4 
366 BRITISH BIRDS. 
slightly smaller species occur in Australia. ‘The Western species (A. longi- 
rostris) is very rufous in colour; and the Eastern species (4. 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. 
