242 BIRD WATCHING 



the line of its course winds round and around the 

 trunk of the tree. This last, however, has not been 

 quite my experience. I have watched the bird often 

 and carefully, and I should say that a true spiral 

 ascent by it is decidedly exceptional. Often one 

 has alighted upon the tall stem of a Scotch fir, on 

 the side away from me, and never come round into 

 view at all. On other occasions, after some time, I 

 have seen its tiny form outlined against the sky on 

 one or other side of the trunk, considerably, higher 

 up, and then, again, it has disappeared back, or flown 

 to another tree. This can hardly be called a spiral 

 ascent, and I have seen no nearer approach to one. 

 Often, too, I have seen it mount quite perpendicularly 

 for a considerable distance. To me it appears that 

 the tree-creeper recollects, occasionally, that he ought 

 to ascend a tree spirally, and begins to do so, but 

 the next moment he forgets this tradition in his 

 family, and creeps individually. One might expect, 

 indeed, that insects or likely chinks for them would 

 act as so many deflections from the path of spiral 

 progress, which, as it seems likely, may have been 

 originally adopted for the same reason and upon the 

 same principle that a road is made to wind round a 

 mountain instead of being carried up the face of it. 

 But how is it, then, that the wren and the blue-tit 

 ascend tree -trunks perpendicularly? for one would 

 have thought that the less au fait a bird was, the 

 more would the advantages of an easy gradient have 

 forced themselves upon it. But these birds are still — 

 sometimes, at any rate — aided by their wings, so that 

 it would seem as though their tree-creeping had been 

 developed, or was being developed, as an adjunct to 



