540 THE BIRDS OF HELIGOLAND 



dull and foggy, with stormy westerly winds, after which it suddenly 

 changed to frost. 



On the 16th the wind was S.E., freshening, with some frost : 

 a strong migration of Charadrius auratus, flocks of from fifty to 

 sixty passing continuously ; Vanellus and Tringa alpina likewise 

 migrating in large numbers all of them precursors of approaching 

 wintry weather, which had undoubtedly already set in to the east 

 of the island. 



On the 17th and 18th, wind S.E., very strong, frost ; Anser in 

 flocks of hundreds and more passing continuously, also a very 

 strong migration of all species of Anas. 



On the 19th, S.E., stormy, frost ; Anser niveus, eight to ten 

 individuals ; Mergus albellus, three examples ; besides these a very 

 strong migration of all the above-named, notably Anas. 



On the 20th, E.S.E., clear, strong wind and frost. Falco 

 albicilla, Mergus merganser, Anser, and Anas all in large numbers : 

 Larus glaucus, a few examples ; and Charadrius virginicus, a bird 

 in winter plumage, the first example of the kind seen here. Under 

 the circumstances we can only assume this individual to have 

 reached Heligoland by an east- to-west flight. 



Until the end of the month, with similar conditions of weather, 

 Anas, Anser and Mergus serrator continued to migrate in enor- 

 mous numbers ; on the 25th, Falco albicilla, an old white- tailed 

 bird, L. glaucus and L. leucopterus, and, strange to say, a Chat, 

 Saxicola cenanthe (Wheatear) in excellent condition : on the 26th, 

 Fulica atra, and on the 31st, Cinclus pallasi. 



These wintry conditions lasted throughout the whole of the 

 following January 1848, the cold reaching from 18'5 to 14 F., 

 (=6 J to8 R), and on one occasion actually 7'25 F. ( = 11 R), 

 quite exceptionally low temperatures for Heligoland, where the sea, 

 which never sinks below freezing-point, exercises a highly moderat- 

 ing influence on the temperature of the atmosphere. The sea 

 around the island, as far as one could see with the telescope, literally 

 teemed with myriads of Ducks and Divers, notably M. serrator ; 

 long chains of Whooper Swans passed over the island, or swam 

 about amongst the ice at shorter or longer distances off; M. albellus 

 was seen repeatedly, and large as well as small flocks of Anser 

 torquatus frequented the vicinity of the island, or migrated past. 

 Moreover, Larus rossii was undoubtedly seen on the 8th of January 

 1848, for several of the most careful shooters brought me re- 

 ports of a small white Gull, with the central feathers of the tail 

 much longer than the rest, like Lestris parasitica ; any possible 

 confusion with L. crepidata is quite excluded here. 



On the 1st of February the winter came to an end with the 



