THE BIRDS OF FAIR ISLE 177 



sea off the Isle, but they have only once come under my 

 observation. Terns, probably this species, are said 

 to have bred on the island in the early decades of the 

 19th century. 



Larus ridibundus. Black-headed Gull. — Visits the 

 Isle at intervals in winter, and is a common visitor before 

 and after the nesting season. 



It passes northwards in spring during March, April, 

 and May, being most numerous during the latter month. 



In autumn it occurs regularly in mid-July, and 

 onwards to the end of September. A few are seen 

 occasionally in October and November. 



Larus canus, Common Gull. — A few are seen in 

 winter, but the bird is much in evidence during the 

 seasons of passage. It has not been known to nest. 



It appears late in April and during May, and a few 

 are seen in the first week in June. 



In autumn small numbers appear from the second 

 week of July until mid- August, after which the bird 

 becomes more numerous, and is observed until near the 

 end of October. Very few have been seen later. 



Larus argentatus, Herring-Gull — A common 

 resident, nesting in considerable numbers. Many young 

 birds desert the sea in the autumn, and endeavour to eke 

 out an existence on the land, with the result that many 

 perish. The young birds are much preyed upon by the 

 Peregrine, and what this bird leaves of its victims often 

 becomes the food of other Herring-Gulls, both old and 

 young — hence the bird is guilty of cannibalism. 



Larus fuscus, Lesser Black-backed Gull — This Gull 

 is a common summer visitor to the Isle. 



It makes its first appearance between 17th March 

 and 5th April, and nests in numbers. 



II. M 



