30 THE BIKDS OF HELIGOLAND 



are they met with regularly every autumn, but they frequently 

 attam to the comparatively large numbers of from ten to fifty, and in 

 two or three instances of even a hundred individuals in a single day. 



With Richard's Pipit might also be associated the small Yellow- 

 browed Warbler {Sylvia superciliosa). This bird likewise has its 

 breeding home in eastern Asia, but nevertheless, in addition to its 

 normal southerly autumn migration, it migrates in fairly large 

 numbers far towards the west. The bird appearing in Heligoland 

 in favourable Aveather regularly every autumn, two, three, or more 

 individuals being frequently observed in one day, it surely ought 

 also to occur in Germany with equal regularity and in fairly 

 large numbers; it thence undoubtedly continues its journey to 

 France, and perhaps even farther. In England it has only been 

 killed twice, but there can be no doubt of its having reached that 

 country far more frequently via Heligoland without having been 

 observed. When we reflect that it requires the coincidence of very 

 many favourable conditions before so tiny a creature could be 

 noticed, distinguished, and shot, amid the countless bushes and 

 shrubs of gardens and river-banks, this scarcity of observations 

 need not surpx'ise us ; more especially because, probably, but very 

 few European ornithologists are acquainted with its call-note. 



When we turn from the birds considered above to such others 

 the direction of whose migratory flight we can verify by the direct 

 perception of our senses, we find, that during the day. Larks, Star- 

 lings, many Waders, and especially the dense droves of the large 

 dark-pluniaged Hooded Crows, furnish us with clear, though, as 

 regards the numbers of individuals, still limited supjjorts for the con- 

 clusions as to the direction of the migratory flight which we enun- 

 ciated at the outset of this chapter. The matter assumes, however, 

 a quite different aspect on those dark autumn nights in which strong 

 migrations take place ; these nights offer far more extensive and 

 interesting opportunities for conducting observations on the subject 

 of our inquiry. On such nights the sky is often completely 

 obscured by vast multitudes of Plovers, Curlews, Godwits, Oyster- 

 catchers, Greenshanks, Sandpipers, and many other less vociferous 

 species, such as Larks and Thrushes, whose voices, resonant from 

 afar, proclaim clearly through the stillness of the night from 

 what direction in the sky they are arriving, while the notes of 

 the departing travellers, gradually growing fainter and fainter, 

 announce, in a manner equally distinct, in what direction they are 

 continuing their journey. The whole flight proceeds without pause 

 or change in one incessant stream from east to west. 



The most varied observations of others, conducted directly 

 in the open air, have yielded similar results. Among such, 



