Popular Science Monthly/Volume 42/February 1893/Birds of the Grass Lands
| BIRDS OF THE GRASS LANDS. |
By Prof. SPENCER TROTTER.
AN eastern North American landscape is chiefly characterized, at least in the more settled portions of the country, by its diversified aspect of woods and fields. All other distant features gradually melt away and leave to the involuntarily closing eye a checkered expanse of darkly shaded masses and broadly open sunlit spaces. In the wilder parts, along the ranges and spurs of the Appalachians, the forests still hold undisputed sway over the fields, yet surely and rapidly the venerable woods are falling away as the axe sweeps with ever-widening swath along the clearing's edge. Year after year we have gone to some beloved spot of wilderness and learned to love the great, tall hemlocks that were ever whispering their secret to the wind. Some spring morning we are again at the old place; alas! what a pitiful sight awaits us! The giants of a hundred springs are fallen, and their long, white trunks and ghostly arms make a picture more desolate than the deepest gloom of the forest. To me the sighing of the hemlocks is a death song—a melancholy prophecy of the fate that awaits them.
The forest does not yield without a struggle. The tangled underwoods and seedlings so long stunted in the evergreen shade spring up with renewed life in the refreshing sunlight, and a sturdy "second growth" takes in a few years the place of the primeval forest. These are the woods of oak, hickory, and chestnut; of maple, birch, beech, and gum; of dogwood and sassafras, tulip, elm, ash, and linden, that invite us with their shade, their cool depths and reaches of sunlight, their fragrant blossoms and mystery of hidden things, from the broad fields of grass and grain that encompass them on every side.
Not less diverse than the woods and fields themselves are the living things that people them. Each offers its own peculiar environment and each has brought its own peculiar changes. There are woodland flowers and flowers of the field, and flowers that grow on the border line among the briers and cripple as though undecided which dwelling place to choose, or lingering in the delights of both. Who ever found the mullein and the toadflax in the depths of a wood or picked an anemone in open fields? Yet there are flowers that find a congenial home in each, like the bluets, spring beauties, and the star of Bethlehem. In every province of life we find forms peculiar to the open grass lands and forms characteristic of the woodland, each "to the manner born."
These points of comparison apply especially to bird life. Every boy who has indulged the natural propensity to haunt running streams and wild, delectable places, to pursue shy birds and pry into the secret of their nests, knows full well that there are birds
Fig. 1.—Vesper Sparrow.of the fields and birds of the woods. A student of ornithology soon learns that certain groups or families of birds are peculiar either to the woods or to the fields, and that their organization is in more or less entire accordance with the manner of life induced by the physical conditions of the area they inhabit. Among our Eastern American birds the titmice, wrens, creepers, nuthatches, wood warblers, tanagers, vireos, shrikes, waxwings, tyrant fly-catchers, the woodland group of thrushes, crows, jays, and woodpeckers are all tree-lovers, for the most part nesting in trees, and, if on or near the ground, usually in the depths of tangled underwood. On the other hand, a number of species belonging to the large family of the finches (sparrows, buntings, etc.) are strictly birds of the grass lands, and this is true also of some members of the closely allied family of starlings, blackbirds, and orioles, notably in the case of the field lark, some blackbirds, and the bobolink.
Among the finches that are strictly grass-loving and dwellers in fields are three well-known Eastern species—the vesper, savanna, and grasshopper sparrows. The vesper sparrow, so called from its soft, rich song that fills the still evening air on upland pastures and immortalized by the pen of John Burroughs, is a familiar inhabitant of open fields and roadsides. Like most of its relatives it is a plain-colored bird, streaks of soft brown blending into gray, but easily distinguished by the white-edged tail that it flirts open when started from the dusty highway or flitting before us along the fence-rows. In old fields and pastures the darker-
Fig. 2.—Savanna Sparrow.streaked savanna sparrow and the little earth-colored grasshopper sparrow with its yellow-edged wings and dry, cricket-like song, start out of the grass beneath our feet; and if in June days we search long and patiently, a glimpse of a nest and its treasures may reward our pains.
Every one knows the meadow lark stalking over fields of short grass or swiftly rising from weedy cover with sharp note of alarm; the bobolink with throat full of song hovering above the lush meadows and acres of waving herd's grass or gathering in dense autumnal flocks among the river reeds; the swamp blackbird with its brilliant epaulets of red; the shore lark and titlark—all these are birds of the open, grass-grown fields.
Glancing at a physical map of North America we see that the continent is characterized by regions of widely different aspect. By far the largest area is forest clad, including the vast territory
Fig. 3.—Grasshopper Sparrow. east of the Mississippi Valley and the great portion of British America. West of this, and extending from the Gulf and the Mexican highlands northward to the Athabasca River, is the region of the great plains, rolling, grass-covered prairies, dry and treeless, except in the river bottoms of the eastern portion. To the west the plains rise into the greater plateau of the continent, a steppe region crowned by the lofty, pine-clad ranges of the Rocky Mountain system. Between this and the Sierra Nevada ranges lies an alkaline waste, the Great Desert Basin, while along the Pacific slope a forest region again prevails.
It is evident, from this hasty view of the entire continental area, that we have before us precisely the same factors, though on a much larger scale and much more pronounced in character, as are present in the settled Eastern portion, namely, an open grass-covered region bordered by a vast forest. The same conditions hold good as in the case of the smaller areas of field and woodland, and we are not surprised to find differences in life of a corresponding nature. A fauna and flora distinct and characteristic of the prairie region on the one hand are in contrast with a more or less distinct forest life.
America at the time of its discovery presented a vast and unbroken expanse of forest embracing all the now cleared and thickly settled portions of the Eastern wooded region. Early explorers, as their records clearly show, were forcibly impressed with this endless reach of forest. The past two centuries have witnessed the steady downfall of the woods and their conversion over a wide territory into fields of grain and grass. Conditions of a prairie nature have, in other words, been introduced into the forest region, and we are naturally led to reflect upon the effect that this has had upon the life. When the region was one unbroken forest, where were the birds that to-day are found only in our fields?
Two solutions of this problem offer themselves to the mind. There has either been a radical change of habit among certain species in the past two hundred years, or an emigration and occupancy of the new lands have taken place from the prairie regions
Fig. 4.—Black-throated Bunting.on the Western border. This latter view is, I think, the more probable from the fact that all the above-mentioned field birds are found on the plains or are represented there by varieties which differ only in slight shades of color.
The range of the vesper sparrow covers the entire United States from the Atlantic to the Pacific and north to the plains of the Saskatchewan, so that it appears to be equally at home in the Eastern fields and on the Western praries. A paler variety occurs in the middle province, undoubtedly the result of the arid conditions of the region. Equally as extensive is the range of the savanna sparrow, though in the choice of localities it is not so entirely an upland bird as the vesper sparrow, haunting marshes along the coasts and river valleys as well as the higher open country. Several geographical races occur in the West and North. The little grasshopper sparrow is another East and West form, spreading over the dry central plains and presenting a paler variety in the latter region. The familiar song sparrow, whose bright, cheery ditty enlivens the closing days of winter, though a haunter of garden shrubbery and brier patches, is a bird of the grass, building its nest upon the ground. It is widely distributed over the continent, and in the West is broken up into a number of geographical races.
A remarkably interesting case is that of the black-throated bunting or dicksissel. This bird is one of the most abundant species in the grass lands of the Mississippi Valley and on the
Fig. 5.—Meadow Lark. prairies of Kansas and Nebraska. In the time of the ornithologist Wilson and to within fifteen or twenty years ago, it was an abundant bird in the fields of the Eastern States. Now it is rarely seen along the Atlantic seaboard. Some years ago I knew of several pairs breeding each spring in a restricted area in southeastern Pennsylvania. Timothy and clover fields were their favorite nesting places, and a bird-loving friend who had watched these pairs from year to year suggested a cause for their increasing scarcity. About the time the young were hatched the remorseless reaper appeared upon the scene, and the keen-edged knife soon laid waste the home of the unfortunate dicksissel. It was not long before these birds disappeared altogether from their once favorite fields, and a probable clew to the cause seemed to point toward the reaping machine. This I have never been able to verify, as the harvests on their prairie home must be equally as destructive unless a much larger territory or a difference in the times of hatching and reaping has prevented the rapid destruction of the young birds. Be this as it may, the evidence before us goes to show that the grass-loving dicksissel came early from the Western prairies to the newly opened fields of the East, and has abandoned them for its Western home, disgusted, we may imagine, with the innovations of civilized man.
The meadow lark of the East is replaced on the Western plains by a lighter form. Our curious cowbird, stealing its egg into the nests of other birds, is abundantly spread over the continent, and the remarkable habit of associating with cattle for the purpose of feeding upon the flies that swarm about them suggests the question, Was this habit acquired since the settlement of the country, or did the birds haunt the herds of buffalo on the plains and begin to straggle eastward after the cattle were introduced? An allied form in the West, the yellow-headed blackbird, has similar habits, trooping among the cattle and horses on the plains, though it is a good householder, unlike the loose, vagabond cowbird.
The bobolink may have been a denizen of the river marshes of the East long before the discoverer first set foot upon these shores, though from its wide range toward the West, breeding on the plains of the Saskatchewan, we might infer that it had come eastward with the opening of the country. Similar conclusions might be adduced concerning the red-winged blackbird from its life and distribution, but it is a bird more of marshy land 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.
Several characteristic prairie birds have at times by some accident found their way East, notably in the case of the lark finch, a beautiful Western form, and the yellow-headed blackbird above mentioned, both of which have wandered east as far as Massachusetts and Pennsylvania. This fact at least shows the capability of a bird to wander far from its original home, the regular phenomena of migration being still another proof.
Birds, owing to their superior organization and power of flight, have, more than any other forms of life, a constant tendency to widen their ranges and to occupy adjacent territory whenever the proper physical conditions are presented. This has been very clearly shown in the case of certain species along the Mexican border occupying the lands on which chaparral has lately grown up as a result of the invasion by cattle.[1] We can picture to ourselves a few prairie stragglers finding their way into the newly cleared lands of the settlers and gradually establishing themselves in the Eastern fields. By what route they came is a matter of conjecture—probably from the southwest in the northward-setting tide of the spring migration, or possibly by way of the Great Lakes and St. Lawrence Valley.
Thus has man in his history of progress and discovery unconsciously affected the distribution of other living beings. It is a very small fragment in the history of a country, but one of especial interest as showing how remotely and by what strange means causes and effects operate. Man appears in a new land, clears its face of timber, and erects his home. By and by the swift forsakes the hollow tree to build in the settler's chimney, and the swallow leaves the overhanging tree trunk or rocky ledge for the shelter of the eaves and barn. The robin builds within hand-reach of the doorsill, and the wren and martin, leaving their old homes in the forest to some woodpecker more lazy than his fellows, scold and quarrel for the possession of any hole or box, so long as it is near the dwelling place of man. Last, but by no means the least, this subtle influence reaches across a waste of tossing tree tops, and from the yet unknown prairie land come birds to dwell within his fields and gladden his heart with their sweet evening songs.
- ↑ See a paper by S. N. Rhoads on The Birds of Southeastern Texas and Southern Arizona, etc. Proceedings of the Philadelphia Academy, January 26, 1892.