THE SAND MARTIN 
33 
several successive spots with its beak, until it discovers a suit- 
able locality. It then works in a circular direction, using its 
legs as a pivot, and by dint of turning round and round, and 
SAND MARTINS. 
pecking away as it proceeds, soon chips out a tolerably circular 
hole. After the bird has lived for some time in the tunnel, the 
shape of the entrance is much damaged by incessant passing to 
and fro of the inmates, but while the burrow is still new and 
D 
