CAUSES OF MORTALITY IN THE RED GROUSE 175 



prevent misunderstanding if the meaning of the term is clearly defined. To begin 

 with, young, fresh, green heather of the early summer may be caught by a 

 late black frost which sweeps over the moor and literally " scorches " it red. 

 This is a comparatively frequent occurrence in the north of England, and was 

 well exemplified on a certain Yorkshire moor in the early summer of 1907. The 

 countryside was green one week, and "as red as a fox" the next. Every leaf 

 that was turned red by the freezing winds (there was no snow in the question) 

 died, and eventually dropped off without recovering. But the plant was not 

 killed ; it very soon put out fresh leaves from the lower stalks, and the moor in 

 a few weeks was as green as ever. Still, the fact remains that the birds of that 

 moor were suddenly reduced from a very abundant to a very limited supply of 

 food, for in no case will a Grouse eat such useless stuff, nor has a Grouse's crop 

 ever been found to contain this fox-red frosted heather. It is dead, and the 

 birds know it, and forthwith proceed to look for something that is not dead. 

 They will not eat it, and therefore any harm that accompanies its appearance 

 is due, not to the presence of this useless refuse, but to the sudden reduction of 

 the wholesome food supply. Such fox-red frosted heather must on no account 

 be mistaken for the dark, red-brown, winter heather, which is secure from any 

 ordinarily severe frost, and is merely the resting condition of the healthy living 

 plant. The two are totally distinct in colour, the former being, as has been 

 said, brick-red or fox-red, and the latter a deep brown, or dark, reddish brown, 

 often associated in the leaves of the other side of the twig, with a deep or vivid 

 winter green. Such heather is alive and healthy, and forms perfectly 



" Winter 



wholesome food for the Grouse ; it is, in fact, their staple winter food, heather" 



mi i i i /I'-i-i' not frosted. 



I he only point is that being somewhat dry and sapless (m which lies 

 the whole reason of its immunity to frost), and lacking in food-value when 

 compared with fresh, young, summer heather, about three or four times as much 

 has to be eaten by the bird to get the same amount of nourishment. This dark, 

 winter heather cannot be correctly called "frosted," since the change in it is 

 merely due to a seasonal alteration in the chemical condition of the cell 

 contents, while it remains in the healthy resting winter state. With certain 

 modifications it may be stated generally with regard to the two forms of 

 " frosted " heather that in the one case the heather is dead having been killed 

 by even a moderate frost and that in the other it is living, and is proof 

 against even a severe frost. 



The presence or absence of snow on the ground makes a great difference in 



