THE FOOD OF THE RED GROUSE 109 



specimens from Ross-shire are of interest from the geological 

 point of view, since in some cases they contain a representative 

 collection of the gneissose and schistose rocks of the north- 

 west Highlands. 



A comparison of results shows that in the gizzards of Grouse 

 quartz is nearly always present, although no quartz may be 

 found on the moor where the bird was shot. Two cases of 

 this may be mentioned. On one part of an extensive shooting 

 in^North Wales there is excellent feeding and sheltering ground 

 for Grouse, but no quartz grit, yet the gizzards of the birds 

 always contain quartz ; in order to obtain it they have to 

 fly across a wide valley to. another hill, and then return again 

 to their feeding-ground. Again, on a Ross-shire moor no quartz 

 could be seen on the moor, yet all the gizzards of these birds 

 contained quartz ; this quartz was probably obtained from the 

 burns, foif on examining them small pockets of quartz were 

 found in many of the pools and eddies. 



The quartz is not always angular and sharp, but is frequently 

 water-worn ; in these cases it is probably picked up out of burns 

 in fact, in low-lying moors the water courses are almost sure 

 to be the source of this quartz. 



The grits found in the gizzards of Yorkshire Grouse are 

 very similar to those of the Scotch birds except in one case, 

 where the grit is chiefly composed of small black pebbles. In 

 one gizzard out of every three of the Grouse examined shot were 

 found ; but shot were rarely found in the gizzards of Pheasants. 



It may be noted that whereas Ptarmigan and Grouse seem 

 unable to exist without quartz, Partridges, and still more 

 Pheasants, are more adaptable ; they prefer quartz if they can 

 get it, but failing quartz, Pheasants will content themselves 

 with flint, sandstone, and even coal. Doubtless the tough and 

 fibrous nature of the food eaten by Grouse makes it necessary 

 for him to confine himself to the hardest and most angular 

 descriptions of rock, and even when quartz grits are found in 

 the gizzard the angles are often rounded and smooth from the 

 nature of the work which they have been called on to perform. 



