Phalacrocoracidae

Cormorants are medium to large diving birds commonly seen along coastlines and in many interior wetlands. The main groups in this family include the true cormorants, typified by the widespread Great Cormorant (Phalacrocorax carbo); the small, long-tailed fresh-water 'micro-cormorants'; and the marine species, known as shags.

Additional information

Cormorants may feed solitary, but may also forage in large flocks, which sometimes coordinate their movements to herd prey. The birds hunt underwater, propelled by their feet, and reach depths of 20-30m. They also spend long periods resting on rocks, sea cliffs, pilings, or shorelines. If overheated, they flutter their gullar skin rapidly to lose body heat. Cormorants have a continuous, flapping flight. They usually fly low over the water, and glide or soar only briefly. The birds walk clumsily on land, but many species perch readily on tree branches or cables.

Breeding habitats vary from the bare islands and cliff ledges to marshes and waterside trees and shrubs. Many species are vulnerable at nesting colonies, readily abandoning the sites when disturbed by humans or predators; most notably, the flightless Spectacled Cormorant (P. perspicillatus) of Bering Island was easily killed by humans, and was extinct by 1850. Some breed on only one or a few islands, increasing their vulnerability. Oil spills, pesticide contamination, fishing, and ocean current anomalies have also had severe impacts on populations, as has the unsustainable harvesting of guano at some species' colonies.

Taxonomy 

Number of genera: 1 (Palacrocorax)

Number of species: 39

A list of all species can be found here.

The family's taxonomy is still in flux. Many authorities recognize from four to nine genera. There is also much uncertainty as to the number of species, at least regarding shags (many of which are island endemics) in the southern oceans.