48 THE ZOOLOGIST. 



a line of argument applicable in considering the status of many 

 other birds which visit us — it is true that, while the Icterine 

 Warbler may be classed as a rare visitor to our Isles, it has, never- 

 theless, been overlooked to a considerable extent, and its greater 

 rarity, as disclosed by the earlier records, has been apparent 

 rather than real.* The greater frequency of the appearance of 

 the bird in latter years, as compared with the more lengthened 

 periods which elapsed between the dates of occurrences of the 

 earlier specimens, notably between the first and second, depends 

 largely upon the fact that, not only has the study of ornithology 

 found more favour of late, but also that many more workers have 

 made a special study of migration, and have selected the very 

 best types of observatories — I mean light-stations built on rocks 

 or small islands some miles off the coast, and situated so as to 

 lie along and often to intersect important migration-routes. 

 Now, apart from the fact that the lighthouse is a very great 

 asset, in that it attracts birds, it is also highly important to 

 note that, whether these birds descend from the lantern at 

 night to the rock, as I know many undoubtedly do, or alight 

 in daylight independently of the existence of the lantern, owing 

 to the small compass of ground, bleak and devoid of foliage 

 and other natural cover, it is a difficult matter for a migrant, 

 when it arrives, to escape betraying its whereabouts ; even 

 when in hiding in a- rock crevice it can with ease be dis- 

 lodged and made repeatedly to show up at these excellent 

 observatories. Obviously it is more difficult to make sure of 

 the identity of birds which touch on the mainland, for should 

 they not take wing at once, they quickly make for cover, 

 through which they can thread their way for long distances 

 without being dislodged. And so, outstripping the range of the 

 observer, they soon become lost in the interior of the district. 



* Saunders regarded the Icterine Warbler as " only a very rare visitor to 

 England and Ireland," it being, at the time be wrote, as yet undiscovered 

 in Scotland. I should suggest modifying his sentence somewhat as follows r 

 A visitor on passage in small numbers during the spring and autumn 

 migrations to the southern and eastern seaboards of Great Britain, and 

 probably occurring annually. Seemingly much rarer in Ireland, and 

 occurring probably as a westward straggler from its regular migration fly-lines. 

 Has in all likelihood been overlooked to a greater extent proportionately 

 than in Great Britain. 



