Implications of chronic wasting disease,cougar predation,and reduced recruitment for elk management

Emerging diseases and expanding carnivore populations may have profound implications for ungulate harvest management and population regulation. To better understand effects of chronic wasting disease (CWD) and cougar (Puma concolor) predation, we studied mortality and recruitment of elk (Cervus elaphus) at Wind Cave National Park (WICA) during 2005–2009. We marked 202 elk (83 subadult M and 119 subadult and ad F) with Global Positioning System (GPS) collars, observed 28 deaths during 74,220 days of monitoring, and investigated 42 additional deaths of unmarked elk found dead. Survival rates were similar for males and females and averaged 0.863 (SE = 0.025) annually. Leading causes of mortality included hunting (0.065, SE = 0.019), CWD (0.034, SE = 0.012), and cougar predation (0.029, SE = 0.012). Marked elk killed by hunters and cougars typically were in good physical condition and not infected with CWD. Effects of mortality on population growth were exacerbated by low rates of pregnancy (subadults = 9.5%, SE = 6.6%; ad = 76.9%, SE = 4.2%) and perinatal survival (0.49, SE = 0.085 from 1 Feb to 1 Sep). Chronic wasting disease, increased predation, and reduced recruitment reduced the rate of increase for elk at WICA to approximately λ = 1.00 (SE = 0.027) during the past decade. Lower rates of increase are mitigating effects of elk on park vegetation, other wildlife, and neighboring lands and will facilitate population control, but may reduce opportunities for elk hunting outside the park. © 2011 The Wildlife Society     

How Size and Condition Influence Survival and Cause-Specific Mortality of Female Elk

The size of animal populations fluctuates with number of births, rate of immigration, rate of emigration, and number of deaths. For many ungulate populations, adult female survival is the most important factor influencing population growth. Therefore, increased understanding of survival and causes of mortality for adult females is fundamental for conservation and management. The objectives of our study were to quantify survival rates of female elk (Cervus canadensis) and determine cause-specific mortality. We predicted that hunter harvest would be the leading cause of mortality. Further, we predicted that hunters would harvest animals that were in prime age (2–9 yr) and in better condition than elk predated by mountain lions (Puma concolor). From 2015 to 2017, we captured 376 female elk in central Utah, USA. We assessed body size and condition of captured elk, fitted each animal with a global positioning system-collar, and determined cause of death when we received mortality signals. We estimated survival using Kaplan-Meier estimates and Cox proportional hazard models within an Akaike's Information Criterion model selection framework to identify covariates that influenced survival. We analyzed differences in size and condition measurements between harvested elk and predated elk using analysis of variance tests. Our best model indicated consistent survival across years; mean survival was 78.3 ± 3.5% (SE) including hunter harvest and 95.5 ± 1.7% without hunter harvest. In decreasing order of importance, elk mortality occurred from hunter harvest (21.2%), mountain lion predation (3.7%), depredation removal (0.5%), automobile collision (0.3%), disease (0.3%), complications during calving (0.3%), and those characterized as undetermined (1.3%). Neck circumference and body length were negatively associated with survival, suggesting that larger animals in good condition had lower survival as a result of hunter harvest. Individuals that died because of cougar predation were smaller and had less loin muscle than the average animal. Hunters removed large, healthy, prime-aged females, individuals that likely have a greater effect on population growth than elk lost to other predators. If the proportion of larger, healthy females in the population begins to decline, hunting practices may require adjustment because hunters may be removing individuals with the greatest reproductive value. © 2021 The Wildlife Society.     

Multiple anthropogenic interventions drive puma survival following wolf recovery in the Greater Yellowstone Ecosystem

Humans are primary drivers of declining abundances and extirpation of large carnivores worldwide. Management interventions to restore biodiversity patterns, however, include carnivore reintroductions, despite the many unresolved ecological consequences associated with such efforts. Using multistate capture–mark–recapture models, we explored age‐specific survival and cause‐specific mortality rates for 134 pumas (Puma concolor) monitored in the Greater Yellowstone Ecosystem during gray wolf (Canis lupus) recovery. We identified two top models explaining differences in puma survivorship, and our results suggested three management interventions (unsustainable puma hunting, reduction in a primary prey, and reintroduction of a dominant competitor) have unintentionally impacted puma survival. Specifically, puma survival across age classes was lower in the 6‐month hunting season than the 6‐month nonhunting season; human‐caused mortality rates for juveniles and adults, and predation rates on puma kittens, were higher in the hunting season. Predation on puma kittens, and starvation rates for all pumas, also increased as managers reduced elk (Cervus elaphus) abundance in the system, highlighting direct and indirect effects of competition between recovering wolves and pumas over prey. Our results emphasize the importance of understanding the synergistic effects of existing management strategies and the recovery of large, dominant carnivores to effectively conserve subordinate, hunted carnivores in human‐dominated landscapes.     

Bark Beetle-Affected Forests Provide Elk Only a Marginal Refuge from Hunters

For nearly 2 decades, the forests of the Rocky Mountains in the United States experienced a bark-beetle (Dendoctronus ponderosae) epidemic. The number of dead and falling trees from this epidemic likely will affect how elk (Cervus canadensis) and hunters use the forest and their interactions. Downed trees potentially create a component of refuge habitat that could affect the effectiveness of hunting to regulate abundance of growing elk populations. We evaluated how forests affected by bark beetles in south-central Wyoming, USA, influenced resource selection of 50 female elk and 374 hunters in 2012–2016, and interactions between elk and hunters. We employed global positioning system (GPS) technology on elk and hunters, and developed a satellite-derived land classification specifically depicting beetle-affected forests. We tested the predictions that elk would increase use of beetle-killed areas from summer to the hunting season, and that hunters would avoid beetle-killed areas regardless of elk use. Elk increased use of beetle-killed areas during hunting seasons as did hunters during the archery season; however, during the rifle season, hunters avoided beetle-killed areas. Nevertheless, during the rifle season, areas of beetle-kill with a high probability of elk occurrence dampened the aversion hunters had towards beetle-killed areas. Therefore, in contrast to our expectations, forests that have been altered by the bark-beetle epidemic may only function marginally as a refuge for elk. Our study area was at the beginning of the tree-fall phase (i.e., ~3–7 yr after peak infestation) of the bark-beetle epidemic; thus, future research efforts should focus on how a continued increase in downed trees will influence interactions between elk and hunters. At current levels of tree fall, however, beetle-kill should not limit the ability of managers to regulate elk herds through harvest. © 2020 The Wildlife Society.     

Seasonal variability in survivorship of a cooperatively breeding tropical passerine

Survival of tropical passerines is thought to be higher than those in northern temperate regions, but relatively few tropical studies have addressed this issue, particularly in tropical Asia. We examined factors that may have influenced the survival rate of a cooperatively breeding bird, the puff-throated bulbul (Alophoixus pallidus), in an evergreen forest in northeastern Thailand. These factors included year, season (breeding and non-breeding), sex, and presence of helper(s) in a family group. We present evidence of breeding season-dependent survival in a tropical passerine using an information theoretic approach based on both mark-recapture and resighting data collected during 6 years of study. Based on colour-banded adults the annual survival rate did not vary significantly among years (average = 0.85 ± 0.02 SE). The mean lifespan (MLS) for the population was 6.22 ± 4.38 SE years. Survivorship was lower during the breeding season (0.89 ± 0.02 SE) than during the non-breeding season (0.96 ± 0.02 SE). The MLS of males and females was 6.70 ± 7.73 SE and 5.87 ± 4.88 SE years, respectively. The annual survival rate we observed was high compared to the estimates of other tropical and temperate passerines, possibly due to the relatively stable climatic conditions in tropical latitudes and puff-throated bulbuls being generalists that exploit a wide range of food resources both in space and time.     

Elk survival and mortality causes in the Blue Mountains of Washington

We studied survival of elk (Cervus elaphus) ≥1 yr old and quantified mortality sources in the Blue Mountains of Washington, 2003–2006, following a period of extensive poaching. The population was managed under a spike-only general hunting season, with limited permits for larger males and for females. We radiomarked 190 elk (82 males and 39 females >1 yr old and 65 males 11 months old), most with rumen transmitters and neck radiocollars; 60 elk only received rumen transmitters. We estimated annual survival using known fate models and explored survival differences among sex and age classes and in 2 potentially different vulnerability zones for males. We found little support for differences in survival between younger (2–3-yr old) and older (≥4-yr old) branch-antlered males or zone differences for yearling males. A model with zone differences for branch-antlered males was the second ranked model and accounted for 14% of the available model weight. From the best-supported models, we estimated annual survival for yearling males at 0.41 (95% CI: 0.29–0.53). We estimated pooled adult female survival at 0.80 (95% CI: 0.64–0.93); when an age-class effect was included, point estimates were higher for prime-aged females (2–11 yr: S = 0.81 [0.70–0.88]) than for older females (≥12 yr: S = 0.72 [0.56–0.83]), but confidence intervals broadly overlapped. Only 1 of 7 models with a female age effect on survival was among the competitive models. For branch-antlered males, survival ranged 0.80–0.85, depending on whether zone variation was modeled. We recorded 78 deaths of radiomarked elk. Human-caused deaths (n = 55) predominated among causes and most were of yearling males killed during state-sanctioned hunts (n = 28). Most subadult male deaths were from tribal hunting (n = 5), and most mature males died from natural causes (n = 6) and tribal hunting (n = 5). We detected few illegal kills (n = 4). Our results suggest that increased enforcement effectively reduced poaching, that unreported tribal harvest was not a trivial source of mortality, and that spike-only general seasons were effective in recruiting branch-antlered males. © 2011 The Wildlife Society.     

Targeting hunter distribution based on host resource selection and kill sites to manage disease risk

Endemic and emerging diseases are rarely uniform in their spatial distribution or prevalence among cohorts of wildlife. Spatial models that quantify risk‐driven differences in resource selection and hunter mortality of animals at fine spatial scales can assist disease management by identifying high‐risk areas and individuals. We used resource selection functions (RSFs) and selection ratios (SRs) to quantify sex‐ and age‐specific resource selection patterns of collared (n = 67) and hunter‐killed (n = 796) nonmigratory elk (Cervus canadensis manitobensis) during the hunting season between 2002 and 2012, in southwestern Manitoba, Canada. Distance to protected area was the most important covariate influencing resource selection and hunter‐kill sites of elk (AICw = 1.00). Collared adult males (which are most likely to be infected with bovine tuberculosis (Mycobacterium bovis) and chronic wasting disease) rarely selected for sites outside of parks during the hunting season in contrast to adult females and juvenile males. The RSFs showed selection by adult females and juvenile males to be negatively associated with landscape‐level forest cover, high road density, and water cover, whereas hunter‐kill sites of these cohorts were positively associated with landscape‐level forest cover and increasing distance to streams and negatively associated with high road density. Local‐level forest was positively associated with collared animal locations and hunter‐kill sites; however, selection was stronger for collared juvenile males and hunter‐killed adult females. In instances where disease infects a metapopulation and eradication is infeasible, a principle goal of management is to limit the spread of disease among infected animals. We map high‐risk areas that are regularly used by potentially infectious hosts but currently underrepresented in the distribution of kill sites. We present a novel application of widely available data to target hunter distribution based on host resource selection and kill sites as a promising tool for applying selective hunting to the management of transmissible diseases in a game species.     

A review of vital rates and cause‐specific mortality of elk Cervus elaphus populations in eastern North America

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Effects of wolf pack size and winter conditions on elk mortality

Elk (Cervus canadensis) are high-profile game animals for many states in the western United States, yet over the past several decades some populations have experienced a persistent and broad-scale decline in recruitment. Over this same period, gray wolves (Canis lupus) have become an integral component of many western landscapes and agencies are increasingly challenged to maximize hunting opportunities of ungulates via predator management while simultaneously ensuring wolf conservation. To better understand the implications of predator management on elk populations, we monitored survival of 1,244 adult female elk and 806 6-month-old calves from 29 populations distributed throughout Idaho, USA, from 2004 to 2016. We developed predictive models of mortality that related mortality risk to wolf pack size, winter conditions, and individual-level characteristics. Annual mortality rates (excluding harvest) for adult females and calves were 0.09 and 0.40, respectively. Calf mortality was predicted best with a model that included additive effects of chest girth at time of capture, mean size of surrounding wolf packs, and snow depth. Adult female mortality was predicted best with a model that included female age, mean size of surrounding wolf packs, and snow depth. Based on a sensitivity analysis, chest girth had the largest effect on risk of mortality for calves followed by pack size and snow depth. Other than the effect of senescence in the oldest (>15 yr) individuals, pack size and snow depth had the largest effect on risk of mortality for adult females. We estimated cause-specific mortality and predation was the dominant cause of known-fate mortalities for adult females (35% mountain lion [Puma concolor] and 32% wolf) and calves (45% mountain lion and 28% wolf), whereas malnutrition accounted for 9% and 10% of adult female and calf mortalities, respectively. Wolves preferentially selected smaller calves and older adult females, whereas mountain lions showed little preference for calf size or age class of adult females. Our study indicates managers can increase elk survival by reducing wolf pack sizes on surrounding winter ranges, especially in areas where, or during years when, snow is deep. Additionally, managers interested in improving over-winter calf survival can implement actions to increase the size of calves entering winter by increasing the nutritional quality of summer and early fall forage resources. Although our study was prompted by management questions related to wolves, mountain lions killed more elk than wolves and differences in selection of individual elk indicate mountain lions may have comparably more of an effect on elk population dynamics. Although we were unable to relate changes in mountain lion populations to elk survival in our study, future research should seek a better understanding of multi-predator systems, including how management of one predator affect others and ultimately how these interactions affect elk survival. © 2019 The Wildlife Society     

Carryover effects and climatic conditions influence the postfledging survival of greater sage‐grouse

Prebreeding survival is an important life history component that affects both parental fitness and population persistence. In birds, prebreeding can be separated into pre‐ and postfledging periods; carryover effects from the prefledging period may influence postfledging survival. We investigated effects of body condition at fledging, and climatic variation, on postfledging survival of radio‐marked greater sage‐grouse (Centrocercus urophasianus) in the Great Basin Desert of the western United States. We hypothesized that body condition would influence postfledging survival as a carryover effect from the prefledging period, and we predicted that climatic variation may mediate this carryover effect or, alternatively, would act directly on survival during the postfledging period. Individual body condition had a strong positive effect on postfledging survival of juvenile females, suggesting carryover effects from the prefledging period. Females in the upper 25th percentile of body condition scores had a postfledging survival probability more than twice that (Φ = 0.51 ± 0.06 SE) of females in the bottom 25th percentile (Φ = 0.21 ± 0.05 SE). A similar effect could not be detected for males. We also found evidence for temperature and precipitation effects on monthly survival rates of both sexes. After controlling for site‐level variation, postfledging survival was nearly twice as great following the coolest and wettest growing season (Φ = 0.77 ± 0.05 SE) compared with the hottest and driest growing season (Φ = 0.39 ± 0.05 SE). We found no relationships between individual body condition and temperature or precipitation, suggesting that carryover effects operated independently of background climatic variation. The temperature and precipitation effects we observed likely produced a direct effect on mortality risk during the postfledging period. Conservation actions that focus on improving prefledging habitat for sage‐grouse may have indirect benefits to survival during postfledging, due to carryover effects between the two life phases.     

Survival and cause-specific mortality rates of female sika deer in eastern Hokkaido, Japan

Survival and cause-specific mortality rates of female sika deer (Cervus nippon) were studied using radio telemetry in eastern Hokkaido, Japan. We captured and radio-collared 18 female deer, and monitored their survival from April 1993 to May 1996. Estimated annual survival rate for adult females was 0.779 (95% confidence interval was 0.609–0.997). The harvest mortality rate of adult females was higher than the natural mortality rate. Experimental female hunting during 1994–1996 contributed to an increase in the mortality rate for females and was useful in the control of the sika deer population.     

A human-induced landscape of fear influences foraging behavior of brown bears

Animals adapt their foraging behavior to variations in food availability and predation risk. In Sweden, brown bears (Ursus arctos) depend on a nearly continuous intake of berries, especially bilberries (Vaccinium myrtillus) during late summer and early autumn to fatten up prior to hibernation. This overlaps with the bear hunting season that starts on 21 August. Bilberry occurrence varies across space, as does human-induced mortality risk. Here, we hypothesize that brown bears select for areas with a high probability of bilberry occurrence across a boreal forest ecosystem in Sweden (H1), and that human-induced mortality risk reduces bear selection for bilberries (H2). In addition, we hypothesized that bears that survived the hunting season avoided bilberry areas associated with high risk, whereas bears that were later killed selected more strongly for berries and less against risk prior to the hunting season (H3). To evaluate our hypotheses, we used resource selection functions to contrast bear GPS relocation data (N = 35, 2012–2015) and random positions within the bearś home range with generalized linear mixed effect models against two focal variables: a map predicting bilberry occurrence and a map predicting human-induced mortality risk. We found that bears selected for areas with a high probability of bilberry occurrence (supporting H1), but avoided these areas if they were associated with and high risk of hunting mortality (supporting H2). The killed and surviving bears did not differ in their selection for bilberries, but they did differ in their selection against risk (partially supporting H3). Surviving bears strongly avoided high risk areas, whereas killed bears responded less to risk and selected for high-risk areas with a low probability of bilberry occurrence. This suggests that killed bears selected for other food sources than berries in high risk areas, which exposed them to human hunters. We conclude that bears respond to a landscape of fear during the berry season and that different foraging strategies may have a direct impact on individual mortality during the hunting season.     

Mortality of Rocky Mountain elk in Michigan due to meningeal worm

Mortality from cerebrospinal parelaphostrongylosis caused by the meningeal worm (Parelaphostrongylus tenuis) has been hypothesized to limit elk (Cervus elaphus nelsoni) populations in areas where elk are conspecific with white-tailed deer (Odocoileus virginianus). Elk were reintroduced into Michigan (USA) in the early 1900s and subsequently greatly increased population size and distribution despite sympatric high-density (>or=12/km2) white-tailed deer populations. We monitored 100 radio-collared elk of all age and sex classes from 1981-94, during which time we documented 76 mortalities. Meningeal worm was a minor mortality factor for elk in Michigan and accounted for only 3% of mortalities, fewer than legal harvest (58%), illegal kills (22%), other diseases (7%), and malnutrition (4%). Across years, annual cause-specific mortality rates due to cerebrospinal parelaphostrongylosis were 0.033 (SE=0.006), 0.029 (SE=0.005), 0.000 (SE=0.000), and 0.000 (SE=0.000) for calves, 1-yr-old, 2-yr-old, and >or=3-yr-old, respectively. The overall population-level mortality rate due to cerebrospinal parelaphostrongylosis was 0.009 (SE=0.001). Thus, meningeal worm had little impact on elk in Michigan during our study despite greater than normal precipitation (favoring gastropods) and record (>or=14 km2) deer densities. Further, elk in Michigan have shown sustained population rates-of-increase of >or=18%/yr and among the highest levels of juvenile production and survival recorded for elk in North America, indicating that elk can persist in areas with meningeal worm at high levels of population productivity. It is likely that local ecologic characteristics among elk, white-tailed deer, and gastropods, and degree of exposure, age of elk, individual and population experience with meningeal worm, overall population vigor, and moisture determine the effects of meningeal worm on elk populations.     

Human selection of elk behavioural traits in a landscape of fear

Among agents of selection that shape phenotypic traits in animals, humans can cause more rapid changes than many natural factors. Studies have focused on human selection of morphological traits, but little is known about human selection of behavioural traits. By monitoring elk (Cervus elaphus) with satellite telemetry, we tested whether individuals harvested by hunters adopted less favourable behaviours than elk that survived the hunting season. Among 45 2-year-old males, harvested elk showed bolder behaviour, including higher movement rate and increased use of open areas, compared with surviving elk that showed less conspicuous behaviour. Personality clearly drove this pattern, given that inter-individual differences in movement rate were present before the onset of the hunting season. Elk that were harvested further increased their movement rate when the probability of encountering hunters was high (close to roads, flatter terrain, during the weekend), while elk that survived decreased movements and showed avoidance of open areas. Among 77 females (2–19 y.o.), personality traits were less evident and likely confounded by learning because females decreased their movement rate with increasing age. As with males, hunters typically harvested females with bold behavioural traits. Among less-experienced elk (2–9 y.o.), females that moved faster were harvested, while elk that moved slower and avoided open areas survived. Interestingly, movement rate decreased as age increased in those females that survived, but not in those that were eventually harvested. The latter clearly showed lower plasticity and adaptability to the local environment. All females older than 9 y.o. moved more slowly, avoided open areas and survived. Selection on behavioural traits is an important but often-ignored consequence of human exploitation of wild animals. Human hunting could evoke exploitation-induced evolutionary change, which, in turn, might oppose adaptive responses to natural and sexual selection.     

Survival and Cause-Specific Mortality of Corsac and Red Foxes in Mongolia

ABSTRACT The corsac fox (Vulpes corsac) and red fox (Vulpes vulpes) range widely across northern and central Asia and may be declining in many regions due to overhunting and other causes. However, details of the fundamental causes of survival and mortality of both species remain largely unquantified, but may be crucial for understanding interspecific relationships and developing effective conservation actions. We studied a radiomarked population of sympatric corsac and red foxes in central Mongolia to quantify survival and cause-specific mortality rates from April 2005 to April 2007. Survival probability was 0.34 for corsacs (n = 18) and 0.46 for red foxes (n = 17) and did not vary by year within or between each species. Among both foxes, mortality occurred mainly from hunting by humans, but also from predation by larger canids and unknown causes. Our results suggest that illegal human hunting represents the principal source of mortality for both species and that a recently initiated ranger patrol program in the study area did not affect fox survival. As such, more stringent protective measures will likely be necessary to halt declines of both foxes. Our results also suggest that interference competition occurs between species as red foxes killed but did not consume corsacs. Our results will be useful for developing science-based management strategies to protect foxes in Mongolia, and in understanding the competitive relationships between them.     

Changes in Elk Resource Selection and Distributions Associated With a Late-Season Elk Hunt

ABSTRACT Changes in resource selection associated with human predation risk may alter elk distributions and availability for harvest. We used Global Positioning System data collected from telemetered female elk (Cervus elaphus) to evaluate effects of refuges (areas where hunting was prohibited), spatial variation in hunting risk, and landscape attributes on resource selection within an established Greater Yellowstone Area, USA, winter range. We also evaluated elk distributions during and outside of a late-season hunting period. Refuge areas and landscape attributes such as habitat type and snow water equivalents (SWE) affected resource selection. Elk selection for flat grasslands increased as SWE increased, likely because these areas were windswept, leaving grasses exposed for foraging. Elk distributions differed during hunting and no-hunting periods. During the hunting period, elk shifted to privately owned refuge areas and the estimated odds of elk occupying refuge areas more than doubled. Risk-driven changes in resource selection resulted in reduced availability of elk for harvest. Elk selection for areas where hunting is prohibited presents a challenge for resource managers that use hunting as a tool for managing populations and influences grazing patterns on private ranchlands.     

Behavioral responses of male elk to hunting risk

Prey respond to predation risk with a range of behavioral tactics that can vary based on space use and hunting mode of the predator. Unlike other predators, human hunters are often more spatially and temporally restricted, which creates a period of short-duration, high-intensity predation risk for prey. Consequently, identifying the roles different hunting modes (i.e., archery and rifle), hunts for targeted and non-targeted species, and landscape features play in altering spatial and temporal responses of prey to predation risk by humans is important for effective management of harvested populations. From 2009 to 2016, we used a large-scale experiment including 50 animal-years of location data from 38 unique male elk (Cervus canadensis) to quantify changes in movement and resource selection in response to hunters during 3 separate 5-day controlled hunts for antlered males (elk archery, deer [Odocoileus spp.] rifle, and elk rifle) at the Starkey Experimental Forest and Range in northeast Oregon, USA. We evaluated competing hypotheses regarding elk responses to varying levels of prey risk posed by the different hunt types. We predicted that the strength of elk behavioral responses would increase with perceived hunter lethality (i.e., weak response to elk archery but similar response to elk and deer rifle hunts) and that prey response would be closely associated with hunter activity within the diel cycle (greater during diurnal than nocturnal hours) and across hunting seasons. Elk responses were strongest during diurnal hours when hunters were active on the landscape and were generally more pronounced during both rifle hunts than during the archery hunt (supporting our perceived lethality hypothesis). Male elk avoided open roads across all periods except during nocturnal hours of the breeding season and alternated between avoidance of areas with high canopy cover during nocturnal hours and selection during diurnal hours. In combination these patterns led to distinct distributional changes of male elk from pre-hunt to hunt periods. Patterns of male elk selection highlight the importance of managing for heterogeneous landscapes to meet a variety of habitat, harvest, hunter satisfaction, and escapement objectives.     

The efficacy of highway wildlife collision mitigation in preventing elk mortality in central Ontario

In the Burwash area of north-central Ontario, Canada, expansion of the Trans-Canada highway from 2 to 4 lanes was accompanied by installation of a range of wildlife collision-mitigation infrastructure (e.g., exclusion fencing, underpasses). To assess the overall effectiveness of these measures, we monitored the spatial distribution and mortality rates of elk (Cervus canadensis) prior to and following highway expansion, distinguished by season (winter, snowfree) and corridor-type (highway, railway). We measured herd-level risk by the proportion of positions falling within 200-m railway and highway buffer zones using Bayesian methods. Spatial analysis confirmed that there was a distinct northward shift in the winter distribution of elk following construction, situating the elk past the north end of the exclusion fence. This increased the herd's exposure to highway traffic by 3.6 times (proportion of points before = 0.0041 ± 0.002 [SE], after = 0.0147 ± 0.003, P = 0.005), and resulted in a more than 2-fold increase in elk road mortality from 0.6 elk/yr/20 km during 8 years prior to implementation to 1.5 elk/yr/20 km during 8 years after implementation. Exposure to railways remained unchanged and consistently higher than highway exposure regardless of season (e.g., post-mitigation, winter proportion of points = 0.0453 ± 0.005), matched by consistently high mortality counts (proportion of points before = 6.4 elk/yr/20 km, after = 6.6 elk/yr/20 km). Our results demonstrate that while wildlife-vehicle collision mitigation is generally beneficial to wildlife and humans, failure to account for the local characteristics of wildlife populations can lead to suboptimal mitigation designs that reduce their effectiveness and lead to unintended wildlife impacts.     

Influence of interspecific competition on mule deer birthing and rearing site selection

Ungulates often alter behavior and space use in response to interspecific competition. Despite observable changes in behavior caused by competitive interactions, research describing the effects of competition on survival or growth is lacking. We used spatial modeling to determine if habitat use by female mule deer (Odocoileus hemionus) was affected by other ungulate species prior to, during, and after parturition. We conducted our study in the Book Cliffs region of eastern Utah, USA, during 2019 and 2020. We used resource selection function (RSF) analysis to model space use of 4 ungulate species that potentially competed with mule deer: bison (Bos bison), cattle, elk (Cervus canadensis), and feral horses. We incorporated RSF models for competing species into a random forest analysis to determine if space use by mule deer was influenced by these other ungulate species. We used survival and growth data from neonate mule deer to directly assess potential negative effects of other ungulates. Habitat use by elk was an important variable in predicting use locations of mule deer during birthing and rearing. The relationship was positive, suggesting interference competition was not occurring. Survival of neonate mule deer increased as the probability of use by elk increased (hazard ratio = 0.185 ± 0.497 [SE]). Further, probability of use by elk in rearing habitat had no influence on growth of neonate mule deer from birth to 6 months of age, suggesting that exploitative competition was not occurring.     

Linking anti‐predator behaviour to prey demography reveals limited risk effects of an actively hunting large carnivore

Ecological theory predicts that the diffuse risk cues generated by wide‐ranging, active predators should induce prey behavioural responses but not major, population‐ or community‐level consequences. We evaluated the non‐consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and pregnancy of elk (Cervus elaphus), their primary prey in the Greater Yellowstone Ecosystem. When wolves approached within 1 km, elk increased their rates of movement, displacement and vigilance. Even in high‐risk areas, however, these encounters occurred only once every 9 days. Ultimately, despite 20‐fold variation in the frequency of encounters between wolves and individual elk, the risk of predation was not associated with elk body fat or pregnancy. Our findings suggest that the ecological consequences of actively hunting large carnivores, such as the wolf, are more likely transmitted by consumptive effects on prey survival than NCEs on prey behaviour.