Is conservation based on best available science creating an ecological trap for an imperiled lagomorph?

Habitat quality regulates fitness and population density, making it a key driver of population size. Hence, increasing habitat quality is often a primary goal of species conservation. Yet, assessments of fitness and density are difficult and costly to obtain. Therefore, species conservation often uses “best available science,” extending inferences across taxa, space, or time, and inferring habitat quality from studies of habitat selection. However, there are scenarios where habitat selection is not reflective of habitat quality, and this can lead to maladaptive management strategies. The New England cottontail (Sylvilagus transitionalis) is an imperiled shrubland obligate lagomorph whose successful recovery hinges on creation of suitable habitat. Recovery of this species is also negatively impacted by the non‐native eastern cottontail (Sylvilagus floridanus), which can competitively exclude New England cottontails from preferred habitat. Herein, we evaluate habitat quality for adult and juvenile New England and eastern cottontails using survival and density as indicators. Our findings did not support selection following an ideal free distribution by New England cottontails. Instead, selected resources, which are a target of habitat management, were associated with low survival and density and pointed to a complex trade‐off between density, survival, habitat, and the presence of eastern cottontails. Further, movement distance was inversely correlated with survival in both species, suggesting that habitat fragmentation limits the ability of cottontails to freely distribute based on habitat quality. While habitat did not directly regulate survival of juvenile cottontails, tick burden had a strong negative impact on juvenile cottontails in poor body condition. Given the complex interactions among New England cottontails, eastern cottontails, and habitat, directly assessing and accounting for factors that limit New England cottontail habitat quality in management plans is vital to their recovery. Our study demonstrates an example of management for possible ecological trap conditions via the application of incomplete knowledge.     

Hoarding habitat selection of squirrels (Sciurus vulgaris) in Liangshui Nature Reserve, China

This study was conducted during October 2003–April 2004 in the Liangshui National Nature Reserve of the Xiao Xing'an Mountains of Northeast China. Results showed that hoarding behavior of squirrels exhibited selectivity. The preference order of hoarding habitat selection of squirrels is as follows: original Korean pine forest, secondary natural fir forest, artificial fir forest, mix-conifer leaf forest, artificial fallen leaves pine forest, mix-conifer-broadleaf forest, mix-broadleaf forest birch forest, and artificial Korean pine forest. Compared with the existing results, using the cache spots as an index, the order of habitat selection changed, revealing that this research should include more factors, such as pilferage from other animals and secondary dispersal by the squirrels or other species. The Vanderploeg and Scavia selectivity indexes, Wi and Ei, were used to evaluate the use of microhabitat by squirrels in the original Korean pine forest. Results indicated that the squirrels exhibited a significant microhabitat utilization pattern: (1) Squirrels prefer to use the microhabitat in original Korean pine forest with high canopies, the medium shrubby density, and the medium stub density, where pilferage animals are few (Ei > 0.2); (2) Squirrels did not prefer to use the microhabitat in the original Korean pine forest with a low slope degree, high density of fallen logs and stumps, a high herbage coverage, and an abundance of pilferage animals (Ei < ?0.2), and they showed an aversion for a shaded slope (Ei = ?0.5368). The selectivity of microhabitat utilization for the hoarding behavior of squirrels plays an important role in determining the spatial pattern of Korean pine seedlings.     

凉水自然保护区松鼠（Sciurus vulgaris）贮食生境选择

2003年10月~2004年4月,在黑龙江省小兴安岭凉水国家级自然保护区,应用跟踪观察法、样线调查法、样方调查法等研究方法,采用Vanderploeg和scavia选择系数Wi和选择指数Ei作为衡量指标,对松鼠贮食红松种子生境选择进行了研究。研究表明,松鼠贮食对生境具有选择性:以主要林型为划分标准,松鼠偏爱贮食生境依次为:原始红松林,云杉林,人工云杉林,针叶混交林,人工落叶松林,针阔混交林,阔叶混交林,次生白桦林和人工红松林。在原始红松林内,松鼠对微生境的利用存在选择性差异:松鼠对郁闭良好(郁闭度大于0.6)、灌丛密度中等、倒木和枯立木密度中等(1~5个)、盗食动物活动较弱(大林姬鼠Apodemus peninsulae为主要盗食动物)的原始红松林生境表现出较强的选择性(Ei>0.2);而对坡度小于5°、基质为霉菌土、倒木和枯立木密度较高(大于5个)、草本盖度较高、盗食动物活动中等(花鼠Eutamias sibiricus为主要盗食动物)的原始红松林生境表现出较强的负选择性(Ei<-0.2),对阴坡表现出强烈的回避性(Ei=-0.5368)。     

Avian fitness consequences match habitat selection at the nest‐site and landscape scale in agriculturally fragmented landscapes

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Seasonal patterns of spatial fidelity and temporal consistency in the distribution and movements of a migratory ungulate

How animals use their range can have physiological, ecological, and demographic repercussions, as well as impact management decisions, species conservation, and human society. Fidelity, the predictable return to certain places, can improve fitness if it is associated with high‐quality habitat or helps enable individuals to locate heterogenous patches of higher‐quality habitat within a lower‐quality habitat matrix. Our goal was to quantify patterns of fidelity at different spatial scales to better understand the relative plasticity of habitat use of a vital subsistence species that undergoes long‐distance migrations. We analyzed a decade (2010–2019) of GPS data from 240 adult, female Western Arctic Herd (WAH) caribou (Rangifer tarandus) from northwest Alaska, U.S.A. We assessed fidelity at 2 spatial scales: to site‐specific locations within seasonal ranges and to regions within the herd''s entire range by using 2 different null datasets. We assessed both area and consistency of use during 6 different seasons of the year. We also assessed the temporal consistency of migration and calving events. At the scale of the overall range, we found that caribou fidelity was greatest during the calving and insect relief (early summer) seasons, where the herd tended to maximally aggregate in the smallest area, and lowest in winter when the seasonal range is largest. However, even in seasons with lower fidelity, we found that caribou still showed fidelity to certain regions within the herd''s range. Within those seasonal ranges, however, there was little individual site‐specific fidelity from year to year, with the exception of summer periods. Temporally, we found that over 90% of caribou gave birth within 7 days of the day they gave birth the previous year. This revealed fairly high temporal consistency, especially given the spatial and temporal variability of spring migration. Fall migration exhibited greater temporal variability than spring migration. Our results support the hypothesis that higher fidelity to seasonal ranges is related to greater environmental and resource predictability. Interestingly, this fidelity was stronger at larger scales and at the population level. Almost the entire herd would seek out these areas with predictable resources, and then, individuals would vary their use, likely in response to annually varying conditions. During seasons with lower presumed spatial and/or temporal predictability of resources, population‐level fidelity was lower but individual fidelity was higher. The herd would be more spread out during the seasons of low‐resource predictability, leading to lower fidelity at the scale of their entire range, but individuals could be closer to locations they used the previous year, leading to greater individual fidelity, perhaps resulting from memory of a successful outcome the previous year. Our results also suggest that fidelity in 1 season is related to fidelity in the subsequent season. We hypothesize that some differences in patterns of range fidelity may be driven by seasonal differences in group size, degree of sociality, and/or density‐dependent factors. Climate change may affect resource predictability and, thus, the spatial fidelity and temporal consistency of use of animals to certain seasonal ranges.     

The effects of habitat manipulation on population distribution and foraging behavior in meadow voles

Individuals, free to choose between different habitat patches, should settle among them such that fitness is equalized. Alternatives to this ideal free distribution result into fitness differences among the patches. The concordance between fitnesses and foraging costs among inhabitants of different quality patches, demonstrated in recent studies, suggests that the mode of habitat selection and the resulting fitness patterns may have important implications to the resource use of a forager and to the survival of its prey. We studied how coarse scale selection between habitat patches of different quality and quitting harvest rate in these patches are related to each other and to fine scale patch use in meadow voles (Microtus pennsylvanicus). To demonstrate these relationships, we manipulated habitat patches within large field enclosures by mowing vegetative cover and adding supplemental food according to a 2×2 factorial design. We tracked vole population densities, collected giving‐up densities (GUDs, a measure of patch quitting harvest rate), and monitored the removal of seeds from lattice grids with 1.5 m intervals (an index of fine‐scale space use) in the manipulated habitat patches. Changes in habitat quality induced changes in habitat use at different spatial scales. In preferred habitats with intact cover, voles were despotic and GUDs were low, but increased with the addition of food. In contrast, voles in less‐preferred mowed habitats settled into an ideal free distribution, GUDs were high and uninfluenced by the addition of food. Seed removal was enhanced by the presence of cover but inhibited by supplemental food. Across all treatments, vole densities and GUDs were strongly correlated making it impossible to separate their effects on seed removal rates. However, this relationship broke down in unmowed habitats, where GUDs rather than vole density primarily influenced seed removal by voles. GUDs and seed removal correlated with predation on tree seedlings formerly planted into the enclosures, demonstrating the mechanisms between coarse‐scale habitat manipulations and community level consequences on a forager's prey.     

Linking alternative reproductive tactics and habitat selection in Northern chamois

In polygynous ungulates, males may achieve fertilization through the use of alternative reproductive tactics (ARTs), discrete phenotypic variations evolved to maximize fitness. ARTs are often associated with different male spatial strategies during the rut, from territoriality to female‐following. Although variation in space use patterns of rutting male ungulates is known to be largely affected by the spatial distribution of females, information on the year‐round habitat selection of alternative reproductive types is scant. Here, we investigate the seasonal variation in habitat choice of a large mammal with ARTs (territoriality and nonterritoriality), the Northern chamois Rupicapra rupicapra. Global Positioning System (GPS) data on 28 adult males were collected between February 2010 and December 2013 in the Gran Paradiso National Park (Italy) and used to fit resource selection functions to explore the ART‐specific use of key topographic features, such as elevation, aspect, and slope, and vegetation phenology expressed as NDVI values. Territorial and nonterritorial chamois profoundly differed in their habitat selection not only during the rutting season. Compared to nonterritorial males, territorial males used lower elevations in summer and autumn, preferred southern slopes in spring and summer, and used steeper areas in summer but not in winter. We found no difference in seasonal selection of NDVI values between males adopting ARTs. Our results suggest that territorial males tend to occupy warmer, lower‐food‐quality habitats in late spring and summer, whereas nonterritorial males are free to follow and exploit vegetation phenology and more favorable temperatures. Different patterns of habitat selection may reflect different trade‐offs between the optimization of energy balances throughout the year and the increase of mating opportunities during the rut in males adopting alternative reproductive tactics.     

A predator's perspective of nest predation: predation by red squirrels is learned,not incidental

Nest predation has been used to explain aspects of avian ecology ranging from nest site selection to population declines. Many arguments rely on specific assumptions regarding how predators find nests, yet these predatory mechanisms remain largely untested. Here we combine artificial nest experiments with behavioural observations of individual red squirrels Tamiasciurus hudsonicus to differentiate between two common hypotheses: predation is incidental versus learned. Specifically, we tested: 1) whether nest survival could be explained solely by a squirrel's activity patterns or habitat use, as predicted if predation was incidental; or 2) if predation increased as a squirrel gained experience preying on a nest, as predicted if predation was learned. We also monitored squirrel activity after predation to test for evidence of two search mechanisms: area‐restricted searching and use of microhabitat search images. Contrary to incidental predation and in support of learning, squirrels did not find nests faster in areas with high use (e.g. forest edges). Instead, survival of artificial nests was strongly related to a squirrel's prior experience preying on artificial nests. Experience reduced nest survival times by over half and increased predation rates by 150–200%. Squirrels returned to and doubled their activity at the site of a previously preyed on nest. However, neither area‐restricted searching nor microhabitat search images can explain how squirrels located artificial nests more readily with experience. Instead, squirrels likely used cues associated with the nests or eggs themselves. Learning implies that squirrels could be increasingly effective predators as the density or profitability of nests increases. Our results add support to the view that nest predation is complex and broadly influenced (e.g. by predator experience, motivation), and is unlikely to be predicted consistently by simple relationships with predator activity, abundance or habitat.     

Fine‐scale foraging habitat selection by two diving central place foragers in the Northeast Atlantic

Habitat selection and spatial usage are important components of animal behavior influencing fitness and population dynamic. Understanding the animal–habitat relationship is crucial in ecology, particularly in developing strategies for wildlife management and conservation. As this relationship is governed by environmental features and intra‐ and interspecific interactions, habitat selection of a population may vary locally between its core and edges. This is particularly true for central place foragers such as gray and harbor seals, where, in the Northeast Atlantic, the availability of habitat and prey around colonies vary at local scale. Here, we study how foraging habitat selection may vary locally under the influence of physical habitat features. Using GPS/GSM tags deployed at different gray and harbor seals’ colonies, we investigated spatial patterns and foraging habitat selection by comparing trip characteristics and home‐range similarities and fitting GAMMs to seal foraging locations and environmental data. To highlight the importance of modeling habitat selection at local scale, we fitted individual models to colonies as well as a global model. The global model suffered from issues of homogenization, while colony models showed that foraging habitat selection differed markedly between regions for both species. Despite being capable of undertaking far‐ranging trips, both gray and harbor seals selected their foraging habitat depending on local availability, mainly based on distance from the last haul‐out and bathymetry. Distance from shore and tidal current also influenced habitat preferences. Results suggest that local conditions have a strong influence on population spatial ecology, highlighting the relevance of processes occurring at fine geographical scale consistent with management within regional units.     

Nesting,brood rearing,and summer habitat selection by translocated greater sage‐grouse in North Dakota,USA

Human enterprise has led to large‐scale changes in landscapes and altered wildlife population distribution and abundance, necessitating efficient and effective conservation strategies for impacted species. Greater sage‐grouse (Centrocercus urophasianus; hereafter sage‐grouse) are a widespread sagebrush (Artemisia spp.) obligate species that has experienced population declines since the mid‐1900s resulting from habitat loss and expansion of anthropogenic features into sagebrush ecosystems. Habitat loss is especially evident in North Dakota, USA, on the northeastern fringe of sage‐grouse’ distribution, where a remnant population remains despite recent development of energy‐related infrastructure. Resource managers in this region have determined a need to augment sage‐grouse populations using translocation techniques that can be important management tools for countering species decline from range contraction. Although translocations are a common tool for wildlife management, very little research has evaluated habitat following translocation, to track individual behaviors such as habitat selection and fidelity to the release site, which can help inform habitat requirements to guide selection of future release sites. We provide an example where locations from previously released radio‐marked sage‐grouse are used in a resource selection function framework to evaluate habitat selection following translocation and identify areas of seasonal habitat to inform habitat management and potential restoration needs. We also evaluated possible changes in seasonal habitat since the late 1980s using spatial data provided by the Rangeland Analysis Platform coupled with resource selection modeling results. Our results serve as critical baseline information for habitat used by translocated individuals across life stages in this study area, and will inform future evaluations of population performance and potential for long‐term recovery.     

Habitat change and the scale of habitat selection: shifting gradients used by coexisting Arctic rodents

The conservation and understanding of biodiversity requires development and testing of models that illustrate how climate change and other anthropogenic effects alter habitat and its selection at different spatial scales. Models of fitness along a habitat gradient illustrate the connection between fine‐scale variation in fitness and the selection of habitat as discontinuous patches in the landscape. According to these models, climate change can increase fitness values of static habitats, shift the fitness value of habitat patches along underlying gradients of habitat quality, or alter both fitness and habitat quality. It should be possible to differentiate amongst these scenarios by associating differences in the abundance and distribution of species with metrics of habitat that document the gradient while controlling for changes in density at larger scales of analysis. Comparisons of habitat selection by two species of lemmings, over an interval of 15 years, are consistent with the theory. The pattern of habitat selection at the scale of wet versus dry tundra habitats changed through time. The change in habitat selection was reflected by different, but nevertheless density‐dependent, patterns of association with the structure and composition of habitat. Abundant collared lemmings abandoned stations where altered habitat characteristics caused a shift to new locations along the wet‐to‐dry gradient. The confirmation of scale‐dependent theory provides new insights into how one might begin to forecast future habitat selection under different scenarios of climate and habitat change.     

A Multi-Scale Distribution Model for Non-Equilibrium Populations Suggests Resource Limitation in an Endangered Rodent

Species distributions are known to be limited by biotic and abiotic factors at multiple temporal and spatial scales. Species distribution models, however, frequently assume a population at equilibrium in both time and space. Studies of habitat selection have repeatedly shown the difficulty of estimating resource selection if the scale or extent of analysis is incorrect. Here, we present a multi-step approach to estimate the realized and potential distribution of the endangered giant kangaroo rat. First, we estimate the potential distribution by modeling suitability at a range-wide scale using static bioclimatic variables. We then examine annual changes in extent at a population-level. We define “available” habitat based on the total suitable potential distribution at the range-wide scale. Then, within the available habitat, model changes in population extent driven by multiple measures of resource availability. By modeling distributions for a population with robust estimates of population extent through time, and ecologically relevant predictor variables, we improved the predictive ability of SDMs, as well as revealed an unanticipated relationship between population extent and precipitation at multiple scales. At a range-wide scale, the best model indicated the giant kangaroo rat was limited to areas that received little to no precipitation in the summer months. In contrast, the best model for shorter time scales showed a positive relation with resource abundance, driven by precipitation, in the current and previous year. These results suggest that the distribution of the giant kangaroo rat was limited to the wettest parts of the drier areas within the study region. This multi-step approach reinforces the differing relationship species may have with environmental variables at different scales, provides a novel method for defining “available” habitat in habitat selection studies, and suggests a way to create distribution models at spatial and temporal scales relevant to theoretical and applied ecologists.     

Fitness,risk taking,and spatial behavior covary with boldness in experimental vole populations

Individuals of a population may vary along a pace‐of‐life syndrome from highly fecund, short‐lived, bold, dispersive “fast” types at one end of the spectrum to less fecund, long‐lived, shy, plastic “slow” types at the other end. Risk‐taking behavior might mediate the underlying life history trade‐off, but empirical evidence supporting this hypothesis is still ambiguous. Using experimentally created populations of common voles (Microtus arvalis)—a species with distinct seasonal life history trajectories—we aimed to test whether individual differences in boldness behavior covary with risk taking, space use, and fitness. We quantified risk taking, space use (via automated tracking), survival, and reproductive success (via genetic parentage analysis) in 8 to 14 experimental, mixed‐sex populations of 113 common voles of known boldness type in large grassland enclosures over a significant part of their adult life span and two reproductive events. Populations were assorted to contain extreme boldness types (bold or shy) of both sexes. Bolder individuals took more risks than shyer ones, which did not affect survival. Bolder males but not females produced more offspring than shy conspecifics. Daily home range and core area sizes, based on 95% and 50% Kernel density estimates (20 ± 10 per individual, n = 54 individuals), were highly repeatable over time. Individual space use unfolded differently for sex‐boldness type combinations over the course of the experiment. While day ranges decreased for shy females, they increased for bold females and all males. Space use trajectories may, hence, indicate differences in coping styles when confronted with a novel social and physical environment. Thus, interindividual differences in boldness predict risk taking under near‐natural conditions and have consequences for fitness in males, which have a higher reproductive potential than females. Given extreme inter‐ and intra‐annual fluctuations in population density in the study species and its short life span, density‐dependent fluctuating selection operating differently on the sexes might maintain (co)variation in boldness, risk taking, and pace‐of‐life.     

Early‐life conditions impact juvenile telomere length,but do not predict later life‐history strategies or fitness in a wild vertebrate

Environmental conditions experienced during early life may have long‐lasting effects on later‐life phenotypes and fitness. Individuals experiencing poor early‐life conditions may suffer subsequent fitness constraints. Alternatively, individuals may use a strategic “Predictive Adaptive Response” (PAR), whereby they respond—in terms of physiology or life‐history strategy—to the conditions experienced in early life to maximize later‐life fitness. Particularly, the Future Lifespan Expectation (FLE) PAR hypothesis predicts that when poor early‐life conditions negatively impact an individual''s physiological state, it will accelerate its reproductive schedule to maximize fitness during its shorter predicted life span. We aimed to measure the impact of early‐life conditions and resulting fitness across individual lifetimes to test predictions of the FLE hypothesis in a wild, long‐lived model species. Using a long‐term individual‐based dataset, we investigated how early‐life conditions are linked with subsequent fitness in an isolated population of the Seychelles warbler Acrocephalus sechellensis. How individuals experience early‐life environmental conditions may vary greatly, so we also tested whether telomere length—shorter telomers are a biomarker of an individual''s exposure to stress—can provide an effective measure of the individual‐specific impact of early‐life conditions. Specifically, under the FLE hypothesis, we would expect shorter telomeres to be associated with accelerated reproduction. Contrary to expectations, shorter juvenile telomere length was not associated with poor early‐life conditions, but instead with better conditions, probably as a result of faster juvenile growth. Furthermore, neither juvenile telomere length, nor other measures of early‐life conditions, were associated with age of first reproduction or the number of offspring produced during early life in either sex. We found no support for the FLE hypothesis. However, for males, poor early‐life body condition was associated with lower first‐year survival and reduced longevity, indicating that poor early‐life conditions pose subsequent fitness constraints. Our results also showed that using juvenile telomere length as a measure of early‐life conditions requires caution, as it is likely to not only reflect environmental stress but also other processes such as growth.     

Spatial variation in antler investment of Apennine red deer

Heterogeneity in resource availability and quality can trigger spatial patterns in the expression of sexually selected traits such as body mass and weaponry. While relationships between habitat features and phenotypic quality are well established at broad geographical scales, information is poor on spatial patterns at finer, intrapopulation scales. We analyzed biometric data collected on 1965 red deer Cervus elaphus males over 20 years from a nonmigratory population living on two sides of a mountainous ridge, with substantial differences in land cover and habitat quality but similar climate and population density. We investigate spatial patterns in (i) body mass, (ii) antler mass, and (iii) antler investment. We also tested for site‐ and age‐specific patterns in allometric relationship between body mass and antler mass. Statistically significant fine‐scale spatial variations in body mass, antler mass, and, to a lesser extent, antler allocation matched spatial differences in land cover. All three traits were greater in the northern slope, characterized by higher habitat heterogeneity and greater availability of open habitats, than in the southern slope. Moreover, the allometric relationship between body mass and antler mass differed among age‐classes, in a pattern that was consistent between the two mountain slopes. Our results support the occurrence of spatial patterns in the expression of individual attributes also at a fine, intrapopulation scale. Our findings emphasize the role of environmental heterogeneity in shaping spatial variations of key life‐history traits, with potential consequences for reproductive success.     

Green‐up selection by red deer in heterogeneous,human‐dominated landscapes of Central Europe

The forage maturation hypothesis (FMH) assumes that herbivores cope with the trade‐off between digestibility and biomass in forage by selecting vegetation at intermediate growth. The green wave hypothesis (GWH) extends the FMH to suggest how spatiotemporal heterogeneity in plant quality shapes migratory movements of herbivores. Growing empirical support for these hypotheses mainly comes from studies in vast landscapes with large‐scale habitat heterogeneity. It is unclear, however, to what extent ungulates surf green waves in human‐altered landscapes with small‐scale heterogeneity in terms of land use and topography. We used plant phenological proxies derived from Sentinel 2 satellite data to analyze the habitat selection of 93 collared red deer (Cervus elaphus) in montane and alpine habitats. Using a step selection analysis, we investigated how plant phenology, that is, the instantaneous rate of green‐up (IRG) and normalized difference vegetation index (NDVI), and a set of variables describing topography and human presence influenced red deer resource selection in open habitats. We learned that red deer selected areas with high biomass at green‐up and avoided habitats with possible exposure to human activity. Additionally, landscape structure and topography strongly influenced spatial behavior of red deer. We further compared cumulative access to high‐quality forage across migrant strategies and found migrants gained better access than residents. Many migratory individuals surfed the green wave, and their surfing behavior, however, became less pronounced with decreasing distance to settlements. Within the constraints of topography and human land use, red deer track spring green‐up on a fine spatiotemporal scale and follow the green wave across landscapes in migration movements. Thus, they benefit from high‐quality forage even in human‐dominated landscapes with small‐scale heterogeneity and vegetation emerging in a heterogenic, dynamic mosaic.     

凉水自然保护区松鼠和星鸦贮食生境选择差异

2003 年9 月30 日～2005 年10 月8 日,在黑龙江凉水国家级自然保护区,应用样方调查法, 采用Vanderploeg和Scavia 选择系数Wi和选择指数Ei作为衡量指标,对松鼠和星鸦贮食生境选择进行了研究。结果表明, 二者贮食生境选择优先顺序略有不同,松鼠偏爱的贮食生境依次是: 云杉林、原始红松林、人工红松林、针阔混交林、人工云杉林、白桦林、针叶混交林、人工落叶松林、阔叶混交林、冷杉林和其它。星鸦对贮食生境的偏爱程度依次为: 人工红松林、原始红松林、云杉林、人工云杉林、针阔混交林、阔叶混交林、白桦林、针叶混交林、人工落叶松林、冷杉林和其它。在对贮食微生境因子的选择利用上, 二者大致相同,只是在对优势灌丛的选择上略有差异, 松鼠优先选择在狗枣猕猴桃优势灌丛内贮藏红松种子, 而星鸦优先选择在刺五加优势灌丛内贮食。松鼠和星鸦贮食生境选择的差异将对随后的红松天然更新过程产生不同的影响。     

Living on the edge: Multiscale habitat selection by cheetahs in a human‐wildlife landscape

Animals select habitats that will ultimately optimize their fitness through access to favorable resources, such as food, mates, and breeding sites. However, access to these resources may be limited by bottom‐up effects, such as availability, and top‐down effects, such as risk avoidance and competition, including that with humans. Competition between wildlife and people over resources, specifically over space, has played a significant role in the worldwide decrease in large carnivores. The goal of this study was to determine the habitat selection of cheetahs (Acinonyx jubatus) in a human‐wildlife landscape at multiple spatial scales. Cheetahs are a wide‐ranging, large carnivore, whose significant decline is largely attributed to habitat loss and fragmentation. It is believed that 77% of the global cheetah population ranges outside protected areas, yet little is known about cheetahs’ resource use in areas where they co‐occur with people. The selection, or avoidance, of three anthropogenic variables (human footprint density, distance to main roads and wildlife areas) and five environmental variables (open habitat, semiclosed habitat, edge density, patch density and slope), at multiple spatial scales, was determined by analyzing collar data from six cheetahs. Cheetahs selected variables at different scales; anthropogenic variables were selected at broader scales (720–1440 m) than environmental variables (90–180 m), suggesting that anthropogenic pressures affect habitat selection at a home‐range level, whilst environmental variables influence site‐level habitat selection. Cheetah presence was best explained by human presence, wildlife areas, semiclosed habitat, edge density and slope. Cheetahs showed avoidance for humans and steep slopes and selected for wildlife areas and areas with high proportions of semiclosed habitat and edge density. Understanding a species’ resource requirements, and how these might be affected by humans, is crucial for conservation. Using a multiscale approach, we provide new insights into the habitat selection of a large carnivore living in a human‐wildlife landscape.     

Responses to land cover and grassland management vary across life‐history stages for a grassland specialist

Grassland birds have exhibited dramatic and widespread declines since the mid‐20th century. Greater prairie chickens (Tympanuchus cupido pinnatus) are considered an umbrella species for grassland conservation and are frequent targets of management, but their responses to land use and management can be quite variable. We used data collected during 2007–2009 and 2014–2015 to investigate effects of land use and grassland management practices on habitat selection and survival rates of greater prairie chickens in central Wisconsin, USA. We examined habitat, nest‐site, and brood‐rearing site selection by hens and modeled effects of land cover and management on survival rates of hens, nests, and broods. Prairie chickens consistently selected grassland over other cover types, but selection or avoidance of management practices varied among life‐history stages. Hen, nest, and brood survival rates were influenced by different land cover types and management practices. At the landscape scale, hens selected areas where brush and trees had been removed during the previous year, which increased hen survival. Hens selected nest sites in hay fields and brood‐rearing sites in burned areas, but prescribed fire had a negative influence on hen survival. Brood survival rates were positively associated with grazing and were highest when home ranges contained ≈15%–20% shrub/tree cover. The effects of landscape composition on nest survival were ambiguous. Collectively, our results highlight the importance of evaluating responses to management efforts across a range of life‐history stages and suggest that a variety of management practices are likely necessary to provide structurally heterogeneous, high‐quality habitat for greater prairie chickens. Brush and tree removal, grazing, hay cultivation, and prescribed fire may be especially beneficial for prairie chickens in central Wisconsin, but trade‐offs among life‐history stages and the timing of management practices must be considered carefully.     

Selecting Habitat to Survive: The Impact of Road Density on Survival in a Large Carnivore

Habitat selection studies generally assume that animals select habitat and food resources at multiple scales to maximise their fitness. However, animals sometimes prefer habitats of apparently low quality, especially when considering the costs associated with spatially heterogeneous human disturbance. We used spatial variation in human disturbance, and its consequences on lynx survival, a direct fitness component, to test the Hierarchical Habitat Selection hypothesis from a population of Eurasian lynx Lynx lynx in southern Norway. Data from 46 lynx monitored with telemetry indicated that a high proportion of forest strongly reduced the risk of mortality from legal hunting at the home range scale, while increasing road density strongly increased such risk at the finer scale within the home range. We found hierarchical effects of the impact of human disturbance, with a higher road density at a large scale reinforcing its negative impact at a fine scale. Conversely, we demonstrated that lynx shifted their habitat selection to avoid areas with the highest road densities within their home ranges, thus supporting a compensatory mechanism at fine scale enabling lynx to mitigate the impact of large-scale disturbance. Human impact, positively associated with high road accessibility, was thus a stronger driver of lynx space use at a finer scale, with home range characteristics nevertheless constraining habitat selection. Our study demonstrates the truly hierarchical nature of habitat selection, which aims at maximising fitness by selecting against limiting factors at multiple spatial scales, and indicates that scale-specific heterogeneity of the environment is driving individual spatial behaviour, by means of trade-offs across spatial scales.