THE BIRD-LIFE OF LONDON 



more gregarious. Numbers of nests may be built side 

 by side, but the colonies are never in proportion to the 

 vast gatherings that assemble in autumn before the 

 migration south. Their ways at this season are full of 

 interest, their daily flights and their evening gatherings 

 at osier- and reed-beds, where they roost, being very 

 characteristic. 



The adult House Martin has the general colour of 

 the upper part glossy steel-blue ; the rump and some of 

 the upper tail-coverts are white ; the wings and tail are 

 brownish black, the latter considerably forked ; the under 

 parts are white. Bill black ; tarsi and toes covered with 

 tiny white plumes ; irides brown. Length about 5^ 

 inches. The nestling is brownish black above, without 

 gloss ; the rump is white, as are the under parts, but 

 the wings are margined with white, the secondaries 

 tipped with the same. 



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