Phalacrocorax capensis (Cape cormorant)

Trekduiker [Afrikaans]; Ugwidi (generic term for cormorants) [Xhosa]; Kaapse aalscholver [Dutch]; Cormoran du Cap [French]; Kapkormoran [German]; Corvo-marinho do Cabo [Portuguese]

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Deuterostomia > Chordata > Craniata > Vertebrata (vertebrates)  > Gnathostomata (jawed vertebrates) > Teleostomi (teleost fish) > Osteichthyes (bony fish) > Class: Sarcopterygii (lobe-finned fish) > Stegocephalia (terrestrial vertebrates) > Tetrapoda (four-legged vertebrates) > Reptiliomorpha > Amniota > Reptilia (reptiles) > Romeriida > Diapsida > Archosauromorpha > Archosauria > Dinosauria (dinosaurs) > Saurischia > Theropoda (bipedal predatory dinosaurs) > Coelurosauria > Maniraptora > Aves (birds) > Order: Ciconiiformes > Family: Phalacrocoracidae

Cape cormorant, Brittania Bay, South Africa. [photo Trevor Hardaker ©]	Cape cormorant, Western Cape, South Africa. [photo Jim Scarff ©]

Distribution and habitat

Near-endemic to southern Africa, occurring along the coast of Angola, Namibia, and the west coast of South Africa; it becomes increasingly scarce as you travel east up the South-African coastline. It generally prefers estuaries and coastal lagoons, roosting at areas with good protection from predators, such as islands in wetlands or open beaches with good visibility.

Predators and parasites

• Predators
  • adults and fledglings
    • Aquila verreauxii (Verreauxs' eagle)
    • Falco peregrinus (Peregrine falcon)
    • Arctocephalus pusillus (Cape fur seal)
    • Orcinus orca (Killer whale)
    • Canis mesomelas (Black-backed jackal)
    • Parahyaena brunnea (Brown hyena)
    • Acinonyx jubatus (Cheetah)
    • Panthera leo (Lion)
    • Pelecanus onocrotalus (Great white pelican) 
    • domestic dogs
  • chicks and eggs
    • Pelecanus onocrotalus (Great white pelican) 
    • Larus dominicanus (Kelp gull)  
    • Threskiornis aethiopicus (Sacred ibis)
    • Phalacrocorax carbo (White-breasted cormorant)
• Parasites
  • lice
  • Pasteurella multocida (Avian cholera)
  • Ornithodorus capensis (tick)
  • mites
  • louse-flies (Hippoboscidae)
  • Contraceacum (Nematodes)

Movements and migrations

Mainly sedentary, although it often disperses after the breeding season.

Food 

It mainly eats fish, doing most of its foraging in large flocks 10-20 km offshore, although it rarely travels up to 80 km away from land. It catches prey by diving from the water surface and giving chase, often resting at sea between foraging bouts, unlike most other cormorants. This is because it is more buoyant and has denser foliage, which does not get waterlogged. Its jaw is adapted to handling small, fast-moving fish, so flocks often focus on large shoals of this type. The following food items have been recorded in its diet:

• Fish
  • Sardinops sagax (Sardine)
  • Trachurus trachurus (Horse mackerel)
  • Engraulis encrasicolus (Anchovy)
  • Sufflogobius bibarbatus (Pelagic goby)
  • Merluccius (hakes)
• Crustaceans

Breeding

• Monogamous colonial nester, living in large, tightly packed colonies with each nest fiercely defended by a breeding pair. Males fight for the right to use a nest site by battling with each other with their bills.
• The nest (see image below) is mainly built by the female with material provided by the male, consisting of a loose pile of sticks, feathers, dry seaweed and sometimes other material, such as litter. It is typically placed on offshore islands, cliffs, islands in coastal wetlands, artificial guano platforms, moored boats and shipwrecks.

Cape cormorant, Lambert's Bay, South Africa. [photo Warwick Tarboton ©]

• Egg-laying season is year-round, peaking from August-February.
• It lays 1-4, rarely up to 7 eggs, which are incubated by both sexes in shifts of about 1.2-3.5 hours.
• The chicks are cared for by both parents, leaving the nest at about five weeks old. They swim in groups of up to ten until they fledge at 7-9 weeks old, becoming fully independent several weeks later.

Threats

Near-threatened, as its population has decreased from 277 000 pairs in 1977-1981 to just 72 000 pairs in 1996. This may be part of a natural process, linked to the large natural variations in the population of Anchovies (Engraulis encrasicolus). Human interference also has a negative effect, often causing nest desertion and subsequent predation of chicks and eggs.

References

• Hockey PAR, Dean WRJ and Ryan PG 2005. Roberts - Birds of southern Africa, VIIth ed. The Trustees of the John Voelcker Bird Book Fund, Cape Town.