60 THE BIRD GROWN UP 
all the crows for miles around come there every 
night. Sometimes thousands sleep in this one 
bedroom, called a crow roost. Robins do the 
same, after the young are big enough to fly so 
Fan 
Audubon, who has told us so much about 
birds, once found a hollow tree which was the 
sleeping-room of chimney swifts. The noise 
they made going out in the morning was like the 
roar of a great mill-wheel. 
He wanted to see the birds asleep. So in the 
daytime, when they were away, he had a piece 
cut out at the foot of the tree, big enough for 
him to go in, and the piece put back, so the 
birds would not notice it. 
At night, after the swifts were abed, he took 
a dark lantern and went in. He turned the 
hight upon them little by little, so as not to startle 
them. ‘Then he saw the whole inside of the 
tree full of birds. They were hanging by their 
claws, side by side, as thick as they could hang. 
He thought there were as many as twelve thou- 
sand in that one bedroom. 
a 
