2i6 TEXT-BOOK OF ZOOLOGY 



(Family 7: Cranes Gruidae). 



The Common Crane (Grus cinerea). 

 (Height 4 feet.) 



Large flocks of this, one of our largest birds, may often be seen on 

 the Continent travelling overhead in spring and autumn ; frequently 

 only their loud " groo, groo !" during the night announces the passage 

 of the migratory hosts high up in the air. The flocks in their passage 

 always arrange themselves in the form of a wedge, an arrangement 

 which facilitates movement through the air, and, further, allows each 

 individual bird an unimpeded view of its surroundings. One of the 

 stronger birds always acts as leader at the apex of the wedge, and is 

 relieved from time to time by one of its fellows. In its shape, the crane 

 bears some likeness to a stork, and also resembles it in its mode of life. 

 The plumage is of a beautiful light gray colour, and is distinguished by 

 the fact that the wing-coverts are elongated and curled (ornamental 

 feathers). The bird, which is intelligent and shy, nests in remote 

 marshy and swampy localities in Scandinavia, North and East Germany, 

 Eussia and Siberia. The female while incubating the eggs smears its back 

 over with the dark marshy soil to prevent its light-coloured plumage from 

 betraying its presence. At one time the crane bred in Britain ; now it is 

 a rare visitor. 



ORDER XL: DUCKS (LAMELLIROSTRES, OR 

 ANSERIFORMES). 



BEAK covered with a soft skin, except at the tip, which is hard; the 

 edges of the bill furnished with horny transverse plates. Legs short ; 

 anterior toes united by webs (swimming-feet). Aquatic birds. Young 

 "precocious." (Forming with the three following orders the division of 

 natatorial birds.) 



The Wild Duck, or Mallard, and its Descendant, the Domestic 

 Duck (Anas boschas and A. domestica). 



(Length 25 inches.) 



Our domestic duck is the descendant of the wild duck, a species 

 which is met with throughout the whole Northern Hemisphere. (Why 

 has the duck been domesticated ?) In spite of a domestication extending 

 over some hundreds of years, the duck has not laid aside the habits and 



