2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



PAGE 



Coleoptera (beetles) 63 



Mecaptera (scorpionflies) 84 



Diptera (flies ) 84 



Hymenoptera (ants, bees, wasps) 88 



Arachnida (scorpions, spiders, ticks, etc.) 97 



Mollusca (snails, slugs, mussels, limpets) loi 



Chordata (lancelets, tunicates, vertebrates) no 



Pisces (fishes ) 112 



Amphibia (salamanders, toads, frogs ) 120 



Reptilia (turtles, lizards, snakes) 123 



Aves (birds) 126 



Mammalia (mammals) 131 



Discussion I35 



Indiscriminancy of predators other than birds 136 



More theoretical aspects of indiscriminancy by predators 140 



Indiscriminancy of normal checks other than predators 141 



Relative importance of natural checks 141 



Summary I43 



Bibliography MS 



INTRODUCTION 



In a previous paper ^ the writer set forth reasons for beheving 

 that the results of experimental tests of the effectiveness of the so- 

 called protective adaptations in protecting animals from their enemies 

 are not trustworthy indications of what occurs under natural condi- 

 tions. In the present contribution he proposes to show just what 

 insects and other animals are actually preyed upon by wild birds 

 of the United States, Canada, and Alaska, giving also incidental 

 notes on other enemies. This evidence reflecting food habits under 

 natural conditions goes far to show how little the alleged protective 

 devices have to do with choice of food by vertebrates. 



Judging from the literature of the subject since 1912, the con- 

 tentions of the article on the experimental study of the food habits 

 of animals seem to have been generally admitted, or at least regarded 

 as too well supported to be lightly attacked. Only one essay has been 

 seen l)y the writer, that seems in any way a reply, namely an account 

 of " Experiments and Observations Bearing on the Explanation of 

 Form and Colouring," "" by C. F. M. Swynnerton, who refers to my 

 criticism of the experimental method as " rather over-vigorous." The 

 vigor of the criticism is admitted l)ut in view of the absurdity of the 

 arguments against which it was directed, it can hardly be considered 



'The experimental method of testing the efficiency of warning and cryptic 

 coloration in protecting animals from their enemies. Proc. Acad. Nat. Sci. 

 Philadelphia, June 1912, pp. 281-364 (Sept. 6, 1912). 



* Journ. Linn. See, Zool., vol. 33, pp. 203-385, London, June 30, 1919. 



