104 HILL BIRDS OF SCOTLAND 



his flight. As she rose she was ahnost at once joined by 

 the cock, and the birds took up their station about 200 

 yards from me. The nest contained eight eggs, laid in a 

 hollow of exceptional depth, and during the time I was 

 photographing my find, both the owners kept up a succes- 

 sion of soft croaking cries of anxiety. Tlie eggs of this 

 nest disappeared mysteriously a short time after my 

 visit, but for a number of years the nesting hollow was 

 clearly visible, and could, I believe, even now be identified. 

 The nest of the White Grouse is merely a hollow, 

 usually shallow, but sometimes of considerable depth, as 

 in the case just mentioned, scraped on the hillside amongst 

 plants of the crowberry — Empeirum nigrum — or the 

 short Alpine grasses which flourish on the high hills. It 

 is never, so far as my experience goes, placed at a lower 

 level than 2500 feet above the sea, and as a result is com- 

 paratively seldom found in heather. I have only on one 

 occasion found a Ptarmigan brooding in long heather, 

 and, strangely enough, she was more wild than any of her 

 neighbours who were covering their eggs quite unprotected 

 on the bare hillside. It may be worth while recording 

 here that I have endeavoured as far as possible to fix the 

 upward limit of growth of the common heather — Calluna 

 vulgaris — in this country, and from these observations 

 place its greatest elevation on the w^estern slopes of Ben 

 Mac Dhui, w^here it is met with up to a height of 3300 feet 

 above sea-level, though rarely flowering near the limits 

 of its range. Though the Ptarmigan never nest on the 

 lower hills, they are rarely found at the 4000 foot level — 

 in fact, I do not remember having discovered a nest at a 

 greater altitude than 3G00 feet, though the parent birds 

 move up w^ith their broods even to the highest tops (4300 

 feet) when the -weather is fine. The nest is sometimes 

 scraped out between two stones, which afford the brooding 

 bird a certain amount of shelter, but is often extremely 



