326 Mr. A. J. North on the Seasonal Changes 



careful observation and the collecting of a number of specimens 

 of Zosterops found in the neighbourhood of Sydney. For a 

 liberal supply of these birds every month, from January until 

 the end of August, the thanks of the Trustees are chiefly due 

 to Mr. H. J. Acland, of Greendale, and for a small series of 

 Tasmanian skins to Mr. E. Leefe Atkinson, of Table Cape. 

 Mr. J. A. Thorpe, the taxidermist, too, lias assisted at various 

 times, and from the specimens collected or sent me for exam- 

 ination has prepared a series of nearly fifty skins in every 

 stage of plumage. The results of my observations conclu- 

 sively prove that the Z. westernensis of Quoy and Gaimard, 

 the type of which was obtained by them at Western Port, 

 Victoria, is only the spring and summer attire of Z. cceru- 

 lescens of Latham. Taking the two extreme phases of winter 

 and summer plumage exhibited in Z. ccerulescens, it can be 

 easily understood why each phase should be thought to belong- 

 to a distinct species ; and it is only where one has these birds 

 under daily observation and obtains specimens during every 

 month of the year that the intermediate stage or the gradual 

 transition of one phase of plumage to the other is observed. 

 These changes in the plumage of Z. cairulescens have already 

 been pointed out by me in a series of skins exhibited in 

 August last at a meeting of the Linnean Society of New 

 South Wales. Typical examples of Latham's Z. cterulescens* 

 with the deep tawny-buff flanks and grey throat, the autumn 

 and winter attire of this species, may be obtained in the 

 neighbourhood of Sydney from the middle of April until the 

 end of August. Some specimens, however, are to be found 

 during April that have not quite lost their summer plumage, 

 and in August others that have already began to attain their 

 spring livery ; these birds have the yellow throat more or 

 less clearly defined. Usually the first indications of losing 

 the deep tawny-buff flanks and acquiring the yellow throat 

 are seen, during a normal winter, about the second week in 

 August, in some seasons a fortnight earlier ; but in two 

 specimens examined the grey throat was retained as late as 

 19th September. During August and September, however, 

 the gradual transition from the winter to the spring attire 

 (the Z. westernensis of Quoy and Gaimard) f is slowly taking 

 place, and by the middle of October not a bird is to be seen 

 with the deep tawny-buff flanks and the grey throat. Speci- 

 mens shot in November have the throats of a brighter olive- 

 yellow than at any other period of the year, the flanks at 

 that time being of a very pale tawny brown. At midsummer, 



* Z. dorsalis (Gould), Birds of Austr. iv. p. 81. 

 1" Voy. de P Astrolabe, pi. xi. ti<s. 4. 



