RECOGNITION OF COLOURS 233 



Just as Macgillivray suggested the Sparrow-Hawk 

 was short-sighted, so Professor Newton, in his 

 " Dictionary of Birds," remarks, with reference to 

 the easy-going way in which the Hedge- Sparrow 

 accepts an alien egg, that for all we know to the 

 contrary it may be colour-blind ; and within the 

 last few years, a fancier writing to the Feathered 

 World about Homing Pigeons has said that though 

 they can distinguish black from white, this is not 

 the case with colours. 



The possibility of some birds not seeing as we 

 do must therefore be borne in mind, but as regards 

 the class as a whole the general evidence certainly 

 tends to bear out the commonly accepted idea that 

 their vision for colour is the same as our own. 

 This is shown in several ways ; for instance, they 

 recognize colour in other birds, and display either 

 friendship or hostility in consequence, according 

 to whether they are at the time in need of com- 

 panionship or in a position to feel jealousy. Birds 

 which are normally spiteful, for instance, are likely 

 to attack a species which bear colours reminiscent 

 of their own ; thus Jenner Weir told Darwin of 

 a case in which a Robin in an aviary killed a red- 

 breasted Crossbill and injured a Goldfinch ; and 

 an American Indigo-bird (Cyanospiza cyanea) at- 

 tacked a Nonpareil (C. ciris), which has a blue 

 head, and nearly scalped it. I have myself seen a 

 mated Blue Australian Wren (Malurus cyaneus) in 

 one of the Zoo aviaries furiously pursue a cock 

 Yellow- winged Blue Sugar-bird (C&reba cyanea), 



