366 



BRITISH BIRDS. 



slightly smaller species occur in Australia. The Western species (A. longi- 

 rostris) is very rufous in colour ; and the Eastern species (A. australis) has 

 a comparatively shorter bill. Both species breed in the south, retiring 

 north on the approach of the cold season. A fifth near ally of our bird, 

 Kittlitz's Great Reed- Warbler (A. syrinx), appears to have become slightly 

 differentiated by its isolation on some of the Caroline Islands in the 

 Pacific Ocean. There are several other more distantly allied species. 



