THE HOME OF A BIRD 177 



opening, as it does, upon a narrow passage over- 

 shadowed by trees, is a very exceptional place for it 

 to occupy. The chances against any Martin building 

 there were great ; the probability of a second pair 

 doing so in default of the first, would be remote in 

 the extreme. In fact, the improbability amounts 

 almost to impossibility ; so that it may reasonably be 

 concluded that the pair that yearly returns to the old 

 site is the same pair. 



Further, House-martins are to a large extent 

 gregarious in their habits, and I know a colony 

 containing some hundred and fifty nests in one barn, 

 the birds returning to it spring after spring. But 

 no second pair ever present themselves at this loft 

 to share it with the original tenants ; and as it is 

 certain that the original tenants, if alive, would return 

 to claim it, as is the general habit of their kind, it is 

 safe to affirm that the pair that for three years have 

 so presented themselves are indeed the original 

 tenants of the loft. It is conceivable that one 

 member of the pair might die, and that the bird 

 remaining might take a new mate ; but this would 

 only serve to strengthen the argument that, so far 

 as they are able, these birds remain constant to the 

 old home. I do not emphasise this case as being 

 in any way special, except as it affords, by the 

 exceptional nature of the building site, and by the 

 fact that one pair only builds yearly against the same 

 beam, a sure means of identifying these birds through 

 three successive years. 



It is highly probable that when these two birds 

 leave us in the autumn they become lost to one 

 another in the general mixing-up of this gregarious 



