24 DISTRIBUTION OF BIRDS. 



tall vegetation, and some by open places and naked ground ; 

 yet the lines of demarcation between the localities of those 

 birds are not drawn with anything like precision, so that one 

 species is often found, at least seasonally, upon those grounds 

 which we would be apt to suppose belonged exclusively to 

 another. 



The common distinction of land birds and water birds is, 

 indeed, a very imperfect and unsatisfactory one. All birds 

 deposit their eggs on land, and therefore, if we consider only 

 the places of their nativity, they would all deserve the name 

 of land birds ; and if we attend to the places in which they 

 seek their food, these are so varied, and often so varying in 

 the individual, that they cannot be made the foundation of 

 any general arrangement : thus we are under the necessity of 

 considering the haunt along with the genus, or, in many 

 instances, along with the species. 



The proper element of birds is the air; and as nearly 

 all birds, and certainly all British birds, can transport them- 

 selves from place to place by means of that element, they are 

 enabled to shift their localities with changes of season, or 

 of the circumstances of different places, so as to be always 

 in that part of the country which is the best adapted to 

 their habits.* Wherever there is food for a bird to be found, 



* There is one exception to this, so far as British birds are concerned; 

 for the great auk (Alca impennis), which occasionally visits the northern 

 isles of Scotland, has its wings so abbreviated, and clad with feathers of 

 such a character, as to be useless as organs of flight ; but they constitute 

 admirable oars, as the bird swims submerged in the water, the head and 

 part of the neck excepted. 



The great auk may be said to be the northern representative of the 

 penguins of the southern seas. In these the wings are formed as rigid 

 oars ; in one species, however, the jackass penguin (Sptieriscus demersus), 

 abundant at the Falkland Islands, the wings, when the bird is on shore, 

 are used as front legs. " When crawling, it may be said, on tour legs, 

 through the tussocks, or on the side of a grassy cliff, it moved so readily 

 that it might easily have been mistaken for a quadruped. When at sea 

 and fishing, it comes to the surface, for the purpose of breathing, with 



