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A relationship between winter weather and survival of northern ungulates has long been established, yet the possible roles of biological (e.g., nutritional status) and environmental (e.g., weather) conditions make it important to determine which potential limiting factors are most influential. Our objective was to examine the potential effects of individual (body mass and age) and extrinsic (winter severity and snowmelt conditions) factors on the magnitude and timing of mortality for adult (>2.5 years old) female white‐tailed deer (Odocoileus virginianus [Zimmerman, 1780]) during February–May in the Upper Peninsula of Michigan, USA. One hundred and fifty deer were captured and monitored during 2009–2015 in two areas with varying snowfall. February–May survival ranged from 0.24 to 0.89 (mean = 0.69) across years. Mortality risk increased 1.9% with each unit increase in cumulative winter severity index, decreased 8.2% with each cumulative snow‐free day, and decreased 4.3% with each kg increase in body mass. Age and weekly snow depth did not influence weekly deer survival. Predation, primarily from coyote (Canis latrans [Say, 1823]) and wolves (Canis lupus [L., 1758]), accounted for 78% of known‐cause mortalities. Our results suggest that cumulative winter severity, and possibly to a lesser degree deer condition entering winter, impacted deer winter survival. However, the timing of spring snowmelt appeared to be the most influential factor determining late‐winter mortality of deer in our study. This supports the hypothesis that nutrition and energetic demands from weather conditions are both important to northern ungulate winter ecology. Under this model, a delay of several weeks in the timing of spring snowmelt could exert a large influence on deer survival, resulting in a survival bottleneck. Northern ungulate population dynamics are correlated with winter weather patterns, and our goal was to evaluate when and why white‐tailed deer winter mortality occurs. We modeled weekly mortality risk of 150 adult female white‐tailed deer in Michigan in response to environmental and biological factors. The results suggested that body mass, severity of winter weather, and timing of spring snowmelt are influential on deer mortality, with the timing of snowmelt explaining the greatest amount of variation.

Although most prey have multiple predator species, few studies have quantified how prey respond to the temporal niches of multiple predators which pose different levels of danger. For example, intraspecific variation in diel activity allows white‐tailed deer (Odocoileus virginianus) to reduce fawn activity overlap with coyotes (Canis latrans) but finding safe times of day may be more difficult for fawns in a multi‐predator context. We hypothesized that within a multi‐predator system, deer would allocate antipredation behavior optimally based on combined mortality risk from multiple sources, which would vary depending on fawn presence. We measured cause‐specific mortality of 777 adult (>1‐year‐old) and juvenile (1–4‐month‐old) deer and used 300 remote cameras to estimate the activity of deer, humans, and predators including American black bears (Ursus americanus), bobcats (Lynx rufus), coyotes, and wolves (Canis lupus). Predation and vehicle collisions accounted for 5.3 times greater mortality in juveniles (16% mortality from bears, coyotes, bobcats, wolves, and vehicles) compared with adults (3% mortality from coyotes, wolves, and vehicles). Deer nursery groups (i.e., ≥1 fawn present) were more diurnal than adult deer without fawns, causing fawns to have 24–38% less overlap with carnivores and 39% greater overlap with humans. Supporting our hypothesis, deer nursery groups appeared to optimize diel activity to minimize combined mortality risk. Temporal refuge for fawns was likely the result of carnivores avoiding humans, simplifying diel risk of five species into a trade‐off between diurnal humans and nocturnal carnivores. Functional redundancy among multiple predators with shared behaviors may partially explain why white‐tailed deer fawn predation rates are often similar among single‐ and multi‐predator systems. We assessed how adult and juvenile white‐tailed deer balanced temporal overlap with humans and 4 species of carnivores, when the level of threat posed depended on deer age and the species encountered. Juvenile deer in particular exploited a \"safe\" temporal window in the morning and evening hours, which avoided peak human activity but capitalized on suppression of carnivores by moderate human activity. This behavior appeared optimal from radio‐collared fawn mortality, where vehicle collisions killed some fawns but were far outweighed by the combined predation of 4 carnivore species.

Growth of ungulate populations is typically most sensitive to survival of neonates, which in turn is influenced by maternal nutritional condition and trade-offs in resource selection and avoidance of predators. We assessed whether resource use, multi-predator risk, maternal nutritional effects, hiding cover, or interactions among these variables best explained variation in daily survival of free-ranging neonatal white-tailed deer (Odocoileus virginianus) during their post-partum period (14 May-31 Aug) in Michigan, USA. We used Cox proportional hazards mixed-effects models to assess survival related to covariates of resource use, composite predation risk of 4 mammalian predators, fawn body mass at birth, winter weather, and vegetation growth phenology. Predation, particularly from coyotes (Canis latrans), was the leading cause of mortality; however, an additive model of non-ideal resource use and maternal nutritional effects explained 71% of the variation in survival. This relationship suggested that dams selected areas where fawns had poor resources, while greater predation in these areas led to additive mortalities beyond those related to resource use alone. Also, maternal nutritional effects suggested that severe winters resulted in dams producing smaller fawns, which decreased their likelihood of survival. Fawn resource use appeared to reflect dam avoidance of lowland forests with poor forage and greater use by wolves (C. lupus), their primary predator. While this strategy led to greater fawn mortality, particularly by coyotes, it likely promoted the life-long reproductive success of dams because many reached late-age (>10 years old) and could have produced multiple generations of fawns. Studies often link resource selection and survival of ungulates, but our results suggested that multiple factors can mediate that relationship, including multi-predator risk. We emphasize the importance of identifying interactions among biological and environmental factors when assessing survival of ungulates.

Estimating spatial and temporal resource use and partitioning among carnivore species varies based on life history and is critical to understanding ecological relationships of sympatric carnivores and their prey. Temporal variation in food availability can have a substantial influence on distribution, foraging behavior, prey selection, and population dynamics of carnivores. We investigated shifts in space use of black bears (Ursus americanus), bobcats (Lynx rufus), coyotes (Canis latrans), and gray wolves (C. lupus) in response to seasonal availability of white‐tailed deer (Odocoileus virginianus) fawns in Michigan, USA, May–August 2009–2011. We used generalized linear mixed models to identify whether probabilistic fawn space use resulted in shifts in carnivore space use from deer pre‐parturition (PPP, 1 May–24 May) to fawn limited mobility (LMP, 25 May–30 June) and social mobility (SMP, 1 July–31 August) periods. We developed a rule‐based algorithm to identify “clusters” of carnivore GPS locations and investigated carnivore clusters to identify fawn predation sites. Carnivores shifted space use among periods, but responses varied among species regarding fawn space use. Black bears selected against areas with greater fawn use during LMP and selected areas with greater fawn use during SMP. We suggest black bear space use was unrelated to fawn space use and reflected availability of vegetative forage. Bobcats selected areas with greater fawn use during LMP and SMP. Coyotes were indifferent to areas where fawns occurred during LMP but selected against areas with greater fawn use during SMP, likely foraging on alternative prey. Coyotes were spatially constrained by wolves, selecting against areas with greater wolf use during LMP and SMP. Wolves selected against areas with greater fawn use during LMP and SMP and selected areas near habitat edges and areas containing livestock carcasses. Carnivore responses to fawn white‐tailed deer distribution and vulnerability were congruent with life history strategies, resulting in space use shifts in response to temporarily abundant resources. Carnivores did not overall rely predominantly on fawns, likely shifting their space use to maximize intake of other seasonal resources. These events provide additional insight into life history strategies among co‐occurring species and dynamics of multi‐species predator–prey systems.

Female ungulate reproductive success is dependent on the survival of their young, and affected by maternal resource selection, predator avoidance, and nutritional condition. However, potential hierarchical effects of these factors on reproductive success are largely unknown, especially in multi-predator landscapes. We expanded on previous research of neonatal white-tailed deer (Odocoileus virginianus) daily survival within home ranges to assess if resource use, integrated risk of 4 mammalian predators, maternal nutrition, winter severity, hiding cover, or interactions among these variables best explained landscape scale variation in daily or seasonal survival during the post-partum period. We hypothesized that reproductive success would be limited greater by predation risk at coarser spatiotemporal scales, but habitat use at finer scales. An additive model of daily non-ideal resource use and maternal nutrition explained the most (69%) variation in survival; though 65% of this variation was related to maternal nutrition. Strong support of maternal nutrition across spatiotemporal scales did not fully support our hypothesis, but suggested reproductive success was related to dam behaviors directed at increasing nutritional condition. These behaviors were especially important following severe winters, when dams produced smaller fawns with less probability of survival. To increase nutritional condition and decrease wolf (Canis lupus) predation risk, dams appeared to place fawns in isolated deciduous forest patches near roads. However, this resource selection represented non-ideal resources for fawns, which had greater predation risk that led to additive mortalities beyond those related to resources alone. Although the reproductive strategy of dams resulted in greater predation of fawns from alternative predators, it likely improved the life-long reproductive success of dams, as many were late-aged (>10 years old) and could have produced multiple litters of fawns. Our study emphasizes understanding the scale-dependent hierarchy of factors limiting reproductive success is essential to providing reliable knowledge for ungulate management.

The parallel niche release hypothesis (PNR) indicates that reduced competition with dominant competitors results in greater density and niche breadth of subordinate competitors and which may support an adaptive advantage. We assessed support for the PNR by evaluating relationships between variation in niche breadth and intra‐ and interspecific density (an index of competition) of wolves (Canis lupus) coyotes (C. latrans), and bobcats (Lynx rufus). We estimated population density (wolf track surveys, coyote howl surveys, and bobcat hair snare surveys) and variability in space use (50% core autocorrelated kernel density home range estimators), temporal activity (hourly and overnight speed), and dietary (isotopic δ13C and δ15N) niche breadth of each species across three areas of varying wolf density in the Upper Peninsula of Michigan, USA, 2010–2019. Densities of wolves and coyotes were inversely related, and increased variability in space use, temporal activity, and dietary niche breadth of coyotes was associated with increased coyote density and decreased wolf density supporting the PNR. Variability in space use and temporal activity of wolves and dietary niche breadth of bobcats also increased with increased intraspecific density supporting the PNR. Through demonstrating decreased competition between wolves and coyotes and increased coyote niche breadth and density, our study provides multidimensional support for the PNR. Knowledge of the relationship between niche breadth and population density can inform our understanding of the role of competition in shaping the realized niche of species. Locations of study areas (ESC, CF, and SM) used to assess patterns in niche variability of gray wolves (Canis lupus), coyotes (C. latrans), and bobcats (Lynx rufus), Upper Peninsula of Michigan, USA, 2010–2019.

Currently 1677 species are listed under the U.S. Endangered Species Act (ESA), yet only a small percentage have been delisted due to recovery. In the fall of 2021, the U.S. Fish and Wildlife Service proposed delisting 23 species due to extinction. Tracking changes in species ‘recovery status over time is critical to understanding species’ statuses, informing adaptive management strategies, and assessing the performance of the ESA to prevent further species loss. In this paper, we describe four key obstacles in tracking species recovery status under the ESA. First, ESA 5‐year reviews lack a standardized format and clear documentation. Second, despite having been listed for decades, many species still suffer major data gaps in their biology and threats, rendering it difficult if not impossible to track progress towards recovery. Third, many species have continued declining after listing, yet given the above (1 & 2), understanding potential causes (proximate and/or ultimate) can be difficult. Fourth, many species currently have no path to clear recovery, which represents a potential failing of the process. We conclude with a discussion of potential policy responses that could be addressed to enhance the efficacy of the ESA. The U.S. Endangered Species Act protects about 1700 species, but no concise, standardized metrics exist for assessing changes in species recovery status. We helped develop and test novel metrics that track changes in recovery status using six components. Our testing also revealed several key challenges to species recovery.

Radiotelemetry and unmarked occupancy modeling have been used to estimate animal population growth, but have not been compared for ungulates. We compared white-tailed deer (Odocoileus virginianus) population growth estimates from radiomarked individuals and occupancy modeling of unmarked individuals and evaluated advantages and disadvantages of each method. Estimates of population growth were obtained using remote camera (N = 54/year) detection/non-detection occupancy surveys of unmarked deer and from survival and recruitment data of radiomarked adult females (N = 87) and neonate fawns (N = 127) in a predominantly forested region of the Upper Peninsula of Michigan, USA, 2009–2011. We hypothesized that occupancy models and radiotelemetry data would have similar population growth trends because both methods sampled the same temporally closed population. Percent changes in camera trap data generally reflected finite population growth (λ) of radiomarked deer which increased (λ = 1.10 ± 0.01) from 2009 to 2010, but decreased (λ = 0.87 ± 0.02) from 2010 to 2011. Also, unmarked adult female abundance and fawn:adult female ratios generally reflected trends in radiomarked deer survival and recruitment. Royle–Nichols occupancy model abundance estimates had wide confidence intervals, which may preclude using this method from accurately estimating deer population growth. Radiotelemetry provided more precise population growth estimates, while allowing collection of vital rates and location data. However, the Royle–Nichols occupancy model may be preferred to radiotelemetry because it reflected yearly variation in population growth with reduced labor and no invasive marking. Researchers should consider the objectives and logistics of their study when choosing a specific method.

American black bears (Ursus americanus) are opportunistic omnivores and can be proficient predators of neonate ungulates, but predation of adult ungulates is rare. In November 2009 we investigated a probable black bear predation of a radiocollared, adult (7.5 years old) female white-tailed deer (Odocoileus virginianus) in a densely vegetated, lowland conifer forest in the Upper Peninsula of Michigan, USA. The deer carcass was 80% buried with puncture wounds and lacerations on the back and hindquarters. The hide was everted, the intestines and stomach partially eaten, the mammary glands were punctured, and the skeleton remained articulated. All woody vegetation <5.0 cm diameter within 5 m of the carcass was trampled and contained bear and deer hair. We found no evidence of other carnivores. Based on the condition of the carcass, physical evidence at the site, and the similarity of this predation to reported black bear predations, we suggest this deer was attacked and killed by a black bear.

The presence of bovine tuberculosis (TB) in cattle can negatively impact a state's economy and cattle industry. In Michigan, USA, wild white-tailed deer (Odocoileus virginianus) are a reservoir for reinfecting cattle herds. Although direct TB transmission between deer and cattle is rare, infected deer may contaminate cattle feed. To mitigate this risk, we designed and evaluated a deer-resistant cattle feeder (DRCF) device for deterring deer from feeders. The device delivered negative stimuli to condition deer to avoid cattle feeders. We tested the device by conducting a comparative change experiment at a high-density captive white-tailed deer operation in northeastern lower Michigan using pretreatment and treatment periods and random allocation of DRCF protection to 3 of 6 feeders during the treatment period. We used animal-activated cameras to collect data on deer use of feeders. Deer use was similar at protected and unprotected feeders during the pretreatment period but was lower at protected feeders during the treatment period. Deer-resistant cattle feeders were 100% effective during the first 2 treatment weeks, 94% during the first 5 weeks, but effectiveness then dropped to 61% during the final week. Excluding problems associated with low battery power and infrared sensors, DRCFs were 99% effective at deterring deer. Our results suggest that DRCFs can effectively limit deer use of cattle feed, potentially with minimal impact on feeding behavior of cattle, thus reducing potential transmission of bovine TB through contaminated feed. By employing DRCFs in bovine TB endemic areas, especially at times that deer are food stressed, agencies and producers can practically and economically reduce the potential for bovine TB to be transmitted from deer to cattle.