THE BIRDS OF HELIGOLAND 245 



which were very dingy but not black, on a faint yellow ground. 

 The sides and other lower parts were whitish. 



About 1833 this specimen, so interesting by reason of its rarity, 

 passed over into Brandt's possession, as has been the case in many 

 similar instances. On seeing, more than ten years later, the first 

 few hundred birds which I had collected, Brandt expressed his 

 surprise at finding among them so few of the rarer Sylvise and 

 Thrushes, of which he said he had very often received many inter- 

 esting examples from this island. It appeared strange that he 

 had never received from here rare Eastern species of Buntings, 

 and he was therefore much surprised at seeing in my collection 

 Emberiza pusilla, of which species I possessed at that time my 

 first example. 



Buntings from Siberia have, however, within the latter decades, 

 become particularly numerous. May we perhaps be allowed to 

 assume that, side by side with changes of meteorological condi- 

 tions which, as already frequently mentioned, have set in within 

 the last thirty years and acted as disturbing agents on the ap- 

 pearance of Eastern insectivorous species other meteorological 

 influences, too delicate to be perceptible, have come into play 

 and favoured the appearance of Eastern Buntings and other 

 granivorous species ? 



This small Thrush occurs as a resident breeding bird in the 

 central and northern parts of North America, from the Atlantic 

 Ocean to the Rocky Mountains. 



Despite their apparent similarity and almost equal size, it is 

 nevertheless very easy to determine any one of the three preceding 

 small species of Thrush. Turdus swainsoni is distinguished from 

 the two others by its olive-coloured upper side, which never has 

 the least tinge of the rusty orange brown (rostorange-braun) which 

 characterises the two other species ; and of these T. pallasi is 

 unmistakably recognisable by its ferruginous (rostroth) tail, which 

 in T. fuscescens has nearly the same colour as the large flight- 

 feathers. The three species are equally distinct in the marking of 

 their under parts. In T. pallasi the black spots characteristic of the 

 Thrushes extend down to the middle of the breast ; in T. swainsoni 

 only as far as the upper breast ; while in T. fuscescens they are of a 

 very pale dingy brownish colour, and reach only to the base of the 

 neck. 



