Species distribution models (SDMs) are often calibrated using presence‐only datasets plagued with environmental sampling bias, which leads to a decrease of model accuracy. In order to compensate for this bias, it has been suggested that background data (or pseudoabsences) should represent the area that has been sampled. However, spatially‐explicit knowledge of sampling effort is rarely available. In multi‐species studies, sampling effort has been inferred following the target‐group (TG) approach, where aggregated occurrence of TG species informs the selection of background data. However, little is known about the species‐ specific response to this type of bias correction. The present study aims at evaluating the impacts of sampling bias and bias correction on SDM performance. To this end, we designed a realistic system of sampling bias and virtual species based on 92 terrestrial mammal species occurring in the Mediterranean basin. We manipulated presence and background data selection to calibrate four SDM types. Unbiased (unbiased presence data) and biased (biased presence data) SDMs were calibrated using randomly distributed background data. We used real and TG‐estimated sampling efforts in background selection to correct for sampling bias in presence data. Overall, environmental sampling bias had a deleterious effect on SDM performance. In addition, bias correction improved model accuracy, and especially when based on spatially‐explicit knowledge of sampling effort. However, our results highlight important species‐specific variations in susceptibility to sampling bias, which were largely explained by range size: widely‐distributed species were most vulnerable to sampling bias and bias correction was even detrimental for narrow‐ranging species. Furthermore, spatial discrepancies in SDM predictions suggest that bias correction effectively replaces an underestimation bias with an overestimation bias, particularly in areas of low sampling intensity. Thus, our results call for a better estimation of sampling effort in multispecies system, and cautions the uninformed and automatic application of TG bias correction.
Aim The recent recovery of large carnivores in Europe has been explained as resulting from a decrease in human persecution driven by widespread rural land abandonment, paralleled by forest cover increase and the consequent increase in availability of shelter and prey. We investigated whether land cover and human population density changes are related to the relative probability of occurrence of three European large carnivores: the grey wolf (Canis lupus), the Eurasian lynx (Lynx lynx) and the brown bear (Ursus arctos). Location Europe, west of 64° longitude. Methods We fitted multi‐temporal species distribution models using >50,000 occurrence points with time series of land cover, landscape configuration, protected areas, hunting regulations and human population density covering a 24‐year period (1992–2015). Within the temporal window considered, we then predicted changes in habitat suitability for large carnivores throughout Europe. Results Between 1992 and 2015, the habitat suitability for the three species increased in Eastern Europe, the Balkans, North‐West Iberian Peninsula and Northern Scandinavia, but showed mixed trends in Western and Southern Europe. These trends were primarily associated with increases in forest cover and decreases in human population density, and, additionally, with decreases in the cover of mosaics of cropland and natural vegetation. Main conclusions Recent land cover and human population changes appear to have altered the habitat suitability pattern for large carnivores in Europe, whereas protection level did not play a role. While projected changes largely match the observed recovery of large carnivore populations, we found mismatches with the recent expansion of wolves in Central and Southern Europe, where factors not included in our models may have played a dominant role. This suggests that large carnivores’ co‐existence with humans in European landscapes is not limited by habitat availability, but other factors such as favourable human tolerance and policy.
Urbanisation and climate change are two global change processes that affect animal distributions, posing critical threats to biodiversity. Due to its versatile ecology and synurbic habits, Kuhl's pipistrelle (Pipistrellus kuhlii) offers a unique opportunity to explore the relative effects of climate change and urbanisation on species distributions. In a climate change scenario, this typically Mediterranean species is expected to expand its range in response to increasing temperatures. We collected 25,132 high-resolution occurrence records from P. kuhlii European range between 1980 and 2013 and modelled the species' distribution with a multi-temporal approach, using three bioclimatic variables and one proxy of urbanisation. Temperature in the coldest quarter of the year was the most important factor predicting the presence of P. kuhlii and showed an increasing trend in the study period; mean annual precipitation and precipitation seasonality were also relevant, but to a lower extent. Although urbanisation increased in recently colonised areas, it had little effect on the species' presence predictability. P. kuhlii expanded its geographical range by about 394 % in the last four decades, a process that can be interpreted as a response to climate change.
the link between spatio-temporal resource patterns and animal movement behaviour is a key ecological process, however, limited experimental support for this connection has been produced at the home range scale. In this study, we analysed the spatial responses of a resident large herbivore (roe deer Capreolus capreolus) using an in situ manipulation of a concentrated food resource. Specifically, we experimentally altered feeding site accessibility to roe deer and recorded (for 25 animal-years) individual responses by GPS tracking. We found that, following the loss of their preferred resource, roe deer actively tracked resource dynamics leading to more exploratory movements, and larger, spatially-shifted home ranges. Then, we showed, for the first time experimentally, the importance of site fidelity in the maintenance of large mammal home ranges by demonstrating the return of individuals to their familiar, preferred resource despite the presence of alternate, equally-valuable food resources. This behaviour was modulated at the individual level, where roe deer characterised by a high preference for feeding sites exhibited more pronounced behavioural adjustments during the manipulation. Together, our results establish the connections between herbivore movements, space-use, individual preference, and the spatio-temporal pattern of resources in home ranging behaviour. Animals move to change the environmental conditions they experience 1 such as the presence of predators and competitors, and the availability of resources. Because foraging efficiency can be linked to individual fitness 2 , food acquisition is thought to be a primary driver underlying animal movements 3. Consequently, space-use represents the geographic realization of optimizing fitness as a function of resource availability and acquisition costs 4. Food resources are usually dynamic in both space and time 5. In the case of herbivores, animals typically feed on vegetation distributed in patches, which are characterized by important temporal variations in quantity and quality 6. In this context, strong spatio-temporal gradients in resource availability, at either landscape or regional scales, appear to drive migration and nomadism tactics 7. In many herbivore populations, however, individuals show a high year-round fidelity to a spatially-localized home range. It has been suggested that the foraging benefits of site familiarity, where resources are constant or predictable, are responsible for the formation of a stable home range (see Fagan et al. 8 for a review). While the home range has traditionally been perceived as a relatively static space-use tactic, recent evidence suggests that animals have sub-seasonal home ranges 9 i.e.,
Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions (Panthera leo) and subordinate African wild dogs (Lycaon pictus) with high-resolution remote sensing in an integrated step selection analysis to investigate how fine-scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa's Hluhluwe-iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion-avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion-avoidance strategy was to select landscape features that aid in avoidance of lion detection. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion-encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as evershrinking carnivore ranges force inferior competitors into increased contact with dominant species.
13Many animals restrict their movements to a characteristic home range. This pattern of 14 constrained space-use is thought to result from the foraging benefits of memorizing the 15 locations and quality of heterogeneously distributed resources. However, due to the 16 confounding effects of sensory perception, the role of memory in home range movement 17 behavior lacks unequivocal evidence in the wild. Here, we analyze the foraging decisions of a 18 large mammal during a field resource manipulation experiment designed to disentangle the 19 effects of memory and perception. Using a cognitive movement model, we demonstrate that 20 roe deer (Capreolus capreolus) rely on memory, not perception, to track the spatio-temporal 21 dynamics of resources within their home range. Our findings show a memory-based spatial 22 transition model parametrized with experimental data can successfully be used to quantify 23 cognitive processes and to predict how animals respond to resource heterogeneity in space 24 and time. 25
Digital tracking technologies have considerably increased the amount and quality of animal trajectories, enabling the study of habitat use and habitat selection at a fine spatial and temporal scale. However, current approaches do not yet explicitly account for a key aspect of habitat use, namely the sequential variation in the use of different habitat features. To overcome this limitation, we propose a tree-based approach that makes use of sequence analysis methods, derived from molecular biology, to explore and identify ecologically relevant sequential patterns in habitat use by animals. We applied this approach to ecological data consisting of simulated and real trajectories from a roe deer population (Capreolus capreolus), expressed as ordered sequences of habitat use. We show that our approach effectively captured spatio-temporal patterns of sequential habitat use by roe deer. In our case study, individual sequences were clustered according to the sequential use of the elevation gradient (first order) and of open/closed habitats (second order). We provided evidence for several behavioural processes, such as migration and daily alternating habitat use. Some unexpected patterns, such as homogeneous sequences of use of open habitat, could also be identified. Our findings advocate the importance of dealing with the sequential nature of movement data. Approaches based on sequence analysis methods are particularly useful and effective since they allow exploring temporal patterns of habitat use in a synthetic and visually captive manner. The proposed approach represents a useful and effective way to classify individual movement behaviour across populations and species. Ultimately, this method can be applied to explore the temporal scale of ecological processes based on movement
1. 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.2. 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.3. 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.4. 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.5. 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 1330 |
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