Safety first: seasonal and diel habitat selection patterns by red deer in a contrasted landscape

Remote sensing reveals the role of forage quality and quantity for summer habitat use in red deer

BACKGROUND

The habitat use of wild ungulates is determined by forage availability, but also the avoidance of predation and human disturbance. They should apply foraging strategies that provide the most energy at the lowest cost. However, due to data limitations at the scale of movement trajectories, it is not clear to what extent even well-studied species such as red deer (Cervus elaphus) trade-off between forage quality and quantity, especially in heterogeneous alpine habitats characterized by short vegetation periods.

METHODS

We used remote sensing data to derive spatially continuous forage quality and quantity information. To predict relative nitrogen (i.e. forage quality) and biomass (i.e. forage quantity), we related field data to predictor variables derived from Sentinel-2 satellite data. In particular, our approach employed random forest regression algorithms, integrating various remote sensing variables such as reflectance values, vegetation indices and optical traits derived from a radiative transfer model. We combined these forage characteristics with variables representing human activity, and applied integrated step selection functions to estimate sex-specific summer habitat selection of red deer in open habitats within and around the Swiss National Park, an alpine Strict Nature Reserve.

RESULTS

The combination of vegetation indices and optical traits greatly improved predictive power in both the biomass (R2 = 0.60, Root mean square error (RMSE) = 88.55 g/m2) and relative nitrogen models (R2 = 0.34, RMSE = 0.28%). Both female and male red deer selected more strongly for biomass (estimate = 0.672 ± 0.059 SE for normalised values for females, and 0.507 ± 0.061 for males) than relative nitrogen (estimate = 0.124 ± 0.062 for females, and 0.161 ± 0.061 for males, respectively). Females showed higher levels of use of the Swiss National Park.

CONCLUSIONS

Red deer in summer habitats select forage quantity over quality with little difference between sexes. Females respond more strongly to human activities and thus prefer the Swiss National Park. Our results demonstrate the capability of satellite data to estimate forage quality and quantity separately for movement ecology studies, going beyond the exclusive use of conventional vegetation indices.

A highly variable habitat selection in moose across diel and seasonal scales

PURPOSE

Habitat selection in animals is a hierarchal process that operates across multiple temporal and spatial scales, adapting to changes in environmental conditions, human disturbances, and predation risks. Despite its significance, previous research often oversimplifies temporal dynamics by categorizing them into broad seasonal and diel patterns, overlooking the continuous nature of temporal variability and habitat specificity.

METHODS

We investigated the temporal patterns in habitat selection of moose (Alces alces) in highly heterogenous landscapes at the southwestern edge of their European range using step-selection functions. Utilizing over 700,000 GPS locations from 34 adult moose, we aimed to assess seasonal and diel patterns in their selectivity for both natural and human-related habitats.

RESULTS

Our findings revealed significant overall temporal variation in moose habitat selection at both seasonal and diel scales. Moose selectivity toward different habitats showed low repeatability over time, with 35% of cases displaying negative correlation between selectivity in different time windows. Diel changes were more pronounced, showing 5.6-fold difference in cumulative selectivity, compared to 1.4-fold difference in seasonal dynamics. Notably, moose exhibited lower selectivity during nighttime hours throughout the year compared to daytime hours. The study also highlighted distinct habitat selection patterns across different habitat types: natural habitats (deciduous forests, coniferous forests, wetlands) exhibited pronounced seasonal variation, while anthropogenic habitats (grasslands, arable land, roads and settlements) showed more diel variability. Moose generally avoided human-related habitats during daytime hours, but their preferences during nighttime varied depending on the habitat type and time of year.

CONCLUSION

This research advances our understanding of the complex temporal patterns in habitat selection by large herbivores and underscores the importance of considering temporal dynamics in habitat selection modelling.

Review: A theoretical framework to define foraging behaviour syndromes in ruminants using wearable technologies

Due to intensification processes that have had negative impacts on environmental externalities, pastoral farmers, worldwide, are facing increasing scrutiny and pressure from consumers, governments, and the public to reduce the environmental footprint of their operations. Developing tools and systems that farmers can use to maintain profitability and productivity while decreasing the negative externalities of their operations is important for the vitality of rural sectors. Capitalising on individual animal variation has been promoted as an opportunity to increase animal productivity and enhance welfare while decreasing the negative environmental impacts of pastoral farming. Of particular interest are behaviours that are associated with foraging, as these are the primary drivers of variation in animal performance in pastoral farming. Developing a methodology that can identify consistent foraging behavioural variations across individuals is a critical step in making this a practical solution for farmers and herders. As with all behavioural research, the fundamental challenge is selecting the appropriate behaviours to measure. Understanding the contextual drivers of behavioural expression is a major development in this process. Herd management and composition, environmental variables and many more contexts alter the expression of behaviours, so how do we capture behaviours of interest? We propose the use of a systematic methodology to capture behaviours of significance from large groups of foraging ruminants using wearable technology, namely Global Positioning System and accelerometers. This contrasts with traditional reductionist methodologies used in behaviour research and has the benefit of providing large objective datasets from undisturbed animals. Statistical analysis of the data will inform behaviours of interest that are clustered together to inform a three-factor foraging behaviour syndrome model adapted from the animal five-factor model (activity, aggression, boldness, exploration, sociability) of personality. Syndromes, unlike personalities, include correlated suites of behaviours that are expressed across spatial and temporal contexts. By capturing foraging behaviour syndromes, selection can be used to match appropriate syndromes to different pastoral farming landscapes, thereby potentially improving the system's productivity while reducing their negative environmental impact.

Experimentally testing animal responses to prescribed fire size and severity

Deserts are often highly biodiverse and provide important habitats for many threatened species. Fire is a dominant disturbance in deserts, and prescribed burning is increasingly being used by conservation managers and Indigenous peoples to mitigate the damaging effects of climate change, invasive plants, and land-use change. The size, severity, and patchiness of fires can affect how animals respond to fire. However, there are almost no studies examining such burn characteristics in desert environments, which precludes the use of such information in conservation planning. Using a before-after control-impact approach with 20 sampling sites, we studied the outcomes of 10 prescribed burns of varying size (5-267 ha), severity, and patchiness to identify which variables best predicted changes in small mammal and reptile species richness and abundance. Three of the 13 species showed a clear response to fire. Captures increased for 2 species (1 mammal, 1 reptile) and decreased for 1 species (a reptile) as the proportional area burned around traps increased. Two other mammal species showed weaker positive responses to fire. Total burn size and burn patchiness were not influential predictors for any species. Changes in capture rates occurred only at sites with the largest and most severe burns. No fire-related changes in capture rates were observed where fires were small and very patchy. Our results suggest that there may be thresholds of fire size or fire severity that trigger responses to fire, which has consequences for management programs underpinned by the patch mosaic burning paradigm. The prescribed burns we studied, which are typical in scale and intensity across many desert regions, facilitated the presence of some taxa and are unlikely to have widespread or persistent negative impacts on small mammal or reptile communities in this ecosystem provided that long unburned habitat harboring threatened species is protected.

Habitat visibility affects the behavioral response of a large herbivore to human disturbance in forest landscapes

Wildlife can perceive humans as predators and human disturbance, whether lethal (e.g., hunting) or non-lethal (e.g., hiking, biking, and skiing), triggers antipredator behavior among prey. Visibility is the property that relates habitat structure to accessibility of visual information that allows animals to detect predators and evaluate predation risk. Thus, the visibility of a habitat (hereafter referred to as habitat visibility) for prey species alters the perceived risk of predation and therefore has a strong influence on their antipredator behavior. Yet, knowledge of how habitat visibility affects the response of animals to different types of human disturbance is limited, partly, because it is challenging to measure habitat visibility for animals at a fine spatial scale over a landscape, particularly in highly heterogeneous landscapes (e.g., forests). In this study, we employed a newly described approach that combines terrestrial and airborne LiDAR to contiguously measure fine-scale habitat visibility in a forested landscape. We applied the LiDAR-derived habitat visibility to examine how habitat visibility in forests affects the summer space use of 20 GPS-collared female red deer (Cervus elaphus) modeled with integrated step-selection functions in the Bavarian Forest National Park, Germany when exposed to various types of human disturbance including recreational activities, forest roads, hiking trails, and hunting. We found that red deer in our study area avoided areas with higher all types of human disturbance, especially during daylight hours. Furthermore, habitat visibility significantly modified the use of space by red deer in response to human recreational activities, forest roads, and hiking trails, but not to the hunting area. Red deer tended to tolerate a higher intensity of human recreational activities and to use areas closer to forest roads or hiking trails when they have lower habitat visibility (i.e., more cover). Our findings highlight the importance of considering visual perception when studying the response of wild animals to human disturbance. We emphasize the potential to mitigate negative consequences of human disturbance on wildlife, through measures such as maintaining vegetative buffers around recreational infrastructure (e.g., roads and skiing tracks) in order to reduce habitat visibility around areas frequented by humans.

The presence of wolves leads to spatial differentiation in deer browsing pressure on forest regeneration

With the recent return of large carnivores to forest ecosystems, an important issue for forest owners and managers is how large predators influence the behaviour of their natural prey and, consequently, cervid browsing pressure on forest regeneration. To investigate this issue, we analysed deer pressure on Scots pine and European beech plantations in northern Poland's ecosystems with and without permanent wolf populations. Two characteristics were used to describe deer browsing patterns in plantations: distance from the forest edge (spatial pattern of browsing) and number of saplings browsed (browsing intensity). Beech saplings were more intensively browsed by deer compared to pine saplings. In a forest ecosystem not inhabited by wolves, spatial variation in browsing patterns on small-sized beech plantations was the same between the edge and the center. In contrast, browsing pressure by deer was greater at the edges on large-sized pine plantations. The presence of wolves reduced deer browsing on beech and increased browsing on pine saplings. In addition, deer foraging behaviour changed in large-sized pine plantations, and browsing pressure increased only in the central areas of the plantations. We assume that the presence of wolves in a forest landscape is an important factor that alters browsing pressure on the youngest stands and their spatial pattern, and that this may be a major factor in stand regeneration, especially in small forest patches.

Accounting for behaviour in fine-scale habitat selection: A case study highlighting methodological intricacies

Animal habitat selection-central in both theoretical and applied ecology-may depend on behavioural motivations such as foraging, predator avoidance, and thermoregulation. Step-selection functions (SSFs) enable assessment of fine-scale habitat selection as a function of an animal's movement capacities and spatiotemporal variation in extrinsic conditions. If animal location data can be associated with behaviour, SSFs are an intuitive approach to quantify behaviour-specific habitat selection. Fitting SSFs separately for distinct behavioural states helped to uncover state-specific selection patterns. However, while the definition of the availability domain has been highlighted as the most critical aspect of SSFs, the influence of accounting for behaviour in the use-availability design has not been quantified yet. Using a predator-free population of high-arctic muskoxen Ovibos moschatus as a case study, we aimed to evaluate how (1) defining behaviour-specific availability domains, and/or (2) fitting separate behaviour-specific models impacts (a) model structure, (b) estimated selection coefficients and (c) model predictive performance as opposed to behaviour-unspecific approaches. To do so, we first applied hidden Markov models to infer different behavioural modes (resting, foraging, relocating) from hourly GPS positions (19 individuals, 153-1062 observation days/animal). Using SSFs, we then compared behaviour-specific versus behaviour-unspecific habitat selection in relation to terrain features, vegetation and snow conditions. Our results show that incorporating behaviour into the definition of the availability domain primarily impacts model structure (i.e. variable selection), whereas fitting separate behaviour-specific models mainly influences selection strength. Behaviour-specific availability domains improved predictive performance for foraging and relocating models (i.e. behaviours with medium to large spatial displacement), but decreased performance for resting models. Thus, even for a predator-free population subject to only negligible interspecific competition and human disturbance we found that accounting for behaviour in SSFs impacted model structure, selection coefficients and predictive performance. Our results indicate that for robust inference, both a behaviour-specific availability domain and behaviour-specific model fitting should be explored, especially for populations where strong spatiotemporal selection trade-offs are expected. This is particularly critical if wildlife habitat preferences are estimated to inform management and conservation initiatives.

Meeting the challenges of wild boar hunting in a modern society: The case of France

Modern hunting is an ambivalent practice, torn between leisure and labor. Nowhere are these conflicting dimensions better manifested than for wild boar-a simultaneous game and pest species in many countries. Here, we consider the sociological, political and cultural phenomenon of wild boar hunting from a change perspective, starting at its historical roots to future implications concerning the changing demographics, drivers, needs and practices of a modernizing hunting community. Using the case context of France, we present an approach to deconstructing each component of wild boar hunting firstly, and subsequently the external forces that change the nature of hunting. The objective of this manuscript is to discuss of the wild boar optimal harvesting to be applied in changing social and ecological environment. Findings show that the challenges facing wild boar management will likely intensify in the future, especially under the spotlight of a controversial public debate.

Are several small wildlife crossing structures better than a single large? Arguments from the perspective of large wildlife conservation

Crossing structures for large wildlife are increasingly being constructed at major roads and railways in many countries and current guidelines for wildlife mitigation at linear infrastructures tend to advocate for large crossing structures sited at major movement corridors for the target species. The concept of movement corridors has, however, been challenged and pinching animal movements into bottlenecks entails risks. In this paper, I address the SLOSS dilemma of road ecology, i.e. the discussion whether a Single Large Or Several Small crossing structures along a linear barrier would produce the most benefit for wildlife, using the case of crossing structures for large wildlife in Sweden. I point out risks, ecological as well as practical, with investing in one large crossing structure and list a number of situations where it may be more beneficial to distribute the conservation efforts in the landscape by constructing several smaller crossing structures; for example, when the ecological knowledge is insufficient, when animal interactions are expected to be significant, when the landscape changes over time or when future human development cannot be controlled. I argue that such situations are often what infrastructure planning faces and that the default strategy, therefore, should be to distribute, rather than to concentrate passage opportunities along major transport infrastructures. I suggest that distributing passage opportunities over several smaller crossing structures would convey a risk diversification and that this strategy could facilitate the planning of wildlife mitigation. What to choose would however depend on, inter alia, landscape composition and ecology and on relationships amongst target species. A single large structure should be selected where it is likely that it can serve a large proportion of target animals and where the long-term functionality of the crossing structure can be guaranteed. New research is needed to support trade-offs between size and number of crossing structures. Cost-effectiveness analyses of wildlife crossing structures are currently rare and need to be further explored. Camera trapping and video surveillance of crossing structures provide opportunities to analyse details concerning, for example, any individual biases according to sex, age, status and grouping and any antagonism between species and individuals. Wildlife ecology research needs to better address questions posed by road and railway planning regarding the importance of specific movement routes and movement distances.

The spatial ecology of red deer under different land use and management scenarios: Protected areas, mixed farms and fenced hunting estates

The knowledge regarding the spatial ecology of red deer (Cervus elaphus) in different environments is crucial if effective management actions are to be designed. However, this knowledge continues to be scarce in the complex contexts of mixed land use and management circumstances. This study describes the spatial ecology of red deer monitored using GPS collars in Mediterranean ecosystems of South-Central Spain, considering the effect of individual and seasonal (food shortage period, rut, hunting season and food abundance period) factors on different land use and management scenarios, namely protected areas, mixed farms and fenced hunting estates. Our results showed less activity (ACT), a shorter daily range (DR) and a smaller home range (HR) during the food shortage period: ACT: 0.38 ± (SD) 0.12; DR: 3010.9 ± 727.3 m; and weekly HR: 122.2 ± 59.6 ha. With regard to land use, individuals were less ACT and had a smaller DR on fenced hunting estates (ACT: 0.24 ± 0.12; DR: 1946.3 ± 706.7 m) than in protected areas (ACT: 0.59 ± 0.12; DR: 4071.4 ± 1068.2 m) or on mixed farms (ACT: 0.57 ± 0.29; DR: 5431.1 ± 1939.5 m) in all the periods studied. Red deer selected land cover with forage and shelter when foraging and resting, respectively. When drive hunt events occurred (mixed farms and fenced hunting estates), the deer were more prone to select safer habitats (scrublands) and avoid open areas (crops or grasslands) than were their counterparts in protected areas. The patterns observed can be explained by sexual and seasonal differences as regards requirements, the response to disturbances and, interestingly, population management. Our results provide useful information with which to design scientifically-based species adaptive management in response to relevant and timely situations in Europe, such as the potential transmission of shared infections, vehicle collisions, and damage to crops and ecosystems.

Temporal trends (1953-2012) of toxic and essential elements in red deer antlers from northeastern Poland

Red deer antlers have a number of advantages that make them a unique material for monitoring trace elements. As antlers are shed and regrown every year, results of toxicological investigations can be applied to a particular region and time. We analyzed the content of four toxic (Pb, Cd, Hg, As) and three essential (Cu, Zn, Fe) trace elements in 254 red deer antler samples spanning between 1953 and 2012. Age of stags did not influence concentrations of analyzed elements in antlers, except for Zn whose level increased with age. The highest concentrations of toxic elements occurred at the beginning of the analyzed period. Levels of Pb, Hg and Zn in antlers decreased over the course of the study. Levels of Cd and As were low and presented a steady trend. Variations in the levels of the analyzed elements in red deer antlers are considered to reflect levels of exposure of animals in their habitat over the sixty-year study period. The range of essential element levels did not indicate any contamination. Environmental conditions in the Mazury Region during the last decades appeared to have improved significantly, as established by declining trends of toxic elements levels in deer antlers.

Trading fear for food in the Anthropocene: How ungulates cope with human disturbance in a multi-use, suburban ecosystem

Resource distribution, predation risk and disturbance in space and time can affect how animals use their environment. To date few studies have assessed the spatiotemporal trade-off between resource acquisition and avoidance of risks and human disturbance in small protected areas embedded in an urban matrix. A better understanding of the forage-safety trade-off in urban protected areas (UPA) is key to the design of evidence-based approaches to deal with the ever-increasing human-wildlife impacts typical of UPA. Herein, we analyzed camera trap data to evaluate how two ungulate species trade fear for food in a 60 km² human-dominated UPA without natural predators. We found that wild boar (Sus scrofa) were predominantly active at night, while roe deer (Capreolus capreolus) showed a typical bimodal crepuscular activity pattern. Occupancy analysis indicated that deciduous forest and the presence of high seats for hunting played an important role in determining the space use of wild boar. For roe deer, we found indications that the presence of forest influenced space use, although the null model was retained among the top ranked models. Our results confirm that wild boar and roe deer are able to thrive in heavily human dominated landscapes characterized by intensive recreational use and hunting, such as protected areas embedded in an urban matrix.

Winter severity and anthropogenic factors affect spatial behaviour of red deer in the Carpathians

Spatial ecology of red deer Cervus elaphus is shaped by both natural and anthropogenic factors. We used radio telemetry to investigate factors affecting habitat selection on two spatial scales, home range sizes and migratory behaviour of red deer (N = 8 individuals) in two mountain ranges of the western Carpathians in 2004–2007. The two study areas differed in terms of environmental conditions: Beskid Sądecki had higher altitudes, higher human population and road density and milder winters than Beskid Niski. Red deer in both areas selected forests and avoided agricultural habitats on both spatial scales. Elevation affected site selection only in Beskid Sądecki: deer selected higher altitudes for their home ranges, but lower altitudes within them. Deer avoided major roads when selecting their home ranges in both sites, but only in Beskid Sądecki, they also avoided roads within their home ranges. Deer in both study sites selected locations closer to supplementary feeding sites in winter. In years with more severe winters, deer in Beskid Niski displayed seasonal migration to south-facing slopes. Deer in Beskid Sadecki showed short-distance altitudinal movements from low elevations in winter to high elevations in summer, and a short-term descent to low elevations in August–September. Our results fit the general concept that climatic conditions and human-related factors shape spatial behaviour in ungulates, and that snow conditions are particularly important for migration. Climate change will likely contribute to diminishing migration in red deer in the Carpathians.