250 THE BIRDS OF THE BRITISH ISLES. 



taken on the wing when indulging in nuptial flight ; Bewick's 

 well-known cut is evidence of close observation Butterflies, 

 and even large moths, such as the yellow-underwings, are hunted 

 and captured ; the last when disturbed by mowing machines or 

 the feet of cattle. The height of the Swallow's flight varies 

 from just above the ground or water to an altitude at which the 

 wheeling birds appear mere specks ; it is indirectly connected 

 with weather, for insects vary their altitude according to atm^L^ 

 spheric and seasonal conditions ; the Swallow follows the food. / 

 Bundles of insects are collected for the young, and the " packets^ 

 delivered to the offspring in turn. 



Originally the Swallow nested in caves or under the shelter 

 of rocks, and a few still use such situations, but the inside of a 

 building is its usual home. On a beam or joist in a barn, shed 

 or stable it constructs a saucer of mud and lines it with grass 

 and feathers. More rarely it places the nest against a wall or 

 beam ; then it is a half saucer, approaching in shape the nest 

 of the House-Martin beneath the eaves, but lacking buttresses. 

 These unsupported nests often fall, though I have known broods 

 safely reared. Exceptionally nests are built in trees. One 

 bird saved labour by using a shrimp-pot on a shelf, merely 

 adding lining, and I have seen a nest built in an old hat which 

 had been left in ^ shed. As frequently proved by the capture 

 of marked birds. Swallows often return year after year to the 

 same nest, and patch up the old cracked mud. The mud has 

 at times to be brought from a distance, the nearest pond or 

 river, but in wet weather road puddles are useful ; a little hair 

 and straw is usually mixed with it. Both birds build, and 

 before and during incubation the male feeds the female, either 

 in the air or on the nest. The first clutch of four to six white 

 eggs, speckled with reddish brown and grey (Plate 84), is laid 

 in May and two or three more may follow ; indeed young may 

 still be in the nest in October, but when migratory overcomes 

 parental instinct they are left to perish. It is stated that the 



