422 NATATGRES. URIA. GUILLEMOT. 
is increased by the number of Kittiwakes (Larus tridactylus), 
which hover around, and which breed in the small side clefts, 
or on the projecting angles of the rock ; and by the nests of 
two or three Crested or Green Cormorants, which, from the 
unusual confidence they display in continuing to sit upon 
their eggs, even when overlooked from the opposite preci- 
pice at only a few yards distance, seem to be well aware of 
the security of the station they have chosen. The great 
body of the breeding birds arrives towards the end of March 
or the beginning of April, at which time most of them have 
acquired the perfect nuptial plumage. I have, however, ob- 
tained them much earlier, and when the white upon the 
throat was only giving place to the pitch-coloured black that 
distinguishes them till after the sexual intercourse. After 
the period of reproduction they leave the rocks, and betake 
themselves entirely to the ocean, when the old birds undergo 
the moult that assimilates them to the young, or Lesser Guii- 
lemot of authors. At this time they often lose so many of 
their quill-feathers, as to be totally incapable of flight ; but 
these are soon reproduced, and the colonies which had made 
the English coasts their summer quarters, retire to more 
southern latitudes to pass the winter months. Their place 
in this country is but sparingly supplied by a few stragglers 
from the great bodies that, being bred in still higher lati- 
tudes, make the friths of Scotland and its isles the limit of 
their equatorial migration. Much difference of opinion pre- 
vailed amongst ornithologists a few years ago, as to whether 
this bird in the summer plumage was not specifically distinct 
from that state of it in which, together with the young, it 
has been called the Lesser Guillemot. But the question seems 
now to be satisfactorily determined by the investigations that 
have been instituted, and the increased attention latterly be- 
stowed upon the changes, that so many birds periodically 
undergo, and which prove their identity beyond a doubt. It 
may not, nevertheless, be amiss to glance at the reasons ad- 
vanced by Monracu, in favour of this distinction, as how- 
