152 SPRING 



the following summer favours their nesting, the numbers 

 cut off in spring may be made good by the time of the 

 autumn journey. All the swallows like a warm and genial 

 summer, profuse in insect life ; but the barn-swallow and 

 house-martin particularly benefit from mingled showery and 

 sunny weather in May and early June. This is because their 

 curious nests, compacted of many hundreds of beakfuls of 

 tempered mud, present some of the most difficult tasks 

 accomplished by any of our birds in the nesting season. In 

 cold, damp weather the pellets dry so slowly that progress 

 grows very tedious ; while in a spell of spring drought there 

 is a scarcity of mud. House-martins especially like to collect 

 mud from the puddles in the roads, and in dry weather 

 there are no puddles. Cold and droughty weather added 

 to the birds' rather desultory and idle method of building often 

 postpones the first of the two normal layings of their species 

 until midsummer. Then, if July is wet and stormy, there 

 may either be no second brood, or it may linger so late that 

 the young birds perish in the early autumn frosts and storms. 

 House-martins, again, are terribly plagued in their work by the 

 piratical house-sparrows, which wait till they have built part 

 or the whole of their nest, and then drive them out of it. 

 The open swallows' nests do not take their fancy so well, and 

 they seldom attack them. Occasionally, however, a similar 

 trick is played on the swallow by the wren, which fits its own 

 domed nest into the cuplike foundation of the swallow's nest 

 before the swallows arrive. We know of no instance of a 

 struggle between the wren and the swallow, such as often 

 takes place between the sparrows and house-martins, and 

 is always won by the sparrow. But the wren, though so 

 tiny, has an even more persistent character than the sparrow, 

 and it can well be believed that the shy and timid swallow 

 has to yield. 



