DAYS AMONG THE ROBINS 129 



tette was within a radius of forty yards. By 

 January a proud pair led forth a lusty brood, and 

 their confidence in the locality was sufficiently 

 restored to persuade them to nest there again dur- 

 ing the ensuing Spring. 



Our familiar little friend is the only one of its 

 kind in the south-eastern portion of the continent. 

 At some indefinite point in New South Wales the 

 species blends into a prettier relative, in whose case 

 the yellow of the breast is continued on the lower 

 portion of the back. Then, in the coastal district 

 of central Queensland, the brightness of the rump 

 fades, and a replica of the southern bird, albeit a 

 trifle smaller, appears, to be replaced in turn by 

 another brightly-marked species in the jungles of 

 the north. 



Why this curious undulation in color? With such 

 markings as the orange wing-patch of the Tree- 

 Creepers, the yellow rump of the Tit-Warbler, and 

 similar features of other birds of the open areas, 

 the Wallace theory of "warning colors" may well 

 apply and it would seem that yellow is a distinc- 

 tive color to the eye of a bird. But the considera- 

 tion must be carried further in the remarkable case 

 of the Robins, where the bright patch is possessed 

 only by those birds which dwell in the thick jungles 

 and dimly-lit gullies. As in the other cases quoted, 

 this feature is noted most distinctly when the bird 

 is flying; but the Robin's quaint habit of clinging to 

 the side of a tree, with its back to the visitor and 

 wings poised inquiringly, makes the golden rump 

 to be noticeable even when the bird is at rest. 



This fact became vividly apparent on an evening 



i 



