192 REPORT— 1881. 



gales have also, no doubt, affected the direction of the migration to a 

 considerable extent, and indications of this agency may be found in the 

 occurrence, on our shores, of many rare wanderers, in the autumn of 

 1880. 



Notwithstanding the enormous number of immigrants arriving, as 

 shown in the schedules returned from each station, it is quite certain that 

 these returns only represent an almost inappreciable percentage of the 

 actual number on passage. On days of uncertain light, or on clear, fine, 

 starlight nights, when migration is carried on at a considerable height, 

 immense numbers of birds might pass any of the stations for hours 

 without being observed ; and it is quite possible that, if the whole 300 

 miles of the east-coast line of England were studded with floating posts 

 of observation at the distance of half-a-mile, equal average results would 

 have been obtained ; the present stations on the light- vessels affording no 

 more especial line of advantage than any other imaginary line drawn 

 across the North Sea. 



As, in 1879, birds have crossed at all hours of the day and night, and 

 in all winds and weathers. The returns also shoM^ as did the preceding, 

 that they seldom fly dead to windward, except with very light breezes, 

 and that strong opposing winds are invariably prejudicial to their passage. 

 The line of flight mostly adopted is within three or four points of the 

 wind ; they will go on well with a beam- wind, or some points even aft o£ 

 beam, if not too strong. Small weak-winged birds have often, as noticed 

 on the light-vessels, great difficulty in making head against strongly- 

 opposing winds. If the wind changes during the actual passage, birds 

 have been observed to change the direction of their flight to suit the 

 wind. Even the sti-ong-winged wild geese and swans are observed, when 

 well-up in the wind, to drift to one side a little, having the appearance of 

 flying left shoulder first instead of head first. 



Birds are noticed at the stations as sometimes flying high, sometimes 

 low ; often with northerly and easterly winds they fly high, and with 

 winds in opposite quarters, low. The state of the weather at the time of 

 migration has more, we think, to do with the height at which birds travel 

 than the direction of the wind. On clear light nights they travel high, 

 as a rule ; but in fog, rain or snow, or in thick murky weather, low — not 

 many feet above the waves. On thick dark nights, indeed, lost birds will 

 wheel for hours round a light-vessel, but with the first break in the 

 clouds, the stars appearing, or streak of early dawn, are on their course 

 again to the nearest land. At times birds are seen passing high in aii*, 

 almost beyond the ken of human vision, and when clouds or fogs rapidly 

 lift or clear off during the time of migration, the said migration appears 

 often to cease to mortal vision, indicating an ascent to a higher level. 

 Birds are also known to descend upon Heligoland and the light-vessels 

 almost perpendicularly from the sky, indicating a course of migration at 

 a great height. The height at which birds travel in foggy weather, or in 

 snow or rain, has probably a good deal to do with the various numerical 

 returns of those killed at lanterns. Broadly speaking it is the brightest, 

 ■whitest, fixed lights which, having most influence in penetrating fog or 

 haze, attract the most birds. In 1877, at Skerryvore, in the month of 

 October, the number of birds killed was 600, chiefly the common thrush 

 and the ring-ousel. This year the mortality has been heavy at some of 

 the light- vessels. At the Casquets, off Aldemey, on October 7, from 

 11 P.M. to 3 A.M., S.S.E., rain, land-rails, water-rails, woodcocks, ring- 



