CLASS II AVES. 7 
THE YOUNG CURLEW. 
presents a barn-owl, which has reached the comparative old age of a month, and yet — though it 
may possess something of the serious and knowing aspect of the Bird of Wisdom — seems still sadly 
puzzled to know which foot he ought to put first. 
The longevity of birds is various, and, differing from the case of men and quadrupeds, seems to 
bear little proportion to the age at which they acquire maturity. A few months, or even a few 
weeks, are sufficient to bring them to their perfection of stature, instincts, and powers. Land 
animals generally live five or six times as long as the period of their growth, that is, the time re- 
quired for reaching their maturity ; while birds live ten times as long as the period of their growth. 
Domestic fowls, pigeons, and canaries live to the age of twenty years ; parrots thirty, geese fifty, 
pelicans eighty; swans, ravens, and eagles exceed a century. 
The velocity with which birds are able to travel in their aeriai element has no parallel among 
terrestrial animals. The swiftest horse may run a mile in something less than two minutes, but 
this speed can only be sustained for a very brief period, while birds in their migrations move at 
the rate of a mile a minute for several successive hours. Many of them, no doubt, actually travel 
six to eight hundred miles a day, and are thus able to go from the arctic to the torrid zones in 
three or four days. A falcon, sent to the Duke of Lerma from Teneriffe to Andalusia, returned 
in sixteen hours, a distance of seven hundred and eighty miles. The gulls of Barbadoes go to the 
distance of two hundred miles in search of their food, making a daily flight of four hundred miles. 
The migrations of birds are among the most curious and wonderful phenomena connected with 
their natural history. In some cases these are of comparatively small extent, being prompted 
only by the necessity of obtaining a supply of food ; but many species, known as Birds of Pas- 
sage^ perform long journeys twice in the year, visiting temperate or even cold climates during the 
summer, and quitting them on the approach of winter for more genial climes. The great object 
of this movement in the economy of nature is to rear their young in the solitude or security 
of the colder zones, away from the destructive animals — serpents, monkeys, cats, and other preda- 
ceous beasts — which infest the tropics. As these birds have neither reason nor experience, they 
are endowed with instincts which guide them in their wanderings, often extending across seas 
