Neotropic Cormorant Life History

Habitat

Habitat Lakes and Ponds

The Neotropic Cormorant is a very versatile species that occupies a tremendous variety of fresh, brackish, and saltwater wetlands. In the United States, these cormorants are equally at home on inland lakes and coastal bays. The water bodies they use typically have plenty of fish and places where the birds can rest, such as trees, pilings, rocks, islands, duck blinds, or embankments. Along the coast of the Gulf of Mexico, they inhabit estuaries, lagoons, inlets, and bays. Usually, their habitats are sheltered (and relatively shallow) rather than exposed to high winds and waves. Away from the coast, they use freshwater marshes with open water, wooded swamps, fish farms, borrow pits, lakes, reservoirs, and rivers. Usually, the waters in which they forage are relatively clear, but on occasion they forage in murky waters. South of the United States, Neotropic Cormorants occur in similar habitats as well as open ocean coasts, interior river systems, and in high-elevation lakes and streams (to 16,000 feet elevation).

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Food

Food Fish

Neotropic Cormorants eat mostly fish and shrimp, as well as frogs and insect larvae such as dragonfly nymphs. They hunt prey visually, pursuing fish or other prey by diving and swimming, capturing the item with the bill. When they take small fish, they usually consume them quickly. With larger prey, they may bring them to the surface to soften them or to remove aquatic vegetation before swallowing. On occasion, these cormorants also dive from the air, usually making a shallow, angled dive while flying very low over the water’s surface. In this case, they are hunting schools of small bait fish that have gathered near the surface. Normally, Neotropic Cormorants hunt by themselves or in small, uncoordinated flocks, but sometimes they hunt as a group, beating their wings on the surface to force schools of fish into shallower water where they make easier prey. Neotropic does not dive as deeply, or for as long, as the larger Double-crested Cormorant, nor does it forage as far from land. Unlike some cormorants, Neotropic only hunts during the daytime. Among known prey items are a host of both saltwater and freshwater fishes: western mosquitofish, sailfin molly, sheepshead minnow, striped mullet, Atlantic croaker, gulf killifish, bayou topminnow, golden topminnow, bullhead minnow, pugnoe minnow, warmouth, bluegill, pinfish, inland silverside, common carp, spotted gar, black crappie, white crappie, spotted sunfish, orange-spotted sunfish, redear sunfish, longear sunfish, green sunfish, blacktail shiner, red shiner, golden shiner, bowfin, threadfin shad, gizzard shad, channel catfish, freshwater drum, and largemouth bass.

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Nesting

Nest Placement

Nest Tree

The male selects the nest site, in a small tree (often a dead tree) or tall shrub, but sometimes on a human-made structure or on bare ground.

Nest Description

Both male and female construct a sloppy-looking platform of sticks, lined with twigs, leaves, grass, feathers, small bones, shells, or algae. Nests average about 13.5 inches across and 5.6 inches tall, with interior bowl about 8.4 inches across and 2.2 inches deep.

Nesting Facts
Clutch Size:1-6 eggs
Egg Description:

Light blue.

Condition at Hatching:

Naked and helpless.

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Behavior

Behavior Surface Dive

Neotropic Cormorants spend much of their time out of the water, resting or holding the wings open to dry. After a short time in the water, their plumage becomes waterlogged, which reduces their buoyancy, making it easier for them to swim quickly underwater and capture prey efficiently. While drying, they often preen the plumage, using the bill to take oil from the uropygial gland at the base of the tail and spread it through the feathers. As the breeding season approaches, males select a nest site, usually in a tree or tall shrub, and wave their wings while calling in a display to attract a female. When a female appears, males raise the head and neck, open the bill, and sway slowly, giving a long call. Both male and female build the nest, with the male bringing the material and the female placing it. Both incubate the eggs and greet the returning mate with a display, pointing with the bill and waving the neck and head slowly. Both parents defend the area around the nest, both incubate the eggs, and both feed the young. Conflicts between nesting pairs are uncommon. Pair bonds usually last for just one breeding season.

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Conservation

Conservation Low Concern

The North American Waterbird Conservation Plan estimated in 2002 that there were 16,000 breeding Neotropic Cormorants in the United States. The species’ U.S. population has been increasing slowly after a sharp decline in Texas during the 1960s. Partners in Flight rates the species a 6 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Global populations of this widespread and abundant species have not been the subject of extensive study, and no estimates of its numbers are available. Neotropic Cormorants are shot by farmers at fish farms and shrimp farms, and their nesting colonies are often disrupted by humans.

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Credits

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Telfair II, Raymond C. and M. L. Morrison. (2005). Neotropic Cormorant (Phalacrocorax brasilianus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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