^ INTRODUCTION 13 



Along these lines of expansion there are certain 

 breaks, over which many birds do not pass. The 

 Hawkesbury River system is one, and Bass Strait 

 another ; the first of forest foods, the second a water 

 barrier. 



In the north the birds of area 2 could easily 

 travel to area 1, after which a break in type of 

 forest occurs. Many species, however, journeyed 

 in the region of the North-West Cape (southern 

 8), and there came to a stand against a desert 

 barrier. 



Avifaunal areas show difference at once, and 

 Australia the sub-region is colour stamped. Map 

 2 presents seven colour groups and colour schemes, 

 the effect of moist or dry forests, and of variable 

 deserts. 



In colour sorting of a large collection of birds 

 from all parts of the continent three ground plans 

 show. We see the rich metallic sheens of coastal 

 Queensland and Northern Territory, then the dull 

 grades of Victorian and Tasmanian coast land, and 

 very prominently the pale birds of area 3 (map 2). 

 Finally several ground tints of the varying areas 

 of country of the great balance of the Common- 

 wealth can be separated. A million pipits agree in 

 colour with these different areas of land upon 

 which they are living. 



The colour pattern of the numberless sea birds* 



*An Australian Bird Book, col. pis.; 1911, J. A. Leach, D.Sc. 



