COCOI HERON 95 



Heron's breast when it fishes in the dark, and which 

 serves to attract the fish, or to render them visible 

 to the bird. Naturalists have, I believe, dismissed 

 the subject of this light as a mere fable without any 

 foundation of fact ; but real facts regarding habits 

 of animals have not infrequently been so treated. 

 Mr. Bartlett's interesting observations on the Flam- 

 ingoes in the Society's Gardens show that the ancient 

 story of the Pelican feeding its young on its own 

 blood is perhaps only a slightly embellished account 

 of a common habit of the Flamingo. 



I have not observed Herons fishing by night very 

 closely, but there is one fact which inclines me to 

 believe it probable that some species might possess 

 the light-emitting power in question. I am convinced 

 that the Ardea cocoi sees as well by day as other 

 diurnal species ; the streams on the level pampas 

 are so muddy that a fish two inches below the sur- 

 face is invisible to the human eye, yet in these thick 

 waters the Herons fish by night and by day. If the 

 eye is adapted to see well with the bright sun shining, 

 how can it see at night and in such unfavourable 

 circumstances without some such extraneous aid to 

 vision as the attributed luminosity t 



Herons of all birds have the slowest flight ; but 

 though incapable of progressing rapidly when flying 

 horizontally, when pursued by a Hawk the Heron 

 performs with marvellous ease and grace an aerial 

 feat unequalled by any other bird, namely that of 

 rising vertically to an amazing height in the air. 

 The swift vertical flight with which the pursued 



