ar 



e suited to their Haunts and Habits. 53 



by Providence for the double purpose of preserving their 

 bodily heat, and of enabling them to elude the observation of 

 their enemies. Certain it is, that their conspicuousness would 

 otherwise expose them to inevitable destruction. If I had 

 here space, I could satisfactorily prove that the high-flying 

 Falconidae can, in most cases, only perceive their prey when 

 it is moving ; just, as on the sea-shore, we qan only distinguish 

 sanderlings when they move. Small Mammalia which fre- 

 quent open situations are rarely much abroad, except in the 

 twilight j and ground-feeding birds are ever on the watch, 

 and even the smaller kinds (as I have repeatedly observed) 

 can perceive a hovering falcon long before it comes within the 

 sphere of human vision; and they instantly flee to shelter, or 

 they crouch, and lying motionless, so exactly resemble a por- 

 tion of the surface, that even a hawk's eye cannot distinguish 

 them. Why should the falcon race be endowed with such 

 wonderful powers of enduring hunger and fatigue, if, as is 

 said, at the elevations at which they soar, they can clearly 

 distinguish every living object scattered over the wide expanse 

 beneath them ? It is only on such animals as are off their guard. 

 that they descend ; or otherwise, food being so abundant, 

 they would soon multiply to the extirpation of their prey ; 

 which, of course, would be very speedily followed by that of 

 the preyer. 



How beautifully do we thus perceive, as in a thousand 

 other instances, the balance of nature preserved : and even here 

 we see another reason why sickly or degenerate animals 

 (those, I mean, which are less able to maintain the necessary 

 vigilance) must soon disappear ; and why the slightest de- 

 viation from the natural hue must generally prove fatal to the 

 animal. How different, thus, are even simple variations from 

 the seasonal changes of colour which naturally take place ! 

 Properly followed up, this subject might lead to some highly 

 interesting and important results. It certainly points to the 

 conclusion, that every, even the slightest, tint and marking 

 has some decided use, and is intimately connected w r ith the 

 habits and welfare of the animal; and it also furnishes a 

 satisfactory reason, why closely allied animals (or, in other 

 words, animals of very similar form and habits) should so very 

 commonly nearly resemble each other in their colours and in 

 the general character of their markings. 



(To be continued.) 



E 3 



