Introduction 5 



of the shaft. If barbicels, or even barbules, are absent, 

 the feather is called decomposed ; if the barbs also are 

 wanting, we have bare quills, wires or bristles. 



Birds do not, however, perpetually keep the same 

 coat of feathers, but have periodical " moults," or 

 annual changes. The young do not always lose their 

 main quLUs in their first year ; on the other hand 

 certain groups of birds not only pass through a regular 

 autumnal moult, but have a second change of the smaller 

 feathers in the following spring. These processes 

 account for the difference between the summer and 

 winter plumages, while some species are known to have 

 three moults, and therefore a distinct summer, autumn, 

 and winter coloration. Decorative plumes are generally 

 assumed in the spring, and are chiefly to be found 

 among the males, which are ta the great majority of 

 cases brighter — and larger — than the females. The 

 young are generally similar to the female in colour 

 before they moult. 



There are curious exceptions to the above rules, for 

 instance in the Phalaropes and Hemipodes the female 

 is the larger and brighter bird — and there the male 

 takes her place in courtship and incubation ; in 

 Penguins the feathers flake off, instead of moulting 

 properly ; Gannets take some six years to attain their 

 fuU adult plumage ; most of the Duck tribe lose all 

 their wing-quflls at once and then become flightless, 

 while the males temporarily assume the plumage of 

 the females and are said to suffer "eclipse." 



The colour of a bird's plumage varies with the 

 seasonal moults, for the most part by new feathers 

 taking the place of the old, but also by the partial or 

 entire wearing away of the edges, whereas change of the 



