142 
BIRDS. 
highest part of the screes immediately below the crest of the 
mountain, where walking is difficult, and even dangerous ; while in 
the humid climate of the west coast there are few days in early 
summer that find the hill- tops clear of mist above the 2500 feet line. 
On the other hand, it is very possible that a climatic change, 
such as the lowering of the general summer temperature over a 
particular part of the country, might induce conditions which 
would cause some of the birds to remain on the higher hill-tops 
for the breeding season. And for such a change within recent 
times there is a certain amount of indirect evidence, although 
satisfactory data, such as would be afforded by a series of reliable 
meteorological observations, are unfortunately wanting. 
Oral tradition, of whatever value it may be, recognises a deteri- 
oration in the summer climate of the north-west coast and Outer 
Hebrides within recent times ; as, for example, the undoubted fact 
that salt-pans, which were formerly largely employed, are now 
useless from want of sufficient sunshine in ordinary summers. 
Botanical evidence is more trustworthy, and observations made 
on the mountains of West Sutherland point to a tendency in the 
Alpine plants to creep further down the hill-sides. Strictly Alpine 
species, such as Sihbaldia procumhens, Saxifraga oppositifolia, S. 
hypnoides, Luzida spicata, and others,^ are found growing on spots 
laid bare by the recent decay of the peat, where sphagimms and' 
1 I am indebted to my friends Messrs. B. N. Peacii and A. Gray for the 
following list of Alpine plants found in, and in the immediate neighbourhood of, 
the corrie in which the nest was obtained : — 
Caltha palustris, y var. minor. 
Cochlearia oflBcinalis, var. alpina. 
Draba rupestris. 
Cerastium latifolium. 
Cherleria sedoides. 
Sibbaldia procumbens. 
Epilobium alsinifolium. 
Saxifraga oppositifolia. 
S. hypnoides. 
Cornus suecica. 
Saussurea alpina. 
Gnaphalium supinum. 
Loiseleuria procumbens. 
Veronica humifusa. 
Oxyria reniformis. 
Luzula spicata. 
Juncus trifidus. 
Eriophorum angustifoliuni, j3 var, 
minor. 
Lyco])odium alpinum. 
L. selago. 
Selaginella spinulosa. 
