The neotropic cormorant (Phalacrocorax brasilianus) is a species of cormorant found in the Americas. Its common names include Neotropic cormorant, Olivaceous cormorant, and Mexican cormorant.
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The common name for the neotropic cormorant is the olivaceous cormorant or Mexican cormorant.
The neotropic cormorant (Phalacrocorax brasilianus) is a medium-sized cormorant species found throughout the Americas from the southwestern United States south through Mexico and Central America to southern South America. It inhabits both coasts and inland waterways and is never found very far from water. Its preferred habitats include mangrove swamps, sandy beaches, mudflats, lakes, rivers, and ponds.
This cormorant goes by several common names, including the neotropic cormorant, olivaceous cormorant, and Mexican cormorant. The term “neotropic” refers to its range being in the Neotropics, the biogeographic realm that includes Central and South America. “Olivaceous” refers to its predominantly olive-colored plumage. And “Mexican” denotes part of its range being in Mexico.
Naming and Taxonomy
The neotropic cormorant was first described scientifically in 1816 by the French naturalist Louis Jean Pierre Vieillot, who gave it the binomial name Phalacrocorax brasilianus. The genus name Phalacrocorax is derived from the Ancient Greek words for “bald” and “raven” in reference to the bald head and black coloration of cormorants. The specific epithet brasilianus refers to Brazil, part of this species’ range.
No subspecies of the neotropic cormorant are currently recognized. Its closest relative is the flightless cormorant (Phalacrocorax harrisi) of the Galapagos Islands. These two cormorants are unique in having rough surfaces on the underside of their feet to help them cling to slippery rocks. Other close relatives include the double-crested cormorant (P. auritus) and the red-faced cormorant (P. urile) of the North Pacific.
Physical Description
The neotropic cormorant is a mid-sized cormorant, averaging 70–80 cm (28–31 in) in length and weighing around 1.5 kg (3.3 lb). Its wingspan is typically around 1.3 m (4.3 ft). Males tend to be larger than females. This species has mainly dark plumage that appears black from a distance but is actually glossed with purple, green, and bronzy iridescence up close. The feathers have a scaly appearance. The throat pouch and facial skin are bright orange, becoming brighter during the breeding season. The eyes are green and the bill is hooked and greyish.
During the breeding season, both sexes develop white thigh patches and bright blue-green eye rings. Breeding males also gain white filoplumes on the head and neck. Immature birds are browner overall with a pale throat pouch. The neotropic cormorant is very similar in appearance to the double-crested cormorant, which overlaps in range with it in some areas.
Table comparing physical features of neotropic and double-crested cormorants:
| Feature | Neotropic Cormorant | Double-crested Cormorant |
|---|---|---|
| Size | 70-80 cm long | 70-90 cm long |
| Wingspan | Around 130 cm | Around 150 cm |
| Weight | Around 1.5 kg | Around 2 kg |
| Plumage | Mainly dark with purple, green, bronzy iridescence | Mainly dark with green and purplish iridescence |
| Throat pouch | Bright orange | Bright orange |
| Eye color | Green | Blue-green |
| Bill color | Grayish | Grayish |
Distribution and Habitat
The neotropic cormorant has a very large range spanning North America, Central America, South America, and the Caribbean. Its breeding range extends from the southwestern United States (southern California, Arizona, New Mexico, Texas) south through Mexico and Central America. On the Atlantic side, it breeds in the Caribbean, along the coast of Central America, and south to Argentina and Chile. On the Pacific side, it is found along the coast of South America as far south as central Chile and Argentina.
This species inhabits coastal areas, including rocky and sandy shorelines, mangrove swamps, estuaries, and lagoons. It uses both freshwater and saltwater habitats. Inland, it occurs on lakes, rivers, swamps, reservoirs, and ponds. It roosts communally in trees, on docks, and other structures. It is typically found at elevations below 1,000 m (3,300 ft), though occasionally as high as 3,000 m (9,800 ft) in the Andes Mountains.
Behavior
The neotropic cormorant is colonial when breeding, forming colonies of up to several thousand pairs. Their nests are located low down or on the ground in trees and bushes. Both the male and female help build the nest out of sticks, vegetation, and debris. Nests are reused and added to each year.
Courtship displays include the “butterfly flight”, where the birds fly in vertical loops above the colony. Mating involves the male mounting the female and grasping her neck in his bill. These cormorants produce an average of three eggs per clutch which are incubated for around 28 days. Both parents feed the chicks by regurgitating food. Young fledge at 45-55 days old.
Outside of breeding season, these cormorants are highly gregarious. They feed together, migrating and roosting communally sometimes in groups of over 1,000 birds. They are skilled swimmers and divers, propelling underwater with their feet while pursuing small fish. They can dive to depths over 20 m (65 ft) to hunt. Their main diet consists of small fish like anchovies, mullet, and eels. They also eat crustaceans and occasionally aquatic insects and plants.
Migration
The neotropic cormorant exhibits variable migration patterns depending on the population. Northern breeders are migratory, heading south after breeding to winter from the Gulf Coast of the U.S. through Mexico, Central America, and into South America. Southern populations tend to be year-round residents. Some southern groups undergo shorter distance migrations or local movements.
Birds that breed inland in places like the southwestern U.S. migrate east and south to the coasts during the nonbreeding season. There is also evidence of leapfrog migration, where northern breeders winter further south than southern breeding birds. Young birds typically migrate later and do not migrate as far as adults.
Status and Threats
The neotropic cormorant has an extremely large range estimated at 5.6 million square km. Its global population is estimated at 500,000 to 1 million individuals and is suspected to be increasing. For these reasons, the IUCN Red List categorizes this species as Least Concern. Its numbers dipped historically due to persecution, hunting, and egg collection by humans. This activity has declined and their populations are rebounding as a result.
Ongoing threats include habitat degradation, pollution, disturbance of nesting colonies, and entanglement in fishing gear. In some areas they come into conflict with fisheries. But their large, increasing population size makes them less vulnerable overall. Conservation efforts include reducing human disturbance at breeding sites and public education programs to promote awareness.
Conclusion
The neotropic cormorant, also known as the olivaceous cormorant or Mexican cormorant, is a common cormorant species found throughout the Americas. It lives in coastal areas and inland waterways, feeding on small fish and nesting in colonies. Though it faced threats in the past from hunting and persecution, its populations have rebounded. With its large range and increasing numbers, the future of this adaptable water bird looks secure.
