The question naturally arises—When the region was one unbroken forest, as in aboriginal times, where were the birds that to-day are found only in our fields? Two answers appear possible to this question. There may have been a radical change in the habits of these birds since the first clearing of the land, or they may have come from the western prairie region. This latter view, is, I think, the more probable from the fact that all of the above-mentioned birds are found throughout the prairies and on the Great Plains, or are represented there by varieties which differ only in slight shades of color. The three sparrows are widely distributed over the country, though the savanna sparrow in its choice of localities is not so entirely an upland bird as are the other two species, haunting marshes along the coasts and river valleys as well as the higher open country. The familiar meadow lark of our eastern fields is abundant throughout the prairie region and is replaced on the drier western plains by a closely related form. The cowbird is another species that is widely spread over the continent and its habit of associating with cattle for the purpose of feeding upon the flies that swarm about them suggests the question—whether this habit was acquired since the settlement of the country, or did these birds haunt the bison herds on the plains and begin to straggle eastward after the cattle were introduced. The bobolink may have been a bird of the river marshes throughout the Atlantic region long before the discoverer set foot upon these shores, though from its wide range over the interior valleys and prairie lands we might infer that it had come east after the opening of the country. Similar conclusions could be adduced concerning the red-winged blackbird, but it is a bird more of marshland than of upland fields. Certain shore birds seem also to have taken advantage of the clearing of the country, as the killdeer and the grass plover, both being frequenters of plowed and fallow land.
A remarkably interesting case is that of the black-throated bunting or dicksissel. This bird is an abundant species in the glasslands of the middle prairie region. In the time of the ornithologist Wilson, and as late as the year 1880, it was not uncommon in certain localities in the east. Since this latter date it seems to have entirely disappeared from the Atlantic seaboard. For several years previous to that time I knew of a few pairs of these birds which nested each spring in certain fields of timothy and clover in the vicinity of Philadelphia. Their disappearance from these localities was remarkably sudden and apparently without reason, unless, as was suggested, it was due to the mowing of the fields and the destruction of nests and young birds. The evidence seems clear, however, that a part of the dicksissel population spread early into the newly opened fields of the east and abandoned them later, returning to their original prairie home.
In old, settled lands, as in England and the countries of western Europe, bird life has in large measure adapted itself to the human
