David Bustos

The application of occupancy modeling to evaluate intraguild predation in a model carnivore system

Intraguild predation (IGP) is an extreme form of competition that involves a dominant predator (IG predator), a subordinate predator that is also a superior exploitative competitor (IG prey), and their shared prey. Theory predicts three possible equilibria, which parallel increasing resource enrichment: exclusion of the IG predator, stable coexistence, and exclusion of the IG prey. Here, we report on the existence of two concurrent states in a model carnivore system dominated by IGP. Using species occurrence data obtained from randomly distributed remote cameras, we modeled the probabilities of detection and occupancy of the kit fox (Vulpes macrotis) and its IG predator, the coyote (Canis latrans), at White Sands National Monument, New Mexico, USA, using a recently developed conditional two-species occupancy model. Kit foxes persisted in habitats of low resource abundance, which could not support coyotes. Coexistence occurred in adjacent habitats of higher resource enrichment, with coyote occupancy strong...

Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America

Contemporaneous sloth and human footprints from the terminal Pleistocene at White Sands National Monument suggest stalking. Predator-prey interactions revealed by vertebrate trace fossils are extremely rare. We present footprint evidence from White Sands National Monument in New Mexico for the association of sloth and human trackways. Geologically, the sloth and human trackways were made contemporaneously, and the sloth trackways show evidence of evasion and defensive behavior when associated with human tracks. Behavioral inferences from these trackways indicate prey selection and suggest that humans were harassing, stalking, and/or hunting the now-extinct giant ground sloth in the terminal Pleistocene.