When any of the winged creatures are engaged in a life and death race in that way, or in any other race, the tactics of the squirrel do not work; the pursuer never overshoots nor shoots by his mark. The flight of the two is timed as if they were parts of one whole. A hawk will pursue a sparrow or a robin through a zigzag course and not lose a stroke or half a stroke of the wing by reason of any darting to the right or left. The clew is held with fatal precision. No matter how quickly nor how often the sparrow or the finch changes its course, its enemy changes, simultaneously, as if every move was known to it from the first.
The same thing may be noticed among the birds in their love chasings; the pursuer seems to know perfectly the mind of the pursued. This 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 was but one bird, instead of a hundred. The same impulse 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. Without word or signal, how is it done?