7y THE SPECIES ns TA\0\UMY, RAXGE, BIOLOGY, & ECONOMIC IMPORTANCE 



may be noted from their annual growth rings. In certain reptiles the comijlcte skin is shed 

 at intervals during the period of growth. Among birds, a series of regular feather moults main- 

 tains the necessary protection to the body not only by compensating for growth but also by 

 adequately covering the surface to a greater or lesser degree in accordance with seasonal 

 changes in temperature. 



Apparently the primar) function of feathering is protection. This coat is not only a tem- 

 perature regulating device offsetting the effects of the elements, but also affords protection 

 fiiini natural enemies. Probably everyone who has hunted grouse has had the experience of 

 picking up a bird, only to have it make its escape leaving but a handful of feathers. The 

 shedding of feathers in this way seems to be controlled by voluntary muscular action and is 

 undoubtfdlv utilized in escaping from predators. The replacement of feathers lost in this way 

 or by other accidents probably explains many of the variations in the normal pattern of tlie 

 moult. 



Much has already been written on the moult and sequence of plumage among birds. Dwight"" 

 was one of the first to disoel many of the old theories which persisted even into the 

 present century. His studies of the passerines as well as certain of the gallinaceous species 

 represented a major advance in our knowledge of this subject. Considerable work, too, has 

 been done on domestic fowl. Warren and Gordon""' carefully noted the number of days required 

 for the replacement of the flight feathers in certain breeds of poultry. Other studies were 

 conducted l)y Radi and Warren'" and by Marble'"' "'■ specifically to determine the relation- 

 ship between feathering and growth as well as egg production. More recently Host"", work- 

 ing willi a close relative of our native grouse, found light to be the main factor controll- 

 ing the development of spring and summer plumages in ptarmigan. Many other researchers 

 have done equally important work on other phases of the subject. In view of the forego- 

 ing, the emphasis in this discussion is placed on the sequence of the moult in the ruffed 

 grouse as an aid in age identification*. 



Students as well as research agencies working with immature gallinaceous game birds 

 have often been at a loss to estimate even approximately the age of specimens with which 

 they were dealing. Sportsmen, too. would like to be able to differentiate between birds of 

 the year and mature specimens a full year old or older. Such knowledge ofttimes might be 

 quite convenient for when the game is divided at the end of the day one could gener- 

 ously give the older heavier birds to his companinn and retain the younger more tender 

 ones for himself. Eaih would be well satisfied since both woidd feel sure that they best- 

 ed in the deal. By studying the feather patterns and sequence of llie moult, paitirularly in the 

 flight feathers, it appears that age can be determined within relatively narrow limits when 

 dealing with average birds. 



Since the feather patterns are discussed in detail in the Appendix under the Pterylography 

 of the Ruffed (Jrouse. il will suffice to say here that the arrangement of the feathers as well as 

 their rcplai I'nicnt during llic mcmlt follows an orderly and regular sequence. This is con- 

 trary to the once pojjular cdtK cpliipn that the feathers are shed like the leaves from a tree and 

 re])laced all at once like buds bursting in the spring. 



Sequence of Moii.t ano Feather Succession 



The sequence of the moidt may be di\ idod into three general plumage classifications, na- 

 tal, juvenile and adult. It should be borne in mind, however, that there is no definite line of 



* Till- fiillowitiK (lifcussiim in baiir.) itii llir tuidy Irnm tinlrh:iit: h> muliirir\ of a Ijrg.- (..-rirs of gr«ii»r rrurni at tlic Rrscarcll 

 Crnlcr, Delmar, N. Y. 



