Oilbird
Two fat Schwalme in Trinidad
The fat Schwalm ( Steatornis caripensis ) or Guácharo is the only extant species of the bird family of fat Schwalme ( Steatornithidae ). The monotypic classification in a separate family is due to the fact that the fat Schwalm is very unusual.
The species is expected to be the order of the Schwalm -like ( Caprimulgiformes ), but recent osteological comparisons reveal a closer relationship to the trogons ( Trogoniformes ) near.
Anatomy
The fat Schwalm is an approximately 40 to 49 centimeters large reddish- brown bird with white patches on the throat, head and wings. It weighs 350-375 grams. The plumage of males and females is equal. Its large beak opening is used to transport food to the nest site.
In addition, he has relatively long wings and a long tail. In contrast, the legs are extremely short and almost useless.
Fat Schwalme have a very good sense of smell and highly specialized night eyes.
Dissemination
The fat Schwalm is the northern and central South America before, from the eastern Panama through Colombia and Venezuela to the east and Guyana to Trinidad and along the Andes to the south over Ecuador and Peru to the central Bolivia.
Way of life
The fat Schwalm is the only nocturnal fruit -eating bird in the world. During the day he stays in colonies of up to a kilometer long, completely dark burrows in the ground, where he sees nothing more despite his night eyes.
In these dark caves that serve as resting and nesting area, but not outside, he is oriented by means of echolocation, which is similar to that of bats. The thus generated click- signals have a low frequency ( 1.5-2.5 kHz) and are therefore different from those of bats, audible to humans. In the group of fat Schwalme produce a deafening noise, so that the fat Schwalm is considered as " the loudest of all the birds ."
At night he travels in search of food up to 75 kilometers. Its diet consists among other things of the oleaginous fruits of palm and laurel. He attacks the fruit, with its strong beak and swallowed it whole. The food is digested the next day at his resting place.
Fat Schwalme live in colonies that can reach a size of up to 50 pairs. The nest is a mound of dried mud, feces and be choked fruits.
Reproduction
The female lays two to four eggs which are hatched jointly by both parents usually. The young hatch after an incubation period of about 23 days. In their first weeks of life, they are fed with palm fruit and so create large fat reserves until they have achieved twice the weight of their parents.
The scientific discovery
Alexander von Humboldt described the species during his Latin American expedition in Venezuela in the cave " Cueva del Guácharo ", within the national park, which is located in the state of Monagas about 13 kilometers from the place Caripe. The cave is named after the fat Schwalm, who is known there as Guácharo named. Humboldt and his friend, the young doctor and botanist Aimé Bonpland, explored on September 18, 1799 the front portion of the largest at 10.5 km long limestone cave in South America and shot down two copies. He reported that the inhabitants collect the young birds just before fledging and gain from them by hours of cooking oil, therefore, also stirred the English name " oilbird ".
Humboldt wrote: " The Guacharo has the size of our chickens, the throat of the nightjar and Procnias, the shape of the vulture -like birds with tufts of stiff silk around the hooked beak. (...) Its plumage is dark gray-blue, with small black stripes and polka dots; Head, wings and tail show large, white, heart-shaped, black -fringed spots. The eyes of the bird can not stand the light of day, they are blue and smaller than in the goat milkers. ( ... ) Heavy makes you look an idea of the noise, the thousands of birds in the dark inside the cave make (...) Only after several fruitless attempts succeeded Bonpland to shoot two Guacharos that blinded by the light of torches, nachflatterten us. So I took the opportunity to draw the bird, which had been quite unknown to naturalists until then. "