Search

Human-induced changes to ecosystems transform the availability of resources to predators, including altering prey populations and increasing access to anthropogenic foods. Opportunistic predators are likely to respond to altered food resources by changing the proportion of food they hunt versus scavenge. These shifts in foraging behavior will affect species interactions through multiple pathways, including by changing other aspects of predator behavior such as boldness, innovation, and social structure.To understand how foraging behavior impacts predator behavior, we conducted a controlled experiment to simulate hunting by introducing a prey model to captive coyotes (We documented increased time spent resting by hunting coyotes paired with decreased time spent active. Hunting coyotes increased boldness and persistence but there were no changes in innovation. Our results illustrate how foraging behavior can impact other aspects of behavior, with potential ecological consequences to predator ecology, predator-prey dynamics, and human-wildlife conflict; however, the captive nature of our study limits specific conclusions related to wild predators. We conclude that human-induced behavioral changes could have cascading ecological implications that are not fully understood.

Conservation and recovery of forest carnivores requires an understanding of their habitat requirements, as well as requirements of their prey. In much of the western United States, trapping and habitat loss led to extirpations of fishers (Pekania pennanti) by the mid-20th century, and reintroductions are ongoing to restore fishers to portions of their former range. Fisher recovery in Washington State has been limited by isolation from other populations, but other potentially important factors, such as diet of fishers in this region and prey availability, have not been thoroughly investigated. We collected hair samples from potential prey and fishers for stable isotope analysis to identify important prey items for fishers within a reintroduction area in southern Washington. We then estimated the abundance of prey species at 21 sites across a gradient of forest structural classes within the fisher reintroduction area, and assessed the effects of forest age and vegetation on the prey community using permutational multivariate analysis of variance and non-metric multidimensional scaling. Stable isotopes revealed that larger prey items, including snowshoe hares (Lepus americanus) and/or mountain beavers (Aplodontia rufa), were the most important prey item(s) for fishers in the southern Cascades. We found distinct but equally diverse prey communities in old-growth (unmanaged) and young (heavily managed) forest stands, with snowshoe hares and mountain beavers most common in young forests, while chipmunks (Neotamius spp.) and small mammals were more common in older forests. Our results suggest a discrepancy between the habitats where important fisher prey are most abundant and habitat requirements of fishers. Snowshoe hares and mountain beavers were most abundant in young forests, whereas fishers are associated with landscapes dominated by older forest stands or those that provide large woody structures, which fishers use for denning and resting. Our results add to growing evidence that forest landscape mosaics provide valuable habitat for fishers in the Pacific Northwest, suggesting that both mature and younger forest stands are important for fishers and fisher recovery.

Foraging by herbivores alters individual plants and vegetation communities directly, and engineering behaviors such as bioturbation (digging and turning soil) and biodeposition (deposition of feces and urine) can affect soils and physical properties that indirectly influence vegetation and other organisms. Patchy environments often concentrate the activities of animals, potentially increasing the magnitude of their impacts on the vegetative community over time. To evaluate the potential for herbivorous engineers to enhance existing heterogeneity, we quantified the direct and indirect effects of a burrowing herbivore, the pygmy rabbit (Brachylagus idahoensis), on soil and vegetation in the sagebrush steppe ecosystem of the western United States, and we evaluated whether the effects were related to duration of occupancy by rabbits. Mounded microtopography (i.e., mima mounds) creates distinct resource islands with relatively tall and dense sagebrush shrubs where pygmy rabbits concentrate burrowing and foraging activities. We quantified soil and vegetation characteristics on mima mounds occupied by rabbits for 1–12 yr and on unoccupied mounds. We expected that browsing would negatively influence slow growing sagebrush shrubs, but that digging and biodeposition would enhance soil nutrients and water infiltration. In addition, we hypothesized that the net effect on sagebrush reproduction would be positive because indirect effects on soil would enhance seed production by mature sagebrush and seedling growth, and because bioturbation would increase seed retention and germination. Pygmy rabbit occupancy had significant cumulative effects on both soil and vegetation properties on occupied mima mounds. Over time, browsing reduced sagebrush canopy cover and percent of individual shrubs that were alive. Soil properties were less influenced by the duration of occupancy of mima mounds than by the localized spatial influence of burrowing; elevated nitrogen levels were associated with burrow entrances. Two measures of sagebrush reproduction (seedling recruitment and inflorescence biomass) increased with duration of burrow occupancy, suggesting that over longer time frames pygmy rabbits enhanced reproduction and recruitment of sagebrush shrubs. Our data demonstrate multiple pathways by which an herbivorous engineer can influence habitat heterogeneity, and they suggest that although pygmy rabbits are inconspicuous on the landscape, the species might play an important role in maintaining and augmenting heterogeneity in the sagebrush steppe.