329 



The data of Tal)le XL, arranged under the different species 

 of birds, may also be classified, as in Table XII., according to 

 the different situations, or the different kinds of crops, frequent- 

 ed by the birds. The one table shows us how each kind of bird 

 is related to the various crops; and the other, how each ci'op 

 is related to the various kinds of birds. Table XL is thus essen- 

 tially ornithological, showing the pi'eferences of each kind of 

 bird with respect to the food resources and places of resort 

 offered it by each kind of crop or other situation. Table Xll. 

 is essentially agricultural, and shows the principal bird vis- 

 itants of each kind of crop, brought into comparison with 

 respect to their preferences for that crop alone. Referring, 

 for example, to the section for corn, we see at the left the names 

 of the principal l)irds of the corn Held, arranged from above 

 dow'nwards in tlie order of their frequency in corn, the least 

 frequent visitants uppermost. We may use this table to com- 

 pare any species with another as a corn-tield bird — the horned 

 lark with the meadow-lark, for instance — l)y finding the place 

 of the one species in the diagonal series of I's and going up or 

 down the column until the line for the other species is reached. 

 The coefficient at the intersection of the column with the line 

 shows the frequency relation of the one bird to the other. In 

 this way we learn that for every hundred horned larks, 532 

 meadow-larks were found in corn, or, what is virtually the same 

 thing, that for every hundred meadow-larks there were 19 

 horned larks on an average iu corn. 



It is also easy to ascertain from these tables whether there 

 is any group of species which seem especially and strongly at- 

 tracted to any special situation. We notice such a group in 

 the horned larks, mourning-doves, and meadow-larks, consid- 

 ered as visitants of fields of stubble, and found there respective- 

 ly al)out 3 times, 5 times, and 7i times as frequently as are 

 blackbirds; in the crows and the horned larks, considered as 

 visitants of plowed fields, found there approximately 6 times 

 and 17 times as frequently as are meadow-larks; and in the 

 field-sparrow's, goldfinches, meadow-larks, mourning-doves, and 

 English sparrows iu the corn fields, in which they occur from 3 



