Phalacrocorax olivaceus (Humboldt, 1805) Phalacrocorax pampeanus Moreno & Mercerat, 1891 Phalacrocorax vigua Phalacrocorax brasilianus Nannopterum olivaceus Nannopterum vigum Nannopterum pampeanum Nesocarbo brasilianum Nesocarbo olivaceus Nesocarbo vigum Nesocarbo pampeanum The neotropic cormorant or olivaceous cormorant (Nannopterum brasilianum) is a medium-sized cormorant found throughout the American tropics and subtropics, from the middle Rio Grande and the Gulf and Californian coasts of the United States south through Mexico and Central America to southern South America, where it is called by the indigenous name of biguá.

[3] Many authors preferred to use Alexander von Humboldt's 1805 description of Pelecanus olivaceus because the identity of Piso's birds was considered uncertain.

[4][5] Later, ornithological authorities such as the American Ornithologists' Union began to use Phalacrocorax brasilianus after Ralph Browning argued that Piso's description and paintings do indeed refer to the neotropic cormorant.

[8] The three species were, therefore, moved to the resurrected genus Nannopterum that had been introduced in 1899 by English ornithologist Richard Bowdler Sharpe to accommodate the flightless cormorant.

Its diet consists mainly of small fish, but will also eat tadpoles, frogs, aquatic insects (such as dragonfly nymphs), and shrimp.

[13] Information about its prey is sparse, but inland birds seem to feed on small, abundant fish in ponds and sheltered inlets, less than 10 cm (3.9 in) in length, with an individual weight of a gram or two, such as Poecilia species especially the sailfin molly Poecilia latipinna.

It is also known to forage in groups, with several birds beating the water with their wings to drive fish forward into shallows.