82 THE SCOTTISH NATURALIST 



In no case in this country have I ever found a nesting- 

 boring in any but a dead tree or branch of a tree. But 

 I suppose this must be accidental — for both in England and 

 in Holland I have found nests in live trees. I have only 

 twice in this country found a boring attempted in a growing 

 tree, and in both cases (very curiously) the tree was an Oak 

 where a fair-sized branch had been torn from the trunk by 

 the wind, leaving a spot bare of bark — but in neither of 

 these cases did the boring go any depth, though it was 

 characteristically rounded in both cases. I therefore omit 

 the Oak from my list of trees. 



SYCAMORE {Acer psendo-platanus). — I have only twice 

 seen this tree used, but have heard of another one being 

 found in my neighbourhood when this tree was felled. 



Gean [Prunus avium). — As this is not a very common 

 woodland tree, it is not to be wondered at that I have only 

 seen it once used. 



ASH (Fraxinus excelsior). — This tree is pretty often 

 bored, but not very often nested in. Ash wood when it 

 rots goes so quickly to dust, that one can easily understand 

 the birds desisting from boring when they find the walls 

 crumbling away rapidly. 



Elm (Ulmus montana, perhaps also Ulmiis campestris). — 

 Not very often used — perhaps its dead wood crumbles too 

 much when bored — but I have only twice found nesting- 

 holes in this species, which seems to be quite a suitable tree 

 for the bird's requirements. 



BlRCH {Betula alba). — A favourite tree. Its wood (in 

 the year or two which elapse between its becoming dead 

 and rotten) is easily bored and does not fly into dust, while 

 the strong tough bark binds the whole stem together (even 

 if it be inclined to crack) as hoops bind barrel-staves and 

 keep them in their places. The Woodpecker seems some- 

 times to bore into this tree in the winter months just for the 

 sheer joy of boring, as I once found two or three new " bores " 

 close beside each other in February. 



Alder (A Inns glutinosa). — The first nesting-hole I ever 

 found was in this species, but it is not a great favourite with 

 the bird — probably because the Alder does not generally 



