124 



BBITISH BIRDS 



of some enemy. The male has, besides, a twittering song, uttered 

 on the wing while hovering before the nesting-hole. 



Two broods are reared, and as soon as breeding is over the birds 

 forsake the bank and scatter about the country, and may then be 

 seen associating with house-martins and swallows. 



The sand-martin is the earliest of the swallows to arrive in this 

 country, and the first to depart ; it is rare to meet with them after 

 the middle of September. 



Tree-Creeper. 



Certhia familiaris. 



Fig. 46.— Tree-Creeper. ^ natural size. 



Upper parts mottled with 

 yellowish brown, dark brown, 

 and white ; a pale streak 

 over the eye ; throat and 

 breast buff-white, becoming 

 dusky on the belly ; wings 

 brown, tipped with white, and 

 barred with white, brown, 

 and dull yellow ; tail-feathers 

 reddish brown, stiff, and 

 pointed. Length, five inches. 



The little creeper appears 

 to move more in a groove 

 than almost any other pas- 

 serine bird, and is the most 

 monotonous in its life ; yet 



it never fails to interest, doubtless because in its appearance and 

 actions it differs so much from other species. A small bird — one of 

 the very smallest — with striped and mottled brown upper, and 

 silvery white imder, plumage ; long and slim in figure, with a slender 

 curved bill and stiff, pointed tail-feathers, it spends its life on the 

 boles and branches of trees, exploring the rough bark with micro- 

 scopic sight for the minute insects and their eggs and larvae it sub- 

 sists on, moving invariably upwards in a spiral from the roots to 

 the branches by a series of rapid jerks ; its appearance as it travels 

 over the surface, against which it presses so closely, is that of a 

 mammal rather than a b7.rd — a small mottled brown mouse with an 



