28 INTRODUCTION. 



which are at this time inefficient, continue their route from pond to 

 pond, floundering over the intervening land by night, until at length 

 they gain some creek of the sea, and finally complete their necessary 

 migration by water. 



Birds of passage, both in the old and new continents, are observed 

 generally to migrate south-west in autumn, and to pass to the north- 

 east in spring. Parry, however, it seems, observed the birds of 

 Greenland proceed to the south-east. This apparent aberration from 

 the usual course, may be accounted for by considering the habits of 

 these aquatic birds. Intent on food and shelter, a part, bending their 

 course over the cold regions of Norway and Russia, seek the shores 

 of Europe ; while another division, equally considerable, proceeding 

 south-west, spread themselves over the interior of the United States 

 and the coast and kingdom of Mexico. 



This propensity to change their climate, induced by whatever 

 cause, is not confined to the birds of temperate regions ; it likewise 

 exists among many of those who inhabit the tropics. Aquatic birds, 

 of several kinds, according to Humboldt, cross the line on either 

 side about the time of the periodical rise of the rivers. Waterton, 

 likewise, who spent much time in Demerara and the neighbouring 

 countries, observed, that the visits of many of the tropical birds were 

 periodical. Thus the wonderful Campanero,* whose solemn voice is 

 heard, at intervals, tolling like the convent bell,, was rare to Water- 

 ton, but frequent in Brazil, where they most probably retire to 

 breed. The failure of particular food at any season, in the mildest 

 climate, would be a sufficient incentive to a partial and overland mi- 

 gration with any species of the feathered race. 



The longevity of birds is various, and, different from the case of man 

 and quadrupeds, seems to bear but little proportion to the age at which 

 they acquire maturity of character. A few months seems sufficient to 

 bring the bird into full possession of all its native powers ; and there 

 are some, as our Marsh Titmouse or Chicadee, which, in fact, as 

 soon as fledged, are no longer to be distinguished from their parents. 

 Land animals generally live six or seven times as long as the period 

 required to attain maturity ; but in birds the rate is ten times greater. 

 In proportion to their size, they are also far more vivacious and 

 long-lived, than other animals of the superior class. Our know- 

 ledge of the longevity of birds is, however, necessarily limited to 

 the few examples of domesticated species, which we have been able 



* Casmarhynchos carunculatM. 



