so. 7 PROTECTIVE ADAPTATIONS McATEE 129 



and represents so great a variety of birds (55 species) that the late 

 Prof. F. E. L. Beal, taking these facts in connection with his field 

 observations, was constrained to express the beHef that scarcely a 

 species of bird exists that upon good opportunity, can resist the 

 temptation to eat another bird's eggs. Numbers of identifications 

 such as 6 for the yellow-billed cuckoo, 10 for the brown towhee, 

 12 for the Baltimore oriole, 10 for the California towhee, and 11 for 

 the bank swallow prove that egg or at least egg-shell eating is not 

 confined to birds of the recognized predatory groups. Probably a 

 number of the records are due to birds swallowing bits of their own 

 egg-shells. On the other hand eggs may be punctured as by the house 

 wren, or eaten without swallowing any of the shell, occurrences not 

 likely to be registered in the evidence brought to light by stomach 

 examination. 



Of the records for predation upon the various families of birds, it 

 may be said that the high number for Phasianidae represents domestic 

 poultry almost entirely, and that of the other families, the two — 

 sparrows and warblers — undoubtedly most numerous in individuals 

 are those which bear the brunt of predatory attack. The rather high 

 number of determinations of Turdidae reflect the abundance of the 

 robin which contributed nearly 45 (43.6 per cent) of the total. The 

 Icteridae, next in line, are birds of great abundance, which might be 

 expected to rank still higher among the avian contributors to the 

 subsistence of their predatory relatives. However, there is no evidence 

 that they are at all immune to attack, as the great flocks of blackbirds 

 wintering in our southern latitudes are constantly harried by pre- 

 dacious birds in variety and force. 



The sparrows, most persecuted of all, because most available, repre- 

 sent almost the acme of protectively colored birds ; the bob-whites 

 (16 records), ruffed grouse (n), and their allies, also cited, as 

 marvels of cryptic coloration are certainly eaten freely considering 

 their relative numbers. It is of interest that birds of prey by no 

 means spare each other, and it seems that a slight advantage in size 

 is all that is needed to induce this strained predation ; indeed there 

 are records of intra-specific cannibalism. The pugnacious kingbird 

 and other members of the family of tyrant flycatchers do not escape ; 

 the aerially expert swifts and swallows pay their due toll ; and the 

 green-coated Aircos. best l)lended with foliage of any of our birds, 

 are freely eaten. 



Birds " warningly colored "' that are reiH-escnted in the dietary of 

 other birds as illustrated by our tabulations include the bobolink 

 (19 records), Baltimore oriole 4, orchard oriole 3, lark bunting 6, 



