3o8 THE BIOLOGY OF BIRDS 



reproductive success will make for the survival of the 

 emotional altruistic type. 



§ 6. Defence of the Young 



Few birds have much chance when the nest is directly 

 attacked, unless indeed they can enlist the help of their 

 neighbours to drive off an intruder, as cliff-swallows a hawk. 

 There are cases, however, where vigorous defence of the 

 nest is attempted. The cormorant resents an intruder's 

 approach to the nest on the sea-cliff shelf, hissing violently 

 and lunging with its formidable beak. Some of the birds 

 of prey strike even at man, and a swan puts up a strong 

 defence. Black-Headed Gulls and lapwings fly close to 

 one's face, if one draws too near the nest, and the eider-duck 

 has a very unpleasant way of expressing her resentment at 

 being disturbed, or, at any rate, her visceral excitement in 

 the flurry. 



When defence of the nest is quite out of the question 

 because of its position or because of the nature of the bird, 

 recourse is sometimes had to wiles. The redshank is extra- 

 ordinarily successful in leading one astray, and the devices 

 of the lapwing are familiar. Very remarkable is what looks 

 like feigning lameness or a broken wing ; if it is not a trick, 

 it is almost uncannily like one. 



In rare cases the parent bird has been known to shift 

 its eggs, the goatsucker taking them in its capacious mouth. 

 A transport of nestlings to a place of safety has been occasion- 

 ally recorded, as in woodcock and eagle-owl. The question 

 of how the woodcock carries its young ones has been discussed 

 at great length, it is probably correct to say that they are 

 pressed between the thighs and that the long bill may also 

 be used to steady them. 



Among gregarious birds like geese the presence of the 

 father is said to be of great advantage in securing fair-play 

 for the young birds at the feeding-places. Without a 

 paternal champion they are apt to be killed or starved. 

 Even the timid hen will sometimes wax valiant, and her 



