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248 Bobwhites on the Post Oak Savannah Nova J. Silvy [The] restriction of naturally occurring fires and continual overgrazing have converted much of the Post Oak Savannah from true savannah to complex, heavy thickets of woody plants. Scifres (1980) Today, the Post Oak Savannah of Texas supports few huntable populations of northern bobwhites (Colinus virginianus). In this ecoregion, small and relatively isolated populations of quail currently exist in fragmented patches of habitat. There are few published studies of northern bobwhites in the Post Oak Savannah, and little recent work has been done. Some of the classic natural history studies of quail in this region were conducted in places where it intergrades into the Blackland Prairies (chapter 10). This chapter describes the ecological aspects of the Post Oak Savannah in the context of bobwhite management. It presents population trends and provides a general overview of aspects of bobwhite life history that are germane to this region. The chapter also discusses limiting factors and management options and outlines research needs that pertain to bobwhite ecology and management. It summarizes the land-use and management changes that will need to occur if northern bobwhite populations will ever increase within the Post Oak Savannah region of Texas. Post Oak Savannah The Post Oak Savannah comprises about 3.4 million hectares (8.4 million acres). This ecoregion is situated in east-central Texas, extending southward from the Texas-Oklahoma border for a distance of about 563 kilometers (350 miles) and varying in width from 80 to 121 kilometers (50 to 75 miles) (Parmalee 1953a; figure 14.1). Topography is mostly level to gently rolling, with some steep slopes and hilly areas (Gould 1975b). Many areas are considerably eroded, largely by formation of gullies. Kirvin (Norfolk group) and Lufkin (Susquehanna group) are the two major soil types; they are mostly loose, light-colored, sandy-loam topsoil with a subsoil of clay and sandy clay (Parmalee 1953a). Elevation ranges from 91 to 242 meters (250 to 650 feet) (Gould, Hoffman, and Rechenthin 1960). The average annual temperature is 19.3°C (66°F), average annual rainfall is 98.3 centimeters (approximately 40 inches) (Grue 1977), and average length of the growing season is about 250 days (Parmalee 1953a). Climax vegetation is basically a post oak (Quercus stellata) savanna (Gould, Hoffman, and Rechenthin 1960). Most of the Post Oak Savannah is in native or improved pasture, although small farms are common . Almost 75 percent of the area is in pastureland grazed primarily by 14 Figure 14.1. The Post Oak Savannah ecoregion of Texas. Courtesy Caesar Kleberg Wildlife Research Institute (CKWRI) GIS Laboratory 249 Bobwhites on the Post Oak Savannah cattle. Due to intensive grazing practices, much of the area has degenerated to dense stands of oak with an understory of yaupon (Ilex vomitoria ). Post oak and blackjack oak (Q. marilandica) are the two dominant species in the upland areas. Several other woody species are often found growing in association with them: hackberry (Celtis occidentalis), eastern red cedar (Juniperus virginiana), mesquite (Prosopis glandulosa), and cedar elm (Ulmus crassifolia). The understory is dominated by yaupon , winged elm (U. alata), poison oak (Rhus toxicidendron), American beautyberry (Callicarpa americana), and trumpet creeper (Campsis radicans). Wild plum (Prunus mexicana), honey locust (Gleditsia triacanthos ), hawthorn (Crataegus spathulata and C. marshalli), prickly ash (Xanthoxylum clava-herculis), sumac (R. copallian), Osage orange (Toxylon pomiferum), and cedar (J. lucayana) also are commonly found singly in open areas, along streams, and in thickets. Bottomlands consist of hardwoods, predominantly oaks (water oak [Q. nigra] and overcup oak [Q. lyrata]), with pecans (Carya spp.) and black hickory (Hicoria buckleyi) in some areas. The dominant grasses include little bluestem (Schizachyrium scoparium ), indiangrass (Sorghastrum nutans), switchgrass (Panicum virgatum), purpletop (Tridens flavus), silver bluestem (Bothriochloa saccharoides), grama grasses (B. curtipendula and B. hirsute), Texas wintergrass (Stipa leucotricha), panicgrass (Panicum halli, P. obtusum, P. lindheimeri, and P. texanum), bullgrass (Paspalum longipilum and P. pubescens), buffalograss (Buchloe dactyloides), spike uniola (Uniola laxa), and longleaf uniola (U. sessiliflora) (Parmalee 1953a; Gould, Hoffman , and Rechenthin 1960). MostofthelargetractsofPostOakSavannahwereclearedintheearly 1900s. By the early 1950s, much of the cleared areas had been reclaimed by brush and woody species. Today, very little original savanna vegetation remains; most has been plowed and converted to tame pasture for cattle grazing (Gould 1975b). Tame pastures are commonly planted in common and coastal bermudagrass (Cynodon dactylon), crimson clover (Trifolium incarnatum), and white clover (T. repens). Fallow fields consist of common and coastal bermudagrass, threeawn grass (Aristida purpurescens, A. olingantha, and A. intermedia), johnsongrass (Sorghum...

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