ROUTES OF MIGRATION. 91 



and Madeira, a distance of some 550 miles. There 

 is, however, no evidence to show that the migration 

 of land birds over these islands is of any importance, 

 whilst the few that do occur normally are principally 

 Waders, birds well adapted, as we have seen, for 

 extended flights. The land birds of this group are 

 resident, or only classed as accidental stragglers^ 

 and only three species are non-European. That 

 these resident individuals remain unmodified, is 

 however a somewhat convincing proof that many 

 individuals from Europe drift to the islands from 

 time to time and interbreed with them. It is also 

 worthy of remark that with only one exception (the 

 Red-legged Partridge Caccabis rufa, which was 

 probably introduced), the fifteen resident European 

 land birds are all species of known migratory habits, 

 a fact which suggests the colonization of these 

 islands by birds that had wandered or been driven 

 out of their usual course during passage. Our 

 second instance is the ocean passage between the 

 continent of North America and the Bermudas. 

 The nearest land is North Carolina, a distance of 

 700 miles, which, as it is in nearly the same latitude, 

 does not fairly represent the sea passage of possible 

 migrants. North of these islands the nearest land 

 is Cape Sable, about 750 miles distant. This is 

 by far the longest ocean passage habitually taken 

 by any migratory land bird on record ; and it is 

 difficult to believe that the flight is ever made from 

 choice, or is customary with some individuals of 

 certain species. The great bulk of the birds that 



