Pelecaniformes


 


Flightless Cormorant

The flightless cormorant (Nannopterum harrisi) is the only cormorant (family Phalacrocoracidae) found in the Galapagos, and of the 27-28 cormorant species world-wide, it is the only one that has lost the ability to fly. So unusual is the flightless cormorant by comparison to other cormorants, that most authors place it in a separate genus - all other cormorants belong to the genus Phalacrocorax.. Like other flightless birds, the keel on the breast bone, which supports the large flight muscles, is drastically reduced. Instead, the legs are heavier and more powerful than in other cormorants. Unlike the penguin, whose wings are used as paddles to literally fly through the water, the flightless cormorant propels itself by powerful kicks. One year I was snorkeling off of Fernandina and turned back to check on my snorkeling partner when I saw a cormorant dart past. Its speed was impressive. The birds feed no more than 100 m offshore, feeding near the bottom on squid, octopus, eel, and fish. The loss of flight is probably related to both an absence of natural predators in the Galapagos, and to a restricted feeding area. They are only found on the coastline of Fernandina and the northwestern shore of Isabela, where there are upwellings of the cold Cromwell and Humboldt currents. The flightless cormorant is among the rarest of the Galapagos sea birds with a population size of only around 800 pairs. Nevertheless, it is not considered to be endangered.

Although all cormorants feed underwater, their feathers are not completely waterproof. Thus, upon emerging from the water, they typically stand for some time with their wings outstetched to dry. Flightless cormorants preserve this behavior, and it is not uncommon to see them standing with their stunted, scruffy-looking wings held out. The flight and contour feathers are much like those of other cormorants, but the body feathers are much thicker, softer, denser, and more hairlike. They produce very little oil from their preen gland, and it is the air trapped in their dense plumage that prevents them from becoming waterlogged.

Flightless cormorants have a complex courtship behavior which begins in the water and then continues on shore. The pair swims around each other, their long necks bent into a snake-like figure. The male then leads the female ashore, turning back towards the female, and assuming the snake-neck posture. The pair builds a nest composed of sea weed, sea urchins, starfish, and dead fish, and the male continually brings "gifts" to the female, which she incorporates into the nest. They have been known to incorporate bits of flotsam such as rope, bottle caps, and plastic six-pack holders. In 1998, I saw a nest in which the pair had incorporated a dead marine iguana! The female lays three eggs, though usually only one chick survives. Both male and female share in incubation. I observed the owners of the marine iguana nest trade places. The male had been sitting patiently on the nest when his mate emerged from the water. She slowly ambled over to the nest and stood in front for about 15 minutes with her wings outstretched. She then stepped on to the nest and they exchanged some coarse grunts, the only vocalization these birds make. The male got off the nest, walked over to the water and dove in.

Once the eggs have hatched, both parents continue to share responsibilities of feeding and brooding (protecting the chicks from exposure to heat and cold), but once the chicks are old enough to be independent, and if food supplies are plentiful, the female will leave the male to carry out further parenting, and she will leave to find a new mate. Females can breed three times in a single year. Thus, although their population size is small, flightless cormorants can recover fairly quickly from envirnomental disasters like el Nino.

 

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    for more info, contact Dr. Robert Rothman: rhrsbi@rit.edu