PROTECTION OF THE YOUNG 



207 



instance showing how easily nests are overlooked, 

 one may quote that of the plover. These birds are 

 systematically robbed of their eggs on many a country- 

 side, and yet the number of green plovers has only 

 lately sensibly diminished. But in countries where the 



Fig. 39. — Sand-Martin and Young. 

 (From specimens in the Manchester Museum.) 



enemies of birds are more numerous and cunning than 

 in Great Britain, the nesting habits of but a small 

 percentage are known. In tropical America, where 

 the humming-birds are as common as bees on a 

 patch of clover, a naturalist may spend years without 



