BIRDS IN THE GREENWOODS 241 



The tree-creeper, when it flits from tree to tree, gener- 

 ally does so in a downward direction. If trees were 

 of a uniform height, and if the bird usually ascended to 

 the top, or nearly to the top, of each one in succession, 

 one could see the rationale, or even the necessity, of 

 this practice, for the tree-creeper does not at least not 

 usually descend the trunk. But in a wood, the top of 

 one tree may not represent half the height of another, 

 and, moreover, a tree will often be abandoned by the 

 bird when it has reached only a moderate height, or 

 is still quite near to the ground ; and it is not so easy 

 to see how, under these circumstances, the above- 

 mentioned habit should have arisen. But, now, if the 

 forerunners of the tree-creeper had been birds accus- 

 tomed to hop about on the ground, and to peer and 

 pry amongst the projecting roots of trees, and if they 

 had, from these, gradually ascended the trunk, getting 

 back to them at first quite soon, but making longer 

 and longer and more and more accustomed excursions, 

 then we can understand how this habit might have 

 become as one may say rooted, so as to continue 

 after there was no longer any particular advantage 

 in it. Now, however, it is beginning to weaken. I 

 have on several occasions which I duly noted down 

 at the time seen a tree-creeper fly from one tree 

 to another, upon which it clung, in an upward direc- 

 tion. I have little doubt that what is now still a 

 habit will come to be a preference merely, and that, 

 in time, even this will cease to be discernible, and 

 the bird be guided simply by circumstances. 



It is said that the tree-creeper never descends the 

 tree it is on, and, also, that it generally proceeds in 

 a spiral direction, by which, I suppose, is meant that 

 Q 



