450 The Bird 
swooping down one after another upon the nests and 
each impaling an egg upon its beak and flying off with it. 
They would never dare such open villainy were the herons 
undisturbed. 
Fie. 356.—Colony of Great Blue Herons. 
Many of the more isolated cases of exposed white 
eggs are to be explained, I think, by the fact that the 
habits of birds often change rapidly, while their structural 
