Neotropic Cormorant

The Neotropic Cormorant is a small cormorant with a long tail, dark plumage, and a yellow throat pouch bordered with white.

White plumes on sides of neck.

Photograph © Greg Lavaty

Sexes similar.

Loses white neck plumes in winter.

Juveniles are browner.

Lakes and tidal areas.

Fish.

Forages by diving underwater.

Resident in south-central and southwestern portions of the U.S. and from Mexico to South America.

Incubation typically begins when the second egg is laid.

The Neotropic Cormorant was formerly known as the Olivaceous Cormorant.

Grunts or croaks are occasionally given.

The nest is a platform of sticks on the ground or in a tree.

Number: 3-4.
Color: Bluish-white.

Incubation and fledging:
– Young hatch at 25-30 days.
– Young fledge (leave the nest) in 49-56 days after hatching but remain with the adults for some time.

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

This small, but handsome, cormorant is a tropical species which extends its range northward over the Mexican border and into the southern part of the Mississippi valley. It has also been found breeding in some of the West Indes. It is the only one of the North American species of cormorants that I have not seen in life. Comparatively few ornithologists have studied its habits and still fewer have published anything about it, so its life history will be rather meager. It seems to be rare north of Texas and Louisiana, but on the coasts of southern Texas and Mexico it is a common bird of the salt water lagoons, rivers, and inland lakes, much resembling in appearance and behavior the well known Florida cormorant.

Nesting: It is apparently not a migratory species, being a resident throughout the year over practically all of its range and having a much extended breeding season. Dr. E. W. Nelson (1903) has given us the best account of its habits and I shall quote freely from his notes. On Christmas day, 1902, he discovered a breeding colony of Mexican cormorants on Lake Chapala, Mexico, of which he writes:

In the afternoon a long line of whitened bushes growing in the open water some distance away was pointed ont by onr host who said he had passed there a short timo beforo and found a lot of cormorants nesting in them. I could scarcely credit this but the whitened appearance of the bushes showed that the birds used the place as a roost at least and I decided to investigate. As we poled near enough we sn~v that the bushes, or small trees, which projected twelve or fifteen feet from the water were full of cormorants and many could be seen standing on nests. We stopped the boat when within one hundred yards and after removing our clothing slid cautiously overboard into from three to four feet of water. Camera in hand Goldman and I stalked the birds to within about forty yards and secured a few exposures. The bushes extended in a narrow belt for about two hundred yards in the otherwise open water and in them were perched between two to three hundred birds. At our first stop the outstretched necks and changing position of some of the birds gave evidence of their uneasiness and as we waded still nearer most of them flew clumsily down into the open water. After moving out a hundred yards beyond the line of bushes they formed a black line on the water where they remained as long as we stayed in the vicinity. When the birds became alarmed at our approach they began a curious guttural grunting which came In a low continuous chorus from those left In the bushes as well as those in the water. These notes sounded much like the low grunting of a lot of small pigs while feeding. As we waded among the hushes the birds which had remained by their nests pitched off Into the water one after the other and swam out to join the main flock; or took wing, and after a short detour, came circling close overhead, uttering at short Intervals their guttural notes of alarm or protest.

The nests were strong platforms placed on forking orandlies and measured about 15 Inches across and 4 to 6 inches deep, with a shallow depression In the top. They were composed entirely of small sticks compactly arranged, as Is shown In detail In the accompanying photographs. From one to half a dozen nests were placed in a bush and we planted our tripods In the muddy bottom, and, standing nearly waist deep in the water, secured good pictures before calling up the boat and getting aboard. As the bushes were scattered, we had no trouble in poling about and examining the nests at leisure. Most of them were just completed and contained no eggs. Quite a number had a single egg and in a few cases two eggs were found. A series of 18 eggs were taken. They are rather small for the size of the bird and have a palegreen ground color overlaid with the usual chalky white deposit which gives them a greenish-white shade.

Mr. J. H. Riley (1905) found a colony of this species breeding in the Bahamas, of which he writes:

A colony of these cormorants was breeding In some tall mangroves In the large salt-water lake on Watlings Island. Most of the young were found sit. ting on the edge of the nests, that were 15 to 20 feet up, or on the limbs out of the nest. Some of the young were already In the water with their parents, though they could not fly, apparently. A few nests contained heavily Incubated eggs. This was on July 11. A few cormorants were seen on the salt pans around Clarence Harbor, Long Island, but as none were shot here their Identity is in doubt, though they appeared to belong to the same form as those shot on Watlings. The young are eaten by the inhabitants and are said to be very good. The numerous downy skins found along the shores of the salt lakes on Watlings would Indicate that young cormorant Is quite an item in the domestic economy of the Islanders.

Eggs: The Mexican cormorant usually lays four or five eggs, similar to other cormorants’ eggs in shape and texture. The ground color is pale bluish white, but it is almost entirely concealed by a thin coating of white calcareous deposit and the eggs are often nest stained. The measurements of 41 eggs, in various collections, average 53.7 by 33.8; the eggs showing the four extremes measure 58 by 35. 57.5 by 37, 47.5 by 33.5, and 50 by 29 millimeters.

Plumages: T have never seen the naked or the downy young of this species, nor can I find any description of either in print. The nesting season is so prolonged and variable that it is usually impossible to even approximately guess at the ages of immature birds in collections, but apparently the sequence of plumages to maturity is similar to that of other cormorants. In the fresh juvenal plumage, in which I have seen birds in November, January, and April, the head, neck, and under parts are deep, rich, dark brown, “Yandyke or “warm sepia,” paler on the throat and darker on the crown, flanks, and lower belly. This plumage is probably worn for about a year, but it wears and fades out to much paler colors, nearly to white on the throat and belly. The upper parts are much as in the adult, but duller and browner, with less conspicuous black edgings on the back and scapulars. The fully adult nuptial plumage is not acquired until the second breeding season. Adu1ts in winter plumage are similar to those in breeding plumage, except that they lack the white plumes about the head and neck, where there is also more brownish mottling. I have seen adults in full nuptial plumage in July, August, September, November, and December. There is probably one complete molt each year and one partial molt; the tail is apparently molted twice.

Behavior: Doctor Nelson (1903) writes of the behavior of Mexican cormorants as follows:

Last March we camped on a small river at the bottom of a deep canyon in central Michoacan; tbis stream runs a tortuous course between high rocky walls and at short intervals breaks into foaming rapids. Our camp was on a narrow sandy fiat at the water’s edge, under the overhanging branches of some small mahogany and other trees that had secured a foothold in the talus at the foot of a cliff. As we lived here unsheltered except by the foliage, the happenings among the wild life of this solitary place were under constant observation. Among the Interesting daily events was the passage up the river each morning of several Mexican cormorants, always flying singly, their glossy black plumage gleaming in the intense sunlight as they turned. They were evidently on their way to some fishing ground higher up, and several hours later: usually about midday: came back following, as in the morning, all the wanderings of the river, and giving a touch of completeness to the wild character of the surroundings.

In the summer of 1897 we found them in abundance about the lagoons and rapids of the coast country in southern Sinaloa, and especially at some shallow rapids in the Rosario River a few miles above the toxvn of Rosarlo. During the early part of the rainy season the river was low and at the place mentioned a short descent in the boulder-strewn bed of the stream made a stretch, forty or fifty yards long, of brawling rapids. Every morning dozens of cormorants flew up stream to the rapids from the mangrove-bordered lagoons near the coast. They flew low along the water, sometimes singly and sometimes in small parties, usually keeping side by side in a well-formed line when two or more were together. For a time most of them perched about on the numerous projecting stones in the river, preening their plumage and sunning themselves; others swam idly in the slow current about the rapids. At such times the brilliantly green masses of foliage bordering and often overhanging the water, the swift dark stream broken by jutting rocks on which were the numerous, black, sharply outlined forms of the cormorants, and overhead the crystalline depths of the morning sky of the rainy season made a wonderfully beautiful picture.

When a considerable number of cormorants had congregated they seemed to become suddenly animated by a common purpose and followed one another in swift flight to the foot of the rapids. There most of the assembled birds alighted and formed a line across a considerable section of the river. Then with flapping wings, beating the surface of the water into foam, the black line moved up stream, the birds showing much excitement, but keeping their places very well. The surface of the water was churned to spray by the strokes of so many powerful wings and feet, yet in the midst of the apparent confusion the birds could be seen darting to one side or the other, or spurting a few feet ahead on the line, and sometimes disappearing for a moment below the surface, but nearly always securing a fish. When they reached the head of the rapids the birds flew heavily to their perching stones, or swam slowly up the quiet surface of the river. After a short rest the line would reform and again beat up the rapids and this was repeated until the birds had satisfied their hunger.

The cormorants evidently fully appreciated the advantages of thus working in company, so that a fish trying to escape from one bird would almost certainly become the prey of another. The purpose of beating the surface of the water with their wings ivas evidently in order to alarm and confuse the fish so that they would dart blindly about and become more easily captured. I have seen parties of gannets doing the same thing in the midst of fishes off the Tres Marias Islands.

When the corroorants were gorged they deserted the fishing ground for the day and streamed back down the river to the lagoons, where they perched motionless for hours in large mangroves or other trees along the edge of the water.

The west coast lagoons are long lakelike bodies of brackish water varying greatly In size and proportion but nearly always fringed by a more or less dense growth of mangroves. These are low, rarely rising over twenty-five or thirty feet, and as the leafage begins at the water’s edge they present a solid wall of dark green, back of which often rises the larger growth of scattered forests. Here and there among the mangroves occur dead and weathered trees, or, lacking these, wide branching living trees which project over the water. These are favorite congregating places for the Mexican cormorants which, with their somewhat grotesque outlines, form a conspicuous figure of the bird life In such localities. These birds are not considered game by the Mexicans and this combined with the hIgh price of ammunition, is sufficIent to protect theni from wanton killing so that they are not often disturbed and will permit a canoe to approach within easy gunshot before they clumsily take flight. They are heavy-bodied and awkward and frequently fall from the perch into the water and try to escape by swimming in preference to flight. When driven to take wing from such a perch they commonly make a broad circuit and returning pass near the canoe and turn their heads in evident curiosity to examine the cause of the alarm. Their flight like that of other cormorants Is steady and rather labored, and as they circle about an Intruder they often glide for some distance on outspread wings, turning their long outstretched necks toward the object of their curiosity and presenting almost as grotesque an appearance as the snake-bird.”

Mr. H. H. Bailey (1906) saw numbers of cormorants which he took to be of this species fishing near the surf on the west coast of Mexico. Mr. C. William Beebe (1905) says that “their food in the barrancas is partly vegetable, not exclusively fish.” What we know about the behavior and voice of the species is included in the above quotations and I regret that I can add nothing more to its life history. There seems to be no fall migration and its winter home and habits are probably the same as at other seasons.

DISTRIBUTION
Breeding range: Tropical North and Central America. North to northwestern Mexico (Guaymas), southeastern Texas (Brownsville), southern Louisiana (lAke Arthur), Cuba, Isle of Pines, and Bahamas (Watling Island). South to Nicaragua. South American birds are subspecifically distinct.

Winter range: Resident throughout its breeding range.

Casual records: IIas wandered north to Colorado (near Denver, October 15, 1899); Kansas (Lawrence, April 2, 1872); and southern Illinois (near Cairo, spring 1879).

Egg dates: Texas: Eighteen records, February 8, October 12 and 16. Mexico: Four records, May 10, 12, and 20 and December 25. Louisiana: Three records, May 29.