NOTES ON SOME SCOTTISH BIRDS OBSERVED IN I915 75 



xXOTES ON SOME SCOTTISH BIRDS 

 OBSERVED IN 1915. 



By William Eagle Clarke. 



I. Tree-creeper in the Island of Lewis. 



Tree-creepers have, on rare occasions, been observed in 

 the British area in places far removed from their accustomed 

 arboreal haunts, and quite unsuited to their habits and the 

 peculiar manner in which they seek and obtain their food. 

 The appearance of these wanderers in such localities, which 

 include the Orkney and Shetland Islands, is a subject of 

 interest to naturalists on several grounds. Thus the recent 

 occurrence of one of these birds in the Island of Lewis is 

 an interesting event to those who concern themselves with 

 the fauna of the Outer Hebrides, since no Tree-creeper has 

 ever before been known to visit any of the islands of that 

 group; while to the student of bird migration, such a visit 

 affords a remarkable instance of the wanderings of a species 

 which is not accustomed to rove far beyond the limits of its 

 native woodlands, and also one possessed of very limited 

 powers of flight, usually only flitting from tree to tree. 



There are yet other points of interest associated with 

 these wanderers, for there remains to be solved the problem 

 whence came these migrants. Were they emigrants from 

 neighbouring British areas, or were they immigrant 

 voyagers from the Continent ? A few years ago it would 

 not have been possible to give satisfactory answers to these 

 questions, but now, thanks to our knowledge of racial forms, 

 we are able in the case of many species, including the Tree- 

 creepers, to do so, though the writer freely admits that they 

 are more difficult to differentiate in this than in most groups, 

 and that he has had to seek the aid of Dr Hartert in the 

 present case. 



Our own familiar Tree-Creeper belongs to a racial form 

 peculiar to the British Islands, being one of the insular 

 representatives of the Continental bird, and is known as 

 Certhia fainiliaris britannica. The discoverer of its peculiar 



