INTRODUCTION. xlv 
linear ranks ; and, lastly, it is to their leader that the fatigued 
company look up to appoint the most convenient places for 
nourishment and repose. Still, important as is the station and 
function of the aérial director, its existence is but momentary. 
As soon as he feels sensible of fatigue, he cedes his place to 
the next in the file, and retires himself to its extremity. Dur- 
ing the night their flight is attended with considerable noise ; 
the loud cries which we hear, seem to be the marching orders 
of the chief, answered by the ranks who follow his commands. 
Wild Geese and several kinds of Ducks also make their aérial 
voyage nearly in the same manner as the Cranes. The loud 
call of the passing Geese, as they soar securely through the 
higher regions of the air, is familiar to all; but as an additiona 
proof of their sagacity and caution, we may remark that when 
fogs in the atmosphere render their flight necessarily low, they 
steal along in silence, as if aware of the danger to which their 
lower path now exposes them. 
The direction of the winds is of great importance to the 
migration of birds, not only as an assistance when favorable, 
but to be avoided when contrary, as the most disastrous of 
accidents, when they are traversing the ocean. If the breeze 
suddenly change, the aérial voyagers tack to meet it, and di- 
verging from their original course, seek the asylum of some 
land or island, as is the case very frequently with the Quails, 
who consequently, in their passage across the Mediterranean, 
at variable times, make a descent in immense numbers on the 
islands of the Archipelago, where they wait, sometimes for 
weeks, the arrival of a propitious gale to terminate their jour- 
ney. And hence we perceive the object of migrating birds, 
when they alight upon a vessel at sea: it has fallen in their 
course while seeking refuge from a baffling breeze or over- 
whelming storm, and after a few hours of rest they wing their 
way to their previous destination. That Nature has provided 
ample means to fulfil the wonderful instinct of these feeble but 
cautious wanderers, appears in every part of their economy. 
As the period approaches for their general departure, and the 
chills of autumn are felt, their bodies begin to be loaded with 
