BIRD-GUARDIANS OF QUADRUPEDS. 371 



this precaution amongst their species that Admiral Beechey, 

 who had many opportunities of observing them in Spitsbergen, 

 scarcely ever saw a herd, however small, in which he did not 

 notice one of the party on the watch, stretching his long neck 

 in the air every half-minute, to the utmost extent of his muscles, 

 to survey the ground about him. In the event of any alarming 

 appearance, the sentinel begins by seeking his own safety ; and 

 as these animals always lie huddled upon one another, the 

 motion of one is immediately communicated to the whole group, 

 who, scrambling to the edge of the ice as fast as their awkward- 

 ness permits, tumble into the water, head first if possible, but 

 otherwise in any position in which chance may have placed them. 



Some quadrupeds find a remarkable protection in the com- 

 pany of animals belonging not only to the same genus but to a 

 totally different class. Thus the rhinoceros is frequently ac- 

 companied by a bird (Buphaga africana), which feasts upon 

 the larva? that settle in his skin. As the range of his small and 

 deep-set eyes is impeded by his horn, he can only see what is 

 immediately before him, so that, if one be to-leeward of him, it is 

 not difficult to approach within a few paces. But the bird sees 

 all the better, and flying away at the first approach of danger, 

 awakens the short-sighted brute's attention by a shrill cry of 

 warning. In this manner the insects which plague the rhinoceros 

 become the indirect means of his preservation from many 

 perils, as, but for them, his winged monitor would have no in- 

 ducement to seek his company* 



The African buffalo possesses a similar guardian in the Textor 

 erytkrorynchus. When the beast is quietly feeding, the bird 

 may frequently be seen hopping on the ground, picking up food, 

 or sitting on its back, and ridding it of the insects with which its 

 skin is infested. The sight of the bird being much more acute 

 than that of the buffalo, it is soon alarmed by the approach of 

 any danger ; and when it flies up, the buffalos instantly raise 

 their heads to discover the cause which has led to the sudden 

 flight of their companion. 



The smaller monkeys of the tropical forests of America are 

 fond of associating with their more powerful congeners, in whose 

 friendly assistance they find a compensation for their own weak- 

 ness. Thus the saimiri clings to the back of the maquisapa, 



B B 2 



