106 STUDIES IN BIRD-MIGRATION 



weeks. To take a few instances culled from the records 

 in my possession for the spring of 1908: I find that 

 movements of the Common Wheatear, from the date of 

 its first appearance on the south coast to the passing away 

 of the last of the passage birds from our islands, covered 

 61 days; those of the Ring-Ouzel, 49 days; of the 

 Willow- Warbler, 65 days ; of the Blackcap, 76 days ; 

 of the Common Sandpiper, 83 days ; and of the 

 Whimbrel, 54 days. If we knew all, the periods would 

 be longer. On the other hand, the period covered by 

 the Nightingale, a bird which is a summer visitor to 

 England only, was but 24 days, perhaps less. 



As regards the dates of arrival of summer birds, it 

 should be remarked that observations made at inland 

 localities are in a great many instances of little value, 

 since an incomer may remain for a number of days 

 undetected. Another fact, of the accuracy of which I 

 am convinced, is that not one migrant in several thou- 

 sands comes under notice immediately on its arrival in 

 the British Isles. 



In not a few cases, as we shall see, the birds which 

 traverse our coasts on their way to the northern breeding 

 grounds in May and June do so at a time when their 

 British representatives are either engaged in the duties 

 of incubation or in tending their young. Song-Thrushes, 

 for instance, pass northwards when the young of our 

 native birds have left the nest, and Golden Plovers when 

 the chicks of their British cousins are well grown. 



We may now proceed to consider the various move- 

 ments performed during the months which constitute 

 spring from the bird-watcher's point of view. 



February.^ — It requires some stretch of the imagina- 



