372 STUDIES OF NATURE, 



The fame contrafts of colour are obfervable In 

 the wood-pecker, who Hves on the trunks of trees, 

 along which he fcrambles in queft of the infects 

 that are lodged under their rind. This bird is 

 at once green- coloured and brown j fo that, 

 though he lives, properly fpeaking, in the fliade, 

 he is always perceptible, however, on the trunk of 

 trees ; for he detaches himfelf from their dufky 

 rind, by means of that part of his plumage which 

 is of a brilliant green ; and from the verdure of 

 their mofles and hchens, by thofe of his feathers, 

 which are brown. 



Nature oppofes, then, the colours of every ani- 

 mal to thofe of the refpedive ground on which it 

 is to be placed ; and what confirms the truth of 

 this Law is, that the greateft part of birds which 

 live on one ground only, have but a fingle colour, 

 and that one ftrongly contrafted with the colour 

 of the ground. Accordingly, the birds which live 

 aloft in the air, on the azury ground of the Hea- 

 vens, or on the bofom of the waters, in the midft 

 of lakes, are moflly white, which, of all colours, 

 forms the moft ftriking contraft with blue, and is, 

 confequently, moft adapted to render them per- 

 ceptible at a diftance. Such are, between the 

 Tropics, the paillencu, a bird of a glofly white, 

 whofe flight is through the fuperior regions of the 

 air, the heron, the gull, the fea-mew, which fkim 



alons 



