326 



The data of Table XL, arranged under the different species of 

 birds, may also be classified, as in Table XII., according to the differ- 

 ent situations, or the different kinds of crops, frequented by the birds. 

 The one table shows us how each kind of bird is related to the vari- 

 ous crops; and the other, how each crop is related to the various 

 kinds of birds. Table XI. is thus essentially ornithological, showing 

 the preferences 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 XII. is essentially agricultural, and shows the principal bird 

 visitants 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 

 birds of the corn field, arranged from above downwards in the order 

 of their frequency in corn, the least frequent visitants uppermost. 

 We may use this table to compare any species with another as a corn- 

 field bird — the horned lark with the meadow-lark, for instance — by 

 finding the place of the one species in the diagonal series of i's and 

 going up or dow T n 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 in corn. 



It is also easy to ascertain from these tables whether there is 

 any group of species which seem especially and strongly attracted to 

 any special situation. We notice such a group in the horned larks, 

 mourning-doves, and meadow-larks, considered as visitants of fields of 

 stubble, and found there respectively about 3 times, 5 times, and jYi 

 times as frequently as are blackbirds; in the crows and the horned 

 larks, considered as visitants of plowed fields, found there approxi- 

 mately 6 times and 1 7 times as frequently as are meadow-larks ; and 

 in the field-sparrows, goldfinches, meadow-larks, mourning-doves, and 

 English sparrows in the corn fields, in which they occur from 3 to 8 

 times as frequently as blackbirds. The principal meadow birds, by 

 these tables, are mourning-doves, meadow-larks, and cowbirds, since 

 they occur in meadows 7 times, 12 times, and 15 times as commonly 

 as English sparrows; while pastures apparently afford a common 

 meeting ground for* all the birds of this list of most important spe- 

 cies, the coefficient of the blackbird — the most frequent pasture bird 

 — being less than three times that of the English sparrow, the least 

 frequent of these birds in pastures. 



