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

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

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

POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Measurement and Monitoring of the Ecological Impact of Wild Ungulates on Forest Vegetation

Populations of wild ungulates have been increasing since the 1980s to the extent that they now raise economic, social and environmental problems. Sustainable forest management implies that a compromise is found between the harmful effects (on the economy, health and the environment) and the services rendered (to the economy, the heritage and the environment) to man and the ecosystem. A crucial component of sustainable management is evaluation and monitoring of these effects to avoid excessive destruction or irreversible damage. This relies on indicators that we describe here in their essentially ecological aspects in connection with forest vegetation. Based on the principles of adaptive management, ecological change indicators (ECIs) provide decision-makers and managers with indicators as to changes in the animal/habitat pair. However, they do not include indicators enabling damage to forest regeneration to be evaluated or monitored, or ones for effects on ecosystem functioning and biodiversity. We propose using the responses of plants on the scale of populations or plant communities so as to assess and monitor the ecological impact of wild ungulates in forest environments. The notion of ecological impact takes on board the fact that, depending on the particular context, the effects of wild ungulates may be either beneficial or harmful for ecosystem functioning. In the longer term, these indicators could be incorporated into the sustainable management indicator approach in French forests.Les populations d’ongulés sauvages ont progressé depuis les années 1980 au point aujourd’hui de poser des problèmes économiques, sociaux et environnementaux. Une gestion durable des forêts suppose de trouver un compromis entre les effets nuisibles (économiques, sanitaires et écologiques) et les services rendus (économiques, patrimoniaux et écologiques) à l’homme et à l’écosystème. Une composante essentielle de la gestion durable est d’évaluer et de suivre ces effets afin d’éviter des dégâts excessifs ou des dommages irréversibles. Elle repose donc sur des indicateurs, que nous détaillons ici pour les aspects principalement écologiques en lien avec la végétation forestière. Basés sur les principes de la gestion adaptative, les indicateurs de changement écologique (ICE) mettent à la disposition des décideurs et gestionnaires des indicateurs qui renseignent sur l’évolution du couple population animale-milieu. Néanmoins, parmi eux, manquent des indicateurs pour évaluer et suivre les dégâts sur la régénération forestière et les effets sur le fonctionnement et la biodiversité de l’écosystème. Nous proposons ici d’utiliser les réponses des plantes à l’échelle des populations ou des communautés végétales afin d’évaluer et suivre l’empreinte écologique des ongulés sauvages en milieu forestier. La notion de l’empreinte écologique prend en compte le fait que les effets d’ongulés sauvages ont, selon le contexte, des effets bénéfiques ou délétères sur le fonctionnement de l’écosystème. À terme, ces indicateurs pourraient être intégrés dans la démarche des indicateurs de gestion durable des forêts françaises

Tailles du domaine vital du Chevreuil Capreolus capreolus estimée à partir de données VHF et GPS

Dans cette étude, nous avons comparé les estimations noyau de la taille du domaine vital entre le suivi par VHF et par GPS. Nous avons utilisé trois types de données pour évaluer les estimations mensuelles de la taille du domaine vital individuel (données VHF basées sur 17 localisations, données GPS sous-échantillonnées basées sur 17 localisations (avec 1000 réplicats) et données GPS basées sur 720 localisations) en utilisant trois méthodes d'estimation pour le paramètre de lissage, h (référence, validation croisée moindre carré (VCMC) et fixe). Pour les trois paramètres de lissage, les domaines vitaux individuels estimés à partir de données VHF et GPS en utilisant 17 localisations avaient une taille très semblable. En revanche, l'utilisation de valeurs h de référence ou de VCMC aboutissait à des tailles de domaines vitaux supérieures à l'estimation obtenue à partir de l'ensemble des données GPS (720 localisations). Ces résultats soulignent l'influence de l'utilisation d'un nombre trop faible de localisations par mois. Par contre, l'utilisation de h fixé à 60 permettait d'obtenir une taille de domaine vital proche de celle obtenue à partir de l'ensemble des localisations GPS. Le centroïde des localisations pour un individu donné durant un mois donné changeait seulement un peu selon l'ensemble de données utilisé (la différence étant < 100 m), ce qui laisse supposer une grande précision pour nos localisations. Les zones VHF et GPS peuvent donc être regroupées dans la même analyse de l'utilisation de l'habitat, à condition que le paramètre de lissage et le nombre de localisations soient standardisés. ***** In this study, we compared kernel estimates of home-range size between VHF and GPS monitoring. We used three types of data to assess the monthly estimates of individual home-range size (VHF data based on 17 locations, subsampled GPS data based on 17 locations (with 1,000 replicates) and GPS data based on 720 locations) using three estimation methods for the smoothing parameter, h (reference, least-squares cross-validation (LSCV) and fix). For all the three smoothing parameters, individual home ranges estimated from VHF and GPS data using 17 locations had very similar size. On the other hand, the use of reference or LSCV h values led home-range sizes from VHF or GPS data using 17 locations to be larger than the estimate obtained from the whole set of GPS data (720 locations). Such results emphasise the influence of using too few locations per month. On the contrary, using h fixed at 60 led to a home-range size close to that obtained from the whole set of GPS locations. The centroid of locations for a given individual in a given month only changed a little according to the data set used (the difference being < 100 m), suggesting a high accuracy for our locations. VHF and GPS areas can therefore be pooled within the same analysis of habitat use, provided that the smoothing parameter and the number of locations are standardised

Assessment of forage availability in ecological studies

International audienceIn this study we describe and calibrate a quantitative index method to estimate leaf biomass and forage availability for browsers at different feeding heights. The method is based on an index relating leaf biomass to a number of leaf contacts with a vertical, three-dimensional (25×25×165 cm) metallic quadrat with a central rod and takes into account the characteristics of leaves (shape, size, and thickness) to define plant categories and then produce general allometric equations per category. We then discuss the use of this biomass index to evaluate the quality of habitats for browsers in terms of food resources