602 HIRUNDO RIPARIA. 



of a snow-white colour, tinged with a sulphureous yellow when 

 newly deposited. This tinge disappears when the eggs are dis- 

 lodged, and arises from the yolk shining through the shell, which 

 is of a very fine thin texture. 



" When the females are incuhating, their mates sport in the 

 air about the nesting-place, never alighting, as far as I have 

 observed, like the Barn and Window Swallows, and seldom 

 departing to any great distance, but remaining within cry, as 

 if protecting their domiciles from the attack of enemies, I 

 have seen them when a Sparrow-Hawk approached, after utter- 

 ing a peculiar scream, rush in a body towards the invader, and 

 by menacing attitudes and other gestures of resistance, succeed 

 in driving him from the place. It was in vain he endeavoured 

 to catch one of them, and indeed he seemed aware of this, as 

 he only made the attempt twice, but the Swallows were too 

 quick ; and when he might have expected to grasp one in his 

 talons, he found it busy as ever tormenting him from behind. 

 After the young leave the nest, they are fed by the parents on 

 the wing. This feat is performed so suddenly as almost to be 

 imperceptible, and the parents in the act appear as if teaching 

 the young to fly. Being desirous to ascertain the average num- 

 ber of insects destroyed daily by a brood of Swallows, I took 

 ray station on a summer morning opposite four young indivi- 

 duals, which were sitting on a ledge of earth, near the aban- 

 doned nest, enjoying themselves in the rays of the rising sun. 

 Around them the parents were silently engaged in capturing 

 their little prey, which had been roused into life by the new 

 dawn. The male and female both took part in this exercise, 

 although the latter seemed more attentive, and supplied the 

 young more frequently than the former. One or other carried 

 food to them at least every five minutes. I suppose they were 

 thus engaged for ten hours each day, the case admitting of a 

 calculation of about 6000 noxious insects being destroyed 

 by one small brood in a day. This calculation is perhaps 

 much below reality ; but even looking at the subject from this 

 point of view, we find that the destruction of these beautiful 

 birds would be productive of pernicious results. Thus, while 

 the rapidity of its flight enables the Swallow to capture these 



