A multi-patch use of the habitat: testing the First-Passage Time analysis on roe deer paths

A heterogeneous environment includes several levels of resource aggregation. Individuals do not respond in the same way to this heterogeneity depending on the scale at which they perceive it, and develop different foraging tactics accordingly. The development of methods to analyse animal movements has enabled the study of foraging tactics at several scales. Nevertheless, applied to large vertebrates, these methods have generally been used at large scales, such as for migration trips or the study of marine patches several kilometres large. In this study, we applied a recent method, the First-Passage Time analysis, based on a measure of the foraging effort along the path, to a much finer scale, i.e. under 500 meters. We used 30 daily paths of highly sedentary roe deer females. We modified the initial method, developed by Fauchald and Tveraa (2003), to detect a multi-patch use of the habitat. First-Passage Time analysis results showed that most of the female roe deer exploited their home range as a patchy resource, ranging from 1 to 5 areas of intensive use in their home range. These areas were identified as the most attractive sites within the roe deer female home range. Moreover, this method allowed us to rank the attractive areas according to the time spent in each area. Coupled with habitat selection analysis to identify what makes these areas attractive, the First-Passage Time analysis should offer a suitable tool for landscape ecology and management

Same habitat types but different use: evidence of context-dependent habitat selection in roe deer across populations

International audienceWith the surge of GPS-technology, many studies uncovered space use of mobile animals and shed light on the underlying behavioral mechanisms of habitat selection. Habitat selection and variation in either occurrence or strength of functional responses (i.e. how selection changes with availability) have given new insight into such mechanisms within populations in different ecosystems. However, linking variation in habitat selection to site-specific conditions in different populations facing contrasting environmental conditions but the same habitat type has not yet been investigated. We aimed to fill this knowledge gap by comparing within-home range habitat selection across 61 female roe deer (Capreolus capreolus) during the most critical life history stage in three study areas showing the same habitat types but with different environmental conditions. Female roe deer markedly differed in habitat selection within their home range, both within and among populations. Females facing poor environmental conditions clearly displayed a functional response, whereas females facing rich environmental conditions did not show any functional response. These results demonstrate how the use of a given habitat relative to its availability strongly varies in response to environmental conditions. Our findings highlight that the same habitat composition can lead to very different habitat selection processes across contrasted environments

Settle down! Ranging behaviour responses of roe deer to different capture and release methods

16openInternationalInternational coauthor/editorThe 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’sopenBergvall, Ulrika A; Morellet, Nicolas; Kjellander, Petter; Rauset, Geir R; Groeve, Johannes De; Borowik, Tomasz; Brieger, Falko; Gehr, Benedikt; Heurich, Marco; Hewison, A J Mark; Kröschel, Max; Pellerin, Maryline; Saïd, Sonia; Soennichsen, Leif; Sunde, Peter; Cagnacci, FrancescaBergvall, U.A.; Morellet, N.; Kjellander, P.; Rauset, G.R.; Groeve, J.D.; Borowik, T.; Brieger, F.; Gehr, B.; Heurich, M.; Hewison, A.J.M.; Kröschel, M.; Pellerin, M.; Saïd, S.; Soennichsen, L.; Sunde, P.; Cagnacci, F

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

Simple Summary The study of animal movement in wild, free ranging species is fundamental for advancing knowledge on ecosystem relationships and for conservation. The deployment of bio-logging devices to this purpose (often GPS-collars in large mammals) requires relatively invasive procedures, such as capture, handling and release. Capture and manipulation cause behavioural modifications that are largely understudied in wild species and may affect both the welfare of animals and the output of the studies. We evaluated post capture and release ranging behaviour responses of a small deer species (roe deer Capreolus capreolus) for five different capture methods across 14 study sites within the EURODEER collaborative project. Roe deer showed modifications in their movement behaviour, independently of the capture method. However, individuals recovered rapidly, converging towards the average behaviour within a relatively short interval of time (between 10 days and one month), demonstrating a general resilience to such stressful events. We encourage researchers to continually adapt capture and handling methods so as to minimize stress and prioritize animal welfare. 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

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

International audienceWhile 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

Immunosenescence patterns differ between populations but not between sexes in a long-lived mammal

International audienceIn animals, physiological mechanisms underlying reproductive and actuarial senescence remain poorly understood. Immunosenescence, the decline in the ability to display an efficient immune response with increasing age, is likely to influence both reproductive and actuarial senescence through increased risk of disease. Evidence for such a link has been reported from laboratory animal models but has been poorly investigated in the wild, where variation in resource acquisitions usually drives life-history tradeoffs. We investigated immunosenescence patterns over 7 years in both sexes of two contrasting roe deer populations (Capreolus capreolus). We first measured twelve immune markers to obtain a thorough identification of innate and adaptive components of immunity and assessed, from the same individuals, the age-dependent variation observed in parasitic infections. Although the level of innate traits was maintained at old age, the functional innate immune traits declined with increasing age in one of two populations. In both populations, the production of inflammatory markers increased with advancing age. Finally, the adaptive response declined in late adulthood. The increasing parasite burden with age we reported suggests the effective existence of immunosenescence. Age-specific patterns differed between populations but not between sexes, which indicate that habitat quality could shape agedependent immune phenotype in the wild

Age-dependent associations between telomere length and environmental conditions in roe deer

Supplementary methods, tables & figure

Utilisation et sélection de l'habitat chez le chevreuil à différentes échelles spatio-temporelles

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