TASMANIA 149 



northern Asia has innumerable quantities of 

 finches. These are birds with beaks suitable to 

 break the tough food supplied by conifer trees. 



In Australia and Tasmania we have the main 

 forests bearing sweet liquid flowers, so that those 

 forests have an extensive family of honey-eating 

 birds absent from Asia. 



The Indian and Australian Regions have certain 

 perching birds in common, e.g. Bee-eater (Merops) 

 and Wood Swallow (Artamus). The relationship 

 is an ancient one. 



It is wonderful that Wallace's line, g, map 63, 

 proves itself a barrier to distribution; on one side 

 the fauna being largely Asiatic, on the other, Aus- 

 tralian. 



There are examples of birds whose ancestors 

 were somewhat alike but whose descendants now 

 live isolated lives on each side of Wallace's line. 

 At the delta of the Lena River a local water fowl 

 (Diver) is found, while in the estuary of the Der- 

 went River a second one (Mortier's Coot) is com- 

 mon. The Tasmanian migratory birds pass over 

 the 8,000 miles separating these two water fowl, 

 making a return journey of it in the year. The 

 Diver migrates up the Lena River each spring, the 

 Coot does not move. Here we have internal migra- 

 tion, and a complete local habitat. 



True migration is a big affair. The snipe (e) will 

 breed in Japan, the swift (d) in the market place 

 of Yakutsk, the centre of the fur trade in mid- 



