Effects of Coyote Removal on the Faunal Community in Western Texas

Abstract

Coyotes (Canis latrans) play a keystone role in the population regulation of microherbivores and mesopredators in certain ecosystems. Despite this fact, coyote control measures still are implemented. We evaluated the effects of removing coyotes on sympatric populations of rodents, lagomorphs, raptors, and mammalian mesopredators in a shortgrass prairie ecosystem of western Texas. Faunal communities were examined on 2 treatment and 2 comparison 5,000-ha sites of mixed grassland and shrubland habitats for 1 year before coyote removal and for 2 years during coyote removal. We removed 354 coyotes by aerial gunning on treatment sites. Removal efforts were initiated every third month from April 1990 to January 1992. Coyote density was reduced from 0.12 ± 0.01 (x ± SE) to 0.06 ± 0.01 coyotes/km 2 on treatment sites, Density on comparison sites remained stable at 0.14 ± 0.01 coyotes/km 2 , We found no differences in faunal population estimates between comparison and treatment sites for the year before coyote removal. Within 9 months following the initiation of coyote removal, rodent species richness and rodent diversity declined on treatment sites, Without coyote predation, the Ord's kangaroo rat (Dipodomys ordii) became the most abundant rodent in shrublands and was the only rodent species caught in grasslands after 12 months of coyote removal. Rodent density and biomass, black-tailed jackrabbit (Lepus californicus) density, and relative abundance of badgers (Taxidea taxus), bobcats (Felis rufus), and gray foxes (Urocyon cineroargenteus) increased on treatment sites, Variation in the density of desert cottontail rabbits (Sylvilagus audubonii) and raptor richness, diversity, and density was not related to coyote density, Our findings were consistent with the predator-mediated coexistence hypothesis, which suggests that a keystone predator (coyote) can influence faunal community structure.