East of Firebaugh, in the agricultural no man's land between two key Central Valley IBAs (Grasslands Ecological Area and Mendota Wildlife Area), is a 30,000-acre patch of vernal pool-rich grassland, alkali scrub and freshwater marsh (i.e. the slough) with narrow bands of riparian woodland and that has somehow survived the agricultural transformation of western Fresno/Madera Co. Located northeast of Firebaugh, this habitat may represent the largest intact swath of unplowed valley floor in the San Joaquin Valley (R. Hansen, pers. comm.). Originally, this site would have supported a rich riparian woodland associated with the San Joaquin River, from which it is now separated by levees, but today only scattered patches remain. Currently, the entire area is totally privately-owned, heavily grazed and virtually unstudied.
Updated September 2008
From a handful of visits by ornithologists, this IBA is known to support a sizable population of breeding Swainson's Hawks, of which 50-100 birds have been observed at summer roosts in cottonwoods along the slough. These trees also hold rookeries of Great Blue Heron and probably other waders (pers. obs.). The bulrush marsh, which covers several hundred acres, probably supports nesting White-faced Ibis, which summer (pers. obs.). The extensive grasslands may be one of the only places on the San Joaquin Valley floor that could potentially support Grasshopper Sparrow, though more fieldwork is needed. This is also one of the last places to reliably see breeding Lesser Nighthawks in Madera County. (J. Seay pers. comm.)
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The slough itself is apparently a water bank for the local irrigation district, and receives no formal protection. The grasslands are managed exclusively for cattle and sheep grazing. This is a site that urgently deserves study and conservation attention, possibly involving its inclusion into the Grasslands Ecological Area.
Currently, the entire area is totally privately-owned.
This IBA is a 30,000-acre patch of vernal pool-rich grassland, alkali scrub and freshwater marsh (i.e. the slough) with narrow bands of riparian woodland.