294 STUDIES IN BIRD-MIGRATION 



One obtained at the lantern on the last-named date was 

 forwarded for determination. 



Phylloscopus sibilatrix, Wood- Warbler. — This 

 species has on few occasions been observed northwards 

 of the mainland of Britain. The first of these was a 

 bird killed at the Sule Skerry lantern on the night of 

 27 th September 1906, and sent to me for determination. 



Phylloscopus TROCHiLUS, Willow- Warbler. — Judging 

 from the records, this must be a rare visitor, for there 

 are only two instances of its appearance registered, 

 both for September, and at the lantern. The birds 

 were sent. Mr Tomison makes no allusion to the 

 occurrence of this species in his paper on the avifauna 

 of the island. 



Phylloscopus borealis. Northern Willow-Warbler. 

 — An adult male was captured at the lantern on the night 

 of 5th September 1902, and was forwarded to me in the 

 flesh. At the time, this bird was believed to be an 

 example of the Greenish Willow- Warbler {^P. viridanus), 

 and was exhibited as such at a meeting of the British 

 Ornithologists' Club. Later, in September 1908, I shot 

 a specimen of P. borealis at Fair Isle (see p. 130), and 

 this led to the detection of the error in the identification 

 of the Sule Skerry bird. The Sule Skerry and Fair Isle 

 birds are the only ones known to have occurred in the 

 British Isles. 



Phylloscopus collybita, Chiffchaff. — One was 

 killed at the lantern on the night of 3rd November 1901, 

 and was sent for identification. 



Phylloscopus tristis, Siberian Chiffchaff. — The 

 first British example of this North-Eastern European 

 and Siberian summer bird, was killed at the Sule 

 Skerry lantern on the night of 23rd September 1902. 



