JULY. 119 



boundary ? Local circumstances may, however, alter 

 special cases ; and in game-preserving districts the 

 appearance of the sparrowhawk is a sure sign that 

 the autumn migration has commenced. For the 

 sparrowhawk is still a common British bird, although 

 where the gamekeeper is supreme it cannot breed. 

 Its nest would always be discovered and both birds 

 shot. But the most carefully preserved districts are 

 those which offer to hawks and falcons the best hunt- 

 ing-grounds in autumn and winter ; and it is there 

 that they invariably halt on their southward journey 

 in the autumn. In spring we catch only a fleet- 

 ing glimpse of the passage hawks, because then they 

 are travelling with a purpose to reach their breeding 

 haunts ; but in autumn they loiter, stopping wherever 

 young birds, which are so easily caught, are numerous 

 and travelling southwards again only when tempted 

 to accompany large flights of eatable birds that are 

 fleeing before the north wind. 



TRAVELLERS FOR FOOD. 



So, when a few sparrowhawks reappeared where 

 they had not been seen since spring, we knew that 

 other young birds of the year must be already on 

 the move, drifting southwards in July because, when 

 the north wind blew, the air was chilly and insects 

 consequently hard to find. In other years, when we 

 have no such foretastes of cold autumn weather in 

 midsummer, insects remain abundant everywhere, 

 and the young birds remain to eat them, and there 

 is no incentive for the young hawk to travel either, 

 until, at any rate, the shortening days of mid-August, 



