164 STUDIES IN BIRD-MIGRATION 



loth November, the middle weeks of October being the 

 main period for its observance. 



CoLUMBA CENAS, Stock - Dove. — This species was 

 added to the avifauna of the island by the Duchess 

 of Bedford. Single birds were seen on 25th, 29th, 

 and 30th September 191 1 (perhaps the same 

 individual on each occasion), and another on 24th 

 October. 



CoLUMBA LI VI A, Rock-Dove, — The Rock- Dove was 

 formerly a resident species, finding ideal haunts in the 

 numerous caverns and niches in the extensive range of 

 cliffs. Until some fifteen or sixteen years ago it was 

 abundant ; now it is quite unknown. It was subject 

 to some persecution. For instance, numbers were 

 captured in certain caves at night. To accomplish this 

 a sail was placed over the entrance, and then a lantern 

 was lighted in the cave, and the frightened birds 

 dashed against the obstruction in their endeavours to 

 escape, and were secured. The caves, however, where 

 this could be practised were few, and George Stout is 

 of opinion that the introduction of guns during the 

 construction of the lighthouses was the cause of the 

 bird's extermination. 



TuRTUR TURTUR, Ttudle-Dove. — Has occurred annu- 

 ally for several years during both passages, but in small 

 numbers. 



In spring the dates for its appearance range from 

 9th to 27th May. Not more than two have been 

 observed on the same date. One arrived on the 20th 

 of June 1908, and remained until the 27th, but this was 

 an exceptional occurrence, as was also the visit of one 

 on 7th July 1910. 



Autumn records relate to single birds which have 



