CHAPTER VI. 



ISLAND AVIFAUNAS. 



The West Palaearctic Islands — Continental Islands — Birds of 

 Borneo, Formosa, the Philippines, etc.— Ancient Continental 

 Islands— Birds of the Canaries, Madagascar, Azores, Bermuda, 

 etc. — Reasons for the Unequal Dispersion of Species — Islands 

 andlNIigration — The British Islands — Endemic British Species 

 — The Red Grouse — Endemic British Races, or Representative 

 Forms — The St. Kilda Wren — Races of Titmice — Poorness of 

 British Avifauna in Endemic Species — The Channel Islands 

 and Heligoland — West Mediterranean Islands — The Canarj- 

 Islands — Endemic birds of — Number of Eggs laid by Birds in 

 Canary Islands — Madeira and the Azores — Japan and the 

 Benin Isles — Various Tropical Islands— Endemic Avifaunas of 

 — Bearing of Migration on Insular Avifaunas — Conclusions 

 Drawn from Facts — Bearing of Glacial Conditions on Island 

 Avifaunas. 



We have now reached that stage in our investigations 

 where it becomes necessary to deal more specially with 

 the avifaunas of islands, and to ascertain what relation 

 the birds of the various islets that dot the western limits 

 of the Palaearctic Region bear to the species that inhabit 

 the large land masses or continental areas adjacent to 

 such island groups, and the bearing of that fact upon 

 our whole subject. We may commence by stating that 

 all the west Palrearctic islands, with two exceptions, are 

 what are termed Continental Islands, or islands that at 

 some more or less remote epoch formed part of the 



