We examined temporal relationships between characteristics of populations creatton rats (Sigmodon hispidus) and vegetative characteristics of habitats following secondary succession of post oak (Quercus ste/lata)-blackjack (Q. rnarilandica) savannas in central Oklahoma. Successional changes in vegetation were induced on manipulated habitats by one of two herbicides (tebuthiuron, triclopyr) applied in 1983 and used in combination with or without annual prescribed burning during 1985 to 1988, Relative population density (animals caught per 100 trapnights) and percentage of reproductively active adult females (lactating or pregnant) were significantly greater on manipulated habitats dominated by monocots (grasses) than on habitats with monocots and dieats or undisturbed controls. Herbaceous dicots also influenced the density of cotton rats, especially in 1986; relative density peaked on all manipulated habitats following a peak in production of herbaceous dicots in 1985. Nutritional quality of herbaceous vegetation may have been enhanced by annual burning; relative densities and proportions of juveniles in the trapable population were higher in burned than in unburned habitats. This observation was most pronounced in 1986, when herbaceous dicots comprised a greater proportion ofthe primary production, than in 1987 or 1988.

Knowledge of how resident wildlife populations respond to brush management strategies is especially limited for rangelands in the cross timbers vegetation type of Oklahoma. We examined how cottontail rabbit (Sylvf&gu.vfloridanus) density and habitat use were hrfluenced by applications of tebuthiuron or triciopyr, with and without annual burning, on cross timbers rangeland. Line transect flush-counts, mark-recapture livetrapping, and fecal pellet counts were used to evaluate seasonal differences in population density among 5 brush control treatments. Cottontail rabbits (n = 225) were flushed along 362 km of line transects during 5 census periods. Density in winter was consistently lower than summer for all treatments, except for the untreated control in winter 1987. Line transect density estimates varied from 0 to 1.875 rabbits/ha and suggested that herbicide and annual burning treatments had a positive influence on cottontail rabbit populations compared to untreated controls. Mark-recapture density estimates did not differ among treatments. Fecal pellet counts were greater on herbicidetreated pastures than an untreated control in both spring and fail. Prairie-eastern redcedar (Jun@erus virginiM0 L.) and forest-prairie ecotone habitats were utilized greater than expected by cottontail rabbits. Mature hardwood overstory and mixedbrush habitats were avoided. Tebuthiuron and triclopyr effectively decreased hardwood overstory and increased preferred habitats for cottontail rabbits.

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