NOVITATES ZOOLOQICAE XXIV. 1917. 5 



dealing with the Aquatic Warbler from Tuskar I have given cogent reasons to 

 show that although only one bird — a Wheatear — was obtained on the night 

 it struck, none the less this Aquatic Warbler travelled in company with several 

 species, and more than likely with other Aquatic Warblers, and it is all the more 

 reasonable to assume that this Black-eared W'heatear was accompanied by 

 other members of its own kind.* It is perfectly clear that a great company of 

 migrants of different kinds pursuing their regular routes had in their midst 

 as they reached Tuskar a species of Wheatear as yet undiscovered in Ireland. 



Why this bird came along with them is a question deserving close attention. 

 We are told that there were " dozens of Whea tears " in the rays that night. 

 and as already indicated there may have been some more Black-eared examples, 

 It is quite conceivable that a small party of Black-eared Wheatears, detaching 

 themselves for some more or less trivial reason from the main body, may 

 have sighted and joined a company of Common Wheatears steering somewhat 

 in the same direction. If, on the one hand, it may be said that such an idea 

 is but theoretical, I would, on the other hand, remind the reader that in so far 

 as the Common Wheatear is concerned, its migrations at light-stations are almost 

 invariably characterised by marked gregariousness. This is readily under- 

 stood ; for it is an extremely abundant species, has an extraordinarily wide 

 distribution on its vernal migrations, i.e. its breeding-range is of vast extent, 

 so that different companies, as they forge forwards, are apt to meet and join 

 up, and in dark and foggy weather to be held up in large assemblies at the lantern ; 

 and, thirdly, the Wheatear is on the whole amicably disposed to other species and 

 to members of its own family. Hence a few Black-eared Wheatears would not 

 feel strange in the company of their larger relatives ; nay more, being gregarious 

 themselves on migration, and being cut off from the company of their own 

 kind, they might well prefer the presence rather than the absence of the Common 

 Wheatear e?i route. Indeed, being in the minority they might readily accept 

 the escort of the majority and so proceed onwards, oblivious of the fact that 

 they were out-stepping the normal boundaries of their breeding-range. How 

 much farther the Tuskar Black-eared Wheatear might have journeyed, had 

 it not injured itself, is of course a difficult problem to solve. 



* I have already put forward cumulative evidence to show that rare as well as common birds 

 are apt to visit light-stations on migration in the plural even more than in the singular number : 

 witness occurrence of Tree-pipits at Tuskar in September 1913 (Irish Naturalist, November 1913, 

 p. 220) and again in September 1915 (Irish Naturalist, June 1916, pp. 90-91), and ot Reed-warblers 

 in September 1911 (ibid. March 1912, p. 50) ; vide also remarks in my articles on " Grasshopper- 

 warblers on Migration " (ibid. August 1912, p. 139, also on " Aquatic Warbler on Migration at 

 Tuskar Rock" (Zoologist, March 1915, pp. 81-92), and on "Remains of a Tree-pipit found on 

 Tuskar Rock " (Irish Naturalist, June 1916, pp. 85-93). Indeed the term " rare " is often more applic- 

 able to the periodic than to the numeric status ot many species. I have pointed out what an easy 

 matter it is for migrants to escape detection of the Ughtkeepers, because on striking the lantern 

 many may fall into the sea, or on an inaccessible part of the rock, or if the part be accessible it may 

 be uncovered only at ebb-tide, so that birds would probably be carried away at high- water before 

 being retrieved; lastly, many, whilst flying round the lantern, may escape detection, or at all events 

 identification of species, through not striking the glass and thereby not allowing the Ughtkeeper 

 the opportunity of bringing them to hand for close examination. (Vide my article on " Aquatic 

 Warbler on Migration obtained on Tuskar Rock," Zoologist, March 1915, p. 83.) 



