BLACKBIRDS, NIGHTINGALES, ETC. 325 



they return, but, as is the case with the small birds 

 at the stacks, not in nearly so instantaneous or simul- 

 taneous a manner ; and this may be repeated for a 

 greater or lesser number of times. All the remarks 

 that I have made in regard to this phenomenon in the 

 case of other birds apply equally here, perhaps, indeed, 

 to a greater extent ; for, as remarked, at the moment 

 of each sudden exodus a certain number — sometimes 

 about half — of these sand-martins will be more or less 

 hidden within the holes they are excavating, yet out 

 they all dart with the rest. Such sudden flights and 

 disappearances for a few minutes, after which all come 

 back, strike me as being extremely curious. 



Sand-martins appear to be pugnacious. Indeed, 

 they sometimes fight fiercely, and I have seen two, 

 after closing with a sharp, shrill " charr "and struggling 

 in the air for a little, roll down the steep declivity of 

 sand in which the perpendicular face of the pit often 

 ends. It, therefore, seems the more curious that they 

 allow their holes to be taken possession of by sparrows 

 (and, also, by tree-sparrows) — without offering any 

 resistance. I have seen one of the latter birds sitting 

 quietly and calmly in the mouth of a hole, whilst a 

 pair of martins, who had, probably, excavated it, 

 hovered excitedly just over and about him, but 

 without doing more. On many other more or less 

 similar occasions there has been excitement on the 

 part of the martins, but never an attack. Yet a tree- 

 sparrow, or even a sparrow, is not such a very much 

 larger and stronger bird than a sand-martin, and, 

 considering the numbers of the latter, as well as their 

 greater activity and powers of flight, it seems to me 

 an odd thing that they should submit to such a 



