562 Mr. i). A. Bamiennan on the [Ibis, 



Canaries, possibh'^ toucliing tlie continent again near Cape 

 Blanco. This is, of course, a hypothetical line^ bnt it is 

 well known that migrating birds have a strong tendency to 

 follow an extended coast-line. Moreover^ birds passing 

 from Spain and northern Africa (where food is plentiful) to 

 tropical Africa, if they do not hug the coast, find they have 

 to pass through tlie most inhospitable land of the Great 

 Sahara*, where food is scarce over a very large area. It 

 follows^ then, that the birds passing in autumn from north 

 to south have a reason to stick to the African coast-line, and 

 as they cannot possibly see the land at night, many pass 

 over the sea and use the islands of the Madeira and C/anary 

 groups as halting places where they can rest awhile and 

 secure plenty of food with very little trouble. 



The " front ^^ upon which this great migratory advance 

 is made is a very wide one — the Canary Islands being at the 

 extreme westerly end, and, as [ have tried to shew, would 

 certainly not have so many migrants passing through them 

 were it not for the proximity of the African shores. Fartiier 

 to the east hundreds cf birds must follow the Nile Valley, 

 while again countless numbers pass down the eastern sliores 

 of the continent. Dr. Hartert's interesting remarks on 

 Bird Migration in Algeria (Nov. Zool. xx. 1913, pp. 73-76) 

 strongly support the theory of coastal migration. In this 

 article the writer seems to suggest that the Canaries are 

 visited through the migrants following the west European 

 shores, which have a south-westerly direction, and, main- 

 taining this direction during their flight, the birds pass out 

 to sea and eventually come to the Canary Archipelago. 

 That the birds which pass through the Canary Islands come 

 again to the mainland, and do not all perish at sea, is surely 

 proved by the regularity with which many species occur 

 there on migration, shewing to my mind that this is the 

 most western extreme of the regular flight and that the 



* That, nevertheless, large numbers of migratory birds pass over the 

 Sahara itself is well known. At the migration season the oases of the 

 Sahara are teeming Avitli bird-life while at other times of the year they 

 are practically deserted. 



