32 THE CROW FAMILY 



and scraps, and by small birds or rodents too weak to escape pursuit 

 and capture. Now if the bare skin were due to abrasion by boring, 

 one would expect the feathers to sprout anew when, as during the 

 winter of 1814, instanced by Waterton, the ground was hard frozen 

 and covered with snow for months ; but this is not what happens. 

 The strongest objection, however, lies in the fact that, if we except a 

 temporary shedding of the nasal bristles which appears, occasionally 

 at least, to occur at the first autumn moult, the young rook retains 

 intact the facial feathers till its second autumn moult, that is for more 

 than a year after its departure from the nest. This is proved both by 

 the observation of specimens in captivity, and by records and dated 

 skins of immature birds shot in spring, that is after the first autumn 

 moult. It is obvious that if the digging habit is to be taken as the 

 cause of the bare skin, then the young rook would not only now and 

 then, but invariably, show signs of abrasion long before its second 

 moult, unless, of course, we are prepared to assume that it either 

 totally abstains from a diet of worms or is fed by its long-suffering 

 parents for months after it is capable of shifting for itself. A further 

 fact bearing on the question has been supplied me by Dr. E. Hartert, 

 who points out that the Far Eastern form of our rook (C. frugilegus 

 pastinator} has the bare area much more limited, the lores and chin 

 being feathered. If the cause is to be found in digging, one asks why 

 it does not produce the same effect in the case of the two sub-species. 

 Or are we to assume that the soil or the worms of the area inhabited 

 by pastinator (China, Eastern Siberia, Korea, Japan, Formosa) have 

 throughout just that marked unvarying degree of difference from our 

 own that would account for the very definite divergence in the respec- 

 tive bare faces of the two forms ? 



On the other side, it has been said that rooks with the beaks so 

 malformed as to prevent them from digging, have been found to retain 

 the feathering on the face after the second moult. But this proves 

 nothing, for both abnormalities may be the effect of the same cause. 



Setting aside the abrasion theory as yet unproved, we find our- 



