57 



THE WILLOW-WARBLER. 



Phylloscopus trochilus (L.) 



The forerunners of the main body of Willow- Warblers 

 arrived in this country between March 31st and April 8th 

 along the south coast and spread in small numbers over 

 the southern counties, stragglers reaching as far north as 

 Yorkshire. A considerable party must have arrived in the 

 west on April 5th or 6th, as a number were recorded 

 from Somerset on the latter date, and from Radnor on 

 the 7th. 



The main body of our nesting Willow- Warblers, however, 

 arrived without doubt in one great immigration, lasting 

 from April 9th to 14th, in an extended line along the 

 whole of the south coast of England. This movement 

 was evidently at its greatest height on the 10th and 11th, 

 when vast numbers were reported from several of the 

 south coast lights, while the land-records for these days 

 showed an enormous influx of birds. The first records of 

 this immigration were from Somerset and Hampshire on 

 April 9th, while a few birds arrived in Sussex on the same 

 day. On the following three days the birds were coming- 

 in in great numbers all along the south coast, including 

 the south-east corner. The direction of their flight was 

 due north, with the western wing well forward, thus 

 forming an oblique line across the country, so that whereas 

 the western wing had reached Radnor and Shropshire on 

 the 10th, the eastern wing did not reach Essex until two 

 days later. 



On the 13th they had penetrated to North Wales, 

 Cheshire, and Derbyshire ; on the 16th to Lancashire and 

 Yorkshire ; to Durham on the 19th ; and to Cumberland 

 on the 20th. 



