152 NATURAL HISTORY OF SELBORNE. 



before the sun as it advances, and retire to milder regions, and 

 especially birds of prey, whose blood being heated with hot animal 

 food, are more impatient of a sultry climate ; but then I cannot 

 help wondering why kites and hawks, and such hardy birds as are 

 known to defy all the severity of England, and even of Sweden 

 and all north Europe, should want to migrate from the south of 

 Europe, and be dissatisfied with the winters of Andalusia. 



It does not appear to me that much stress may be laid on the 

 difficulty and hazard that birds must run in their migrations, by 

 reason of vast oceans, cross winds, etc. ; because, if we reflect, a 

 bird may travel from England to the Equator without launching 

 out and exposing itself to boundless seas, and that by crossing the 

 water at Dover, and again at Gibraltar. And I with the more 

 confidence advance this obvious remark, because my brother has 

 always found that some of his birds, and particularly the swallow 

 kind, are very sparing of their pains in crossing the Mediterranean ; 

 for when arrived at Gibraltar they do not 



. . ' ' Rang'd in figure wedge their way, 



And set forth 



Their airy caravan high over seas 

 Flying, and over lands with mutual wing 

 Easing their flight :" .... MiLTON. 



but scout and hurry along in little detached parties of six or seven 

 in a company; and sweeping low, just over the surface of the land 

 and water, direct their course to the opposite continent at the 

 narrowest passage they can find. They usually slope across the 

 bay to the south-west, and. so pass over opposite to Tangier, 

 which, it seems, is the narrowest space. 



In former letters we have considered whether it was probable 

 that woodcocks in moonshiny nights cross the German Ocean 

 from Scandinavia. As a proof that birds of less speed may pass 

 that sea, considerable as it is, I shall relate the following incident, 

 which, though mentioned to have happened so many years ago, 

 was strictly matter of fact : As some people were shooting in the 

 parish of Trotton, in the county of Sussex, they killed a duck in 

 that dreadful winter, 1708-9, with a silver collar about its neck,* 

 * "I have read a like anecdote of a swan." 



