the dolts forms an independent family of the Rudder-footwith 9 types. Many zoologist compares the bass-dolt and 2 very near relatives types with the own type Morus the tropical dolts of the type Sula.
Types The 78-88 cm long cape-dolt (Morus capensis) broods on islands before the South African coast, during which 80-96,5 cm long Australtölpel (Morus serrator) nests on islands before southeast-Australia and on New Zealand. From the tropical types, also the guano-bird or guano-dolts (Sula variegata) are quite known because of its economic meaning. This approximately 73 cm long bird broods on islands at the coasts of Peru and Chile where its excrement has an essential share of the production of the guano-fertilizer.
Shape The mostly powerfully colorfully colored feet and larger, also colorful, feather-loose skin-parts are characteristic for the dolts of the type Sula at head and throat. Dolts of the type Morus against it have only a narrow, dark one, unbefiederten Kehlstreif and dark legs.
Stoßtauchen All dolt-types are excellent push-divers, who crash vertically also from heights of 30 m, with what it constantly fixes head and beak on its potential loot holds and executes balancing spins with its entire body. At the moment of the impact on the water-surface, dolts put its long, narrow wings at the body along far to the back, so that the birds with its long one, strengthens, conical beak forward like a harpoon through the water shoots. The neck-part is short and powerful so that also stronger pushes can be caught without damage. Dolts pursue its loot - mainly fish and especially flying fish - but also Kopffüßer, under water and advances up to 30 m also in depths, as Totfunde from in fisher-nets verhakten birds covers.
Brood As sociable birds, dolts nest in often gigantic colonies on coast-rocks and foothills and also go for food-search together. Some types mold only a flat nest-hollow in the ground or in the guano, while others - Z. B. the 73 cm long brown-dolt (Sula leucogaster), downright nests out of plant-material at the ground, in the shrubbery and even in trees, as that 75 cm long gray-foot-dolts (Sula abbotti) - aims.
The nest usually exists from 2, more rarely also from 3 eggs, with the tropical types, while that an egg puts 3 dolts of the type Morus only in each case. A white, limy layer coats the greenish or light-blue eggs, from which still one unbeduntes young slips. Soon however, the young dolt trains a white Dunenkleid. The alto-birds feed its offspring with angedauten fishings, that the young forth-get deeply from the pharynx of the parents.
In the youth-plumage, dolts look mainly brown. After only 2-3 years finally, they molt the white old-age-dress with his black drawing characteristic for every type. With some types, also brown animals brood; whether birds are on this occasion about color-phases or still unausgefärbte, is not yet unequivocally clarified.
Endangering The gray-foot-dolt (Sula abbotti) stands as seriously threatened type in the appendix I of the Washingtoner Artenschutzübereinkommens.
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