YOUNG BIRDS IN THE NURSERY 93 



to leave what has proved a land of plenty to return to us 

 in spring. It may be that they are obliged to seek areas 

 of lower temperature for the sake of the young, though this 

 was not the original cause of their migrations, as I have 

 endeavoured to show in my " History of Birds." But 

 that is another story. Here I propose only to state a few 

 facts in regard to the effect of heat on nestling birds — 

 facts which (we owe to the observation of two of our most 

 expert and enthusiastic bird photographers, Miss E. L. 

 Turner and Mr. W. Bickerton. They have shown that 

 birds when incubating, as well as nestlings, are greatly 

 distressed by prolonged sunshine. 



Their observations show that birds of all kinds are thus 

 affected, the snipe sitting in the sedge-grown swamp, 

 the warblers in the reed-bed, the heath-haunting Norfolk 

 plover, and even such birds as guillemots and razor-bills 

 crouching on ledges of cliffs overhanging the sea, where 

 one would suppose that a breeze, if even a light one, 

 was always present. The signs of distress are evident 

 enough, for the birds sit with their beaks open and all 

 the feathers of the body raised up to admit as much 

 air as possible to the body. Nestlings such as warblers, 

 on these sultry days, evidently suffer much, packed close 

 as they are, and as soon as fledged they will endeavour 

 to find relief by climbing on to the edge of the nest. 



Many of the birds of prey, like the honey buzzard, the 

 golden eagle, and the osprey, make special efforts to 

 protect their young from the sun's rays. The honey 

 buzzard goes so far as to surround the nest with a bower 

 of leafy boughs, and as these wither they are renewed. 

 This device may well have arisen from the custom which 

 prevails, at any rate among some of the Accipitres, of 

 adding fresh leaves to the nest Hning, as if from aesthetic 



