PTARMIGAN. 35 



the birds may feel as warm "while burrowing in the snow, as 

 while basking in the sun. 



The ptarmigan being a bird which, both from its haunts 

 and its habits, is the most exposed to changes of temperature, 

 and the seasonal variations in its plumage being greater than 

 those in any other, we can in it see the causes of those more 

 partial variations, which, to a greater or less extent, take 

 place in all birds which remain the whole year in exposed 

 situations in variable climates. The sun has less influence 

 on the winter plumage : there is less evaporation and waste 

 from that plumage ; and the bird fattens with less food than 

 it requires in summer. 



It is no doubt in order to find more abundant food, and 

 more especially to find insects for the newly-hatched young, 

 that the ptarmigan descends, and, contrary to the general 

 habit of birds, chooses during the breeding season a region 

 having the temperature a little higher. But their descent 

 subjects them to greater dangers than they meet with in 

 their more elevated regions ; and therefore the old birds not 

 only fight desperately for their young while they remain on 

 the slopes, but lead them to the mountain-tops as soon as 

 they can follow. While the female is sitting, and indeed as 

 long as they remain in the lower places, the male is constantly 

 on the watch, and, on the appearance of danger, gives his 

 alarm-call, which is harsh, and has some resemblance to that 

 of the missel thrush. They do not give the alarm on the 

 passage of a human being, or that of a large quadruped ; so 

 that a person may search the last short heath upon the 

 mountains long enough without finding any ptarmigan, even 

 though there may be numbers quite close to the path. But 

 when they are in the exposed situations, they are just as 

 little anxious to hide themselves ; and therefore, the sports- 

 man who meets with a pack, may shoot them one by one, 

 without those that remain after each discharge making any 



D2 



