344 The Bird 
We have seen how wings guard their owners from the 
risk of sudden surprises from enemies, and now let us 
observe how, in a sleeping bird, the tender nostrils and 
eyes are protected against cold and other dangers. Birds 
do not put their heads under their wings, but behind them, 
often using the shoulder-feathers as cover. It is inter- 
Fic. 275.—Green Heron with head behind wing. 
esting to see how many birds, from all quarters of the 
earth, have this same habit. The pelican, however, de- 
parts from this custom and snuggles his tremendous bill 
between the feathers in the centre of his back, and flops 
both wings up so as completely to cover it. Even the 
cassowary vainly tries to tuck his bill behind his absurd 
wing. His smaller wing-coverts are mere soft, loose hair- 
