Effects of coyote removal on the faunal community in western Texas

Coyotes (Canis latrans) play a keystone role in the population regulation o f microherbivores and mesopredators in certain ecosystems. Despite this fac t, coyote control measures still are implemented. We evaluated the effects of removing coyotes on sympatric populations of rodents. lagomorphs, raptor s, 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 far 1 year before co yote removal and for 2 years during coyote removal. We removed 354 coyotes by aerial sinning on treatment sites. Removal efforts were initiated every third month from April 1990 to January 1992. Coyote density was reduced fro m 0.12 +/- 0.01 ((x) over bar +/- SE) to 0.06 +/- 0.01 coyotes/km(2) on tre atment sites. Density on comparison sites remained stable at 0.14 +/- 0.01 coyotes/km(2). We found no differences in faunal population estimates betwe en comparison and treatment sites for the year before coyote removal. Withi n 9 months following the initiation of coyote removal, rodent species richn ess and rodent diversity declined on treatment sites. Without coyote predat ion, the Ord's kangaroo rat (Dipodomys ordii) became the most abundant rode nt ill shrublands and was the only rodent species caught in grasslands afte r 12 months of coyote removal, Rodent density and biomass, black-tailed jac krabbit (Lepus californicus) density and relative abundance of badgers (Tax idca taxus), bobcats (Felis rufus), and gray foxes (Urocyon cincroargenteus ) increased on treatment sites, Variation in the density of desert cottonta il rabbits (Sylvilagus audubonii) and raptor richness, diversity, and densi ty was not related to coyote density. Our findings were consistent with, th e predator-mediated coexistence hypothesis, which suggests that a keystone predator (coyote) can influence faunal community structure.