BLACKBIRDS, NIGHTINGALES, ETC. 323 



part, or intended to be part, of the process of preening 

 themselves. This close pressing seems to be a pleasure 

 in itself, independently of the result of warmth, for 

 sometimes they will come unstuck, as it were, and 

 move a little away from each other along the twig, in 

 order to press and squeeze again. For a little, then, 

 their tails may be separate, but soon they rejoin, and, 

 the heads being now quiet for they are going to 

 sleep and tucked closely in amongst the feathers 

 of the breast, their outlines, never very salient, are 

 entirely lost, and the two birds have become one 

 perfectly globular one, without a head and with a long 

 tail. Thus two of these long- tailed tits have returned 

 again to roost in the same place, but the other pair 

 do not come to the bush." 



It is interesting to watch sand-martins building 

 their nests, or, rather, excavating the tunnels in which 

 they will afterwards be built. To see one enter one 

 of these whilst it is yet but a few inches long, and 

 then to see the dust powdering out at the aperture, 

 as from the mouth of an ensconced cannon, is pretty. 

 The sand is scratched out backwards with the feet, 

 but the bird also uses its bill as a pickaxe, often 

 making a series of rapid little blows with it, almost 

 like a woodpecker, the wings, which quite cover the 

 body, quivering at the same time. Both sexes work 

 at the hole, and both often fly together to it, one 

 remaining clinging at the edge whilst the other 

 scratches out the sand from inside. I have seen one 

 sitting just in the embrasure, quietly regarding the 

 outer world and, thus, impeding the entrance of his 

 partner, who at last squeezed by him with great 

 difficulty. Sometimes three or four will descend upon 



