AQUATIC WARBLER ON MIGRATION. 83 



travelled with several other species which habitually visit the 

 Tuskar on migration, including its close ally the Sedge-Warbler. 

 And it is more than likely that other Aquatic Warblers con- 

 sorted with it but escaped detection,* either because they did 

 not strike the lantern, or, if they did, they fell into the sea, or 

 on to an inaccessible part of the rock or where it is covered 

 by the tide at high water, where they would soon be swept 

 away, instead of falling on an accessible area of the rock 

 where they would remain until the lightkeeper found them and 

 picked them up. Although only one other bird was obtained 

 on the same date, namely, a Wheatear, which struck the 

 lantern at 2.30 a.m., nevertheless, I learn in a letter from Mr. 

 Glanville, written on the morning he obtained the Aquatic 

 Warbler (August 9th), that "there are birds at the lantern 

 every night, but as weather is clear very few are striking." To 

 substantiate the evidence that birds about this time were on the 

 move at Tuskar he sent me : Willow- Warblers, found dead on 

 the rock on August 6th and 8th ; Sedge-Warblers, ditto, August 

 7th and 8th ; a Wheatear, ditto, August 8th ; also Wheatears 

 which struck the lantern on August 7th and 8th. In regard to 

 identification Mr. Glanville exercised due caution in not attempt- 

 ing to put a name on the bird offhand. This is what one 

 would expect, for he had a very brief period in which to examine 

 it before posting it, few specimens with which to compare it, and 

 very little literature to consult. To add to this he was particularly 

 busy preparing to go ashore himself that morning. Albeit he 

 discriminated at once that the bird was no ordinary Sedge- 

 Warbler, not only on account of the characteristic and con- 

 spicuous buff stripe running along the middle of the crown of the 

 head, which many ornithologists lay so much emphasis upon as 

 though it were the only distinguishing mark between the Aquatic 

 and Sedge-Warbler, but also because the pattern of the plumage 



* I have 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 Bock in 

 September, 1913 ('Irish Naturalist,' November, 1913, p. 220), and of Reed- 

 Warblers in September, 1912 (ibid. March, 1912, p. 50). Vide also remarks 

 in my article on " Grasshopper-Warblers on Migration " ('Irish Naturalist,' 

 August, 1912, p. 139). Indeed, the term rare is often more applicable to the 

 periodical than to the numerical status of many species. 



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