[4] The red-legged cormorant was traditionally placed within the genus Phalacrocorax, but this assignment has been contested in recent years.

They lack the white filoplumes, the wing coverts appear less silvery, but more dark grey, and the bill and gular skin are duller in colouration.

Juvenile red-legged cormorants usually possess paler, brown plumage with a speckling of white around the throat.

[11] Red-legged cormorants nest sparsely on steep rock faces, including coastal cliffs, rocky islets, and sea caverns.

They become virtually undetectable against these rocky outcrops by their speckled grey plumage, with the exception of their colourful bills and feet.

[4] When the female advances, the male displays a throwback posture; outstretching the neck and pointing the bill towards the tail.

[4] Nests are constructed on steep cliffs and are usually isolated from other birds, but can form small colonies on rare occasions.

[2][4] Red-legged cormorants are generally solitary foragers, but hunting in pairs or small flocks may occur.

Their diet mainly consists of fish, specifically including eels and anchovies, and planktonic crustaceans.

[2] The red-legged cormorants calls are unlike most seabirds; they consist of high-pitched chirps and chirrups more like a songbird.

[1] Due to the birds' habit of nesting on cliffs with sheer rock faces and no ground approach, they are inaccessible to most predators.

[2][9] The red-legged cormorant's threat display appears to be underdeveloped, consisting only of gaping and thrusting the bill towards the intruder.