142 BRITAIN'S BIRDS AND THEIR NESTS. 



to a depth of fifteen fathoms — ninety feet. This is the 

 usual method of feeding for members of this group as well 

 as for the marine Ducks like the Eider-Duck, the Long- 

 tailed Duck, and the Scoter. These are therefore spoken 

 of generally as 'diving ducks."* They are characterised by 

 having a broad hind-toe, which gives additional propelling 

 surface. The other Ducks of which we have so far treated 

 belong to the non-diving group. This does not mean that 

 they cannot dive on occasion, but only that they do not, 

 as a rule, obtain their food by diving. The Mallard's 

 familiar method of feeding in very shallow water has 

 already been alluded to. Other ' non-diving "* ducks, like 

 the Shoveller, feed largely in the mud at the side of the 

 water. At other times Tufted -Ducks and other diving 

 ducks are followed for the particles of food they loosen 

 from the bottom and allow to float to the surface. 



The distinction between diving and non-diving ducks is 

 not a sharp one, nor one of real systematic importance. 

 The species we discuss here all fall into one group or 

 the other, except the Merganser and Goosander and the 

 Sheldrake. The first two are diving and the last non- 

 diving ; but as regards feeding habits they must be classed 

 in two groups by themselves. Their habits will be dis- 

 cussed later on. 



THE SCAUP 



(Fuligula marila). 



The Scaup resembles the Tufted -Duck, but is larger 

 and without the crest. The back of the adult drake is 

 beautifully grained with silvery gray. It is marine in its 

 habits, and is chiefly known in the British Isles as a 

 winter visitor on the coast. It has nested in the north 



