Geograph- 
ical dis- 
tribution. 
Plumage. 
x. INTRODUCTION 
Coot, and the Phalarope, habitually swim with the same 
ease as a Duck or a Gull. 
Most aquatic birds are migratory, and some take im- 
mense aérial journeys in spring and autumn to and from 
their breeding-haunts. Being widely distributed over the 
face of the Globe, their geographical distribution is an 
important and interesting study. For information on this 
part of the subject, and regarding allied species and repre- 
sentative forms, frequent references have been made to 
Mr. Howard Saunders’s Manual, and to several volumes of 
the Catalogue of the Birds in the British Museum. 
The seasonal plumage-changes, so marked in many 
aquatic birds, may well attract the attention of the student 
of ornithology. Some birds, such as Gulls, several of the 
Ducks, the Gannet and others, do not attain their mature 
dress until the third, fourth, fifth, or even sixth year, and the 
transition stages are often somewhat difficult to determine. 
It is hoped that the descriptions given in the text, though 
of a general character, will enable the reader to assign to 
its species a bird whether immature or adult, male or 
female, in winter or 1n nuptial garb. 
It is well to understand that the term winter-plumage 
is used only in a general sense to signify other than the 
nuptial plumage, and in all cases does not indicate the dress 
assumed in our winter months. Many Petrels, for instance, 
which breed in the Southern Hemisphere are in winter- 
plumage in our summer months, though, as a matter of fact, 
in this particular group, it would appear that the plumage 
in the two seasons is, as a rule, identical. It may also be 
added that, while the winter and nuptial plumages are 
always described under separate headings in the text, there 
are some birds which undergo only one moult in the year, 
and so the expression ‘ similar to the nuptial plumage, 
does not necessarily imply a comparison, but rather that 
the winter and nuptial plumages are one and the same 
dress. 
The feathers of the different regions of the body have 
been for the most part described in ordinary rather than in 
technical terms, though such words as scapulars, secondaries, 
primaries, and axillaries, could not well be dispensed with. 
The positions of these groups of feathers are seen in Plate IT. 
