650 The Outline of Science 



There is a vivacious plover that lives in an interesting 

 partnership with the crocodile, as Herodotus reported long ago. 



Observant, inquisitive, excitable, clamorous, 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. 1 



This sentinel is at home on the sandbanks on the Nile where 

 the crocodiles are wont to rest. It often perches on the reptile's 

 back, from which it picks leeches, and it will even jerk a morsel 

 of food from between the teeth. Dr. Leith Adams writes that 

 the Egyptians of to-day have put a tail to the account that 

 Herodotus gave of the partnership. 



They say, that in addition to its office of leech-catcher to 

 the crocodile, it occasionally does happen that the zic-zac 

 so called from its note of alarm in searching for the leeches, 

 finds its way into the reptile's mouth when the latter is bask- 

 ing on a sandbank, where it lies generally with the jaws wide 

 open. Now this is possible and likely enough, but the captain 

 of our boat added, that occasionally the crocodile falls asleep, 

 when the jaws suddenly fall, and the zic-zac is shut up in the 

 mouth, when it immediately prods the crocodile with its horny 

 spurs, as if refreshing the memory of his reptilian majesty, 

 who opens his jaws and sets his favourite leech-catcher at 

 liberty. 2 



There seem to be two of these crocodile-birds, both plovers, 

 the black-headed Pluvianus cegyptius and the spur-winged 

 Hoplopterus spinosus. This case must serve in illustration of 

 partnership, but we may mention the small horse-mackerels that 

 sometimes swim about under the shelter of a big jellyfish's 

 umbrella, the beef-eater birds that perch on cattle and clean their 



'Brehm's From North Pole to Equator. 

 'Notes of a Naturalist in the Nile Valley, 1870. 



