Effect of coyote removal on the faunal community ecology of a short-grass prairie
Henke, Scott E
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The primary objective of this study was to evaluate the effect of removing coyotes (Canis latrans) on the ecosystem. The population response of rodents, lagomorphs, raptors, and mammalian predators were evaluated on 2 experimental and 2 comparison areas for a year prior to coyote removal measures, and then for 24 months after the initiation of seasonal coyote removal. A total of 328 coyotes were removed on 55,000-ha experimental areas of mixed grassland and shrubland in western Texas during April, 1990 - January, 1992. This effort reduced coyote density on experimental areas by 48%; whereas, the density on comparison areas remained constant at 0.144 coyotes per km^. Scent station index was sensitive to short- and long-term changes in coyote density caused by coyote removal. Vocalization and scat indices were sensitive to acute changes in coyote density, but were poor correlates of long-term effects. During the period prior to coyote removal, no differences in faunal population estimates between comparison and experimental areas were observed. After the initiation of coyote removal, rodent species richness and rodent diversity declined on experimental areas. Rodent density, rodent biomass, percent of kangaroo rats (Dipodomvs ordii). jackrabbit (Lepus califomicus) density, and relative abundances of badgers (Taxidea taxus). bobcats (Felis rufus). and gray foxes (Urocyon cineroargenteus) increased on experimental areas. Cottontail rabbit (Sylvilagus audubonii) density and raptor richness, diversity, and density appeared to be little affected by coyote removal. Coyotes consumed 29 different food items, as determined by stomach analysis. Mesquite pods were a major diet component during spring, grasshoppers during the summer and fall, and mammals during winter. Livestock, either as carrion or as coyote-killed, appeared sporadically as a diet component, but was found most frequently during the winter. Cottontail rabbits were the most preferred mammalian food item of coyotes. A reduced coyote density on experimental areas did not stimulate a greater reproductive response in adult females. Percent of females breeding, litter size, nor percent of resorptions appeared affected by a reduced coyote density.