THE GROUSE SUBFAMILY 35 



this species has attained a marvellous degree of perfection ; for it is 

 only by movement that their presence is betrayed, so closely does their 

 coloration agree with the ground against which in times of terror they 

 cower. A heavy toll is levied on their eggs by the common gull, which 

 of late years has increased in numbers, while crows and ravens tax 

 them still further. To avoid persecution from these enemies, some 

 ptarmigan, at any rate, take the precaution to cover their eggs more 

 or less completely when leaving the nest to feed ; and Mr. Seton 

 Gordon cites a case of a pair which had sought concealment for their 

 eggs beneath the cover of a large stone. Possibly this represents 

 the initial stage of a new nesting-habit, due to repeated robberies, for 

 the eggs are less perfectly harmonised with their surroundings, and 

 are readily detected by egg-stealing birds. How perfect is the 

 resemblance between the sitting-bird and its surroundings has been 

 demonstrated by the late E. T. Booth, who made a special pilgrimage 

 to the ptarmigan's haunts on the hills of Loch Rannoch. After 

 searching in vain for eggs, one of his dogs sat down, by accident, on a 

 brooding bird, and so led to the discovery of the first nest, albeit he 

 and two or three keepers had been sitting for more than an hour 

 within a few feet of this particular hen ! a The second nest was found 

 between the legs of the pony which had brought up the lunch. With 

 amazing persistency this bird had remained on its eggs for several 

 hours with the pony towering above her; and only disclosed her 

 presence by flying off in a great flurry when a pannier strap fell on 

 her back during the repacking of the luncheon-baskets at the end of 

 the day ! These two nests, and a third disclosed by the attempt of a 

 terrier to seize a sitting hen, were the only nests discovered after a 

 long and careful search by Mr. Booth and his helpers ! The male 

 keeps a jealous guard over the sitting hen, never straying far from her 

 vicinity. If alarmed he circles round his mate, and finally alights on 

 the top of some high rock, and there remains protesting. The hen 

 commonly sits close, and will often allow the eggs to be taken from 



1 E. T. Booth, Catalogue of the Cases of Birds in the Dyke Hood Museum, Brighton, p. 59. 



