ORNITHOLOGICAL RECORD FROM NORFOLK. 117 



Yellow-browed Warbler. With them it must be the nature of 

 the weather when they arrive in Norfolk, Lincolnshire, and York- 

 shire which determines whether they halt or pass on. 



A certain number of Russian and Eastern Asiatic birds pro- 

 bably pass over Norfolk and the east coast every autumn, for the 

 most part by night, and at so high an altitude as to be beyond the 

 limits of human sight. As they are not seen their presence is 

 never suspected. Migratory phenomena of this sort only become 

 apparent when brought within our ken by unsettled weather and 

 sometimes fog, as clearly demonstrated by Herr Gatke in his long 

 course of observations on Heligoland. 



There is no migrant whose movements can be better observed 

 than the Blackbird's. They come from the east, for the most 

 part in " rushes," from October to Christmas Day, first dropping 

 into turnip-fields with an incredible number of Thrushes, and 

 then swarming in plantations. It is in December and January 

 that Norfolk obtains the old yellow-billed cock Blackbirds, which 

 indicates either that the adults are the last to migrate from 

 Scandinavia, or that, owing to dull plumage and brown bills, 

 these old cocks are not recognized as such by English observers 

 in October and November. 



By the 1st of February the northward movement has begun 

 again, almost before the southward movement of individuals 

 nesting in the higher latitudes is over; and, under certain 

 circumstances of wind and weather, it is probable the two 

 streams sometimes amalgamate, or actually cross one another. 

 If any ornithologist possessed of keen sight would go to sea in 

 one of our Yarmouth herring smacks, or obtain the Trinity 

 Board's permission for a week's sojourn on such a floating light- 

 ship as " The Outer Dowsing," or " The Leman and Ower," in 

 the month of October, he could not fail to identify a number of 

 species in transit, especially if the wind was from the west. A 

 wind which the migrants (nearly always to be seen at Cromer 

 arriving from the east) would have to fly against would delay nine- 

 tenths of them until sunrise, or later, when they could be easily 

 identified. Its velocity must be an important factor, and it would 

 probably be found that they choose a high or low stratum, 

 according as they are thereby enabled to minimize its power. 

 By anchoring a boat at a measured distance of half a mile from 



