The Carson River Delta IBA was recognized largely for its habitat values; the site constitutes the last best remnant of a cottonwood-willow riparian forest in northwestern Nevada (and perhaps an even larger area). This habitat type was once extensive along perennial water courses in Nevada, including the Truckee, Carson, and Humboldt Rivers. These forests suffered as they were cut for fuel, grazed, eliminated as rivers were diverted or dammed. Regeneration in these forests is tightly linked to natural flood cycles, with the release of cottonwood seeds timed to take advantage of receding spring floods. As rivers have been dammed and diverted, these events which were almost annual in their occurrence now rarely occur at all.
In spite of these problems, the Carson River Delta IBA is spectacular to the eye, and appears as a dense, verdant forest spread along the historic flood plain. The scene is striking against the starkness of the surrounding desert shrub communities and barren rock outcrops on adjacent hillsides. The cottonwood overstory is particularly striking in early October as the green of summer gives way to the golden hues of fall. The IBA encompasses the historic flood plain of the Carson River from Fort Churchill downstream to the rivers delta at the Lahontan Reservoir. In high runoff years the river leaves its banks and floods the forest in spring. In sharp contrast, above-ground flow in this stretch of the Carson River usually vanishes in early July and does not resume again until mid-to-late October.
Riparian forests have been severely impacted in Nevada and throughout much of the west. As a result, many of the bird species dependent on this habitat type have also experienced dramatic declines in numbers. Both Yellow-billed Cuckoos and Willow Flycatchers, two species whose ranges have shrunk dramatically from historic levels, have been recorded in recent years on the Carson River Delta IBA. Other NV PIF species of concern include White-faced Ibis, Swainsons Hawk, Western Bluebird, and Wilsons Warbler. The forest is also likely to be an important migration corridor, providing stop-over habitat for Neotropical migrants. To increase our understanding of the bird community on this IBA, point count surveys were initiated in 2002 and a banding station was established in the same year using MAPS protocol.
salt cedar, tall whitetop, other invasive weeds gaining a significant foothold. Upstream seed sources will likely persist. off-road vehicle use. Nevada's only Superfund site, due to presence of mercury in sediments. Source of mercury is partly natural, but primarily from historic mining activities in the Carson River watershed. cowbird parasitism. over-appropriation of water from the system.
MAPS banding station since 2002. Great Basin Bird Observatory all-bird monitoring survey transect also located here (since 2002).