THE CHANGES OF PLUMAGE IN RED GROUSE 59 



In June there is another characteristic appearance in the 

 hens, namely the bare patch of abdominal skin which results 

 from the shedding of the abdominal feathers, grown in the 

 previous September. The loss of these feathers leaves a naked 

 patch of skin on the abdomen of a hen that has been sitting, 

 and this patch remains naked for the next few months. The 

 general character of a June hen in health is that of the com- 

 pleted summer-nesting plumage, broad-barred buff and black 

 over all the upper and under parts, excepting the abdominal 

 area, the lower breast, wings, and tail. But it looks already 

 somewhat faded and worn ; and it is quite probable that in 

 acquiring so perfect a plumage for sitting unnoticed on a nest 

 built amongst the heather, the economic absence of the redder 

 pigment in the feathers is in part a result of the acknowledged 

 fact that for longer and more trying use, and for wear and tear 

 in feathers, darker pigments are required, whereas for the short- 

 lived and less exacting requirements of the summer plumage 

 in the hen Grouse from April to June the buff and black feathers, 

 with very much poorer wearing qualities, are found to be suffi- 

 cient. The black pigmented parts of the feather stand wear 

 and tear far better than the yellow parts. Certain pigments 

 have a value, therefore, of a very practical nature apart al- 

 together from the aesthetic point of view of attractiveness, 

 or the rather hypothetical view of assimilation to surroundings 

 for the purposes of safety or to assist in obtaining food. 



It very occasionally happens that the hen Grouse, instead 

 of retaining the redder plumage of the previous autumn's 

 growth on the abdomen until it drops off during incubation, 

 grows an almost universal spring plumage of buff and black 

 broad-barred feathers covering the lower breast and abdomen 

 as well as the remainder of the body from head to tail. A skin 

 showing this condition is preserved in the National Collection, 

 and there is an almost equally perfect specimen in the Com- 

 mittee's Collection. 



The more usual procedure is that the abdominal patch of 

 autumnal plumage is lost during incubation, and is then quickly 



