I 76 BRITISH BIRDS. 



species are described as breeding on the shores, 

 and depositing their two eggs upon the bare rock; 

 others lay three or four eggs in a hole made in the 

 dry sand; and some nestle among the reeds and 

 rushes in the marshy borders of lakes. The young 

 keep the nest a considerable time after they have 

 been hatched, not offering to leave it until their 

 wings have attained sufficient length and strength 

 to enable them to fly with ease. Though almost 

 wholly web-footed, they are seldom seen to swim; 

 the moult occurs twice a year in all the known 

 species: no outward difference is observable be- 

 tween the sexes. 



One kind or another of these birds is met with in 

 almost every part of the world. Latham enumerates 

 twenty-three species, besides varieties. 



