SWALLOW AND HOUSE-MARTIN 



a -upportinj: ledgr. Where, as is sometimes the case, the farther side 

 of the nest is not against a wall or beam, it is circular. Illustrations 

 of lx>th forms are given on Plat* \\x. But to attach an open nest 

 to the face of a wind-swept cliff would be to court disaster : lining, 



s. and i iiml aii M- bird might easily be blown out and away. It is 

 not difficult, therefore, to understand why the house-martin, unlike 

 the swallow, builds a closed nest, leaving towards the top only a small 

 hole for entrance. In this snug abode, of which the mud walls may 

 be half an inch thick, the bird has little to fear from the elements, 

 provided, as already explained, there is a sheltering projection to 

 break the direct downward flow of the rain on the flat of the wall or 

 cliff. Notwithstanding this precaution, nests fall during heavy con- 

 tinuous rain, possibly because it beats against them from the side, if it 

 does not flow round under the overhanging ledge. 



' Swallows, to a rule, are less sociable during the breeding season 

 than martins. A German ornithologist, who made a census of the 

 swallow population in one village, found that twenty-eight buildings 

 out of forty were occupied, all except two by single pairs, and the 

 exceptions by not more than two pairs each. The latter, however, 

 were not under the same roof, and, according to the writer, would not 

 have submitted to the intrusion of a second pair into their own 

 shed. 1 Yet more than one pair may be found not only in a shed, but 

 in the much more confined area of a porch ; and Naumann states 

 that he has seen as many as forty nests together in one large cow- 

 house. House-martins, on the other hand, though they may be found 

 breeding in isolated pairs, often crowd their nests together to such an 

 extent that, so to speak, they elbow and squeeze each other. In a 

 length of nine yards under one eave, forty-six nests have been 

 counted 3 and twenty-one in a space of five to six yards. 1 



The solid mud homes of swallows and martins are not built for 

 one season only : they may be used again and again, much time being 



1 Zooloyiichet Garten, 1870, 208 (H. Schacht). * Nelson. Bird* of Yorkshire, L p. 1 



1 Field, 1808, xxil 127. See aUo PI. XXXI. 



