Carnivore reintroduction is often expected to revert community and ecosystem properties to their natural states via risk effects and the direct killing of prey. Because large carnivore extirpation and reintroduction are usually believed to have symmetric and offsetting effects, fulfilling this "assumption of reciprocity" is crucial to realizing the potential of large carnivores to passively restore community structure and ecosystem function. We were unable to find any study in which the assumption of reciprocity was rigorously tested in predator-prey systems featuring large carnivores, their ungulate prey, and primary producers through a comprehensive literature search. We therefore used studies involving (1) the reintroduction of any native apex predator (including but not limited to large mammalian carnivores); and (2) the removal of any introduced apex predator (also including but not limited to large mammalian carnivores) to examine the assumption of reciprocity. Reintroduction of native apex predators did not affect any of four trophic groups (mesopredator, omnivore, herbivore, primary producer) in a positive or negative way, but removal of introduced apex predators consistently increased the abundance and biomass of mesopredators. Further, outcomes of apex predator reintroduction and removal were variable across systems, regardless of system complexity (ranging from single predator-single prey to multiple predator-multiple prey systems). We suggest that the assumption of reciprocity-in which predator extirpation and reintroduction are believed to have consistent, counterbalancing effects-is unsupported by current evidence, and perhaps unrealistic. We discuss potential directions for research that might illuminate when and why the assumption of reciprocity would be valid.

Challenges in monitoring rare and elusive species often involve low detection and sampling success. Noninvasive methods have allowed researchers to more efficiently monitor rare and elusive species while reducing costs of more invasive, traditional techniques. We evaluated the use of a noninvasive method as an alternative to live‐trapping pocket gophers. We found that tunnel diameter can be used to help distinguish between occupancy by the Wyoming pocket gopher (Thomomys clusius; a species of conservation concern) and its more abundant and widespread congener, the northern pocket gopher (T. talpoides). Our method reduces reliance on more invasive methods of monitoring occupancy (i.e., live‐ or kill‐trapping) for co‐occurring pocket gopher species, and likely can be extended to survey for other species of fossorial mammals. © 2020 The Wildlife Society.

Throughout North America, all 5 species of prairie dogs (Cynomys spp.) have experienced drastic population declines over the past century, which has subsequently affected a host of affiliated species. Tools and techniques used to monitor prairie dogs have important implications for the management and conservation of grassland ecosystems. Behavioral responses by prairie dogs to predators may offer an opportunity to improve techniques that rely on visually based survey techniques by increasing the visibility of individuals. We evaluated whether the use of a visual stimulus resembling a common predator could increase the number of white-tailed prairie dogs (C. leucurus) observed during visual count surveys conducted in June and July of 2017 in Wyoming, USA. We designed a visual stimulus consisting of a remote-controlled toy car fitted with a badger (Taxidea taxus) pelt. We found counts of prairie dogs increased from 14.2 (95% CI ¼ 10.4-18.0) to 32.6 (95% CI ¼ 24.1-41.1) individuals/4-ha plot when this visual stimulus was deployed. Our top model predicted counts to be 2.3 times greater when a visual stimulus was used. The increase in counts elicited by use of a visual stimulus may therefore improve the accuracy and efficiency of traditional visual counts and other visually based monitoring techniques for prairie dogs. By enabling managers to take advantage of behavioral responses, use of a visual stimulus as described here could aid efforts to monitor and manage prairie dog populations and consequently conserve prairie ecosystems. Ó

Understanding the determinants of species rarity is a perennial challenge for ecologists and conservation biologists. In addition to resource specialization, competitive interactions may limit the abundance and distribution of species, thereby accentuating rarity. However, resource partitioning can reduce or altogether offset such competitive effects, and thus permit species to thrive alongside more common, widespread competitors within a narrow range of environmental conditions. In south-central Wyoming, the Wyoming Pocket Gopher (Thomomys clusius) is restricted to areas dominated by Gardner’s Saltbush (Atriplex gardneri); it inhabits a geographic range that is entirely encompassed by a relatively abundant and widespread congener (T. talpoides, the Northern Pocket Gopher). However, the consumer–resource dynamics underlying the relationships among Wyoming pocket gophers, northern pocket gophers, and Gardner’s Saltbush are poorly understood. We assessed one dimension of consumer–resource interactions—diet selection—between Wyoming pocket gophers, northern pocket gophers, and Gardner’s Saltbush, using a combination of path analysis, DNA metabarcoding, and cafeteria-style feeding experiments. We rejected the null hypothesis that Wyoming pocket gophers and Gardner’s Saltbush co-occur solely because they require similar soil conditions. Although we could not distinguish between obligate and facultative specialization by Wyoming pocket gophers, the checkerboard-like distributions of these two Thomomys likely reflect the outcome of selection and avoidance of Gardner’s Saltbush. We suggest that Wyoming pocket gophers can persist within their small geographic range by capitalizing on Gardner’s Saltbush, a halophyte that probably requires some combination of physiological, morphological, and behavioral adaptations to exploit. Low abundances, restricted geographic ranges, or both are hallmarks of rarity, each of which are shaped by diet selection and other consumer–resource interactions. Quantifying consumer–resource interactions can therefore provide a mechanistic basis for the further refinement and testing of hypotheses on the abundance and distribution of closely related species.