144 SQUIRRELS AND OTHER FUR-BEARERS 



concert of action among birds is very curious. 

 When they are on the alert, a flock of sparrows, 

 or pigeons, or cedar-birds, or snow buntings, or 

 blackbirds, will all take flight as if there were but 

 one bird, instead of a hundred. The same im- 

 pulse seizes every individual bird at the same 

 instant, as if they were sprung by electricity. 



Or when a flock of birds is in flight, it is still 

 one body, one will ; it will rise, or circle, or swoop 

 with a unity that is truly astonishing. 



. A flock of snow buntings will perform their 

 aerial evolutions with a precision that the best- 

 trained soldiery cannot equal. Have the birds 

 an extra sense which we have not? A brood of 

 young partridges in the woods will start up like 

 an explosion, every brown particle and fragment 

 hurled into the air at the same instant. With- 

 out word or signal, how is it done ? 



