NO COLOUR-LINE OBSERVED 239 



snow is on the ground. Moreover,Mr. J. G. Millais 

 in his " Breath from the Veldt " describes how 

 the Bateleur Eagle (Helotarsus ecaudatus) often 

 captures prey owing to its habit of scanning the 

 ground behind as well as before it as it soars, other 

 Eagles passing straight on and missing prey which 

 has squatted on their approach, only to get up and 

 move directly they have passed. 



In all these cases, however, we must remember 

 that immobility may be a more important factor 

 than colour. With regard to the fruit food of 

 birds, it is to be noted that they eat red currants 

 sooner than the white variety of that fruit, but 

 colour may not decide this. 



Whatever attention birds pay to the colour and 

 pattern of their prey or foes, they seem singularly 

 inattentive to it as regards recognizing their own 

 racial affinities, for the theory of recognition-marks, 

 which supposes that species of birds which are 

 closely alike except for colour and pattern are 

 aided in selecting partners by such differences, 

 is not borne out by facts. Whenever the difference 

 between two forms is so slight that colour, not 

 structure or note, is the only distinction, the birds 

 themselves disregard it, no matter how glaring the 

 difference may be. 



This is best known in the case of the Hooded 

 Crow and Carrion Crow (Corvus comix and C. cor one) 

 in the case of our own fauna ; these birds seldom 

 breed in the same district, but when they do they 

 frequently cross, and the same is the case with these 



