Mr. H. Seebohm on the Birds of Natal S^c. 341 



ing in the southern, it is not known that any land-bird breeds 

 in the southern hemisphere and habitually winters in the 

 northern. It seems probable that most of the accidental 

 visits of southern species of land-birds to the northern hemi- 

 sphere which have been from time to time recorded are of 

 doubtful authenticity ; and amongst sea-birds it is confined 

 to one or two species of Petrel, of which it is not unlikely 

 that undiscovered breeding-grounds exist in the northern 

 hemisphere. One cause of this apparent anomaly may be 

 the difference in the distribution of the land. North of the 

 British Islands and a corresponding latitude on the continent 

 of Europe and Asia is an Arctic Region which is the breeding- 

 ground of great numbers of migratory birds. Many of these 

 winter in our islands, whilst others are regular spring and 

 autumn visitors, passing along our coasts on migration from 

 their Arctic breeding-grounds to their winter-quarters in 

 Southern Europe or Africa. In the southern hemisphere 

 there are no Antarctic breeding-grounds whence similar 

 migrants could visit Natal. No part of South Africa is cold 

 enough to be a breeding-ground of Arctic birds, and the land 

 at the Antarctic pole is too cold for them. The natural con- 

 sequence of this state of things is, that in South Africa there 

 are no migrants from the Antarctic region, either in winter, 

 or passing through in spring and autumn to winter further 

 north. To compensate for the absence of such an important 

 section of migratory birds. Natal and other parts of South 

 Africa are visited, every year by an equally important section 

 of migratory birds, a migration which has no parallel in the 

 northern hemisphere. 



The fact that in the Antarctic region there is no land suit- 

 able for the breeding of birds, except a few species of Penguins 

 and Petrels, is the cause of the apparently anomalous circum- 

 stance that the northern hemisphere is only accidentally 

 visited^ by migratory birds whose breeding-grounds are in 

 the southern hemisphere. South Africa is, however, visited 

 by numerous regular migrants from the northern hemisphere, 

 birds which spend half the year, from September to March, in 

 the summer of the southern hemisphere, surrounded by other 



SER. V. VOL. V. 2 A 



