Designing Studies of Predation Risk for Improved Inference in Carnivore-Ungulate Systems

Quantifying both the lethal and non-lethal (or “risk”) effects of predation has emerged as a major research focus in carnivore-ungulate systems. While numerous studies have examined predation risk and risk effects in recent decades, a lack of standardization in approaches has impeded progress in the field. We provide an overview of five major study design considerations involved in assessing predation risk and responses of prey in carnivoreungulate systems, highlighting how different design choices can impact the strength and scope of inference. First, we stress the importance of distinguishing measures of predation risk (probability of being killed) from measures of risk effects (costs of antipredator behaviors in response to risk). Second, we recommend explicit consideration of spatial and temporal scales using a standardized framework to facilitate cross-study comparisons. Third, ungulates use visual, auditory, and olfactory sensory pathways to evaluate predation risk. Experiments that manipulate signals of risk (e.g., auditory playbacks or application of predator scent) can be powerful approaches, but the dosages and types of cues need to be carefully considered. Fourth, ungulates usually face threats from multiple predators simultaneously, and we highlight the potential for remote cameras and structural equation modeling to help address this challenge. Fifth, emerging technologies may substantially improve our ability to assess risk. We discuss several promising technologies, such as animal-borne video, unmanned aerial vehicles, and physiological sensors. We conclude with general recommendations for study design, which may improve the utility of predation risk research for the conservation and management of carnivore-ungulate systems

Conflict, coexistence, or both? Cougar habitat selection, prey composition, and mortality in a multiple-use landscape

Western North America is experiencing remarkable human population growth and land-use change. Irrigation and associated cultivation have led to colonization of urban-wildland interface (UWI) environments by mule deer (Odocoileus hemionus), and consequently, cougars (Puma concolor). In the wake of these changes, human-wildlife conflicts have increased in tandem with questions about long-term species conservation. To address these concerns, we fit 79 cougars with radio-telemetry collars in the Oquirrh Mountains near Salt Lake City, Utah (2002–2010). Our goal was to evaluate variation in cougar habitat selection, diet, and cause-specific mortality in a landscape dominated by urban, military, and industrial activities. We used radio-telemetry data in concert with Re-source Selection Functions to address three hypotheses: (1) that cougars would select wildland over UWI land-uses; (2) prey composition would reflect differences in land-use; and (3) mortality would be predominantly human-caused. Cougars largely selected wildland habitats associated with seasonal mule deer presence, but contrary to expectation, they also selected habitats closer to urban and mined areas. Prey composition in the UWI did not differ from wildland habitats. Domestic ungulates represented only 2% of 540 recovered prey items and were found primarily in wildlands. Native ungulates comprised \u3e 90% of the total kill, irrespective of season or land-use, suggesting that use of UWI habitats was linked to mule deer presence. Cougar mortality was disproportionately due to natural causes in wildlands, but individuals that died of human causes in UWI habitats were more likely to be inexperienced hunters, supporting young kittens, or compromised by physical handicaps. In general, presence of mule deer was the key predictor of cougar habitat use, even in this highly disturbed, anthropogenically altered landscape. As such, management designed to reduce conflict and ensure conservation will need to focus on urban deer, land-use planning, and targeted education campaigns to reduce food subsidies

Predicting Dispersal and Conflict Risk for Wolf Recolonization in Colorado

1. The colonization of suitable yet unoccupied habitat due to natural dispersal or human introduction can benefit recovery of threatened species. Predicting habitat suitability and conflict potential of colonization areas can facilitate conservation planning. 2. Planning for reintroduction of gray wolves (Canis lupus) to the United States state of Colorado is underway. Assessing which occupancy sites minimize the likelihood of human-wolf conflict during dispersal events and seasonal movements is critical to the success of this initiative. 3. We used a spatial absorbing Markov chain (SAMC) framework, which extends random walk theory and probabilistically accounts for both movement behavior and mortality risk, to compare the viability of potential occupancy sites (public lands \u3e 500 km2 to minimally meet wolf pack range area). The SAMC framework produced spatially explicit predictions of wolf dispersal, philopatry and conflict risk ahead of recolonization prior to reintroduction efforts. Our SAMC model included: (1) movement resistance based on terrain, roads and housing density; (2) mortality risk and potential conflict (absorption) based on livestock presence, social tolerance, land ownership and state boundaries; and (3) site fidelity based on habitat quality. Using this model, we compared 21 public land units by deriving predictions of: (A) relative survival time outside each site, (B) intensity of use and retention time within each site, and (C) the probability of use on adjacent public lands. We also predicted and mapped potential conflict hot spots associated with each site. 4. Among the units assessed, a complex of United States Forest Service Wilderness areas near Aspen, chiefly the Hunter-Fryingpan and Collegiate Peaks Wilderness areas, had the best overall rankings when comparing predictions of each metric. The area balances high-quality, well-connected habitat with relatively low livestock density and high social tolerance. 5. Synthesis and applications. Our findings highlight the utility of the SAMC framework for assessing colonization areas and the capacity to identify locations for effective proactive management, especially of conflict prone species. The flexibility of the SAMC framework enables predicting likely areas of philopatry and human-wildlife conflict using spatially explicit metrics which can improve the success of conservation translocations and management of species with changing geographic extents

Navigating the wildland-urban interface: Sensory pollution and infrastructure effects on mule deer behavior and connectivity

Climate and land-use change are modifying the availability of food and water resources, which is driving more wildlife to the wildland-urban interface. For many wildlife populations, use of these areas still requires habitat connectivity both within the interface and/or to wildland habitats. However, navigating these areas can be difficult due to human development and sensory pollutants, such as artificial night light. Determining how these components of urbanization influence the behaviors and functional connectivity of species is important for managing wildlife within these mixed-use landscapes. Here we used a movescape approach based on graph theory to characterize functional uses of the landscape using metrics for behavior, connectivity, and space use intensity. We found that mule deer (Odocoileus hemionus; n = 43) functional uses of anthropogenic landscapes in the Intermountain West, USA, were dependent not only on physical barriers, terrain, and sensory factors, but also the local levels of light exposure and vegetative greenness. Remotely sensed artificial light levels had a strong influence on how mule deer used the landscape by reducing the intensity of use in the most illuminated areas given forage availability. In contrast, relatively high local light levels were associated with increased use intensity within less developed areas—highlighting the foraging tradeoffs for species using the wildland-urban interface. Corridor use was reduced in areas where road and housing density were higher, and within-corridor movement was faster when artificial light was high and vegetative greenness was low. Developing a more mechanistic understanding of how species functionally use the landscape in relation to features of urbanization can enhance conservation by delineating areas important for connectivity and foraging, while providing insights into how future development and climate change may alter movement and behavior. Spatially-explicit estimates of functional uses can directly guide management decisions to maintain species resiliency and improve land-use planning

Human Herpesvirus Replication and Abnormal CD8+ T Cell Activation and Low CD4+ T Cell Counts in Antiretroviral-Suppressed HIV-Infected Patients

Most HIV-infected patients receiving virologically suppressive antiretroviral therapy continue to have abnormal, generalized T cell activation. We explored whether the degree of ongoing cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV) replication was associated with higher virus-specific T cell activation and the failure to achieve normal absolute CD4+ T cell counts in the face of long-term suppressive antiretroviral therapy.Longitudinally collected PBMC and saliva specimens obtained from HIV-infected patients on effective antiretroviral therapy for at least one year (plasma HIV RNA <75 copies/mL) were examined using a multiplex CMV, EBV and KSHV DNA PCR assay. Eleven cases were chosen who had CD8+ T cell CD38+HLA-DR+ expression >10% and plateau absolute CD4+ T cell counts <500 cells/microL. Five controls from the same study had CD8+ T cell CD38 expression <10% and plateau absolute CD4+ T cell counts >500 cells/microL.Among all subjects combined, 18% of PMBC samples were positive for CMV DNA, and 27%, 73% and 24% of saliva samples were positive for CMV, EBV and KSHV DNA, respectively. No significant differences or trends were observed between cases and controls in proportions of all CMV, EBV or KSHV DNA positive specimens, proportions of subjects in each group that intermittently or continuously shed CMV, EBV or KSHV DNA in saliva, or the median number of genome copies of CMV, EBV and KSHV DNA in saliva. Overall, number of genome copies in saliva were lower for KSHV than for CMV and lower for CMV than for EBV. Although replication of CMV, EBV and KSHV persists in many antiretroviral-suppressed, HIV-infected patients, we observed no evidence in this pilot case-control study that the magnitude of such human herpesvirus replication is associated with abnormally increased CD8+ T cell activation and sub-normal plateau absolute CD4+ T cell counts following virologically suppressive antiretroviral therapy

Artificial Nightlight Alters the Predator–Prey Dynamics of an Apex Carnivore

Artificial nightlight is increasingly recognized as an important environmental disturbance that influences the habitats and fitness of numerous species. However, its effects on wide‐ranging vertebrates and their interactions remain unclear. Light pollution has the potential to amplify land‐use change, and as such, answering the question of how this sensory stimulant affects behavior and habitat use of species valued for their ecological roles and economic impacts is critical for conservation and land‐use planning. Here, we combined satellite‐derived estimates of light pollution, with GPS‐data from cougars Puma concolor (n = 56), mule deer Odocoileus hemionus (n = 263) and locations of cougar‐killed deer (n = 1562 carcasses), to assess the effects of light exposure on mammal behavior and predator–prey relationships across wildland–urban gradients in the southwestern United States. Our results indicate that deer used the anthropogenic environments to access forage and were more active at night than their wildland conspecifics. Despite higher nightlight levels, cougars killed deer at the wildland–urban interface, but hunted them in the relatively darkest locations. Light had the greatest effect of all covariates on where cougars killed deer at the wildland–urban interface. Both species exhibited functional responses to light pollution at fine scales; individual cougars and deer with less light exposure increasingly avoided illuminated areas when exposed to greater radiance, whereas deer living in the wildland–urban interface selected elevated light levels. We conclude that integrating estimates of light pollution into ecological studies provides crucial insights into how the dynamic human footprint can alter animal behavior and ecosystem function across spatial scales

Artificial night light helps account for observer bias in citizen science monitoring of an expanding large mammal population

The integration of citizen scientists into ecological research is transforming how, where, and when data are collected, and expanding the potential scales of ecological studies. Citizen‐science projects can provide numerous benefits for participants while educating and connecting professionals with lay audiences, potentially increasing the acceptance of conservation and management actions. However, for all the benefits, collection of citizen‐science data is often biased towards areas that are easily accessible (e.g. developments and roadways), and thus data are usually affected by issues typical of opportunistic surveys (e.g. uneven sampling effort). These areas are usually illuminated by artificial light at night (ALAN), a dynamic sensory stimulus that alters the perceptual world for both humans and wildlife.Our goal was to test whether satellite‐based measures of ALAN could improve our understanding of the detection process of citizen‐scientist‐reported sightings of a large mammal.We collected observations of American black bears Ursus americanus (n = 1,315) outside their primary range in Minnesota, USA, as part of a study to gauge population expansion. Participants from the public provided sighting locations of bears on a website. We used an occupancy modelling framework to determine how well ALAN accounted for observer metrics compared to other commonly used metrics (e.g. housing density).Citizen scientists reported 17% of bear sightings were under artificially lit conditions and monthly ALAN estimates did the best job accounting for spatial bias in detection of all observations, based on AIC values and effect sizes (β^ = 0.81, 0.71–0.90 95% CI). Bear detection increased with elevated illuminance; relative abundance was positively associated with natural cover, proximity to primary bear range and lower road density. Although the highest counts of bear sightings occurred in the highly illuminated suburbs of the Minneapolis‐St. Paul metropolitan region, we estimated substantially higher bear abundance in another region with plentiful natural cover and low ALAN (up to ~375% increased predicted relative abundance) where observations were sparse.We demonstrate the importance of considering ALAN radiance when analysing citizen‐scientist‐collected data, and we highlight the ways that ALAN data provide a dynamic snapshot of human activity.Remotely‐sensed artificial nightlight improves inference in ecological studies using wildlife sightings collected by citizen scientists through better accounting of sampling bias.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166334/1/jane13338-sup-0001-Supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166334/2/jane13338.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166334/3/jane13338_am.pd

Data from: Moose movement rates are altered by wolf presence in two ecosystems

Predators directly impact prey populations through lethal encounters, but understanding non-lethal, indirect effects is also critical because foraging animals often face tradeoffs between predator avoidance and energy intake. Quantifying these indirect effects can be difficult even when it is possible to monitor individuals that regularly interact. Our goal was to understand how movement and resource selection o a predator (wolves; Canis lupus) influences the movement behavior of a prey species (moose; Alces alces). We tested whether moose avoided areas with high predicted wolf resource use in two study areas with differing prey compositions, whether avoidance patterns varied seasonally, and whether daily activity budgets of moose and wolves aligned temporally. We deployed GPS-collars on both species at two sites in northern Minnesota. We created seasonal resource-selection functions (RSF) for wolves and modeled the relationship between moose first-passage time (FPT), a method that discerns alterations in movement rates, and wolf RSF values. Larger FPT values suggest rest/foraging, whereas shorter FPT values indicate travel/fleeing. We found that the movements of moose and wolves peaked at similar times of day in both study areas. Moose FPTs were 45% lower in areas most selected for by wolves relative to those avoided. The relationship between wolf RSF and moose FPT was nonlinear and varied seasonally. Differences in FPT between low and high RSF values were greatest in winter (-82.1%) and spring (-57.6%) in northeastern Minnesota and similar for all seasons in the Voyageurs National Park ecosystem. In northeastern Minnesota, where moose comprise a larger percentage of wolf diet, the relationship between moose FPT and wolf RSF was more pronounced (ave. across seasons: -60.1%) than the Voyageurs National Park ecosystem (-30.4%). These findings highlight the role wolves can play in determining moose behavior, whereby moose spend less time in areas with higher predicted likelihood of wolf resource selection

Artificial Night Light and Anthropogenic Noise Interact to Influence Bird Abundance Over a Continental Scale

The extent of artificial night light and anthropogenic noise (i.e., “light” and “noise”) impacts is global and has the capacity to threaten species across diverse ecosystems. Existing research involving impacts of light or noise has primarily focused on noise or light alone and single species; however, these stimuli often co-occur and little is known about how co-exposure influences wildlife and if and why species may vary in their responses. Here, we had three aims: (1) to investigate species-specific responses to light, noise, and the interaction between the two using a spatially explicit approach to model changes in abundance of 140 prevalent bird species across North America, (2) to investigate responses to the interaction between light exposure and night length, and (3) to identify functional traits and habitat affiliations that explain variation in species-specific responses to these sensory stimuli with phylogenetically informed models. We found species that responded to noise exposure generally decreased in abundance, and the additional presence of light interacted synergistically with noise to exacerbate its negative effects. Moreover, the interaction revealed negative emergent responses for several species that only reacted when light and noise co-occurred. Additionally, an interaction between light and night length revealed 47 species increased in abundance with light exposure during longer nights. In addition to modifying behavior with optimal temperature and potential foraging opportunities, birds might be attracted to light, yet suffer inadvertent physiological consequences. The trait that most strongly related to avian response to light and noise was habitat affiliation. Specifically, species that occupy closed habitat were less tolerant of both sensory stressors compared to those that occupy open habitat. Further quantifying the contexts and intrinsic traits that explain how species respond to noise and light will be fundamental to understanding the ecological consequences of a world that is ever louder and brighter

Data from: American black bears perceive the risks of crossing roads

Roadways may negatively impact wildlife species through vehicular-related mortality and spatial displacement or obstruction. Here we investigated physiological responses, which provide insights into the animal’s perception of its environment. We deployed GPS-collars in combination with cardiac biologgers on American black bears (Ursus americanus; 18 bear-years) in areas with differing road densities across Minnesota, USA. We tested whether bears exhibited acute stress responses, as defined by significant increases in heart rate (HR), associated with road crossings. Maximum HR between successive telemetry locations were, on average, 13 bpm higher when bears were known to cross a road. They crossed a road, on average, once per day. Different demographic groups (males, females with and without cubs) responded similarly. We found stronger HR responses when crossing high-traffic roads relative to low-traffic in half of the bear-year combinations we sampled. Bears crossed high-traffic roads mainly at night, but low traffic roads during daylight. Bear HRs first became elevated when 73−183 meters away from roadways. Our findings suggest that roadways act as an acute stressor, but the magnitude of the stress response appears to be mild. Elevated HRs may reflect an increased vigilance and recognition of threat when preparing to cross a road. Bears’ recognition and alertness to human-related threats is adaptive for living in human-altered landscapes