest measured 22 inches in diameter outside and 9 inches inside; they were usually built up 4 or 5 inches, but one was 9 inches high. Many of the nests were incomplete or empty, but most of them contained from one to five fresh eggs. Two similar colonies containing about 75 pairs each were noted a little farther along the coast. We watched them through our high-power glasses and saw them building their nests; most of the seaweed was obtained near by, the birds diving for it in deep water and bringing it up in their bills; the sticks and green twigs were, of course, brought from the mainland several miles away. Although they were not breeding in the interior anywhere we frequently saw these cormorants flying up the rivers, probably in search of fishing grounds.

The most southern breeding resort of the double-crested cormorant that I know of on the Atlantic coast is at Black Horse Ledge, a precipitous crag of rough black rock, towering 60 or 70 feet up out of the ocean off Penobscot Bay, Maine. I visited this rock on June 19, 1899, where I had some difficulty in landing and climbing up its steep sides. I had seen eight or ten cormorants fly off as I approached and the top of the rock was filthy with their excrement and swarm ing with flies, but no nests had been built. Mr. Ora W. Knight, who told me about the colony, said that a few pairs bred there nearly every year, but did not lay their eggs until late in June or in July.

A few pairs of herring gulls also nest on this rock.

The most populous summer resort for this species that I have ever seen is Lake XVinnipegosis in Manitoba, a large shallow lake, about 120 miles long and averaging about 15 feet deep, with numerous rocky shoals and low reefs of loose boulders. The whole country around the lake is low, flat, and largely marshy, a fine country for water fowl of many species. The waters of the lake are teeming with fish, mostly white fish, pickerel, and pike, which furnish an abundant food supply for thousands of cormorants, grebes, loons and pelicans. Numerous small islands and rocky reefs furnish convenient nesting places, which are well patronized. During a short cruise of less than a week we saw no less than five breeding colonies of double-crested connorants, ranging in size from 45 to 1,500 pairs. The largest colony that I have ever seen was visited on June 18, 1913, on a small triangular island near the northern end of the lake. As we approached the island and anchored in the lea of it, preparing to land, an imense cloud of the large black birds poured off the rocky shores and began circling around us in a bewildering maze, and mingled with them were a few of the great white pelicans, which were also breeding on the island. It was an impressive sight The birds were much tamer than usual, for when we landed they were still sitting on their nests on the farther side of the island behind a little ridge, but they went scrambling off in haste and confusion as soon as we were in plain sight The cause of their tameness was soon apparent for we were surprised to find that nearly all of the nests contained young; this was rather remarkable, for none of the other colonies contained any young at all and nearly all the eggs we had collected were fresh or only slightly incubated. Perhaps this was the oldest colony, for it was by far the largest, and had been occupied by the earliest arrivals. In an average space 3 yards square I counted 25 nests and by roughly measuring the whole occupied area I estimated that there were between 1,500 and 2,000 nests in the colony. The island was about 50 yards long by 40 yards wide, consisting of a mass of boulders piled up quite high at one end with an accumulation of bare soil in the center, probably the result of generations of guano deposits. Except for a bare space in the center where the pelicans were nesting, the whole island was covered with cormorants’ nests nearly down to the water’s edge, even on and among the boulders. The nests were made of sticks, dead weeds, canes, and flags, most of which had been picked up as drift material along the shore; they were lined with straws, grasses, and often with green leaves and fresh twigs; some were decorated or lined with gulls’ feathers. One large nest measured 14 inches in height and 18 by 22 inches in diameter; most of the nests were much smaller than this and some of them consisted of only a few sticks and straws. The nests and their surroundings were far from atractive as the whole island was slimy with excrement and reeking with dead fish; the odor was almost unbearable. Some of the nests still held eggs but the great majority held young of various ages, from naked, helpless, newly-hatched chicks to well-developed, half-grown young, covered with jet black down and squa\vking vigorously.

Although I have never seen the double-crested cormorant nesting in trees, as is the universal custom with its southern representative, the observations of others indicate that it frequently does so in the southern portion of its range in the interior of the United States. Mr. 1?. M. Barnes (1890) has described a large herony, formerly existing in Illinois, in which these cormorants nested with great blue herons and American egrets, all three species building their nests in trees, just as they do in Florida. More recent information on the nesting of double-crested cormorants in Illinois is given us by Mr. Frank Smith (1911). Mr. Arthur H. Howell (1911) describes a recent colony in Arkansas, as follows:

A large colony, probably the only large one now remaining In the State, breeds in a rookery at Walker Lake, Mississippi County, In company with great blue herons and water-turkeys. When I visited this rookery the first week In May, 1910, I found the cormorants sitting on their nests in the tops of the tall cypresses growing in the lake. The nests, of which there were between 100 and 200, were placed in crotches either close to the trunks or some distance out on the limbs and were compactly built of green cypress twigs with a few strips of bark as a lining. Most of the nests examined contained three or four bluish eggs, but in one were four little naked coal-black cormorants a few days old. The number of nests in a single tree varied from 1 to 6: usually S or 4: and In many instances the cormorants shared the tree with several great blue herons. Specimens taken in this colony are referable to the northern form, and this Is probably the southern limit of Its breeding range.

Mr. P. A. Taverner (1915) found a colony of about 30 pairs near the Gasp6 Basin in Quebec, where the nests were built in trees, mostly small birches, growing from the top and upper face of a bluff overlooking the sea at a height of about 150 feet, a most unusual situation.

Eggs: The double-crested cormorant lays ordinarily three or four eggs, frequently five, rarely six, and I have taken one set of seven. They vary in shape from elongate ovate to cylindrical ovate. Their color is very pale blue or bluish white, more or less concealed by a white calcareous coating which is thinner than in some other species, and they are often badly soiled or nest stained.

The measurements of 40 eggs in the United States National Museum and the writer’s collections average 61.6 by 38.8 millimeters; the eggs showing the four extremes measure 65.5 by 40, 63 by 42, 56 by 38, and 57.5 by 36.5 millimeters.

Young: The young when first hatched are purplish black in color, naked, blind, and helpless. Their downy covering begins to grow when they are about 10 days old, and at the age of about three weeks they are fully covered with thick, short, black down. The plumage appears first on the wings and scapulars; the wings and tail are practically fully grown before the body plumage is fairly started, which does not appear until the bird is fully grown; the head and neck are the last portions to become feathered when the bird is about six weeks old. A populous colony often contains young birds of all ages from naked helpless chicks to full sized birds, and presents a most interesting, if not an attractive, picture. Such a colony is the filthiest place imaginable, for no other birds can equal cormorants in this respect. The nests and their surroundings become thoroughly whitewashed with excrement, which also accumulates in slimy pools swarming with flies; the nests are often alive with fleas, lice, and other vermin; and the odor of decaying fish scattered about adds to the nauseating stench. Among such unhealthful surroundings the young cormorants begin life and seem to flourish. At first they are too xveak to even hold up their heads, and the heat of the sun on the black, naked bodies often brings fatal results, if they are left too long without the brooding care of their parents. Even when older and covered with black down, they seem to suffer greatly with the heat, panting with wide open mouths, the gular sacks vibrating rapidly as if in distress; perhaps this action may be caused by fear rather than by suffering, but it strongly suggests the panting of a dog on a hot day.

The young are fed by their parents until they are fully grown and able to fish for themselves; at first the helpless youngster sips the semidigested liquid food from the tip of the old bird’s bill; later on he learns to thrust his head and neck deep down into the parental throat where he finds a more substantial supply of food; and finally when he has learned to eat solid food his fish are brought to him whole. The young remain in the nests until about fully grown, but after their wings and tails are grown and while their bodies are still downy they begin to wander about and gather in groups near the shore; they walk about freely, exercising their wings and legs, but do not attempt to enter the water; if one falls into the water by accident, it makes no attempt to swim and soon becomes thoroughly water soaked and chilled. Mr. Ilersey once rescued one from such a predicament, which seemed to be benumbed and lay fiat on the rocks as if dead, although it had been in the water but a few seconds. As soon as the body is fully feathered the young bird takes to the water and soon learns to swim; probably it learns to catch fish before it can fly, which accomplishment is not acquired until it is about eight weeks old.

Plumages: The first winter plumage is complete in September, being acquired gradually from the downy stage, as explained above, and is worn with but slight progress toward maturity during the following winter and spring. The plumage of the back suggests the color pattern of the adult, each brown feather being bordered with brownish black, but it is dull and lusterless, instead of glossy greenish black; the under parts are dull brown, lighter on the throat and belly than elsewhere; the colors become lighter and duller as the season advances, by wear and fading. The progress of the molt into the next plumage is very variable; some vigorous individuals begin to molt as early as February, but with most birds this does not begin until late in the spring or in the summer; the latter is probably the normal time at which the first postnuptial molt takes place. This molt is complete, though much prolonged, and produces the second winter plumage, which is similar to that of the adult when complete. It is often not completed, however, until the latter part of the winter, when the bird may be said to be in its second nuptial plumage. This is similar to the adult nuptial plumage except that the crests are lacking on the sides of the head. Up to this time the young bird has been undergoing an almost constant change and development of plumage and it is now ready to breed.

The plumage changes of the adults are simple; a complete postnuptial molt in the late summer produces the winter plumage and a partial prenuptial molt early in the spring produces the nuptial plumes on the sides of the head which are characteristic of the mating season and constitute the only marked difference between the nuptial and the fall or winter plumages. These nuptial plumes are apparently shed during the nesting period, as they are seldom seen after the season is well advanced.

Food: The food of the double-crested cormorant consists almost entirely of fish, which it obtains by diving from the surface or swimming below it, at which it is an adept, capable of making great speed under water, diving to great depths and remaining under for a long time. I have seen it stated that cormorants use their wings in flying under water, but I doubt if they do so regularly; their long slender bodies and powerful totipalmate feet are highly specialized for rapid swimming, without the aid of wings. On the New England coast they are frequently seen flying up the larger rivers and tidal estuaries to fish, where they live largely on eels. Mr. George H. Mackay (1894) makes the following interesting statement regarding the food of this species in Rhode Island:

All the double-crested cormorants (P. dilophus) obtained had eels (AnguWa vu~oaris Turton) in their throats. In four of the birds the heads of the eels had been apparently torn off and they rested In the throat in every instance In the form of a loop or ox bow, the two ends being nearest the stomach. In the fifth and largest bird an eel in perfect condition, measuring sixteen Inches long and one Inch in dIameter, rested lengthwise In the throat with the tall at the mouth. Those taken from the other four birds were seven to ten inches long. It would therefore seem that eels constitute a large part of their food In this locality, at least at this time. I also picked up on the top of the rock an eel In a partially dried condition, minus its head, which was probably seven or eight inches long before the head had been torn off. It was in the form of an ox bow or loop, having dried as It was probably ejected.

He also speaks in the same paper of finding their ejected pellets of fish bones on a rock off Seaconnet Point, Rhode Island:

On the fiat top of the rock I found and saw a large number of curious balls (and brought fourteen away with me) varying from an inch to two inches In diameter and composed almost entirely of fish bones, chiefly the bones of young parrot-fishes (Labroids) and drums (Sciaenoids) firmly cemented together with gluten, hard in the dried specimens and soft and gelatinous In those more recent. One of the largest of the former, which was five and a quarter inches in circumference and quite black, while all the others were of a light color, contained three crabs (Cancer irroratuj Say: Panopcus sayi Smith) in a fairly perfect condition, with some of the claws still remaining in place, showing that they were probahly swallowed whole. I am consequently Inclined to the opinion, in the absence of absolute facts, that these birds, like the owls, have the power of ejecting indigestible substances.

Mr. Taverner (1915) says of their fishing habits:

In the morning us soon as the sun is well up the cormorants fly in through the narrow channel separating the basin from the bay, their numbers increasing until about nine o’clock, when most of the birds are to be found fishing in the shallow water at the head of the basin. On first coming in they alight in the water, look about a minute, and then disappear with an easy gliding dive. They generally remain under the water for about a minute. If they have been successful in their fishing, their prey can be easily seen when they reappear. They catch a fish crossways, and it takes a little manipulation and sundry jerks of the head to get it placed properly in the mouth; then there is an upward flirt of the bill and the fish Is swallowed. A few gulps are given and the bird Is ready to repeat the operation.

He says of their food:

With the exception, then, of a few wandering birds, the cormorants feed either along the sea coast, as at Perc4, or in the tidal mouths of the rivers. ~Ve collected some thirty stomachs from such localities, but none of them contained salmonoid remains. The food contents were mostly capelin, flounder, herring, and an occasional eel and tom cod.

Of the thirty-two stomachs examined, five were empty, one so nearly so as to make the contents unrecognizable, and two were from nestlings with contents regurgitated from the parents’ throat and, having been subject to double digestive action, were not recognizable.

Of the remaining twenty-five, sixteen contained sculpins, five herring, one each capehin and eel, and two tom cod or allied fish. Nearly all had asearia and other parasitical remains. The evidence Indicates that these were incidentally obtained from the flesh of the original hosts. In many stomachs there were fragments of ed-grass, crustaceans, molluscs, and pebbles, but in small quantities and evidently derived from the stomachs of the prey or taken accidentally with it.

Behavior: Except for an occasional hoarse grunting croak, when alarmed, I have never heard the double-crested cormorant make any vocal sound whatever and believe it is usually silent. Its flight, which I have previously described, is characteristic of the genus, slow and heavy, with occasional periods of scaling. When flying from a spar buoy, one of its favorite perches, it drops downward at first nearly to the water and flies along close to the surface, rising in an upward curve to its next alighting place. On bright, sunny days it frequently stands on some convenient perch in an upright position, with its wings outstretched in spread-eagle fashion, enjoying a sun bath. Unless facing a strong wind it experiences considerable difficulty in rising from the water, pattering along its surface for a long distance.

Winter: As soon as the young birds are large enough to fly they gather into great flocks and prepare for the fall migration, which begins in August. They are deliberate in their movements, loitering along the coast for two or three months. In Massachusetts the main flight passes between the middle of September and the first of November. The south Atlantic and gulf coasts are the principal winter resorts of the double-crested cormorants, where they mingle with their close relatives, the Florida cormorants, and lead a similar roving life.

On the North Carolina coast Mr. T. Gilbert Pearson (1919) says that this is the common cormorant in winter and that ” as evening comes they congregate in flocks of from ten to forty individuals, and in solid ranks, go flying low over the water to some favorite ‘lump’ of shell or small sandy island on which to roost.” Once he “dug a hole in the shells of a miniature island, where, lying concealed, he was enabled to watch unobserved the hundreds of cormorants which came there to roost. Without exception the flocks all pitched in the water a short distance away, and later swam leisurely ashore.”

Mr. Arthur T. Wayne (1910) says that, on the coast of South Carolina,” every afternoon these birds fly out to sea to pass the night, and at break of day flock after flock may be seen returning to the tidal creeks and sounds in quest of food.”

DISTRIBUTION
Breeding range: Temperate North America, east of the Rocky Mountains. East to the Gulf of St. Lawrence (from Cape Whittle to Perch Rock). South to the coast of Maine (Penobscot Bay), west central Ohio (near Celina. formerly at least), central Illinois (Havanna and Persia, on Illinois River), northeastern Arkansas (Walker Lake. Mississippi County), central northern Wyoming (Buffalo), and northern Utah (Great Salt Lake). West to above point and south central Alberta (Buffalo Lake). North to central Mackenzie (Great Slave Lake), central Manitoba (Lake Winnil)egosis) and James Bay. Utah records may refer to aibodliatus or the two forms may intergrade here. Breeding grounds protected in the following reservations: In Quebec, Pcrc4 Rock; in North Dakota, Stump Lake; and in Arkansas, Walker Lake.

Winter range: Mainly on the Atlantic and Gulf coasts from New Jersey to northern Florida and Louisiana. Has been recorded as far north in winter as eastern Maine (Calais) and Michigan (Grosse Isle).

Spring migration: Northward along the coast and throughout the interior. Early dates of arrival: New York, Long Beach, March 31; Massachusetts, Plymouth County, March 26; Quebec, Godbout, May 19; Illinois, Mount Carmel, March 1: 7; Michigan, Ann Arbor, April 12; Manitoba, Shell River, May 13. Late dates of departure: New Jersey, Sea Island City, May 23; New York, Montauk Point, May 15; Rhode Island, Newport, May 17; Massachusetts, June 18; Missouri, St. Louis, May 22; Louisiana, Lake Catherine, April 14.

Fall migration: Reversal of spring routes. Early dates of arrival: Massachusetts, Essex County, August 22; New York, Montauk Point, August 26; New Jersey, Wildwood, August 30; Missouri, October 5. Late dates of departure: Quebec, Montreal, November 1; Massachusetts, Essex County, November 24; New York, Onondaga Lake, November 30; Pennsylvania, Erie, December 14; Michigan, Ann Arbor, November 25; Illinois, Chicago, November 20.

Casual records: Wanders occasionally to Bermuda (October 10, 1847, February 8, 1848, etc.)

Egg dates: North Dakota and Minnesota: Thirty-one records, May 12 to July 11; sixteen records, May 23 to June 15. Manitoba and Saskatchewan: Eighteen records, June 4 to July 21; nine records, June 14 to 18. Quebec: Six records, May 26 to June 30. Utah: Five records, April 9 to May 17.

FARALLON CORMORANT
PHALACROCORAX AURITUS ALBOCILIATUS Ridgway
HABITS

This name is somewhat misleading, for this is the least abundant of the three species of cormorant known to breed on the Farallon Islands; it is much more abundant at many other places; and it is widely distributed from southern Oregon to Lower California, breeding on the islands along the coast and in many lakes in the interior. It has a much wider range and is much better known than the northern subspecies, the white-crested cormorant. Its life history is so similar to that of the eastern double-crested cormorant that it would involve a useless repetition to give much more than a brief account of some of its characteristic breeding colonies.

Nesting: Mr. W. Otto Emerson, in his notes Sent to Major Bendire says that on the Farallon Islands they begin to assemble about the first of April or earlier if the season is favorable.

They gather about the old rookeries and collect great pieces of dry kelp and Farrallone weed to repair their old nests; they may be a month or more about the nests, adding bit by bit to the home; sometimes all leaving for a fishing trip to sea, then back again, sitting around the nests or on them; purloining one from another’s nest to add to its own; bits of sea-moss and broken sticks are stuck in the nest here and there. By the first of May some of the nests contain eggs, both sexes sharing the work of incubation, one staying on the eggs to protect them from the thieving gulls, while the other is off fishing. I found these cormorants to be the tamest of the three species on the island; one can get up to within two feet of the nests.

The tameness of the Farallon cormorant has been referred to by several writers and a number of good photographs of birds on their nests have been taken at short range; this trait is not shared by the eastern subspecies which is usually so shy that it is difficult to come within gunshot of one on its nest.

Mr. Milton S. Ray (1904) describes the nests of this species, on the Farallon Islands, as follows:

The weed nests were like those of the gull but much larger and shallower, measuring twenty inches across, the cavity being nine in width and three in depth. I counted but forty-seven nests in the colony, which shows that the numberï of these birds, now the least abundant cormorant on the islands, Is continually decreasing. On subsequent visits we noticed the birds did not relay in the nests from which we had taken eggs. The gulls did not molest the eggs and young in this rookery, for the reason the old birds did not give them a chance, they settling back on the nest as soon as we passed it. While It was interesting to watch these avian snakes in their summer home, the decaying remains of numerous fish about the colony and the swarms of seal-files rendered it a pleasant place to be away from.

A vast breeding colony of this cormorant was found on San Martin Island, Lower California, by Mr. Howard ~V. Wright (1913) he made a careful estimate of the area covered by this colony and figured that it occupied about ij square miles; then allowing one nest for each 100 square feet, based on a count in an average measured area, he concluded that the colony contained the astonishing number of 348,480 nests. This is certainly the largest colony of cormorants of which we have any record. He says:

We became very much interested in estimating the amount of fish these birds consumed per day. We noted the amount each young cormorant threw up when molested, and found on several occasions a bunch of fish as big as a man’s two fists. This mass was generally composed of surf fish, smelt, and sardines. I have heard of other estimates of from three to six sardines a day for a cormorant, so I consider a half pound of fish a day very conservative.

Allowing half a pound of fish a day for each of the 1,800,000 birds, the entire population would consume four hundred tons a day or about ten thousand tons a month. The fishing was done In San Quentin bay, exclusively, but in that bay and in Hassler’s Cove, on the Island, fish were found very plentiful, and always hungry, showing that the birds do not seriously lessen the number of fish.

Referring to the early morning flight witnessed at this island, he writes:

From the hills there poured a steady stream of cormorants, flying about eight or ten abreast. This stream poured from these hills continuously and reached as far as we could see, toward the bay of San Quentin. The stream was like a great black ribbon that waved In the breeze and reached to the horizon. It was truly a wonderful sight. The birds kept coming as though there were no limit to their numbers.

At about seven-thirty a stream began to return, each individual heavily laden with fish. The ribbon of birds was now double: one part leaving and the other returning. The flow of birds was continuous during the daylight hours of each day we were there. The flow was unbroken: simply one steady stream going, all day, and a steady stream returning.

A colony found by Dr. Joseph Grinnell (1908) on an island in Salton Sea was evidently much like inland lake colonies of the eastern subspecies. lie says of it:

A census of cormorant’s nests showed 147 containing eggs, besides many others partly built. The nests were tail, compact structures composed altogether of angular shrub-trunks, and lined with mesquite barkstrlps and old feathers. The outer basal sticks and the surrounding rocks were ail whitewashed with excrement. A typical nest was 414 mm high and 552 mm across, slightly saucered. The tendency seemed to be to locate the nests en prominent rock ledges or pinnacles. The number of eggs in a nest ranged from one to six, commonly four or five.

Several writers report inland colonies nesting in trees. One of the most interesting of these is described by Mr. Corydon Chamberlain (1895) as follows:

Early in March of the present year I visited Lakeport (California), a small town on the west shore of Beautiful Clear Lake in Lake County. Big Valley lying on the south side of the upper basin of the lake is a forest of large white oaks. The trees extend down toward the lake as far as the moist soil will support them. Some trees standing within a hundred yards of the low water mark are wholly or partially dead, as though the unfavorable moisture of the soil had early completed the work of senile decay. In such a place where they were within easy reach of their feeding grounds, the cormorants occupied a rookery that had been in use many years.

We landed on a graveily beach (the only one for several miles) among some willow bushes and poplar trees. A number of cormorants fluttered excitedly from the poplars and flew away in a frightened manner. Under these trees we found pieces of carp which the birds had dropped and the whole place had a vile smell. About two hundred yards beyond us were two trees covered with cormorants. Both of these trees stood apart from the great body of the forest and one of them was dead, only the trunk remaining, and that, though bleached, was charred deeply on one side. The other had some bunches of leaves about the body and a few more trailing from the ends of some branches, but the upper parts were white, seemingly dead, but really covered with the limey excrement of the birds. South of the trees in the edge of the forest were several containing nests but none having the bare appearance of the two described. There were probably a hundred nests in this rookery all built in the very highest places in the trees. I found no nest lower than 75 feet from the ground, while the average height was about 80 feet. Those measurements were made with a tape from the treetop. One tree, which contained a few nests, looked to be considerably over a hundred feet high, though I did not climb it to verify my estimation.

Of the two trees described the dead one contained a single nest and the other one 19. As I climbed the latter tree all the cormorants left their nests and perches and went wheeling around until I descended, when they ininiediately settled down on their empty nests seemingly as contented as over. Of the 19 nests in the tree all but one contained complete sets of eggs, the usual number being four, though sets of three and of five were common. All of the sets were incubated slightly, though not enough to cause trouble in blowing. The nests were solid, well-built affairs, having a width of from 15 to 20 inches and a depth of about 6 or 5 inches. They were built of oak twigs and the stalks of marsh weeds as a base, seine of the oak twigs having leaves on them; and dead tubs and other green weeds from the lake as a lining. Sumac had a further lining of green oak leaves. The birds continue to put on nest materials after the eggs are laid. Some birds could be seen flying around with great ribbonlike tules streaming from their mouths.

Mr. A. B. Howell writes to me:

June 8, 1912, C. C. Lamb and I found them breeding abundantly at Buena Vista Lake, California. Their nests were either near those of the white pelicans or in the standing dead timber in the mouth of the Kern River, and held eggs in various stages of incubation. At Salton Sea they also breed in the dead trees in the uater near the shore, and as the sea is receding rapidly. tbe height of the water from year to year may be gauged accurately by the position of the old nests on the shore.

Eggs: The eggs of the Farallon cormorant can not be distinguished from those of the double-cresteti cormorant, though eggs from northern latitudes average larger than those from southern localities. The measurements of 71 eggs, in the United States National Museum, average 62.9 to 38.8 millimeters; the eggs showing the four extremes measure 69.5 by 40.5, 68.5 by 42.5, 54 by 37, and 67.5 by 36 millimeters.

The sequence of plumages, the behavior and other details of the life history of the Farallon cormorant are apparently similar to those of the double-crested cormorant. It is a common and wellknown bird throughout its range. Together with the Brandt cormorant, with which it is often associated, it is a familiar feature at all seasons along the California coast, frequenting all suitable fishing grounds about the islands or perching conspicuously on buoys, posts, or floating timbers about the harbors.

DISTRIBUTION
Breeding range: Paeifie coast region of United States and Mexico. On inland waters from southern Oregon (Lake Malheur and Klamath Lakes) to western Nevada (Pyramid Lake) and southern California (Salton Sea). On islands off the coast from northern Oregon (Three Arch Rocks) southward along the coasts of California and Lower California to the Revillagigedo Islands. The breeding birds of Great Salt Lake may be intermediate between this and the eastern form. Breeding grounds protected in the following reservations: In Oregon, Three Arch Rocks, Kiamath Lake, and Maiheur Lake; and in California, Farallon.

Winter range: Includes most of the breeding range, except perhaps the more northern inland resorts, and extends to the valley of the Colorado River and the Gulf of California.

Egg dates: F’arallon Islands: Twenty-seven records, May 9 to July 12; fourteen records, I~1ay 30 to June 28. Los Coronados Islands: Eighteen records, March 27 to June 3; nine records, April 3 to May 10. Oregon, California, and Nevada: Twelve records, February 5 to June 6; six records, April 20 to May 20.

FLORIDA CORMORANT
PHALACROCORAX AURITUS FLORIDANUS (Audubon)
HABITS

About the mangrove keys of southern Florida, principally in that broad expanse of shallow water known as the Bay of Florida, between Cape Sable and the Keys, this smaller form is exceedingly abundant and one of the characteristic birds of the region. It is decidedly gregarious in its habits, flying about in large flocks and roosting in immense numbers on certain keys, .to which it regularly resorts, the mangroves becoming thoroughly whitewashed with the accumulated droppings of hundreds of cormorants. These roosts are occupied by day as well as by night and it is an interesting experience to row around one of them in a small boat and see the great black birds pour off the trees down to the surface of the water and go flying off in large flocks. They are much tamer than their northern relatives, as they are seldom molested. They are called “niggergeese” by the natives, who consider the young good eating, but even the negroes and conchs do not care for adults.

Courtship: As I have never witnessed the nuptial performance of this species I must quote the following graphic account from the pen of the illustrious Audubon (1840):

The Florida cormorant begins to pair about the first of April, and commences the construction of its nest about a fortnight after. Many do not lay quite so early, and I found some going through their preparations until the middle of May. Their courtships are performed on the water. On the morning, beautiful but extremely hot, of the 8th of that month, while rambling over one of the k: eyes, I arrived at the entrance of a narrow and rather deep channel, almost covered by the boughs of the mangroves and some tall canes: the only tall canes I had hitherto observed among those islands. I paused, looked at the water, and observing it to he full of fish, felt confident that no shark was at hand. Cocking both locks of ray gun, I quietly waded in. Curious sounds now reached my ears, and as the fishes did not appear to mind me much, I proceeded onward among them for perhaps a hundred yards, when I observed that they had all disappeared. The sounds were loud and constantly renewed, as if they came from a joyous multitude. The inlet suddenly became quite narrow and the water reached to amy arm pits. At length I placed umyseif behind some mangrove trunks, whence I could see a great mmii umber of cc mom mints not inure than fifteen or t~venty yards from me. None of them, it seemed, had seemi or heard me; they were engaged in going through their nuptial ceremonies. The males, while swimming gracefully around the females, would raise their wings and tail, draw their head over their back, swell out their neck for an instant, and with a quick forward thrust of the head utter a rough, guttural note, not unlike the cry of a pig. The female at this mmmonicut would crouch as it were on the water, sinking into it, xvhea her mate would sink over her until nothing more than his head was to be seen, and soon afterwards both sprung up and swam joyously around each oilier, croaking all the while. Twenty or inure pairs at a time were thus emngaged~ Indeed, the water was covered with cormnomants, and had I chosen I might have shot several of thema. I now advanced slowly toward them, when they stared at me as you might stare at a goblin, and began to splash the water with their wings, many diving. On my proceeding they all dispersed, either plunging beneath or flying ott. and making rapidly toward the mouth of mime inlet. Only a few nests were on the mangroves, and I looked upon l:he spot as analogous to the tournamneul grounds of the pinnated grouse, although no battles took place in my presence. A few beautiful herons were sitting peaceably on tli,~ir nests. time mosquitoes were very abundant, large, ugly blue land crabs crawled among the umangroves, hurrying toward their retreats, and I retired, as I had arrived, in perfect silence. While proceeding, I could not help remarking the instinctive knowledge of the fishes, and thought how curious it was that, as soon as they had observed the cermuorants’ hole none had gene farther, as if they were well aware of the danger, but preferred meeting me as I advanced toward the birds.

Nesting: The most northern breeding colony of the Florida cormorant that I have heard of was well described Lv Mr. 1′. Gilbert Pearson (1905) as lie found it during the early days of June, 1904, in Great Lake, among the cypress swamps of eastern North Carolina, and surrounded by a heavy forest, far from the haunts of man. On his former visit to time lake he had found 150 pairs of cormorants breeding here, but the colony has decreased in numbers since. I quote from his description of time colony as follows:

The colony at that time was found to lie iii the height of the breedimig season. The heavy nests of sticks arid twigs occulmied low-spreading cypress trees standing solitary here and there in time ~vater, usually from fifty to one hundred yards from shore. A unrulier of the trees ~vere occupied by the domicile of a single pair of birds; others comitained two, three, five, seven, or eight nests; one tree held sixteen and another thiiry-six cradles of these great birds. One hundred and twenty-one homes of the cormorants were counted, twenty-eight trees in all being used for their accommodation.

Alligators gather about the colony, probably to feed, in part, upon the fragments of food which fall from the nests above. Six were counted at one time within easy rifle range of the boat. One of the young, while climbing along a slender limb, lost its balance and fell with a splash into the water. It immediately dived, and, coming to the surface about twenty feet away, began swimming up the lake with long and rapid strokes. By the time I had descended to the boat ~vith my cameras the bird was fully fifty yards away. To our horror, a large alligator had given chase, and was rapidly approaching the swimmer. We immediately started in pursuit, and, after an exciting chase, rescued the young cormorant; but not until the alligator had made two unsuccessful snaps at his intended victim, which escaped only by diving with marvelous quickness just at the proper instant.

Mr. C. J. Pennock (1889) described a somewhat similar colony, nesting in large cypress trees in an inland pond, near St. Marks, Florida. His account of the immense size of the trees chosen and the unusual height of the nests is well worth quoting:

The nests were placed for the most part on the horizontal limbs well out from the body of the tree, some, however, ~vehl op in the tops of the trees. Eight trees were occupied, and ninety-seven nests were counted. The largest tree xvas at least six feet in diameter at a height of eight feet from the ground, and carried its size in good proportion well up to the lo~ver limbs, xvhich we estimated to be over sixty feet from the ground. This tree contained txventythree nests, but none of the others had over sixteen nests. The lo~vest nest was over fIfty feet from the ground, the majority ~vere over sixty feet high, and on the large tree referred to several nests must have been one hundred feet high. This tree, by the way, was not molested by our party; the combined girth of the strap and a pair of long arias not being sufficient to compass it by fully six feet.

I think the above two instances nine rather unusual, although illustrating the nesting habits of the Florida cormorant in inland lakes, for this cormorant evidently prefers to frequent the shores, hays, estuaries, inlets, and mouths of rivers, where it is more frequently found nestina in low red mangrove trees or bushes on islands. On my first visit to Cuthbert Lake, near Cape Sable in southern Florida, we found, on May 1, 1903, a colony of about 600 Florida cormorants nesting on a small mangrove island with large numbers of Louisiana and little hlue herons, American egrets, white ibises, roseate spoonbills, and water-turkeys. The cormorants’ nests were on the extreme outer edge of the red mangroves which grew well out into the water of the lake. The nests were closely bunched in compact colonies on the very tops of the trees or bushes, from 6 to 10 feet above the water, which was from 2 to 3 feet deep at this point. They xvere well made of sticks, compactly interwoven, and were lined with green leaves, but, like all cormorants’ nests, they were very filthy; the nests and the trunks, branches, and leaves of the trees were completely whitewashed with excrement, which peeled off in large flakes, where it had become dry, making climbing very unpleasant. Most of the nests contained two or three eggs each, but in some cases we found newly hatched young, black, naked, and feeble. The old cormorants were quite tame and soon returned to their nests even within 10 feet of us. Their only note was a loud guttural croak or grunt, which seemed to roll up through their long necks with a hollow, rattling noise. I visited Cuthbert rookery again on March 29, 1908; the herons were incubating on full sets of eggs, but the cormorants had not begun to lay at that time. Apparently the Florida cormorant does not ordinarily lay its eggs before April, probably early in that month in the southern portion of its range and later farther north, but evidently not until May in the Carolinas. Its nesting habits seem to vary considerably in different localities, as do those of its relatives, but, as far as I know, it never nests on the ground. Some observers state that it uses no lining in its nest, but, as most cormorants do line their nests with grasses, leaves, or other soft substances, it is probably exceptional when it fails to do so.

Eggs: The Florida cormorant usually lays three eggs, sometimes only two, or rarely four; except for an average difference in size, they are not distinguishable from those of its northern relatives. The measurements of 41 eggs, in the United States National Museum and the author’s collections, average 58.2 by 36.8 millimeters; the eggs showing the four extremes measure 64.5 by 38.5, 62 by 39, 50 by 35, and 53 by 33 millimeters.

Food: The feeding habits of the Florida cormorant are similar to those of the northern subspecies. Mr. John T. Nichols (1918) speaks of seeing “a school of porpoises breaking not far from our anchorage,” with “three or four cormorants following them closely, screaming and making short flights, diving close after them.” He refers to this as a common habit, perhaps for the purpose of securing pieces of fish left by the porpoises. According to Mr. T. Gilbert Pearson (1919), “In the summer of 1905 H. H. Brimley saw an immature bird disgorge a portion of a large water snake (Natria, taa,ispilota).”

In other respects the life history and habits of the Florida cormorant are not essentially different from those of the double-crested cormorant, though it is less migratory and, except in the northern portion of its breeding range, is practically resident..

DISTRIBUTION
Breeding range: On the Atlantic coast from North Carolina (Craven County) southward, along both coasts of Florida and the coast of Louisiana; on some of the Bahama Islands (Great Abaco Andros Island, and probably others); and on the Isle of Pines. Has been recorded as breeding in southern Illinois and Ohio, but these birds are now considered referable to auritus, though perhaps they may be intermediate.

Winter range: Practically resident throughout its breeding range. Winter range includes most of the Bahamas, the Greater and Lesser Antilles, and the coasts of Texas, Honduras, and Yucatan. Withdraws from the Carolinas in winter.

Egg dates: Florida; thirty-six records, March 5 to June 21: eighteen records, April 3 to May 14.

WHITE-CRESTED CORMORANT
PHALACROCORAX AURITUS CINCINATUS (Brandt)
HABITS

The northwestern race of the double-crested cormorant is restricted in the breeding season to the northwest coast region from southern Alaska to Oregon. Reported records of its breeding in the interior are probably erroneous and refer to the eastern subspecies, or to the Farallon cormorant; such errors may have arisen from the fact that in high nuptial plumage a few white feathers are occasionally found in the crests of the eastern bird. All of the subspecies of Piwlacrocora~ auritus habitually shed their crests during the season of incubation, the long curling plumes serving merely as courtship and nuptial adornments. The species can always be distinguished, however, from the other Pacific coast species by the conspicuous yellow gular sac.

Nesting: The best known breeding resorts of the white-crested cormorant are in the great sea-bird reservations off the coasts of Washington and Oregon, which have been so well described by Mr. XV. L. Dawson and Prof. Lynds Jones in their various writings. I can not do better than to quote freely from one of Professor Jones’s (1908) excellent papers on the subject, as follows:

The proper study of the white-crested cormorants (Phelecrocora~r dilophus c~,zcinatus) was made during our stay on Carroll Islet. The reader has already seen enough pictures of the rocks and islands characteristic of this coast to become familiar with the precipitous sides, jagged outlines, verdure-clad top, and crumbling ledges. The accompanying halftone pictures will give some idea as to what parts of Carroil Isiet these cormorants select as nesting sites, and illustrate certain details which the camera was able to record. These pictures represent two somewhat different kinds of nesting places, and fairly represent the life of these birds during the breeding season.

Figure 2 is a representation of nearly the entire colony which occupied a sharp ledge jutting out from the northeast corner of the island, a ledge with a sharp and jagged summit ridge, as the picture shows. This was the only colony of this species found In such a situation. Figure 1 represents a part of one of the other and apparently more usual nesting site of this species: a rather narrow ledge of hroken shelving rock at the foot of a precipice or overhang. Apparently any relatively flat space sufficiently large to accommodate the nest may he utilized, either upon the sharp ledge or precipice’s foot A careful scrutiny of any of the nests shown will reveal the fact that one of the prime requisites in a nesting site for the individual nest is that on one side the ground or rock must fall abruptly away. It is on this side that the excrement forms a limy smear, often extending many feet below the nest The uphill side of the nest is always relatively clean.

Nests are made of coarse sticks arranged much after the manner of a hawk’s nest, cupped to the depth of five or six inches, and with a lining of grassy materIal which covers scarcely more than the bottom of the depression. The sticks used were such as might have been found upon the Island, and the grass seemed to correspond to that within a short distance of the colony. There was no evident attempt at conceahnent In any case, nor was there any clear indication that any nests were placed with a view to shelter either from the weather or from the scorching rays of the sun. The evident distress of both old and young birds when exposed tO the direct sunlight would certainly afford excuse enough for seeking a shady nook among the rocks. The very young birds were nearly baked when left uncovered for any great length of time. One such died under our eyes, evidently from the heat The varying ages of the young: none of which were yet feathered: and the fresh eggs In a nest which showed no signs of having been a victim of the pilfering crows, both point to the conclusion that there must be a great deal of Individual variation In the time of nesting of these birds. It is true that nests containing fresh eggs may represent a second set after the loss of the first one, but the fact that none of the young birds were anywhere near ready to leave the nests seem conclusive that only one brood is reared in a season. The nesting season was too far advanced to afford any opportunity for studying nest building or egg deposition.

The colony shown in Figure 1 was shared by a few California murres who occupied the spaces between nests which were level enough to keep an egg from rolling into the water, or off from the ledge. There was no apparent discord in such a mixed colony, even though the murres were within reach of the weapons of the cormorants. In one other place the same conditions prevailed. I could discover no reason for regarding this as a case of true communalism. If there was any benefit derived from this association it must have been to the advantage of the murres.

Besides these tivo nesting sites there were a few small ledges on the ocean side of the island ~vhere we found nests of this species, usually not more than two or three nests together. Here there was some distant intimacy with Baird cormorants, but the different manner of nesting of these two species precludes the possibility of any competition between them.

The perpetual noises made by the birds of the island seriously interfered with any careful study of the various notes of these cormorants. When the old birds were disturbed or alarmed they gave vent to a spluttering squawk and often a low grunting. The young yelped something like a puppy, particularly when they were calling for food. They were usually silent when crouchlag away from danger. The very young birds showed no fear, but the older ones clearly did.

Eggs: The eggs of this subspecies seem to be scarce in co11ection~.

They are apparently indistinguishable from eggs of the other subspecies. A small series of 0 eggs collected by William L. Dawson on the coast of Washington average, in measurements, 62.4 by 40.8 millimeters; the eggs showing the four extremes measured 64.2 by 42, 59.4 by 40.2, and 00.7 by 40.2.

Behavior: It hardly seems necessary to go into further details of the life history of this bird, about which comparatively little has been published, as it is the rarest and the least known of the four subspecies. There is no reason for thinking, that it differs essentially in its habits from its better known relatives.

Winter: Mr. William H. Kobb4 (1900) say of its winter habits, near Cape Disappointment, Washington:: This cormorant is a very abundant species during the entire year, but especially so in the winter and spring. They are rather wary birds to hunt, but may always be shot while sitting upon the stakes which support the fish pots. They sometimes perch upon these poles for hours and oftentimes may be seen with their wings half spread, by which means they dry them. Although the birds remain throughout the summer, I did not find them nesting upon the numerous cliffs of the cape and am certain they do not breed in th!s locality.

DISTRIBUTION
Breeding range: Northwest coast region. From the coast of Washington (The Olympiades) northward throughout southern Alaska to Kodiak Isand and the base of the Alaska Peninsula (Lake Iliamna). Aleutian Islands records are open to question. Breeding grounds protected in the following reservations: In Alaska, St. Lazaria, and Forrester Island; and in Washington, Flattery Rocks, Quillayute Needles, and Copalis Rock.

Winter range: Practically resident in its breeding range.

Egg dates: Washington: Four records, June 3, 12, and 20, and July 10.