1912.] NATURAL SCIENCES OF PHILADELPHIA. 363 



Fortunately, this is not the case in the United States, where we have 

 data enough to prove the point. 



A selection of the more conspicuous cases of refusal of favorite 

 natural foods by the birds tested by Judd are given in the following 

 tabulation. Other instances are cited in the summaries of the 

 separate experiments (pp. 340, 346, 349, 350 and 351). 



Eaten by wild individuals of the 

 Rejected by captive birds. same species. 



A ruby-throated hummingbird All of these items are corn- 

 rejected small leaf -hoppers, flies, monly eaten by wild birds of 

 flea-beetles, and spiders. this species. 



A bluejay refused a hen's egg, In a state of nature jays f re- 

 living birds and mice, and mul- quently break up outlying nests 

 berries. Acorns also were refused, of fowls. Birds and mice are 



preyed upon and mulberries are 

 eaten. Acorns have been found 

 in dozens of stomachs of wild 

 birds and are a very important 

 element of the normal diet. 



English sparrows rejected Whole flocks of English spar- 

 fruiting heads of dandelion. rows pass days in rifling the ripe 



involucres of this plant. 



A snowbird, a white-throated These seeds are a common 

 sparrow, and a song sparrow re- natural food of all three birds, 

 fused seeds of lamb's quarters. 



The song sparrow rejected, also, All are eaten by wild song 



seeds of smartweed and beetles sparrows, the smartweed seeds 



of the genera Diabrotica, Hippo- in abundance. 

 damia, and Lachnosterna. 



These facts show that the feeding reactions of various animals 

 are strikingly modified by confinement. Some animals refuse items 

 of food which are a favorite with wild individuals of the species, 

 some of which may form a notable percentage of the total subsist- 

 ence. Others refuse all food. The birds experimented upon by 

 Judd together disregarded or rejected 108 articles of food. Forty- 

 two of these items have been found in stomachs of wild birds of the 

 same species that ignored or refused them in captivity. Investiga- 

 tions carried on while this paper was in preparation raised this 

 number to 42 from 35, and it must be borne in mind that subsequent 

 stomach examinations will increase, never diminish the total. The 



