Comparative Energy in Birds 87 



COMPARATIVE ENERGY IN BIRDS. 



THE members of trie feathered tribe, especially 

 small birds, appear to be the most restless of all 

 animals — a circumstance which might lead one 

 to conclude that animals are restless in proportion to their 

 diminutive size, were this not in opposition to many other 

 facts. 



The bee, for example, is equally noted for industry and 

 bustling activity with the ant, which is not one-fourth of 

 its size ; nay, the Large Wood Ant {Formica rufa) is 

 greatly more active than the very small Black Ant (Ponera 

 contractu) . 



The Gnat (Culex) again, a comparatively small insect, 

 seems to repose during the greater part of its existence, 

 remaining fixed in one spot for whole days together, and 

 only moving about for an hour or two in the evening ; 

 while there may be observed on the same wall a still 

 smaller insect (Neiedes elegans), seldom moving quicker 

 than the minute-hand of a clock, the motion of which, by 

 interrupted jerks, much resembles that of the insect. 



There cannot, however, be a doubt that the wren and 

 the tom-tit are more active and restless than the bustard, 

 the ostrich, or even than the eagle ; and the activity, more- 

 over, of such small birds is not, l'ke that of the gnat, 

 confined to an hour or two, but continues almost uninter- 

 ruptedly during sunlight, sleep being, it would appear, 

 less necessary than it is to larger animals to restore vigour 

 after exertions so long continued. 



Motion of some kind indeed seems as indispensable 

 to life as food and air ; and even the motions of animals, 

 which may be primarily accounted for by referring to 

 their exertions to procure subsistence, and shelter, and the 

 like, must always, in a secondary point of view, give them 

 beneficial exercise. 



