Reproductive tactics, birth timing and the risk-resource trade-off in an income breeder.

In variable environments, habitats that are rich in resources often carry a higher risk of predation. As a result, natural selection should favour individuals that balance allocation of time to foraging versus avoiding predation through an optimal decision-making process that maximizes fitness. The behavioural trade-off between resource acquisition and risk avoidance is expected to be particularly acute during gestation and lactation, when the energetic demands of reproduction peak. Here, we investigated how reproductive female roe deer adjust their foraging activity and habitat use during the birth period to manage this trade-off compared with non-reproductive juveniles, and how parturition date constrains individual tactics of risk-resource management. Activity of reproductive females more than doubled immediately following parturition, when energy demand is highest. Furthermore, compared with non-reproductive juveniles, they increased their exposure to risk by using open habitat more during daytime and ranging closer to roads. However, these post-partum modifications in behaviour were particularly pronounced in late-parturient females who adopted a more risk-prone tactic, presumably to compensate for the growth handicap of their late-born offspring. In income breeders, individuals that give birth late may be constrained to trade risk avoidance for foraging during peak allocation to reproduction, with probable consequences for individual fitness.

Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data.

Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species. Location: Worldwide. Time period: 1998-2021. Major taxa studied: Forty-nine terrestrial mammal species. Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types. Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively. Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.

On this side of the fence: Functional responses to linear landscape features shape the home range of large herbivores.

Understanding the consequences of global change for animal movement is a major issue for conservation and management. In particular, habitat fragmentation generates increased densities of linear landscape features that can impede movements. While the influence of these features on animal movements has been intensively investigated, they may also play a key role at broader spatial scales (e.g. the home range scale) as resources, cover from predators/humans, corridors/barriers or landmarks. How space use respond to varying densities of linear features has been mostly overlooked in large herbivores, in contrast to studies done on predators. Focusing on large herbivores should provide additional insights to understand how animals solve the trade-off between energy acquisition and mortality risk. Here, we investigated the role of anthropogenic (roads and tracks) and natural (ridges, valley bottoms and forest edges) linear features on home range features in five large herbivores. We analysed an extensive GPS monitoring database of 710 individuals across nine populations, ranging from mountain areas mostly divided by natural features to lowlands that were highly fragmented by anthropogenic features. Nearly all of the linear features studied were found at the home range periphery, suggesting that large herbivores primarily use them as landmarks to delimit their home range. In contrast, for mountain species, ridges often occurred in the core range, probably related to their functional role in terms of resources and refuge. When the density of linear features was high, they no longer occurred predominantly at the home range periphery, but instead were found across much of the home range. We suggest that, in highly fragmented landscapes, large herbivores are constrained by the costs of memorising the spatial location of key features, and by the requirement for a minimum area to satisfy their vital needs. These patterns were mostly consistent in both males and females and across species, suggesting that linear features have a preponderant influence on how large herbivores perceive and use the landscape.

Behavioural heat-stress compensation in a cold-adapted ungulate: Forage-mediated responses to warming Alpine summers.

Alpine large herbivores have developed physiological and behavioural mechanisms to cope with fluctuations in climate and resource availability that may become maladaptive under climate warming. We tested this hypothesis in female Alpine ibex (Capra ibex) by modelling annual and daily movement and activity patterns in relation to temperature, vegetation productivity and reproductive status based on bio-logging data and climate change projections. In summer, ibex moved upslope, tracking the green wave. Ibex decreased diel activity sharply above a threshold temperature of 13-14°C, indicating thermal stress, but compensated behaviourally by foraging both earlier and later in the day, and by moving further upslope than on cooler days, especially reproductive females. This critical temperature will be exceeded three times as often under climate change projections. Under such scenarios, the altitudinal extent of the area will limit the available habitat providing thermal shelter, potentially impacting performance and population distribution of this emblematic mountain ungulate.

Short-term telomere dynamics is associated with glucocorticoid levels in wild populations of roe deer.

While evidence that telomere length is associated with health and mortality in humans and birds is accumulating, a large body of research is currently seeking to identify factors that modulate telomere dynamics. We tested the hypothesis that high levels of glucocorticoids in individuals under environmental stress should accelerate telomere shortening in two wild populations of roe deer (Capreolus capreolus) living in different ecological contexts. From two consecutive annual sampling sessions, we found that individuals with faster rates of telomere shortening had higher concentrations of fecal glucocorticoid metabolites, suggesting a functional link between glucocorticoid levels and telomere attrition rate. This relationship was consistent for both sexes and populations. This finding paves the way for further studies of the fitness consequences of exposure to environmental stressors in wild vertebrates.

Accelerating across the landscape: The energetic costs of natal dispersal in a large herbivore.

Dispersal is a key mechanism enabling species to adjust their geographic range to rapid global change. However, dispersal is costly and environmental modifications are likely to modify the cost-benefit balance of individual dispersal decisions, for example, by decreasing functional connectivity. Dispersal costs occur during departure, transience and settlement, and are levied in terms of energy, risk, time and lost opportunity, potentially influencing individual fitness. However, to the best of our knowledge, no study has yet quantified the energetic costs of dispersal across the dispersal period by comparing dispersing and philopatric individuals in the wild. Here, we employed animal-borne biologgers on a relatively large sample (N = 105) of juvenile roe deer to estimate energy expenditure indexed using the vector of dynamic body acceleration and mobility (distance travelled) in an intensively monitored population in the south-west of France. We predicted that energy expenditure would be higher in dispersers compared to philopatric individuals. We expected costs to be (a) particularly high during transience, (b) especially high in the more fragmented areas of the landscape and (c) concentrated during the night to avoid disturbance caused by human activity. There were no differences in energy expenditure between dispersers and philopatric individuals during the pre-dispersal phase. However, dispersers expended around 22% more energy and travelled around 63% further per day than philopatric individuals during transience. Differences in energy expenditure were much less pronounced during the settlement phase. The costs of transience were almost uniquely confined to the dawn period, when dispersers spent 23% more energy and travelled 112% further than philopatric individuals. Finally, the energetic costs of transience per unit time and the total distance travelled to locate a suitable settlement range were higher in areas of high road density. Our results provide strong support for the hypothesis that natal dispersal is energetically costly and indicate that transience is the most costly part of the process, particularly in fragmented landscapes. Further work is required to link dispersal costs with fitness components so as to understand the likely outcome of further environmental modifications on the evolution of dispersal behaviour.

Fear of the dark? Contrasting impacts of humans versus lynx on diel activity of roe deer across Europe.

Humans, as super predators, can have strong effects on wildlife behaviour, including profound modifications of diel activity patterns. Subsequent to the return of large carnivores to human-modified ecosystems, many prey species have adjusted their spatial behaviour to the contrasting landscapes of fear generated by both their natural predators and anthropogenic pressures. The effects of predation risk on temporal shifts in diel activity of prey, however, remain largely unexplored in human-dominated landscapes. We investigated the influence of the density of lynx Lynx lynx, a nocturnal predator, on the diel activity patterns of their main prey, the roe deer Capreolus capreolus, across a gradient of human disturbance and hunting at the European scale. Based on 11 million activity records from 431 individually GPS-monitored roe deer in 12 populations within the EURODEER network (http://eurodeer.org), we investigated how lynx predation risk in combination with both lethal and non-lethal human activities affected the diurnality of deer. We demonstrated marked plasticity in roe deer diel activity patterns in response to spatio-temporal variations in risk, mostly due to human activities. In particular, roe deer decreased their level of diurnality by a factor of 1.37 when the background level of general human disturbance was high. Hunting exacerbated this effect, as during the hunting season deer switched most of their activity to night-time and, to a lesser extent, to dawn, although this pattern varied noticeably in relation to lynx density. Indeed, in the presence of lynx, their main natural predator, roe deer were relatively more diurnal. Overall, our results revealed a strong influence of human activities and the presence of lynx on diel shifts in roe deer activity. In the context of the recovery of large carnivores across Europe, we provide important insights about the effects of predators on the behavioural responses of their prey in human-dominated ecosystems. Modifications in the temporal partitioning of ungulate activity as a response to human activities may facilitate human-wildlife coexistence, but likely also have knock-on effects for predator-prey interactions, with cascading effects on ecosystem functioning.

Résumé Les humains, en tant que 'super-prédateurs', peuvent avoir des effets importants sur le comportement de la faune sauvage, y compris des modifications profondes de leurs rythmes circadiens d'activité. A la suite du retour des grands carnivores dans les écosystèmes anthropisés, de nombreuses espèces proies ont ajusté leur comportement spatial à ces paysages de la peur contrastés, générés à la fois par les pressions liées aux risques anthropiques et à la présence de leurs prédateurs naturels. Les effets du risque de prédation sur les modifications temporelles des rythmes circadiens d'activité des proies restent cependant largement inconnus dans les écosystèmes dominés par l'homme. Ici, nous avons étudié l'influence de la densité de lynx Lynx lynx, un prédateur nocturne, sur les rythmes circadiens d'activité de leur proie principale, le chevreuil Capreolus capreolus, à travers un gradient de pressions anthropiques à l'échelle Européenne. Sur la base de plus de 11 million de données d'activité issues de 431 suivis individuels de chevreuils équipés de colliers GPS provenant de 12 populations au sein du réseau EURODEER (http://eurodeer.org), nous avons analysé comment le risque de prédation par le lynx, associé aux risques létaux et non-létaux des activités humaines, influence la diurnalité des chevreuils. Nous avons démontré une forte plasticité des rythmes circadiens d'activité des chevreuils en réponse aux variations spatio-temporelles du risque, et notamment face aux activités humaines. Plus particulièrement, les chevreuils diminuent leur degré de diurnalité d'un facteur de 1.37 lorsque le dérangement humain est important. La chasse accentue cet effet, puisque durant la saison de chasse les chevreuils basculent la plupart de leur activité de nuit, et dans une moindre mesure, durant l'aube également, bien que ce patron soit essentiellement variable en fonction de la densité de lynx. En effet, en présence de lynx, leur principal prédateur, les chevreuils sont relativement plus diurnes. Globalement, nos résultats révèlent une forte influence des activités humaines et de la présence de lynx sur l'ajustement des rythmes circadiens d'activité des chevreuils. Dans le contexte du retour des grands carnivores en Europe, notre étude apporte de nouvelles connaissances sur les effets des prédateurs sur la réponse comportementale de leur proie dans des écosystèmes anthropisés. La modification de la répartition temporelle de l'activité des ongulés en réponse aux activités humaines pourrait être un facteur facilitant la coexistence homme-faune sauvage, avec toutefois des conséquences autres sur les interactions prédateurs-proies et leurs effets en cascade sur le fonctionnement des écosystèmes.

Stay home, stay safe-Site familiarity reduces predation risk in a large herbivore in two contrasting study sites.

Restricting movements to familiar areas should increase individual fitness as it provides animals with information about the spatial distribution of resources and predation risk. While the benefits of familiarity for locating resources have been reported previously, the potential value of familiarity for predation avoidance has been accorded less attention. It has been suggested that familiarity should be beneficial for anti-predator behaviour when direct cues of predation risk are unclear and do not allow prey to identify well-defined spatial refuges. However, to our knowledge, this hypothesis has yet to be tested. Here, we assessed how site familiarity, measured as the intensity of use of a given location, is associated with the probability of roe deer Capreolus capreolus being killed by two predators with contrasting hunting tactics, the Eurasian lynx Lynx lynx and human hunters. While risk of human hunting was confined to open habitats, risk of lynx predation was more diffuse, with no clear refuge areas. We estimated cause-specific mortality rates in a competing risk framework for 212 GPS-collared roe deer in two ecologically distinct areas of Central Europe to test the hypothesis that the daily risk of being killed by lynx or hunters should be lower in areas of high familiarity. We found strong evidence that site familiarity reduces the risk of being predated by lynx, whereas the evidence that the risk of being hunted is linked to site familiarity was weak. We suggest that local knowledge about small-scale differences in predation risk and information about efficient escape routes affect an individual's ability to avoid or escape an attack by an ambush predator. Our study emphasizes the role of site familiarity in determining the susceptibility of prey to predation. Further research will be required to understand better how a cognitive map of individual spatial information is beneficial for avoiding predation in the arms race that drives the predator-prey shell game.

The influence of early-life allocation to antlers on male performance during adulthood: Evidence from contrasted populations of a large herbivore.

To secure mating opportunities, males often develop and maintain conspicuous traits that are involved in intrasexual and/or intersexual competition. While current models of sexual selection rely on the assumption that producing such traits is costly, quantifying the cost of allocating to secondary sexual traits remains challenging. According to the principle of allocation, high energy allocation to growth or sexual traits in males should lead to reduced energy allocation to the maintenance of cellular and physiological functions, potentially causing them to age faster, with impaired survival. We evaluated the short-term and delayed consequences of energy allocation to antlers early in life in two contrasted populations of roe deer, Capreolus capreolus. Although most males mate successfully for the first time in their fourth year, antlers are grown annually from the first year of life onwards. We tested the prediction that a high level of allocation to antler growth during the first two years of life should lead to lower body mass, antler size and survival during the early and late prime stages, as well as to reduced longevity overall. Growing and carrying long antlers during the first years of life was not associated with any detectable cost in the late prime stage. The positive association between antler growth in early life and adult body mass instead supports that fawn antler acts as an honest signal of phenotypic quality in roe deer. For a given body mass, yearling males growing longer antlers displayed impaired performance during their late prime. We also found a trend for a short-term survival cost of allocation to relative antler length during the second year of life. Yearling males that grow long antlers relative to their mass might display a fast life-history tactic. We argue that differential allocation to secondary sexual traits generates a diversity of individual trajectories that should impact population dynamics.

Truly sedentary? The multi-range tactic as a response to resource heterogeneity and unpredictability in a large herbivore.

Much research on large herbivore movement has focused on the annual scale to distinguish between resident and migratory tactics, commonly assuming that individuals are sedentary at the within-season scale. However, apparently sedentary animals may occupy a number of sub-seasonal functional home ranges (sfHR), particularly when the environment is spatially heterogeneous and/or temporally unpredictable. The roe deer (Capreolus capreolus) experiences sharply contrasting environmental conditions due to its widespread distribution, but appears markedly sedentary over much of its range. Using GPS monitoring from 15 populations across Europe, we evaluated the propensity of this large herbivore to be truly sedentary at the seasonal scale in relation to variation in environmental conditions. We studied movement using net square displacement to identify the possible use of sfHR. We expected that roe deer should be less sedentary within seasons in heterogeneous and unpredictable environments, while migratory individuals should be seasonally more sedentary than residents. Our analyses revealed that, across the 15 populations, all individuals adopted a multi-range tactic, occupying between two and nine sfHR during a given season. In addition, we showed that (i) the number of sfHR was only marginally influenced by variation in resource distribution, but decreased with increasing sfHR size; and (ii) the distance between sfHR increased with increasing heterogeneity and predictability in resource distribution, as well as with increasing sfHR size. We suggest that the multi-range tactic is likely widespread among large herbivores, allowing animals to track spatio-temporal variation in resource distribution and, thereby, to cope with changes in their local environment.

Mismatch between birth date and vegetation phenology slows the demography of roe deer.

Marked impacts of climate change on biodiversity have frequently been demonstrated, including temperature-related shifts in phenology and life-history traits. One potential major impact of climate change is the modification of synchronization between the phenology of different trophic levels. High phenotypic plasticity in laying date has allowed many bird species to track the increasingly early springs resulting from recent environmental change, but although changes in the timing of reproduction have been well studied in birds, these questions have only recently been addressed in mammals. To track peak resource availability, large herbivores like roe deer, with a widespread distribution across Europe, should also modify their life-history schedule in response to changes in vegetation phenology over time. In this study, we analysed the influence of climate change on the timing of roe deer births and the consequences for population demography and individual fitness. Our study provides a rare quantification of the demographic costs associated with the failure of a species to modify its phenology in response to a changing world. Given these fitness costs, the lack of response of roe deer birth dates to match the increasingly earlier onset of spring is in stark contrast with the marked phenotypic responses to climate change reported in many other mammals. We suggest that the lack of phenotypic plasticity in birth timing in roe deer is linked to its inability to track environmental cues of variation in resource availability for the timing of parturition.

Immunogenetic heterogeneity in a widespread ungulate: the European roe deer (Capreolus capreolus).

Understanding how immune genetic variation is shaped by selective and neutral processes in wild populations is of prime importance in both evolutionary biology and epidemiology. The European roe deer (Capreolus capreolus) has considerably expanded its distribution range these last decades, notably by colonizing agricultural landscapes. This range shift is likely to have led to bottlenecks and increased roe deer exposure to a new range of pathogens that until recently predominantly infected humans and domestic fauna. We therefore investigated the historical and contemporary forces that have shaped variability in a panel of genes involved in innate and acquired immunity in roe deer, including Mhc-Drb and genes encoding cytokines or toll-like receptors (TLRs). Together, our results suggest that genetic drift is the main contemporary evolutionary force shaping immunogenetic variation within populations. However, in contrast to the classical view, we found that some innate immune genes involved in micropathogen recognition (e.g. Tlrs) continue to evolve dynamically in roe deer in response to pathogen-mediated positive selection. Most studied Tlrs (Tlr2, Tlr4 and Tlr5) had similarly high levels of amino acid diversity in the three studied populations including one recently established in southwestern France that showed a clear signature of genetic bottleneck. Tlr2 implicated in the recognition of Gram-positive bacteria in domestic ungulates, showed strong evidence of balancing selection. The high immunogenetic variation revealed here implies that roe deer are able to cope with a wide spectrum of pathogens and to respond rapidly to emerging infectious diseases.

Reduced microsatellite heterozygosity does not affect natal dispersal in three contrasting roe deer populations.

Although theoretical studies have predicted a link between individual multilocus heterozygosity and dispersal, few empirical studies have investigated the effect of individual heterozygosity on dispersal propensity or distance. We investigated this link using measures of heterozygosity at 12 putatively neutral microsatellite markers and natal dispersal behaviour in three contrasting populations of European roe deer (Capreolus capreolus), a species displaying pre-saturation condition-dependent natal dispersal. We found no effect of individual heterozygosity on either dispersal propensity or dispersal distance. Average heterozygosity was similar across the three studied populations, but dispersal propensity and distance differed markedly among them. In Aurignac, dispersal propensity and distance were positively related to individual body mass, whereas there was no detectable effect of body mass on dispersal behaviour in Chizé and Trois Fontaines. We suggest that we should expect both dispersal propensity and distance to be greater when heterozygosity is lower only in those species where dispersal behaviour is driven by density-dependent competition for resources.

A one night stand? Reproductive excursions of female roe deer as a breeding dispersal tactic.

Breeding dispersal, defined as the net movement between successive breeding sites, remains a poorly understood and seldom reported phenomenon in mammals, despite its importance for population dynamics and genetics. In large herbivores, females may be more mobile during the breeding season, undertaking short-term trips (excursions) outside their normal home range. If fertilisation occurs, leading to gene flow of the male genome, this behaviour could be considered a form of breeding dispersal from a genetic point of view. Here, we investigated ranging behaviour of 235 adult roe deer using intensive GPS monitoring in six populations across Europe within the EURODEER initiative. We show that excursions are common from June to August among females, with 41.8% (vs. 18.1% of males) making at least one excursion. Most individuals performed only one excursion per season and departure dates for females were concentrated in time, centred on the rutting period, suggesting a link with reproduction. The distance females travelled during excursions was significantly greater than the site-specific average diameter of a male home range, while travel speed decreased once they progressed beyond this diameter, indicating search behaviour or interaction with other male(s) outside the resident male's territory. Because adults are normally highly sedentary, the potential for mating with relatives is substantial; hence, we conclude that rut excursions could be an alternative tactic enabling females to avoid mating with a closely related male. To understand better the ultimate drivers at play, it will be crucial to explore the genetic causes and consequences of this behaviour.

How does climate change influence demographic processes of widespread species? Lessons from the comparative analysis of contrasted populations of roe deer.

How populations respond to climate change depends on the interplay between life history, resource availability, and the intensity of the change. Roe deer are income breeders, with high levels of allocation to reproduction, and are hence strongly constrained by the availability of high quality resources during spring. We investigated how recent climate change has influenced demographic processes in two populations of this widespread species. Spring began increasingly earlier over the study, allowing us to identify 2 periods with contrasting onset of spring. Both populations grew more slowly when spring was early. As expected for a long-lived and iteroparous species, adult survival had the greatest potential impact on population growth. Using perturbation analyses, we measured the relative contribution of the demographic parameters to observed variation in population growth, both within and between periods and populations. Within periods, the identity of the critical parameter depended on the variance in growth rate, but variation in recruitment was the main driver of observed demographic change between periods of contrasting spring earliness. Our results indicate that roe deer in forest habitats cannot currently cope with increasingly early springs. We hypothesise that they should shift their distribution to richer, more heterogeneous landscapes to offset energetic requirements during the critical rearing stage.

Parturition date for a given female is highly repeatable within five roe deer populations.

Births are highly synchronized among females in many mammal populations in temperate areas. Although laying date for a given female is also repeatable within populations of birds, limited evidence suggests low repeatability of parturition date for individual females in mammals, and between-population variability in repeatability has never, to our knowledge, been assessed. We quantified the repeatability of parturition date for individual females in five populations of roe deer, which we found to vary between 0.54 and 0.93. Each year, some females gave birth consistently earlier in the year, whereas others gave birth consistently later. In addition, all females followed the same lifetime trajectory for parturition date, giving birth progressively earlier as they aged. Giving birth early should allow mothers to increase offspring survival, although few females managed to do so. The marked repeatability of parturition date in roe deer females is the highest ever reported for a mammal, suggesting low phenotypic plasticity in this trait.

Spatial scaling in bed-site selection by roe deer fawns: Implications for mitigating neonatal mortality during mowing.

When habitat use by field-dwelling animals coincides in space and time with agricultural practices such as spring mowing of meadows, human-wildlife conflicts can have deadly consequences for wildlife. Roe deer (Capreolus capreolus L.) fawns are particularly vulnerable because they hide in meadows during the rearing phase. Thus, a better understanding of the habitat drivers of bed-site selection is critical to mitigating fawn mortality during mowing. Here, we tease apart the among-field (presumably driven by maternal behaviour) and within-field (driven by fawn behaviour) components of bed-site selection of roe deer during the spring mowing season. We collected over 600 fawn bed sites across an environmentally diverse study region. At the among-field scale, we implemented a used versus available design and employed a two-part statistical model (GAMLSS) to identify habitat characteristics that were linked to either fawn presence (vs. absence) or abundance on a given field. At the within-field scale, we compared habitat characteristics at fawn bed-sites with paired random sites using a conditional logistic regression model. At the among-field scale, fawns were more likely to be present, and were more abundant, in fields within more diverse, rural landscapes, with nearby woodland. Surprisingly, fawns were more often present in fields that were near roads and had lower vegetation productivity. At the within-field scale, however, fawns preferred bed-sites which were further from both roads and woodland, but that provided the best visual cover to minimise predation risk. Our findings revealed substantial and novel scale-dependent differences in the drivers of habitat selection of mothers and fawns, which, together, determine the precise locations of bed-sites between and within meadows. These results may aid wildlife managers in identifying areas where there is a high probability of encountering a roe deer fawn so as to initiate targeted searches prior to mowing and, ultimately, mitigate fawn mowing mortality.

Landscape fragmentation generates spatial variation of diet composition and quality in a generalist herbivore.

Forest fragmentation may benefit generalist herbivores by increasing access to various substitutable food resources, with potential consequences for their population dynamics. We studied a European roe deer (Capreolus capreolus) population living in an agricultural mosaic of forest, woodlots, meadows and cultivated crops. We tested whether diet composition and quality varied spatially across the landscape using botanical analyses of rumen contents and chemical analyses of the plants consumed in relation to landscape metrics. In summer and non-mast winters, roe deer ate more cultivated seeds and less native forest browse with increasing availability of crops in the local landscape. This spatial variation resulted in contrasting diet quality, with more cell content and lower lignin and hemicellulose content (high quality) for individuals living in more open habitats. The pattern was less marked in the other seasons when diet composition, but not diet quality, was only weakly related to landscape structure. In mast autumns and winters, the consumption of acorns across the entire landscape resulted in a low level of differentiation in diet composition and quality. Our results reflect the ability of generalist species, such as roe deer, to adapt to the fragmentation of their forest habitat by exhibiting a plastic feeding behavior, enabling them to use supplementary resources available in the agricultural matrix. This flexibility confers nutritional advantages to individuals with access to cultivated fields when their native food resources are depleted or decline in quality (e.g. during non-mast years) and may explain local heterogeneities in individual phenotypic quality.

Roads constrain movement across behavioural processes in a partially migratory ungulate.

BACKGROUND: Human disturbance alters animal movement globally and infrastructure, such as roads, can act as physical barriers that impact behaviour across multiple spatial scales. In ungulates, roads can particularly hamper key ecological processes such as dispersal and migration, which ensure functional connectivity among populations, and may be particularly important for population performance in highly human-dominated landscapes. The impact of roads on some aspects of ungulate behaviour has already been studied. However, potential differences in response to roads during migration, dispersal and home range movements have never been evaluated. Addressing these issues is particularly important to assess the resistance of European landscapes to the range of wildlife movement processes, and to evaluate how animals adjust to anthropogenic constraints. METHODS: We analysed 95 GPS trajectories from 6 populations of European roe deer (Capreolus capreolus) across the Alps and central Europe. We investigated how roe deer movements were affected by landscape characteristics, including roads, and we evaluated potential differences in road avoidance among resident, migratory and dispersing animals (hereafter, movement modes). First, using Net Squared Displacement and a spatio-temporal clustering algorithm, we classified individuals as residents, migrants or dispersers. We then identified the start and end dates of the migration and dispersal trajectories, and retained only the GPS locations that fell between those dates (i.e., during transience). Finally, we used the resulting trajectories to perform an integrated step selection analysis. RESULTS: We found that roe deer moved through more forested areas during the day and visited less forested areas at night. They also minimised elevation gains and losses along their movement trajectories. Road crossings were strongly avoided at all times of day, but when they occurred, they were more likely to occur during longer steps and in more forested areas. Road avoidance did not vary among movement modes and, during dispersal and migration, it remained high and consistent with that expressed during home range movements. CONCLUSIONS: Roads can represent a major constraint to movement across modes and populations, potentially limiting functional connectivity at multiple ecological scales. In particular, they can affect migrating individuals that track seasonal resources, and dispersing animals searching for novel ranges.

Settle Down! Ranging Behaviour Responses of Roe Deer to Different Capture and Release Methods.

The fitting of tracking devices to wild animals requires capture and handling which causes stress and can potentially cause injury, behavioural modifications that can affect animal welfare and the output of research. We evaluated post capture and release ranging behaviour responses of roe deer (Capreolus capreolus) for five different capture methods. We analysed the distance from the centre of gravity and between successive locations, using data from 14 different study sites within the EURODEER collaborative project. Independently of the capture method, we observed a shorter distance between successive locations and contextual shift away from the home range centre of gravity after the capture and release event. However, individuals converged towards the average behaviour within a relatively short space of time (between 10 days and one month). If researchers investigate questions based on the distance between successive locations of the home range, we recommend (1) initial investigation to establish when the animals start to behave normally again or (2) not using the first two to three weeks of data for their analysis. We also encourage researchers to continually adapt methods to minimize stress and prioritize animal welfare wherever possible, according to the Refinement of the Three R's.