96 THE GROUSE IN HEALTH AND IN DISEASE 



which is both soft and comparatively soluble. The only really abundant 

 constituents in the gizzards of Grouse are quartz and felspar, and small 

 fratrments of various rocks composed of one or both of these minerals, such 

 as granite, gneiss, quartzite, etc., with occasionally grains of shot and crystals 

 of garnet, and other minerals. Felspar is chiefly found in specimens from 

 Scotland and North Wales, where rocks consisting largely of this mineral are 

 specially abundant. The specimens from Ross-shire are of interest from the 

 o-eolowical 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 exten- 

 sive 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 

 Quartz j.q another hill, and then return again to their feeding - ground. 



present in ^ a a 



gizzards Ao-ain, on a Ross-shire moor no quartz could be seen on the moor, 



thouf^li not o ' 



found on yg^ ^11 the gizzards of these birds contained quartz; it was found that 



moor. -^ ° 1 c 1 1 r • • 



this quartz was probably obtained from the burns, for on examining 

 them small pockets of water-worn 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 writs 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. 



The mineral contents of the gizzards are very fairly representative of 

 the harder rocks and minerals of the district from which each is derived, 

 but it may be noted that whereas Ptarmigan and Grouse seem 

 and " ^^^ 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 



