In the fall of 1813, John James Audubon regained enough strength after a summer of battling malaria to set out from his home in Henderson, Kentucky, to seek opportunities for establishing a trading business in Louisville, Kentucky. The route along the Ohio River between Henderson and Louisville includes crossing through the barrens of Kentucky. The barrens earned their name from the ground consisting largely of limestone, salts and other minerals. The salt is concentrated in some areas to such a degree that buffalo and other immense numbers of herding animals would gather to create what became known as salt licks. In other places the soft and porous ground of the barrens of Kentucky can weaken and fall through to create sink holes. Sink holes often connect into cave systems, like those in the Kentucky barrens that connect into the Mammoth Cave National Park which is recognized as the largest cave system in the world.
In addition to the limestone, there is shale, sandstone, and acidic soil that hinders the growth of trees in the Kentucky barrens, thus allowing a more open or barren landscape that includes other plants and “flowers without number, and vying with each other in their beautiful tints, sprung up amidst luxuriant grass; the fields, the orchards, and the gardens of the settlers, presented an appearance of plenty, scarcely any where [sic] exceeded; the wild fruit-trees, having their branches interlaced with grape-vines, promised a rich harvest, and at every step I trod on ripe and fragrant strawberries.”
Much of the “luxuriant grass” that Audubon refers to is most likely the Buffalo grass (Buchloe dactyloides) in which he places the Prairie warbler in Birds of America. Audubon noticed that Buffalo grass was “found all along the edges of our extensive prairies, in the barrens of Kentucky, and in Louisiana, excepting in the swamps, it being more inclined to grow in dry soil and stiff grounds.” Only remnants of Buffalo grass grow in Kentucky today. Extensive prairies everywhere in North America are being lost to grazing for livestock, crop growing, and development. Along with the loss of Buffalo grass and other prairie plants, the number of grassland birds like the Prairie warbler is crashing.