482 R. T. YOUNG 



former combination presenting the greater contrast. The grackle 

 at first flew to a perch about 2 m. from the backgrounds, from which, 

 three minutes after the start of the experiment it flew to the ground 

 near the latter background, but passed it by and attempted to seize an 

 insect on the former when I interrupted it. 



Experiment. 16. Same as Experiment 15. In aljout seven minutes, 

 the grackle flew over the backgrounds alighting nearer the ash(>s, but 

 seizing an insect from the leaves and straw. 



Experiment 17. Figures 30 and 46. Two Silpha surinanu^nsis were 

 placed on burnt hay and two on ashes. In twenty minutes the grackle 

 flew to the ground at the middle of the cage and began feeding. It 

 soon approached the backgrounds on the side of the burnt hay back- 

 ground, from which it took a beetle. The contrast here was greater 

 l)8tween the beetles and the ashes, but the resemblance between the 

 hay and the beetles was not very close as the latter were a glossy black 

 and the hay dull black. 



Experiment 18. Fiynres 27 and 30. Two Silpha were placed on 

 light ashes and two on charred wood, the former combination presenting 

 much the greater contrast. In one minute the grackle dropped to 

 the ground and began feeding. In two minutes it passed the beetles 

 on the black background and took both from the white, taking no 

 apparent notice of the former. 



Experiment 19. Same as Experiment 18, except that only one beetle 

 was placed on each background. In one minute the grackle flew to 

 the ground ])eside the white ashes from which it took the beetle. It 

 then passed the black background once or twice taking no apparent 

 notice of the insect upon it. After fourteen minutes the latter was 

 taken, but I am uncertain whether by the kingbird or the grackle. 



Experiment 20. Same as Experiment 19. The grackle immediately 

 flew to the ground and approaching the white background first took 

 the insect from it. It then took the insect from the black background. 



Experiment 21 . Figures 27 and Jf.5. One Silpha on charred wood 

 and one on flour, the latter combination presenting the greater con- 

 trast. The grackle at once approached the backgrounds in a fairly 

 direct line, passing nearer the wood, but taking the beetle from the 

 flour. It then took the beetle from the wood. 



Experiment 22. Figures 36 and 60. One moth (Noctuid sp.) was 

 placed on a piece of bark which was partly covered with damp ashes 

 producing a background closely resembling the moth, and one on 

 a strip of very light colored wood.^^ The body of the insect was in- 

 serted in a crack in the bark so as to bring its partly expanded wings 

 close to the surface of the latter, but not in anyway concealing it. The 

 grackle flew from one perch to another and then returned. It then 

 flew to the ground and fed for a few minutes. In ten minutes it ap- 

 proached the backgrounds, passed close to the moth on the bark, and 

 took that from the wood. It was seemingly a little suspicious of the 



2^ A piece of an ordinary berry box was used. 



