222 WAKE-ROBIN 
not only serves as a protection against the cold, but 
supplies the waste of the system when food is scarce 
or fails altogether. 
The crows at this season are in the same condi- 
tion. It is estimated that a crow needs at least half 
a pound of meat per day, but it is evident that for 
weeks and months during the winter and spring they 
must subsist on a mere fraction of this amount. I 
have no doubt a crow or hawk, when in their fall 
condition, would live two weeks without a morsel 
of food passing their beaks; a domestic fowl will 
do as much. One January I unwittingly shut a 
hen under the door of an outbuilding, where not 
a particle of food could be obtained, and where 
she was entirely unprotected from the severe cold. 
When the luckless Dominick was discovered, about 
eighteen days afterward, she was brisk and lively, 
but fearfully pinched up, and as light as a bunch of 
feathers. The slightest wind carried her before it. 
But by judicious feeding she was soon restored. 
The circumstance of the bluebirds being embold- 
ened by the cold suggests the fact that the fear of 
man, which now seems like an instinct in the birds, 
is evidently an acquired trait, and foreign to them 
in a state of primitive nature. very gunner has 
observed, to his chagrin, how wild the pigeons 
become after a few days of firing among them; and, 
to his delight, how easy it is to approach near his 
game in new or unfrequented woods. Professor 
Baird?! tells me that a correspondent of theirs visited 
1 Then at the head of the Smithsonian Institution. 
