BIRDS AND THE WEB OF LIFE 407 



of the Nile and the Crocodile Bird or Trochilus, which 

 Herodotus described long ago. Various naturalists, such 

 as the elder Geoffroy Saint-Hilaire and A. E. Brehm have 

 observed the strange partnership and seen the bird, Pluvianm 

 agypiius, a kind of plover, enter the reptile's mouth, probably 

 to pick off leeches or some morsel of food. It often rests 

 on the crocodile's back and in addition to its cleansing 

 offices it may be of service as a sentinel. For the crocodile 

 is usually a timid animal as far as man is concerned. Brehm 

 says of the bird : " Observant, inquisitive, excitable, clamor- 

 ous, and gifted with a far-reaching voice, it is well fitted to 

 serve as watchman to all less careful creatures. No 

 approach, whether of beast of prey or of man, escapes its 

 suspicious observation ; every sailing-boat or rowing-boat 

 on the river attracts its attention ; and it never fails to tell 

 of its discovery in loud cries. Thus it brings under the 

 notice of all the other creatures who share its home or 

 resting-place the unusual occurrence, enabling them either 

 to find out for themselves if there is really any danger, 

 or to make good their escape on the strength of its warning. 

 Thus it discharges the duties of a sentinel. Its friendly 

 relations with the crocodile can hardly be called mutual, 

 for to credit the crocodile with friendship is going rather 

 far. Certainly the reptile treats the bird as a harmless 

 creature, but this is not out of any benevolence, but simply 

 because he has a thorough knowledge and a correct estimate 

 of his partner " (" From North Pole to Equator," Trans., 

 1896, p. 227). 



A. Leith Adams has an interesting note in this connection. 

 " A sail, or the smoke and noise of a steamboat, sufiice to 

 warn the crocodiles basking on the sand-banks, or their 

 common companions, the black-headed and spur- winged 

 plovers (Pluvianus cegyptius and Hoplopterus spinosus), 

 which are frequently seen perched upon their backs, and 

 always prepared to give timely warning of approaching 

 danger, just as the Father of History noticed them 2,300 

 years ago, and, strange to say, his well-known story is 

 current among the modern Egyptians, who, as usual, have 



