778 NATURAL SCIENCE. ^^^,_ 



in New Zealand, the New Hebrides, and Norfolk Island ; the knot in 

 New Zealand ; the Asiatic golden plover in New Zealand, and the 

 isles of the Pacific ; and the short-eared owl, and others, in the Sand- 

 wich, Ladrone, and Caroline groups, are all suggestive of immense 

 ocean flights undertaken by birds on migration. 



At the same time, we confess we are very sceptical as to the fact of 

 American land-birds crossing the Atlantic without a more or less assisted 

 passage. Possible exceptions are the snowy owl and Greenland 

 falcon, which are known to have occurred occasionally on the west 

 coasts of Scotland and Ireland, arriving most likely by a route direct 

 from Greenland by the Faroes, and, it may be, assisted by drifting 

 ice. American birds which turn up in the British islands probably 

 travel first north along the East Coast of Greenland, and across the 

 Pole, then south along the Scandinavian coast-line ; in support of 

 which it may be urged that the greater portion of stragglers which 

 reach our shores from the New World are recorded from the East 

 and South coasts as far west as Devon and Cornwall. Many of these 

 latter have no doubt first struck the East Coast, and followed the 

 coast-line to the south-west limit of land. 



When on the subject of altitude, Mr. Dixon remarks " that in no- 

 part of the world do any regular migration routes cross seas too wide 

 to be bridged by the eye of a bird liying at a sufficient altitude." 

 Does Mr. Dixon seriously mean that a migrant over the North Sea, 

 between the Elbe and Humber, can bridge the entire distance of 

 four hundred miles with its eyes from shore to shore, and this by 

 night as well as by day, and in all conditions of weather ? What is 

 intended by " sufficient altitude " ? and is it really the case that birds 

 in the sea-passage do move as a rule at vast altitudes ? The height 

 of migratory flight appears to be dependent on wind and weather : 

 under favourable barometric conditions — chiefly anti-cyclonic — birds 

 will fly high,5 but in cyclonic periods, the prevailing w^eather in the 

 autumn, very low ; and when over the sea just clearing the water or 

 following the curve of the wave. Often when on the North Sea in 

 the autumn have we seen for hours in succession flights of birds 

 moving westward low near the surface ; and in the autumnal "great 

 rushes " o\-er and past the East Coast lightships, the observers, 

 acting on behalf of the Migration Committee of the British Associa- 

 tion, have yearly entered in their schedules the records of a low-flying 

 and continuous migration, often lasting for days and weeks. All 

 experience, then, independent of mere theory, is in the direction of a 

 low or medium flight, showing that very lofty flight is the exception 

 and not the rule in the autumnal passage of the sea. The inrush of 

 migrants coming under our own observation on the East Coast of 

 Yorkshire in the last autumn was in many respects very instructive, 



I" With gentle northerly and easterly winds birds are noted as often flying high. 

 Strong winds, however, from any (juarter, are known to beat them down to the 

 surface of the sea. 



