Rock Shag

Identification

At first glance, the rock shag is a striking black and white bird, with a black head, neck and upperparts contrasting sharply with a white chest and underparts. Look closer and you'll discover remarkable iridescence—the black areas shimmer with metallic blue and oily green hues, often flecked with white. The bare skin around the beak and eyes is brick red, while the legs and feet are pink and fleshy. During breeding season, males develop a blackish (though subtle) crest on the forehead and a distinctive white ear patch. Males are noticeably larger than females, typically 5–10% bigger across most measurements, though sexual dimorphism is less pronounced in this species than in many other cormorants.

Range & Habitat

This marine specialist inhabits the southernmost coasts of South America, from around Valdivia in Chile south through Cape Horn and Tierra del Fuego, and north to Punta Tombo in Argentina. The species also breeds around the Falkland Islands. In winter, rock shags disperse further north, with individuals reaching as far as Santiago on Chile's west coast and Uruguay on the east coast, though they remain primarily coastal birds.

Behaviour & Diet

Like all cormorants, the rock shag is a pursuit diver, hunting underwater for fish. It favours shallow coastal waters, often diving at the edges of kelp beds where small fish shelter among the weed. The primary prey consists of cod icefishes (Patagonotothen species). Despite hunting near the seafloor, this species is a relatively shallow diver—depth gauge studies show it typically descends about 5 metres below the surface, with few dives exceeding 10 metres. Typical dive duration is around 30 seconds. Where its range overlaps with the imperial shag, the two species avoid direct competition by foraging in different zones: the imperial shag tends to hunt in deeper water further offshore.

Rock shags are colonial breeders, nesting on ledges of steep, bare rocky cliffs. They typically lay three eggs, though clutches range from two to five. Breeding colonies vary considerably in size, from as few as five pairs to nearly 400 pairs.

Best Time & Places to See It

For the best chance of encountering rock shags, visit the southern coasts of Chile and Argentina during the breeding season, particularly around Punta Tombo, Cape Horn, or Tierra del Fuego, where they congregate in their cliff-based colonies. The Falkland Islands offer another reliable location. In winter months, search further north along both coasts, including the coastlines near Santiago and Uruguay, though sightings become less concentrated.

Photography Tips

The rock shag's striking black-and-white plumage and iridescent sheen photograph beautifully in bright southern light. Position yourself to capture the contrast between dark upperparts and white underparts, and use polarizing filters to enhance the metallic blue and green sheens on the head and neck. Breeding birds with their distinctive white ear patches and forehead crests make particularly striking subjects. Since they nest on cliff ledges and feed close to shore in kelp beds, a telephoto lens is essential for capturing detail without disturbing colonies. Early morning light often provides the best conditions for rendering their subtle colour variations.