Additive, substitutable, and antagonistic prey responses to feral and native predator combinations
In captive experiments of Negev Desert granivores, we investigated the ways in which combinations of feral mesocarnivores and native predators alter wild prey behavior. We hypothesized that feral mesocarnivores would have a greater impact on prey energy acquisition, reflected in foraging dynamics, than native predators. Allenbys gerbils (Gerbillus andersoni allenbyi) and greater Egyptian gerbils (Gerbillus pyramidum) were used as prey species, with feral dogs (Canis lupus familiaris), feral cats (Felis catus), barn owls (Tyto alba), and horned vipers (Cerastes gasperetti) as predators. Gerbil perceived risk was measured using optimal patch-use theory, with exposures to tethered predators occurring hourly throughout the night. Some nights, two predators were alternated every other hour. We found that human-commensal predators, particularly feral cats, induced stronger foraging than native predators, such as barn owls. Combined predators caused gerbils to decrease foraging only when a higher-risk predator was introduced, as indicated by higher giving-up densities (GUDs) for the dog and cat combination compared to the dog alone, and a nonsignificant increase compared to the cat alone. The impact of feral cats especially appears to outweigh that of native predators. This highlights the conservation challenges to arid environments where feral cats have become ubiquitous. HighlightsO_LIFeral predators, particularly cats and dogs, elicit stronger anti-predator responses in Negev Desert gerbils than native predators, significantly altering foraging behavior and habitat use. C_LIO_LIThe presence of feral predators in the Negev Desert leads to cumulative impacts on prey species, resulting in increased vigilance and reduced resource acquisition, which suggests a disruption of native predator-prey dynamics. C_LIO_LIThe studys findings emphasize the unique conservation challenges posed by human-commensal species in arid ecosystems, where limited refugia increases the predation risk from invasive and feral species. C_LIO_LIThis research demonstrates how predator-prey interactions in the arid communities tested are impacted by both additive predator effects between native predators, and between feral predators, but when combining feral predators with native ones, the effect is substitutable with feral predators disproportionately influencing prey behavior. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/612031v2_ufig1.gif" ALT="Figure 1"> View larger version (80K): org.highwire.dtl.DTLVardef@1d2b45eorg.highwire.dtl.DTLVardef@3f9490org.highwire.dtl.DTLVardef@32a733org.highwire.dtl.DTLVardef@17f2111_HPS_FORMAT_FIGEXP M_FIG C_FIG