Phalacrocorax brasilianus
neotropical cormorant
(Also: neotropic cormorant)

Neotropical cormorants breed from Cape Horn, South America to northern Texas, southwestern Louisiana, and southern Arizona. In winter, they have been recorded wandering as far outside their breeding range as California, Saskatchewan, and Pennsylvania. Generally they are restricted to the southern United States, Central America, the West Indies, and South America. They are non-migratory, but are nomadic during the non-breeding season. (Howell, 1995)

Neotropical cormorants are found in a variety of habitats, although close proximity to deep water is preferred. Availability of perches for sunning and drying their wings is also important in habitat preferences. Neotropical cormorants can be found in fresh, brackish, or salt water, bays, lagoons, streams, salt ponds, seashores, and lakes. In the United States, they are commonly found in coastal marshes and swamps. Elevation is not a concern, as birds are found from sea level wetlands to high mountain lakes in the Andes. (Stiles, 1989; Telfair and Morrison, 1999)

Neotropical cormorants are jet black, aquatic birds, weighing between 1.2 and 1.4 kilograms. They range in length from 63.5 to 68.5 cm, with an approximate wingspan of 102 cm. A pale green gular patch at the base of the bill with a white “v” outline distinguishes them from similar species, such as double-crested cormorant (Phalacrocorax auritus). They have roughly equivalent neck and tail lengths, but are easily detectable in flight. Double-crested cormorants have shorter tails. A faint greenish shine on the upper wings and back may be detectable under correct lighting conditions. Juvenile birds lack this green shine and are generally paler. Their breasts are brown instead of black, and their beaks may appear yellower. Juveniles may be especially difficult to tell apart from other cormorant species due to their dull gular patches. There is no discernible sexual dimorphism. (Howell, 1995; Sibley, 2000; Telfair and Morrison, 1999)

The oldest reported wild neotropical cormorant was caught after being banded for 12 years and 7 months. Generally, mortality rates are highest in the initial stages of life. Fledglings often die when parents abandon their nest following human disturbance, starvation, or storms. At this point predators such as common raccoons (Procyon lotor) and grackles (Quiscalus) exploit open, unprotected nests. (Telfair and Morrison, 1999)

Neotropical cormorants awkwardly waddle on land but are effective perchers and agile swimmers. Flight is characterized by gliding with rounded wings. To take-off, cormorants orient towards the wind and run along the water to promote lift. In water, neotropical cormorants sit quite low. Their set back, webbed feet and their sleek bodies allow for effective underwater pursuit of prey. After swimming, much time is spent in preening and sunning in the wing-spread position to dry their feathers. Neotropical cormorants often fly in a V formation and are gregarious nesters. Besides defense of nest site, there are infrequent intraspecific antagonistic interactions. Outside of the breeding season, neotropical cormorants are usually solitary. However, it is not uncommon to see birds engaging in flock feeding. (Quintana, 2004; Telfair and Morrison, 1999)

The majority of intraspecific communication is through vocalizations. When alarmed, neotropical cormorants emit a simple guttural call. During flock feeding, calls are common. Males are generally more vocal than females, but both sexes are usually silent outside of the breeding season. Hatchlings use food-begging calls to beg for food. Neotropical cormorants also communicate through visual displays, primarily during courtship. (Telfair and Morrison, 1999)

Some research suggests that neotropical cormorants are aquatic generalists, eating fish, frogs, tadpoles, and dragonfly nymphs. Other research indicates that fish and shrimp comprise an overwhelming majority of their diets. To forage, neotropical cormorants generally pursuit dive. However, in large flock feeding situations, birds also engage in plunge-diving techniques. Sometimes birds may even line up to "herd" fish. Studies show adults are more adept feeders than juveniles, who take some time to learn effective foraging methods. (King, 1989; Telfair and Morrison, 1999)

Raccoons and grackles, both great-tailed and boat-tailed, feed on eggs and young. However, grackles seem to raid nests only after human disturbance has caused the cormorants to abandon their nests for a short period. Interestingly, neighbors tend to protect other birds’ nests when the parents leave to forage. (Morrison, 1979)

Interspecific competition with double-crested cormorants could contribute to limiting the extent of their northern range. An interesting mutualism between neotropical cormorants and roseate spoonbills (Ajaia ajaja) has been observed in Texas, in which individuals of both species group together for more effective predator protection. Moreover, studies have shown that neotropical cormorant guano provides vital biotic sustenance for aquatic ecosystems, and helps maintain nutrient levels. (Telfair and Morrison, 1999)

Many fishermen think that neotropical cormorants decimate fish populations, thereby depleting fish reserves. These birds are often shot near fisheries. (Telfair and Morrison, 1999)

Some fishermen use neotropical cormorants to locate abundant fish schools. Their guano may even help augment biomass in aquatic ecosystems.

Neotropical cormorants were evaluated as species of least concern in 2001 by BirdLife International due to their large range (18 million km^2) and large population size (estimated 2 million individuals). However, the species is protected under the Migratory Bird Treaty Act. Neotropical cormorants still face human threats, as they are hunted, poisoned by pesticides, and driven from their habitats. (Telfair and Morrison, 1999)