128 NATURAL HISTORY OF SELBORNE. 



seen in the village ; nor do they at all frequent the cottages that are 

 scattered about in that wild district. The only instance I ever 

 remember where this species haunts any building is at the town of 

 Bishop's Waltham, in this county, where many sand-martins nestle 

 and breed in the scaffold-holes of the back-wall of William of Wykeham's 

 stables ; but then this wall stands in a very sequestered and retired 

 enclosure, and faces upon a large and beautiful lake. And indeed this 

 species seems so to delight in large waters, that no instance occurs of 

 their abounding, but near vast pools or rivers ; and in particular it has 

 been remarked that they swarm in the banks of the Thames in some 

 places below London-bridge. 



It is curious to observe with what different degrees of architectonic 

 skill Providence has endowed birds of the same genus, and so nearly 

 correspondent in their general mode of life ! for while the swallow and 

 the house-martin discover the greatest address in raising and securely 

 fixing crusts or shells of loam as cunabula for their young, the bank- 

 martin terebrates a round and regular hole in the sand or earth, which 

 is serpentine, horizontal, and about two feet deep. At the inner end of 

 this burrow does this bird deposit, in a good degree of safety, her rude 

 nest, consisting of fine grasses and feathers, usually goose-feathers, very 

 inartificially laid together. 



Perseverance will accomplish anything ; though at first one would 

 be disinclined to believe that this weak bird, with her soft and tender 

 bill and claws, should ever be able to bore the stubborn sand-bank 

 without entirely disabling herself; yet with these feeble instruments 

 have I seen a pair of them make great dispatch, and could remark how 

 much they had scooped that day by the fresh sand which ran down the 

 bank, and was of a different colour from that which lay loose and 

 bleached in the sun. 



In what space of time these little artists are able to mine and finish 

 these cavities I have never been able to discover, for reasons given 

 above ; but it would be a matter worthy of observation, where it falls 

 in the way of any naturalist to make his remarks. This I have often 

 taken notice of, that several holes of different depths are left unfinished 

 at the end of summer. To imagine that these beginnings were inten- 

 tionally made in order to be in the greater forwardness for next spring 

 is allowing perhaps too much foresight and rerum prudentia to a 

 simple bird. May not the cause of these latebrce being left unfinished 

 arise from their meeting in those places with strata too harsh, hard, 

 and solid, for their purpose, which they relinquish, and go to a fresh 

 spot that works more freely 1 Or may they not in other places fall in 

 with a soil as much too loose and mouldering, liable to flounder, and 

 threatening to overwhelm them and their labours ? 



One thing is remarkable that, after some years, the old holes are 

 forsaken and new ones bored ; perhaps because the old habitations 

 grow foul and fetid from long use, or because they may so abound with 

 fleas as to become untenantable. This species of swallow moreover is 

 strangely annoyed with fleas ; and we have seen fleas, bed-fleas (pulex 

 irritans), swarming at the mouths of these holes, like bees on the stools 

 of their hives. 



