GUILLEMOTS, RAZORBILL, ETC. 127 
respect. During the breeding period some species 
resort to lofty cliffs washed by the sea; others 
burrow into the ground. Many species make no 
nest whatever, but others form slight structures in 
which to deposit their eggs. The young of the 
Auks are hatched covered with down, assuming 
their first plumage in a few weeks. Adult Auks 
moult in September; the difference in the colour 
of the plumage peculiar to the pairing season, 
apparently being entirely due to a change in the 
hue quite irrespective of a moult. The complete 
change from white to brownish-black observed 
prior to the breeding season on the necks and 
heads of Guillemots and Razorbills is very curious 
and interesting. According to the observations of 
Herr Gatke, the shafts of the feathers are the first 
portions in which the black appears; yet almost 
at the same time this colour is seen in the form 
of minute specks on the lower third of the feathers, 
quickly spreading into crescentic markings, and 
ultimately covering the entire surface. Half a 
dozen species are British. Of these, four breed 
more or less abundantly in our area, and the other 
two are irregular winter visitors. The now extinct 
Great Auk—the largest known representative of 
the family—formerly bred in certain parts of the 
British Islands, but, alas, is now only known as 
a fast receding tradition. We will now proceed to 
a short study of these British Auks. 
