BRITAIN^S BIRDS AND THEIR NESTS. 273 



this colour, and a white patch on the ramp is noticeable 

 at all times, but is especially conspicuous when the bird 

 is clinging to a house-wall, collecting mud at a roadside 

 puddle, or flying below the observer. 



It arrives in Britain about a week after the Swallow, 

 early in April in the south, but three or four weeks later 

 in the north. Although becoming scarcer in Ireland and 

 in the north of Scotland, it is found over the greater 

 part of the British Isles until the middle of September. 

 About this time it disappears from the more northern 

 districts, but is found for a fall month longer in the 

 south of England. After some weeks in which it is 

 rarely seen, it not infrequently reappears in some numbers 

 for a short time in November, while individuals are 

 occasionally seen in December. This fact had by no 

 means escaped the observation of Gilbert White ; and, as 

 we have seen, it greatly influenced his beliefs with regard 

 to hibernation. Little is known about its migrations and 

 winter quarters. 



Like the Swallow's, the nest is made of mud 

 strengthened by being mixed with pieces of straw or 

 hair. But while the nest of the Swallow is a mere 

 half-cup entirely open at the top, the Martin's roughly 

 takes the shape of a bowl placed with its open side 

 against a perpendicular wall of rock or the side of a 

 building, and with a small hole near the top as the only 

 opening. 



The most familiar situation for the nest is the wall of 

 a house or shed, just under the shelter of the eaves. 

 Bridges, also, are often used as nesting-sites. In many 

 coastal districts, however, the Martin is best known as a 

 cliff-bird, placing its nest against the cliff'-face under the 

 shelter of an overhanging rock. 



In May the Martins begin their nesting preparations. 



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