218 THE SKUAS 



Killala Bay, several poraatorhines took shelter in Tralee harbour, and 

 remained there as long as the stormy weather lasted. Evidently they 

 were a part of the same flight already noticed by Mr. Warren. 



With regard to the cause of these invasions, the opinion of the 

 late Mr. E. T. Booth 1 has especial weight, as no ornithologist was more 

 familiar with the North Sea than he was. For three or four autumns 

 he made his headquarters at Canty Bay in East Lothian, spending 

 most of his time at sea, and often attaching himself to the North Sea 

 herring fleet. He states that immense numbers of both old and 

 young birds pass over the North Sea every year on their way back to 

 winter quarters from their breeding-grounds, the first arrivals appear- 

 ing off the south-east coast of Scotland about mid- August. These 

 birds are for the most part not quite mature, and the long tail feathers 

 are usually broken or lost ; but a few adult birds accompany them, 

 though they do not form a tenth 'part of the total number observed. 

 As a rule, they migrate ten, fifteen, or twenty miles from land, but 

 occasionally small parties may be seen moving due east or west at a 

 good height in the Firth of Forth (possibly on their way across Scot- 

 land to North Ireland). A few weeks later the full-plumaged adults 

 follow, and they, in turn, are succeeded by the birds of the year. 

 Birds in the second and third years' plumage are very rarely met with. 

 During October and early November the flocks of skuas keep 

 company with the herring-boats as they work up the coast, levying 

 toll on the gulls which congregate round the nets. In fine autumns 

 hardly a bird will approach the land, but continued rough weather 

 will drive hundreds of them in a worn-out and starving condition on 

 to the coast. Sometimes the main body of migrants will keep from 

 forty to sixty miles from our east coast. In some cases the fish 

 captured by the larger vessels are cleaned before stowage, thus pro- 

 viding an abundant supply of food for the thousands of gulls which 

 surround the fleet, while they, in turn, are forced to disgorge to feed 



1 E. T. Booth, Rough Notes on Birds observed in the British Isles, vol. iii. pp. 1-7 (article on 

 " Pomatorhine Skua "). 



