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Cyclical population dynamics are a common phenomenon in populations worldwide, yet the spatial organization of these cycles remains poorly understood. In this study, we investigated the spatial form and timing of a population collapse from 2018 to 2022 in Canada lynx (Lynx canadensis) across the northwest boreal forest. We analyzed survival, reproduction, and dispersal data from 143 individual global positioning system (GPS) collared lynx from populations across five study sites spanning interior Alaska to determine whether lynx displayed characteristics of a population wave following a concurrent wave in snowshoe hare (Lepus americanus) abundance. Reproductive rates declined across the study sites; however, site-level reproduction declined first in our easternmost study sites, supporting the idea of a population wave. Despite a clear increase in percent of dispersing lynx, there was no evidence of directional bias in dispersal following a hare population wave. Analysis did show increasingly poor survival for lynx dispersing to the east compared to combined resident and westward dispersal. This pattern is consistent with a survival-mediated population wave in lynx as the driver of the theorized population wave. The combination of these factors supports the idea of a hierarchical response to snowshoe hare population declines with a drop in lynx reproduction followed by increased dispersal, and finally reduced survival. All of this evidence is consistent with the expected characteristics of a population undergoing a traveling wave and supports the hypothesis that lynx presence may facilitate and mirror the underlying wave patterns in snowshoe hare. [ABSTRACT FROM AUTHOR]

Motion‐sensitive cameras are commonly used to monitor wildlife occupancy rates; however, few studies have assessed whether data from cameras are correlated with density estimates obtained from more traditional labor‐intensive methods such as those based on capture‐mark‐recapture. We used data from a boreal forest community to test whether camera data were correlated with densities estimated from independent monitoring methods. We placed 72 covert cameras in the forest around Lhù'ààn Mân' (Kluane Lake), Yukon, Canada, for 7 years and tracked changes in population densities by camera hit rates. We independently estimated population densities of snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus) using capture‐mark‐recapture via live trapping, and Canada lynx (Lynx canadensis), coyotes (Canis latrans), and moose (Alces americanus) by snow track transects. Density estimates obtained from conventional aerial surveys were also periodically available for moose. Except for red squirrels, camera hit rates were highly correlated with population density estimates obtained by traditional methods, including across a large range of estimated densities corresponding to cyclic population dynamics in several species. Accordingly, we infer that motion‐sensitive cameras could supplement or replace traditional methods for monitoring key species in boreal forest food webs. Using cameras to monitor population change has several advantages; they require less effort in the field, are non‐invasive compared to live‐trapping, include multiple species at the same time, and rely less on weather than either aerial surveys or snow track transects. Tracking changes across the vast boreal forest is becoming increasingly necessary because of climate and landscape change and our data validate the use of motion‐sensitive cameras to provide a useful quantitative method for state‐of‐the‐environment reporting. [ABSTRACT FROM AUTHOR]

Perceived predation risk alters prey behaviour and physiology, but few studies have examined downstream consequences on prey demography in wild populations. Perceived predation risk could alter adult reproductive performance via reduced investment in offspring quality and post-birth care. We manipulated perceived predation risk in snowshoe hare (Lepus americanus Erxleben, 1777) by exposing pregnant mothers to chases by a domestic dog (Canis familiaris Linnaeus, 1758). Litter size was comparable between risk-augmented and control groups, but treated females had more stillbirths and gave birth to leverets of lower body condition. Leverets from risk-augmented females had 88% higher 40-day mortality rate. Maternally preventable causes of death like starvation or predation by red squirrel (Tamiasciurus hudsonicus (Erxleben, 1777)) caused this difference, particularly during the nursing period. Risk-augmented mothers were always more active than controls, but the difference was greatest during the nursing period. We found that perceived predation risk reduces maternal productivity pre- and post-partum, implying downstream consequences to populations. Because our treatment ended before parturition, we can link offspring performance such as survival and behaviour specifically to maternal life-history trade-offs, which has not been shown in a wild mammal. [ABSTRACT FROM AUTHOR]

The conservation of snowshoe hares (Lepus americanus) and their habitat is a major focus in the American West, largely because of their importance to the federally threatened Canada lynx (Lynx canadensis). Understanding the habitat relationships of snowshoe hare populations at the southern periphery of their distribution is particularly important because a warming climate is reducing the mesic forests and persistent snow cover they require. Using fecal pellet density as an index, we examined the factors influencing snowshoe hare relative abundance at 2 study areas in the Southern Rocky Mountains by comparing suites of candidate models containing fine‐scale vegetation and topographical covariates. The Birdseye Gulch study area is within an extensive area containing high elevations, mesic forests, and Canada lynx occurrence. The Three Peaks study area consists of an isolated zone of high elevation and mesic forests surrounded by inadequate habitat and is absent of Canada lynx. Mean hare pellet density in Birdseye Gulch was 2.48 pellets ± 0.46 (SE)/m2 ${{\rm{m}}}^{2}$ (n = 49) versus 2.24 ± 0.48/m2 (n = 57) at Three Peaks. Models containing fine‐scale vegetation variables best explained pellet densities at Birdseye Gulch. Pellet densities at Three Peaks were best explained by topographical variables, with much unexplained variation within all models. The differing trends in these areas may be due to the absence of resident Canada lynx at Three Peaks and differences in topography between the areas. Our results indicate that snowshoe hare populations can persist in the type of isolated habitat that is increasingly common at the southern range periphery; however, the use of vegetation management to conserve habitat in these areas may be less effective because of weaker associations with vegetation structure. [ABSTRACT FROM AUTHOR]

The snowshoe hare (Lepus americanus) possesses a broad suite of adaptations to winter, including a seasonal coat color molt. Recently, climate change has been implicated in the range contraction of snowshoe hares along the southern range boundary. With shortening snow season duration, snowshoe hares are experiencing increased camouflage mismatch with their environment reducing survival. Phenological variation of hare molt at regional scales could facilitate local adaptation in the face of climate change, but the level of variation, especially along the southern range boundary, is unknown. Using a network of trail cameras and historical museum specimens, we (1) developed contemporary and historical molt phenology curves in the Upper Great Lakes region, USA, (2) calculated molt rate and variability in and among populations, and (3) quantified the relationship of molt characteristics to environmental conditions for snowshoe hares across North America. We found that snowshoe hares across the region exhibited similar fall and spring molt phenologies, rates and variation. Yet, an insular island population of hares on Isle Royale National Park, MI, completed their molt a week earlier in the fall and initiated molt almost 2 weeks later in the spring as well as exhibited slower rates of molting in the fall season compared to the mainland. Over the last 100 years, snowshoe hares across the region have not shifted in fall molt timing; though contemporary spring molt appears to have advanced by 17 days (~ 4 days per decade) compared to historical molt phenology. Our research indicates that some variation in molt phenology exists for snowshoe hares in the Upper Great Lakes region, but whether this variation is enough to offset the consequences of climate change remains to be seen. [ABSTRACT FROM AUTHOR]

Climate change and habitat loss are recognized as important drivers of shifts in wildlife species' geographic distributions. While often considered independently, there is considerable overlap between these drivers, and understanding how they contribute to range shifts can predict future species assemblages and inform effective management. Our objective was to evaluate the impacts of habitat, climatic, and anthropogenic effects on the distributions of climate‐sensitive vertebrates along a southern range boundary in Northern Michigan, USA. We combined multiple sources of occurrence data, including harvest and citizen‐science data, then used hierarchical Bayesian spatial models to determine habitat and climatic associations for four climate‐sensitive vertebrate species (American marten [Martes americana], snowshoe hare [Lepus americanus], ruffed grouse [Bonasa umbellus] and moose [Alces alces]). We used total basal area of at‐risk forest types to represent habitat, and temperature and winter habitat indices to represent climate. Marten associated with upland spruce‐fir and lowland riparian forest types, hares with lowland conifer and aspen‐birch, grouse with lowland riparian hardwoods, and moose with upland spruce‐fir. Species differed in climatic drivers with hares positively associated with cooler annual temperatures, moose with cooler summer temperatures and grouse with colder winter temperatures. Contrary to expectations, temperature variables outperformed winter habitat indices. Model performance varied greatly among species, as did predicted distributions along the southern edge of the Northwoods region. As multiple species were associated with lowland riparian and upland spruce‐fir habitats, these results provide potential for efficient prioritization of habitat management. Both direct and indirect effects from climate change are likely to impact the distribution of climate‐sensitive species in the future and the use of multiple data types and sources in the modelling of species distributions can result in more accurate predictions resulting in improved management at policy‐relevant scales. [ABSTRACT FROM AUTHOR]

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, such as coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced, rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5% when mismatch occurred. We suggest that the increased coat insulation and lower metabolic rates of winter‐acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17–77 min less per day than matched brown hares between 0°C and −10°C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, during which mismatch occurred at warmer temperatures, suggesting a potential temperature limit at which the costs of conspicuousness outweigh energetic benefits. [ABSTRACT FROM AUTHOR]

The natural disturbance model for ecosystem management of timber harvesting promotes the emulation of natural disturbance regimes in the patterns of tree removal. Wildfire is a prominent natural disturbance in boreal forests of western Canada, frequently removing most of the tree canopy from patches of 500–10,000 ha in stand-replacing events. However, fire suppression, coupled with a spatial pattern of timber harvesting dominated by small patch cuts of 10–160 ha, have changed the spatial scale of younger stands away from scales within which boreal organisms evolved. In two regions (Sub-Boreal Spruce biogeoclimatic zone of central British Columbia and Liard Basin of southeast Yukon), we tested the hypothesis that different spatial scales of stand-replacing forest disturbance (wildfire and timber harvesting) result in different amplitudes of change in abundance of snowshoe hare, a keystone boreal forest mammal for which mid-seral stand conditions provide optimal habitat. Landscapes with large patches (>2000 ha) of mid-seral forest following stand-replacing disturbance supported consistently and often significantly more hares, with wider amplitude in cyclic fluctuation, than small patches (20–200 ha) of mid-seral habitat and than mature forest landscapes. Densities of hares high enough to support reproduction by Canada lynx (a specialist hare predator) only occurred in landscapes disturbed at the scale of a moderate to large-sized wildfire (1000 – 10,000 ha). Landscapes unaffected by stand-replacing disturbance for at least 80 years (i.e. mature forests) supported very few hares and without cyclic fluctuations. We recommend that the recent pattern of cutting dominated by small patches (20–200 ha) be shifted to include many larger patches (2000–5000 ha). This can happen with incremental, contiguous patch cutting over a period of years short enough that the completed patch will supply high quality, mid-seral habitat for at least the period of one hare cycle (10 y). In designing relatively large patches, mature green tree retention would be desirable for various values, but would be best as small stands of mature forest dispersed within large patch cuts, similar to the legacy of fire. Silviculture (reforestation and stand tending) should create and sustain a mix of conifer and deciduous regeneration in the mid-seral stands. Emulating spatial patterns of stand-replacing natural disturbance appears necessary to sustain snowshoe hare cycles when most fires are suppressed in intensively managed western Canadian boreal forests. [Display omitted] • Sizes of harvested, western boreal, forest patches are often small (10–200 ha). • Large patches (500–10,000 ha), typical of wildfire, are rare in managed landscapes. • Amplitude of snowshoe hare population fluctuations varies with patch size. • Only large patches support wide amplitudes typical of hare and lynx cycles. • Timber harvesting, in place of fire, should include larger patches (2000–5000 ha). [ABSTRACT FROM AUTHOR]

Many ecological processes are profoundly influenced by abiotic factors, such as temperature and snow. However, despite strong evidence linking shifts in these ecological processes to corresponding shifts in abiotic factors driven by climate change, the mechanisms connecting population size to season‐specific climate drivers are little understood. Using a 21‐year dataset and a Bayesian state space model, we identified biologically informed seasonal climate covariates that influenced densities of snowshoe hares (Lepus americanus), a cold‐adapted boreal herbivore. We found that snow and temperature had strong but conflicting season‐dependent effects. Reduced snow duration in spring and fall and warmer summers were associated with lowered hare density, whereas warmer winters were associated with increased density. When modeled simultaneously and under two climate change scenarios, the negative effects of reduced fall and spring snow duration and warmer summers overwhelm the positive effect of warmer winters, producing projected population declines. Ultimately, the contrasting population‐level impacts of climate change across seasons emphasize the critical need to examine the entire annual climate cycle to understand potential long‐term population consequences of climate change. [ABSTRACT FROM AUTHOR]

Cyclical population dynamics are a common phenomenon in populations worldwide, yet the spatial organization of these cycles remains poorly understood. In this study, we investigated the spatial form and timing of a population collapse from 2018 to 2022 in Canada lynx ( Lynx canadensis ) across the northwest boreal forest. We analyzed survival, reproduction, and dispersal data from 143 individual global positioning system (GPS) collared lynx from populations across five study sites spanning interior Alaska to determine whether lynx displayed characteristics of a population wave following a concurrent wave in snowshoe hare ( Lepus americanus ) abundance. Reproductive rates declined across the study sites; however, site-level reproduction declined first in our easternmost study sites, supporting the idea of a population wave. Despite a clear increase in percent of dispersing lynx, there was no evidence of directional bias in dispersal following a hare population wave. Analysis did show increasingly poor survival for lynx dispersing to the east compared to combined resident and westward dispersal. This pattern is consistent with a survival-mediated population wave in lynx as the driver of the theorized population wave. The combination of these factors supports the idea of a hierarchical response to snowshoe hare population declines with a drop in lynx reproduction followed by increased dispersal, and finally reduced survival. All of this evidence is consistent with the expected characteristics of a population undergoing a traveling wave and supports the hypothesis that lynx presence may facilitate and mirror the underlying wave patterns in snowshoe hare., Competing Interests: Competing interests statement:The authors declare no competing interest.

Understanding population dynamics requires reliable estimates of population density, yet this basic information is often surprisingly difficult to obtain. With rare or difficult-to-capture species, genetic surveys from noninvasive collection of hair or scat has proved cost-efficient for estimating densities. Here, we explored whether noninvasive genetic sampling (NGS) also offers promise for sampling a relatively common species, the snowshoe hare (Lepus americanus Erxleben, 1777), in comparison with traditional live trapping. We optimized a protocol for single-session NGS sampling of hares. We compared spatial capture-recapture population estimates from live trapping to estimates derived from NGS, and assessed NGS costs. NGS provided population estimates similar to those derived from live trapping, but a higher density of sampling plots was required for NGS. The optimal NGS protocol for our study entailed deploying 160 sampling plots for 4 days and genotyping one pellet per plot. NGS laboratory costs ranged from approximately $670 to $3000 USD per field site. While live trapping does not incur laboratory costs, its field costs can be considerably higher than for NGS, especially when study sites are difficult to access. We conclude that NGS can work for common species, but that it will require field and laboratory pilot testing to develop cost-effective sampling protocols.

Intraspecific feeding choices comprise a large portion of herbivore foraging decisions. Plant resource quality is heterogeneously distributed, affected by nutrient availability and growing conditions. Herbivores navigate landscapes, foraging not only according to food qualities, but also energetic and nutritional demands. We test three non-exclusive foraging hypotheses using the snowshoe hare (Lepus americanus): (1) herbivore feeding choices and body conditions respond to intraspecific plant quality variation; (2) high energetic demands mitigate feeding responses; and (3) feeding responses are inflated when nutritional demands are high. We measured black spruce (Picea mariana) nitrogen, phosphorus and terpene compositions, as indicators of quality, within a snowshoe hare trapping grid and found plant growing conditions to explain spruce quality variation (R2 < 0.36). We then offered two qualities of spruce (H1) from the trapping grid to hares in cafeteria-style experiments and measured their feeding and body condition responses (n = 75). We proxied energetic demands (H2) with ambient temperature and coat insulation (% white coat) and nutritional demands (H3) with the spruce quality (nitrogen and phosphorus content) in home ranges. Hares with the strongest preference for high-quality spruce lost on average 2.2% less weight than hares who ate the least high-quality spruce relative to low-quality spruce. The results supported our energetic predictions as follows: hares in colder temperatures and with less-insulative coats (lower % white) consumed more spruce and were less selective towards high-quality spruce. Collectively, we found variation in plant growing conditions within herbivore home ranges substantial enough to affect herbivore body conditions, but energetic stats mediate plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

Aim: Variation in the relationship between variables across space, known as spatial non‐stationarity, is a common phenomenon in ecology. Species distribution models (SDMs), however, typically assume stationarity in species–environment relationships across space. Spatial non‐stationarity may be particularly apparent in populations along range boundaries where species are actively adapting to changes in climate, and geographically isolated areas where isolation can facilitate adaptation. We used data collected from the southern range boundary of a winter‐adapted mammal to evaluate spatially varying environmental relationships in a region with a geographically isolated population. Taxon: Lepus americanus. Location: Laurentian Great Lakes region, USA. Methods: We surveyed 320 sites for snowshoe hares near their regional southern range boundary. We related snowshoe hare occurrence to short‐term climate variables (snow cover duration, maximum temperature and their interaction) with a spatially explicit model that allowed the effect of climate variables on snowshoe hare occurrence to vary spatially. Results: We found highest support for an SDM that incorporated geographic barriers when estimating spatial effects, in addition to spatially varying effects of maximum temperate, snow cover duration and their interaction. Hares were more likely to occupy sites with longer snow cover duration but the influence of temperature was more variable. Increasing temperature in northern portions of our study area had a positive influence on hare occurrence, but exhibited a negative relationship along the southern range boundary. Main Conclusions: We provide a robust evaluation of stationarity assumptions in bioclimatic relationships and highlight spatially variable relationships between a cold‐adapted species and short‐term climate variables across a range boundary. However, spatial non‐stationarity was not most apparent across dispersal barriers but coincided with differences in the relationship between climate variables across space. Our study provides evidence that the distribution of a winter‐adapted species is strongly constrained by snow cover, but prevailing temperature modulates the strength of this relationship across space. [ABSTRACT FROM AUTHOR]

Home range size of consumers varies with food quality, but the many ways of defining food quality hamper comparisons across studies. Ecological stoichiometry studies the elemental balance of ecological processes and offers a uniquely quantitative, transferrable way to assess food quality using elemental ratios, e.g., carbon (C):nitrogen (N). Here, we test whether snowshoe hares (Lepus americanus) vary their home range size in response to spatial patterns of C:N, C:phosphorus (P), and N:P ratios of two preferred boreal forage species, lowbush blueberry (Vaccinium angustifolium) and red maple (Acer rubrum), in summer months. Boreal forests are N- and P-limited ecosystems and access to N- and P-rich forage is paramount to snowshoe hares' survival. Accordingly, we consider forage with higher C content relative to N and P to be lower quality than forage with lower relative C content. We combine elemental distribution models with summer home range size estimates to test the hypothesis that home range size will be smaller in areas with access to high, homogeneous food quality compared to areas of low, heterogeneous food quality. Our results show snowshoe hares had smaller home ranges in areas where lowbush blueberry foliage quality was higher or more spatially homogenous than in areas of lower, more heterogeneous food quality. By responding to spatial patterns of food quality, consumers may influence community and ecosystem processes by, for example, varying nutrient recycling rates. Our reductionist biogeochemical approach to viewing resources leads us to holistic insights into consumer spatial ecology. [ABSTRACT FROM AUTHOR]

We studied the diet and reproductive success of Great Horned Owl (Bubo virginianus) at its northern range limit during an apparent high in the Snowshoe Hare (Lepus americanus) population. We performed diet analyses using images from fixed motion sensor cameras and pellet and prey remains collected at active nests, and gathered data on breeding success through camera and visual observations. Pellet data at 14 nests produced 1277 prey records consisting of 65-95% Snowshoe Hare biomass. Great Horned Owls ate 18 different prey types, with overall biomass consisting of 93% mammal, 7% bird, and less than 1% insects, frogs, and fish. The mean prey mass of 714 g (± 34 SE) was 2-25 times the mean prey mass of studies of this species at more southerly latitudes. Camera observations showed that Great Horned Owls delivered an average of 459 g/chick/d (± 75) throughout nesting. This was significantly (P = 0.005) higher than observations from Alberta, at 328-411 g/chick/d. Pellet/prey remains data showed that Great Horned Owls delivering a higher proportion of hares to their nestlings successfully raised more chicks (χ2 1 = 6.3, P = 0.012), highlighting the importance of this prey in the population dynamics of Great Horned Owl. In addition, we observed Snowshoe Hare removing pellets beneath nest sites, revealing an apparently undocumented bias to the use of pellet analysis. [ABSTRACT FROM AUTHOR]

Prey individuals employ several adaptive behaviours to reduce predation risk. We need to learn how those behaviours interact in an overall strategy of risk management, how strategies vary with changing conditions, and whether some behaviours might compensate for others. I addressed these issues with manipulative experiments evaluating how snowshoe hares’ (Lepus americanus) vigilance varies with their giving-up densities (GUDs) in artificial food patches. I tested whether the results, collected when there was no evidence of predation, were congruent with an earlier study under higher predation. When predator sign was common, vigilance depended directly on habitat. But when risk was low, habitat’s influence on vigilance was indirect. Hares were least vigilant during the new moon where the distance to escape habitat was far, but only in open risky habitat. Hares were more vigilant during the full moon, but only at stations far from escape habitat. Moon phase and additional cover had no effect on GUDs that were highest at open risky stations far from escape habitat. The results suggest that reduced risk allowed hares to allocate less time to vigilance, but they needed to forage for similar amounts of food during each moon phase to maintain their energetic state.

Determining the factors driving cyclic dynamics in species has been a primary focus of ecology. For snowshoe hares (Lepus americanus), explanations of their 10-year population cycles most commonly feature direct predation during the peak and decline, in combination with their curtailment in reproduction. Hares are thought to stop producing third and fourth litters during the cyclic decline and do not recover reproductive output for several years. The demographic effects of these reproductive changes depend on the consistency of this pattern across cycles, and the relative contribution to population change of late-litter versus early litter juveniles. We used monitoring data on snowshoe hares in Yukon, Canada, to examine the contribution of late-litter juveniles to the demography of their cycles, by assigning litter group for individuals caught in autumn based on body size and capture date. We found that fourth-litter juveniles occur consistently during the increase phase of each cycle, but are rare and have low over-winter survival (0.05) suggesting that population increase is unlikely to be caused by their occurrence. The proportion of third-litter juveniles captured in the autumn remains relatively constant across cycle phases, while over-winter survival rates varies particularly for earlier-litter juveniles (0.14–0.39). Juvenile survival from all litters is higher during the population increase and peak, relative to the low and decline. Overall, these results suggest that the transition from low phase to population growth may stem in large part from changes in juvenile survival as opposed to increased reproductive output through the presence of a 4th litter. [ABSTRACT FROM AUTHOR]

Abstract Obtaining accurate data on seasonal timing of lifecycle events in the wild is critical for many aspects of ecological research. However, characterizing such phenological processes is difficult, expensive, and time consuming. Remote camera traps are increasingly used in ecology, yet their potential to study key phenological traits in animal populations has been largely unexplored. Here, we examine the potential of remote camera traps to measure the progression of seasonal molts in mammals. We evaluated the accuracy of trained observers to classify the stage of molt from camera‐trap images and identified factors that increase the accuracy of this method in a common, color molting mammal, the snowshoe hare (Lepus americanus). Our results showed that images taken by remote camera traps can be used to classify the stage of color molt with relatively high accuracy (i.e., 84%). Observers achieved the highest accuracy when using a classification protocol with fewer molt categories, and from images acquired during the day. We also found that hare body position in the image, and whether the hare was moving or still had small influences on observer classification accuracy. Camera model had negligible effect on accuracy. Overall, our results suggest that camera traps can be used to classify molt progression to measure molt phenology in the wild. Because many camera‐trap studies are ongoing around the world, images of species that undergo distinguishable seasonal molts could be pooled across studies to characterize molt phenology on local and global scales. In much the same way that remote cameras have revolutionized the study of distribution, abundance, and behavior of some animal populations, so too can remote camera images transform our understanding of key phenological processes across space, time, and taxa.

Prey individuals possess four basic strategies to manage predation risk while foraging: time allocation, space use, apprehension, and foraging tenacity. But there are no direct tests of theory detailing how spatial strategies change and covary from fine to coarse scales of environmental variability. We address this shortcoming with experiments that estimated space use and vigilance of snowshoe hares while we measured foraging tenacity in artificial resource patches placed in risky open versus safe alder habitat. Hares employed only two of eight a priori options to manage risk. Hares increased vigilance and reduced foraging in open areas as the distance from cover increased. Hares did not differentiate between open and alder habitats, increase vigilance at the coarse-grained scale, or reduce vigilance and foraging tenacity under supplemental cover. Hares were more vigilant in the putatively safe alder than in the purportedly risky open habitat. These apparently paradoxical results appear to reflect a trade-off between the benefit of alder as escape habitat and the cost of obscured sight lines that reduce predator detection. The trade-off also appears to equalize safety between habitats at small scales and suggests that common-sense predictions detailing how prey reduce risk may make no sense at all.

From observations of Caribou (Rangifer tarandus) during 1974-2017 on the Lake Superior archipelago that makes up Slate Islands Provincial Park, we infer direct and indirect effects of the arrival of Gray Wolves (Canis lupus) in the winters of 1993-1994, 2002-2003, and 2013-2014. Arrivals consisted of wolf pairs in the first and third cases, and, in each instance, wolves survived at least one additional winter. Wolves created conditions that led to behavioural changes in Caribou consistent with avoiding predators. Caribou did not frequent calving locations near shoreline areas, nor did they use water to escape from wolves. Wolves occupied a Red Fox (Vulpes vulpes) den, and its general location, at one time frequented by Caribou, became the most common area to find Caribou carcasses and was avoided by Caribou when wolves were present. Caribou were functionally extirpated by wolves, with just two to four males remaining in 2017. Wolves also appear to have caused extirpation of American Beaver (Castor canadensis) and Red Fox from the archipelago, while Snowshoe Hare (Lepus americanus) populations were unaffected by wolves. [ABSTRACT FROM AUTHOR]

Obtaining accurate data on seasonal timing of lifecycle events in the wild is critical for many aspects of ecological research. However, characterizing such phenological processes is difficult, expensive, and time consuming. Remote camera traps are increasingly used in ecology, yet their potential to study key phenological traits in animal populations has been largely unexplored. Here, we examine the potential of remote camera traps to measure the progression of seasonal molts in mammals. We evaluated the accuracy of trained observers to classify the stage of molt from camera-trap images and identified factors that increase the accuracy of this method in a common, color molting mammal, the snowshoe hare (Lepus americanus). Our results showed that images taken by remote camera traps can be used to classify the stage of color molt with relatively high accuracy (i.e., 84%). Observers achieved the highest accuracy when using a classification protocol with fewer molt categories, and from images acquired during the day.We also found that hare body position in the image, and whether the hare was moving or still had small influences on observer classification accuracy. Camera model had negligible effect on accuracy. Overall, our results suggest that camera traps can be used to classify molt progression to measure molt phenology in the wild. Because many camera-trap studies are ongoing around the world, images of species that undergo distinguishable seasonal molts could be pooled across studies to characterize molt phenology on local and global scales. In much the same way that remote cameras have revolutionized the study of distribution, abundance, and behavior of some animal populations, so too can remote camera images transform our understanding of key phenological processes across space, time, and taxa. [ABSTRACT FROM AUTHOR]

• Landscape-scale land cover influences the southern limit of spruce grouse occupancy. • Forest understory structure drives occupancy and extinction of forest prey species. • Climate influences local extinction probabilities of grouse and snowshoe hare. • Maintaining dense forest understory may alleviate negative effects of climate change. Climate change is expected to shift the distributions of global biomes. High latitude biomes, such as the boreal forest, are among the most vulnerable and serve as a bellwether for the effects of climate change on other ecosystems. We examined patterns of occupancy, local extinction, and abundance in a guild of forest-associated vertebrate prey species on the southern margin of the boreal forest in Minnesota (USA). We used multi-season, multi-state, and multi-species occupancy modeling approaches to determine the effects of land cover, forest structural characteristics, and climatic variation on two boreal-associated species, spruce grouse (Canachites canadensis) and snowshoe hare (Lepus americanus), and a forest generalist, ruffed grouse (Bonasa umbellus). Occupancy, abundance, and extinction of spruce grouse was strongly associated with landscape-scale characteristics. In particular, deciduous forest cover may govern their southern range limit. Broadly, forest understory structure played a significant role in occupancy, extinction, and abundance patterns of all three species, with ruffed and spruce grouse generally associated with vegetation density in the lower and mid-canopy layer (5.00–15.00 m) and snowshoe hare associated with density in the shrub layer (1.37–5.00 m) in winter. Co-occurrence varied annually but was greatest in mixed forests during an uncharacteristically warm and snow-sparse year. Climatic variables (winter temperature and snowfall) were associated with extinction probabilities for all three species, but the effect was generally weaker than that of forest structure. Our results suggest that forest management practices that promote dense understory structure may help provide climate refugia for vertebrate prey species in boreal forest ecosystems. [ABSTRACT FROM AUTHOR]

Snowshoe hares, Lepus americanus , are the dominant prey species in the boreal forest and they undergo regular, predator-driven population cycles every 8–11 years. Previous research has found that hare stress physiology is highly sensitive to both within-year (seasonal/litter group) and across-year (cycle phase) variation in predation risk and that maternal–offspring stress profiles are tightly correlated. Thus, both pre- and postnatal environments may interact to shape offspring physiological phenotype. If changes in the function and reactivity of the maternal stress axis are associated with variation in offspring behaviours that increase survival during periods of high predation risk, then the maternal effects on offspring physiology seen previously could represent a mechanistic route of adaptive maternal programming. To examine the relationship between physiology and behaviour in snowshoe hares, we monitored free-ranging adult and juvenile stress hormone levels in the first and second litters of the breeding season and assessed open field exploratory behaviour in weaning-age and independent juveniles in the southwestern Yukon (Canada) during 2013–2015, when predator density was low but increasing. Thus, our study spanned the late low phase (2013) and the early increase phase (2014–2015) of the hare population cycle. We found that increased concentrations of faecal cortisol metabolites (FCMs) were associated with aspects of risk avoidance in weaning-age hares. Juveniles with higher stress hormone levels spent more time under cover and were less active during open field trials, highlighting a potential mechanistic route to allow individuals to sensitively cope with a changing environment. Although average FCM levels of breeding females and juveniles were not correlated with one another and litter-based differences in physiology and behaviour were not present during these low-risk phases of the cycle, the association between stress hormone levels and behaviour sets the stage for adaptive maternal effects on offspring behaviour and survival as the cycle progresses and predation risk intensifies. • Wild snowshoe hares are acutely sensitive to fluctuating predation risk. • We measured population-level stress and juvenile open field exploratory behaviour. • High faecal cortisol levels were associated with risk avoidance in juveniles. • Pre- and postnatal environments influenced offspring physiological phenotype. [ABSTRACT FROM AUTHOR]

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Habitat quality and quantity are key factors in evaluating the potential for success of a wildlife translocation. However, because of the difficulty or cost of evaluating these factors, habitat assessments may not include valuable information on important habitat attributes including the abundance and distribution of prey, predators, and competitors. Fishers (Pekania pennanti) are one of the most commonly reintroduced carnivores in North America, and they are a species of conservation concern in their western range. We examined the relative importance of landscape features and species interactions in determining habitat use of a reintroduced population of fishers in the southern Cascade Mountains, Washington, USA. We used detections of prey and predators at 134 remote camera stations, remotely sensed forest structure data, and telemetry locations of fishers in a resource selection function to assess the relative importance of prey, predators, and forest structure in fisher habitat selection. Fishers selected habitats based on forest conditions and activity levels of snowshoe hares (Lepus americanus), whereas bobcat (Lynx rufus) and coyote (Canis latrans) activity levels did not directly affect habitat selection. The probability of fisher use increased in older stands, close to recently disturbed stands, and in areas with intermediate levels of hare activity. Bobcat and hare activity levels were positively correlated, and fishers avoided areas with the greatest hare activity, suggesting that fishers may experience a food‐safety tradeoff in the study area. Temporal activity patterns in photo detections indicate that fishers may mediate this danger by avoiding bobcats temporally. Our findings suggest that fishers in Washington prefer habitat mosaics of old and recently disturbed stands where they have greater access to resting structures and hares. Management that maintains mosaics of young and old forest across large landscapes is likely to support fisher recovery. Future reintroduction efforts would benefit from an assessment of prey and predator abundance in proposed reintroduction areas before project initiation. © 2019 The Wildlife Society. We assessed habitat selection of reintroduced fishers in Washington, USA, and documented selection for mature forests that were near young stands and moderate abundance of a major prey item. Our results also indicate a potential food‐safety tradeoff for fishers, which they may mediate through temporal segregation from bobcats. [ABSTRACT FROM AUTHOR]

ABSTRACT We determined the optimum transect length and spacing for detecting snowshoe hare (Lepus americanus) from snow‐track surveys in a fixed area. We also evaluated the utility of the most reliable and efficient designs for indexing hare density. We constructed enclosures (∼6.1 ha) at 2 locations in the Upper Peninsula of Michigan, USA, and populated the enclosures with radiocollared hares. Hare densities ranged from 0.2 to 1.5 hares/ha in the enclosures, comparable to low and high densities recorded at the southern extent of snowshoe hare range. During winters of 2012–2014, we conducted snow‐track surveys along 9 transects spaced 25 m apart in the enclosures 12–65 hr after a snowfall and mapped the location of every track that intersected a transect. After standardizing the track maps by time since last snowfall, we simulated different transect lengths and spacing and evaluated whether hares were documented on the resultant transect segments. We deemed transect configurations reliable if >90% of the 10,000 simulations correctly denoted the site as occupied. Of the 28 possible transect configurations, only 10 combinations were found to reliably detect hares. We refined the 10 reliable configurations based on efficiency, where efficiency was based on the distance traversed by a surveyor. We recommend using transects that are 150 m in length with 100‐m or 75‐m spacing, or 125 m in length with 75‐m spacing to reliably and efficiently survey a fixed area for snowshoe hares. © 2016 The Wildlife Society.

Carrion consumption by herbivores is increasingly being observed in nature, however, we lack detailed analyses of its occurrence for numerous species. Here, we quantify incidences of scavenging by Snowshoe Hares (Lepus americanus) in Yukon, Canada between January 2015 and July 2017. Hares scavenged 12.4% of carcasses deployed and were more likely to scavenge during the winter. Hares consumed meat from a variety of different species, including Canada Lynx (Lynx canadensis), as well as the carcasses of hares. On one occasion, an individual repeatedly ingested feathers from a Spruce Grouse (Falcipennis canadensis) carcass. Scavenging by hares may result from food or nutrient limitations during winter months and appears relatively common when compared to other lagomorph species. [ABSTRACT FROM AUTHOR]

When generalist predators have wide geographic ranges, diets may differ dramatically, largely as a result of differing prey communities. Bobcats (Lynx rufus) are widely distributed across southern North America, with their northern range edge occurring in southern Canada and in the northern US states. Within this northern range, bobcats are exposed to cold and snowy winters and a limited number of prey species, conditions that are atypical for most of the range of bobcats. We examined winter diets of bobcats in high elevation and very snowy forests in northwest Montana to determine how these generalist predators managed in these harsh conditions in comparison with elsewhere in the northern range. Bobcats consumed five major prey types: Red squirrels (Tamiasciurus hudsonicus) and Cricetid rodents comprised >78% of the dietary biomass, whereas the larger snowshoe hares (Lepus americanus), deer (Odocoileus spp.), and grouse were consumed much less often. The standardized niche breadth of bobcat diets was 0.29; bobcats from across the northern range also routinely ate multiple prey species, although Eastern bobcats appear to consume more lagomorphs than do Western bobcats. These results indicate that bobcats remain generalists in difficult winter conditions while preying primarily on small‐bodied prey, although bobcats have highly variable diets across their northern range. Bobcats (Lynx rufus) are generalist North American predators that make use of a variety of prey types across their broad geographic range. We provide the first description of the winter diet of bobcats in northwest Montana and compare these findings to other studies of winter bobcat diet in similar northern latitudes. [ABSTRACT FROM AUTHOR]

Abstract The San Juan Mountains of southern Colorado provide subalpine habitat for a suite of mammalian species including Canada lynx ( Lynx canadensis ), moose ( Alces alces ) and snowshoe hare ( Lepus americanus ). In the winter field season of 2016 five faecal samples from lynx, and one each from moose and snowshoe hare were collected to identify small single-stranded DNA viruses associated with these three prominent species. Thirty-two novel viruses were identified and classified as members of two well established ssDNA families Genomoviridae (n = 22) and Microviridae (n = 10) and one recently proposed new family, Smacoviridae (n = 1). In addition one highly novel circular ssDNA virus was identified which at present does not group with any known family. A high level of genomovirus diversity was identified from faeces collected between and across the three mammal species, with full genome-wide pairwise comparisons showing 57%–97% identity. Twenty genomoviruses can be assigned to the genus Gemycircularvirus and represent 11 species, and two into a distinct species in the genus Gemykolovirus. The single smacovirus identified from moose also represents a distinct smacovirus species. Ten microviruses, seven from moose, one from snowshoe hare and two from lynx, all are part of the Gokushovirinae subfamily. The two from lynx are highly similar to a microvirus previously detected in domestic cat (sharing 88%–90% genome-wide identity), indicating this may be a common felid gut microbiome associated virus. Our findings highlight the broad range of diverse ssDNA viruses present in three mammals inhabiting the San Juan Mountains. Highlights • Discovery of a diverse range of single-stranded DNA viruses in Canada lynx, moose, snowshoe hare • Characterization of twenty-two unique genomoviruses,one smacovirus and ten from the micorviruses • A novel divergent circular rep-encoding single-stranded DNA virus recovered from moose [ABSTRACT FROM AUTHOR]

Forest managers are often tasked with balancing opposing objectives, such as altering forest structure and conserving forest-dwelling animals. Consequently, to develop holistic strategies managers require information on how forest manipulations influence species of conservation concern, particularly those that are federally threatened or endangered. Here, we characterized how differing silvicultural treatments ( n  = 1,293 – forest thinnings; removal of small trees, selection cuts; trees harvested in small patches, and regeneration cuts; clearcuts of nearly all trees) influenced the resource use of a threatened forest carnivore, Canada lynx ( Lynx canadensis ), over a temporal gradient of 1–67 years after treatment. To do this, we used an extensive GPS dataset on 66 Canada lynx (i.e., 164,593 locations) collected during 2004–2015 within the Northern Rocky Mountains, U.S. We used univariate analyses and hurdle regression models to evaluate the spatio-temporal factors influencing lynx use of treatments. Our analyses indicated that Canada lynx used treatments, but there was a consistent cost in that lynx use was low up to ∼10 years after all silvicultural actions. However, cumulative use (in both winter and summer) by lynx reached 50% at ∼20 years after a thinning treatment, whereas it took ∼34–40 years after a selection or regeneration cut. This indicated that Canada lynx used thinnings at a faster rate post-treatment than selection or regeneration cuts, and that lynx used selection and regeneration cuts in a similar fashion over time. Further, we discovered that lynx occupancy and intensity of treatment use was influenced by the composition of forest structure in the surrounding neighborhood. In some instances, the existing forest structure surrounding the treatment and the time since treatment interactively influenced lynx use; a pattern characterizing a spatio-temporal functional response in habitat use. This demonstrated that both the recovery time as well as the spatial context of a particular area are important considerations when implementing different silvicultural treatments for Canada lynx at the landscape scale. For example, if a selection cut was implemented with abundant mature, multi-storied forest (i.e., a preferred habitat by lynx) in the surrounding landscape, lynx would use these treatments less over time than if the neighborhood contained less mature forest. Forest managers can apply our spatio-temporal understandings of how lynx respond to forest silviculture to refine expectations and develop strategies aimed at both forest management and the conservation of Canada lynx. [ABSTRACT FROM AUTHOR]

Abstract: Predation and predation risk can exert strong influences on the behavior of prey species. However, risk avoidance behaviors may vary among populations of the same species. We studied a population of snowshoe hares (Lepus americanus) near the southern edge of their range, in Pennsylvania. This population occupies different habitat types, experiences different environmental conditions, and are exposed to different predator species and densities than northern hare populations; therefore, they might exhibit differences in risk avoidance behaviors. We analyzed hare survival, movement rates, and habitat use under different levels of predation risk, as indexed by moonlight. Similar to previous work, we found snowshoe hare survival decreased with increased moon illumination during the winter, but we found differences in behavioral responses to increased predation risk. We found that snowshoe hares did not reduce movement rates during high‐risk nights, but instead found that hares selected areas with denser canopy cover, compared to low‐risk nights. We suggest that behavioral plasticity in response to predation risk allows populations of the same species to respond to localized conditions. [ABSTRACT FROM AUTHOR]

Vertebrate populations throughout the circumpolar north often exhibit cyclic dynamics, and predation is generally considered to be a primary driver of these cycles in a variety of herbivore species. However, weather and climate play a role in entraining cycles over broad landscapes and may alter cyclic dynamics, although the mechanism by which these processes operate is uncertain. Experimental and observational work has suggested that weather influences primary productivity over multi-year time periods, suggesting a pathway through which weather and climate may influence cyclic herbivore dynamics. Using long-term monitoring data, we investigated the relationships among multi-year weather conditions, measures of primary productivity, and the abundance of two cyclic herbivore species: snowshoe hare and northern red-backed vole. We found that precipitation (rain and snow) and growing season temperatures were strongly associated with variation in primary productivity over multi-year time horizons. In turn, fourfold variation in the amplitude of both the hare and vole cycles observed in our study area corresponded to long-term changes in primary productivity. The congruence of our results for these two species suggests a general mechanism by which weather and climate might influence cyclic herbivore population dynamics. Our findings also suggested that the association between climate warming and the disappearance of cycles might be initiated by changes in primary productivity. This work provides an explanation for observed influences of weather and climate on primary productivity and population cycles and will help our collective understanding of how future climate warming may influence these ecological phenomena in the future. [ABSTRACT FROM AUTHOR]

Abstract: One of the central goals of the field of population ecology is to identify the drivers of population dynamics, particularly in the context of predator–prey relationships. Understanding the relative role of top‐down versus bottom‐up drivers is of particular interest in understanding ecosystem dynamics. Our goal was to explore predator–prey relationships in a boreal ecosystem in interior Alaska through the use of multispecies long‐term monitoring data. We used 29 years of field data and a dynamic multistate site occupancy modeling approach to explore the trophic relationships between an apex predator, the golden eagle, and cyclic populations of the two primary prey species available to eagles early in the breeding season, snowshoe hare and willow ptarmigan. We found that golden eagle reproductive success was reliant on prey numbers, but also responded prior to changes in the phase of the snowshoe hare population cycle and failed to respond to variation in hare cycle amplitude. There was no lagged response to ptarmigan populations, and ptarmigan populations recovered quickly from the low phase. Together, these results suggested that eagle reproduction is largely driven by bottom‐up processes, with little evidence of top‐down control of either ptarmigan or hare populations. Although the relationship between golden eagle reproductive success and prey abundance had been previously established, here we established prey populations are likely driving eagle dynamics through bottom‐up processes. The key to this insight was our focus on golden eagle reproductive parameters rather than overall abundance. Although our inference is limited to the golden eagle–hare–ptarmigan relationships we studied, our results suggest caution in interpreting predator–prey abundance patterns among other species as strong evidence for top‐down control. [ABSTRACT FROM AUTHOR]

ABSTRACT: Prescribed burning has the potential to improve habitat for species that depend on pyric ecosystems or other early successional vegetation types. For species that occupy diverse plant communities over the extent of their range, response to disturbances such as fire might vary based on post‐disturbance vegetation dynamics among plant communities. Although responses of snowshoe hares (Lepus americanus) to fire have been studied in conifer‐dominated forests in northern parts of the species’ range, there is a lack of information on snowshoe hare habitat use in fire‐dependent communities in southern parts of their range. We used global positioning system (GPS) and very high frequency (VHF) radio‐collars to monitor the habitat use of 32 snowshoe hares in a scrub‐oak (Quercus ilicifolia)‐pitch pine (Pinus rigida) barrens complex in northeastern Pennsylvania where prescribed fire has been used for habitat restoration. The area contained stands that underwent prescribed burning 1–6 years prior to our study. Also, we investigated fine‐scale determinants of habitat use within stands. We found that regardless of season, hares did not select for areas that had been burned within 6 years prior. Hares primarily used stands of older scrub oak, conifer, or hardwoods, which contained dense understory vegetation and canopy cover. Hare habitat use also was positively associated with stand edges. Our results suggest that hares do not respond to prescribed burning of scrub oak in the short‐term. In addition, by focusing on structural determinants of habitat use, rather than broad‐scale characteristics such as stand type, management strategies for snowshoe hares can be adapted over the extent of their range despite the multitude of different land cover types across which the species occurs. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Deep snow can reduce accessibility to vegetation and cover by herbivores by blanketing understory cover, yet simultaneously increase access to foliage at higher levels. Thus, snow depth fluctuation should lead to spatiotemporal variation in herbivore habitat use. We measured shifts in habitat use by snowshoe hare ( Lepus americanus Erxleben, 1777) as a function of snow depth in an eastern Canadian boreal forest where snow depth often exceeds 1 m. We hypothesized that as snow accumulates, snowshoe hares shift from locations with dense vegetation just above ground to locations with dense vegetation higher above ground. We surveyed 58 km of transects over three winters and found 1954 hare tracks. We analyzed track counts as a response to a density index of low vegetation (0-1.5 m above ground), high vegetation (2-4 m above ground), predator tracks, and snow depth. We found more hare tracks in sites with dense high vegetation when snow was deeper, and more hare tracks in sites with dense low vegetation when snow was shallower. Predator track presence did not influence responses to snow depth. Snow depth dynamics can drive hare distribution, and in turn, introduce uncertainty in spatial distribution models for the species and possibly its interactions with predators. [ABSTRACT FROM AUTHOR]