EXPERIMENTS ON PROTECTIVE COLORATION 493 



In regard to my experiments with the martin and kingbird 

 (Series III and VIII) the further objection may be made that 

 I obliged birds, which normally feed on flying insects, to feed 

 on insects placed on the ground. I can only say in answer 

 to such an objection that I have observed both of these birds 

 feed on the ground, and I have also seen the kingbird and other 

 swallows (CheHdon and Tachicineta) feeding from the surface 

 of a lake. 



In the course of these experiments I have found considerable 

 evidence to show that stillness is of more importance than color 

 in determining the immunity of animals to attack by birds. 

 I have frequently found the prey which I had placed on the 

 backgrounds unnoticed by the birds for several minutes, or 

 even in some instances hours, although the latter were unques- 

 tionably hungry, and in many cases were running about the 

 cage, pecking at various objects on its floor. Especially was 

 this delay noticeable in series IV and V with the hawks (Buteo 

 borealis krideri) . 



The failure of hungry birds in many instances to notice the 

 food prepared for them on the backgrounds, ^"^ may be attributed 

 to the duUing of their senses by captivity, in the case of those 

 birds which were taken from the nest and reared in captivity. 

 This will hardly, however, explain such failure, in the case of 

 the grackle (Quiscalus), which was taken when adult and had 

 been a captive for only a few weeks previous to the experiments. 

 It was kept, moreover, during this time in a large cage,^- freely 

 accessible to light and air and was oftener hungry than the 

 reverse. 



If, however, the prey was thrown into the cage so as to attract 

 the notice of the birds it was usually pounced upon immediately. 

 In Series X I saw the kingbird (Tyrannus tyrannus) pass the 

 backgrounds three times in one experiment without feeding, 

 although it was feeding on nearby objects (undoubtedly living 

 insects). In Series I, Experiment 2 a crow dropped a frog 



^1 See for example Experiment 3, Series IV, Experiment 17, Series V, and Experi- 

 ment 25, Series VII. 

 ^23.6 x 1.8 x 1.6 m. 



