UP THE MOUNTAINS. 17 1 



PTARMIGAN ( Tetrao mutus\ and one of the most scotch 



, , - ,_; _^ . /'-"* IT mountain 



local too. The Ptarmigan (and its several climatic south to 



\ 1 ii i i A* Arran. 



races) is a northern bird, strictly speaking an Arctic 

 one, only found on the tundras above forest growth 

 or at high elevations in more southern lands. 

 On the highest hills of Scotland this bird finds 

 a climate equal to that of sea-level above forest 

 growth in Arctic Europe ; and on these bleak, 

 wind-swept summits it lives all the year round, 

 rarely, if ever, descending below the snow in 

 winter, unless temporarily driven down from the 

 highest tops by an unusually severe storm. But 

 its constant residence on the hilltops has been 

 the cause of much modification in its habits and 

 in its plumage. It is a curious fact, and one 

 that goes far to prove the utility of colour in 

 Nature, that white birds or animals are excessively 

 rare. Take birds alone. The number of pure 

 white birds, or birds in which white is the pre- 

 dominating colour of the plumage, is very, very 

 few ; in comparison with the twelve thousand or 

 so known species absolutely a unit of no great 

 importance. But the exceptions prove the rule, 

 and demonstrate how closely the colour of living 

 creatures is in harmony with the conditions of 

 their life. These Ptarmigan that have just risen 

 from the stones at our feet on the mountain-top 

 have constantly to be changing the colour of their 

 plumage with the changing season. Now, in the 

 spring, they are clothed in a dress of dark brown 

 mottled with yellowish brown tints in beautiful 

 harmony with the lichens and mosses. In autumn 

 they will change this dress for one of pale gray, 

 vermiculated with black or rather they are 

 slowly changing colour all the summer through 



