Flightless Cormorant
From Biocrawler, the free encyclopedia.
| Flightless Cormorant Conservation status: Endangered | ||||||||||||||
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| Nannopterum harrisi (Rothschild, 1898) |
The Flightless Cormorant, Nannopterum harrisi, is a cormorant native to the Galapagos Islands. It is the only cormorant that has lost the ability to fly and has been placed in its own genus, Nannopterum.
Like all cormorants, this bird has webbed feet and powerful legs that propel it though ocean waters as it seeks its prey of fish, eels, small octopuses, and other small creatures. They feed near the bottom and no more than 100 m offshore.
They are about 3 feet in length, and their wings are about one-third the size that would be required for a bird of its proportions to fly. The keel on the breastbone, where birds attach the large muscles needed for flight, is also greatly reduced.
Like other cormorants, this bird's feathers are not waterproof, and they spend time after each dive drying their small wings in the sunlight. Their flight and contour feathers are much like those of other cormorants, but their body feathers are much thicker, softer, denser, and more hair-like. They produce very little oil from their preen gland; it is the air trapped in their dense plumage that prevents them from becoming waterlogged.
The female lays three eggs per clutch, though usually only one chick survives. Both male and female share in incubation. 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.
These cormorants evolved on an island habitat that was free of predators. Having no enemies, and taking its food primarily through diving along the food-rich shorelines, the bird eventually became flightless. However, since their discovery by man, the islands have not remained free of predators; cats, dogs, and pigs have been introduced to the islands over the years. In addition, these birds have no fear of man and can easily be approached and picked up. Because of these factors, the Flightless Cormorant is one of the world's rarest birds. Only about 1,000 are believed to remain.
References
- [1] (http://www.rit.edu/~rhrsbi/GalapagosPages/Cormorant.html) - personal observations of the Flightless Cormorant by Dr. Robert Rothman.fr:Cormoran aptère
