Flightless Cormorant
Flightless Cormorant (Phalacrocorax harrisi )
The Flightless Cormorant (Phalacrocorax harrisi ), also called stub Cormorant, is a species of bird in the family of cormorants. It is the only cormorant that has lost its ability to fly, and was once even placed in a separate genus Nannopterum. Today the assignment to the genus Phalacrocorax is common.
Body type, appearance
Full grown cormorants reach a body length of about 89 to 100 cm and then weigh 2.3 to 4 kg. The males are significantly heavier than females, weighing 2.7 kg on average with an average of 4 kg. This flugunfähge cormorants are about twice as heavy as their airworthy relatives. Their wings, however, are shorter than those of all other cormorants with about 18 cm. The blackish brown and fringed wings are thus only one-third as large as a bird of this size it would need to be airworthy. Even the sternum, at the flying birds in the strong muscles are attached, which are required for the ability to fly is, in this species significantly smaller. Like other cormorants, the springs of the Flightless Cormorant are not water resistant and the birds spend a lot of time to dry for prey transitions their plumage in the sun.
Lifestyle and diet
Like other cormorants, the care of this bird webbed feet and powerful legs, under water for a powerful drive. His range of prey include fish, eels and small squid. His prey he is looking away near the sea floor and rarely more than 100 feet from the shoreline.
Evolution and threat
The Flightless Cormorant is one of the rarest seabirds. 2004, only 1,500 individuals were counted. The Flightless Cormorant nests in places where cold water rich in oxygen with many animals that can serve as food flows to the surface. The low distribution and population size of the Flightless Cormorant is probably a consequence of its adaptation to these waters, where food is always plenty to be found. This also behavior and success in breeding are determined.
The Flightless Cormorant developed its present appearance and behavior on an island that was free of predators. Because their food was right on the coast, this bird lost in the course of evolution, his ability to fly. By the people, however, a number of mammals such as cats, dogs and pigs have been introduced that can be dangerous for the bird.
Courtship display
The courtship of cormorants begins when the animals parallel to each other herschwimmen in the water and so strong einkrümmen the neck in snake form that the beak touches the goiter ( neck). You croak occasionally and from time to time, a host and shakes. After 20 to 80 minutes the male leads the female to shore. On the banks of the male raises his head up so that the beak points to the sky and invites the female so that the on-coming one. Then he bows deeply and has the tip of the beak to the ground, while it often keeps nesting material in its beak and inserts it into the nest wall.
Reproduction
Females can breed twice per year. They usually are looking for any breed a new partner, because the female the young leaves earlier than the male. While usually only survived by up to three eggs per clutch a juvenile, once adult birds are usually very old. The population size is mainly limited by the limited availability of food, the more at risk the survival of young animals than that of the parents. With this adjustment, the birds are very quickly able to recover from stock declines.