Water Birds

    Among freshwater birds there are no exact parallels to the extreme adaptations of the penguins. Grebes and divers are the most highly specialised for a life in fresh water. Both have their legs placed very far back on the body. This makes swimming more efficient, but they cannot stand up-right like penguins and are helpless on land. The only time that divers come ashore is during the breeding period and their nests are within inches of the water; grebes make floating nests and never normally leave the water. Divers have webbed feet; grebes have each toe separately lobed with a stiff fin. Both dive and swim expertly under water and both can, in times of danger, expel the air from their feathers and sink from sight slowly and with no disturbance. The great crested grebe is a handsome bird which was much in demand by the plumage trade in the early years of the 20th century. Its numbers have been increased by protection and it is now a fairly common inhabitant of many stretches of inland water. In winter time the red-necked grebe might be mistaken for it, but this bird rarely moves from eastern Europe. The black-throated diver, like all the members of its group, is a northern bird. In winter when it loses its breeding plumage and migrates south it can be distinguished from its near relatives by the slender straight shape of its bill.

   An important group of seabirds is the tubenoses, so called because the bill is covered with horny plates and the nostrils lie in a tunnel which they form. Included among them are the petrels, shearwaters, fulmars and albatrosses. All have long narrow wings adapted to make use of the quirky air currents over the disturbed waters of the sea. Petrels are mostly small, dark-coloured birds, which look as though they are pattering over the surface of the waves.

   Shearwaters and fulmars bank and glide. Albatrosses have a superb control of the air, scarcely moving their wings yet staying aloft and making progress under all sorts of conditions. None of these birds ever comes to land except during the breeding season. The shearwaters, which have their legs set very far back on their bodies and cannot stand upright, nest in burrows to which they return at night and where they are protected from enemies such as gulls.

   The gannets, pelicans and cormorants belong to an order of birds linked by a number of structural and behavioural features. The most im­portant of these is the fully webbed foot, in which the hind toe is turned forward and connected by a web of skin to the inmost of the forward pointing toes. They are used by the birds in swimming