The Sierras de Córdoba lie between the
Espinal ecoregion to the east and the
Chaco ecoregion to the west. Rainfall is generally higher on the eastern slopes, and the western slopes are in the drier
rain shadow of the mountains. The flora and fauna of the Sierras is related to that of the
Chaco region, except for high elevations, where
Andean species predominate. High exposure causes the
limits of tree growth to be much lower than in the Andes, generally about 2000 meters elevation. High-elevation plant communities include grasslands dominated by
Deyeuxia hieronymi, Poa stuckertii, Alchemilla pinnata, and
Festuca circinata; shrublands dominated by
Berberis hieronymi, and
Polylepis australis woodlands in sheltered areas. More than 100
bird species are found in the mountains, but ranching and hunting have reduced most native mammal populations severely. Two species of birds are endemic to the mountains. The
Córdoba cinclodes (
Cinclodes comechingonus) breeds only in the mountains, where it inhabits forest patches of tabaquillo (
Polylepis australis) close to water between 1,600 and 2,800 meters elevation.
Olrog's cinclodes (
Cinclodes olrogi) is found in areas of open grass-covered rock formations near streams and lakes between 1,500 and 2,400 meters elevation. Other native birds include the
Andean condor (
Vultur gryphus),
Andean tinamou (
Nothoprocta pentlandii),
olive-crowned crescentchest (
Melanopareia maximiliani),
cliff flycatcher (
Hirundinea ferruginea),
Chaco sparrow (
Rhynchospiza strigiceps), and
black-and-rufous warbling finch (
Poospiza nigrorufa). Overgrazing, over-hunting, human-caused fires, and firewood harvesting have altered the flora and fauna of the mountains, creating soil erosion in large areas and reducing the extent of forests and woodlands. It is believed that the vegetation of the Sierra de Córdoba has varied greatly over the
Quaternary, with some periods in the
Holocene between 8000 and 500 years before today when
forests extended to the now-dry western side of the mountain range and the adjacent Sierra de San Luis. At other times, such as glacial periods and the earliest part of the Holocene, the whole mountain range was completely treeless due to extremely low rainfall. This may explain why few endemics are found outside the zone above the timberline — where species that have inhabited the area for thousands of years take a kind of refuge from a warmer, wetter climate. ==Protected areas==