CHAP, xvii.] SMALLER SPRING BIRDS. 141 



their long absence and weary flight, and either repairing their 

 old residence or building a new one. 



Great numbers of sand-martins build in the banks of the 

 river, returning to the same places every year, and after clearing 

 out their holes, they carry in a great quantity of feathers and 

 dried grass, which they lay loosely at. the end of their subterra- 

 nean habitation. 



The swifts appear always to take up their abode about the 

 highest buildings in the towns and villages, flying and screaming 

 like restless spirits round and round the church steeple for hours 

 together, sometimes dashing in at a small hole under the eaves 

 of the roof, or clinging with their hard and powerful claws to 

 the perpendicular walls ; at other times they seem to be occu- 

 pied the whole day in darting like arrows along the course of 

 the burn in pursuit of the small gnats, of which they catch great 

 numbers in their rapid flight. I have found in the throat of 

 both swift and martin a number of small flies, sticking together 

 in a lump as large as a marble, and though quite alive, unable 

 to escape. It is probably with these that they feed their young, 

 for the food of all swallows consisting of the smaller gnats and 

 flies, they cannot carry them singly to their nests, but must wait 

 till they have caught a good quantity. 



We are visited too by that very curious little bird the tree- 

 creeper, Certhea familiaris, whose rapid manner of running 

 round the trunk of a tree in search of insects is most amusing. 

 Though not exactly a bird of passage, as it is seen at all seasons, 

 it appears occasionally to vanish from a district for some months, 

 and then to return, without reference to the time of year. I 

 found one of their nests built within an outbuilding, which the 

 bird entered by a small opening at the top of the door. 



