Spatio-temporal dynamics of an introduced predator on a sub-antartic island : toward the example of the feral cat (Felis silvestric catus) on the grand Terre Island of the Kerguelen Archipelago

Les écosystèmes sub-Antarctiques sont particulièrement vulnérables aux perturbations environnementales et notamment aux invasions biologiques. L'introduction du Chat (Felis silvestris catus) sur la Grande Terre de l'archipel des Kerguelen a eu des effets désastreux sur les communautés d'oiseaux marins. Ce prédateur doit sa survie dans cet environnement à la présence d'une proie introduite, le Lapin (Oryctolagus cuniculus), qui constitue sa ressource principale pendant l'hiver lorsque les oiseaux marins sont repartis en mer. L'éradication du chat n'apparaît pas être une solution réaliste compte tenu de la taille de l'île (6675 km2) et son inaccessibilité. De plus elle serait susceptible de conduire à des résultats non souhaités comme par exemple une explosion démographique des populations de lapins. La mise en place d'une politique de gestion adaptée nécessite d'améliorer notre connaissance des facteurs qui conditionnent la dynamique spatio-temporelle des populations de chats. Au cours de cette thèse, j'ai cherché à identi_er les mécanismes des interactions entre le chat, le lapin et la végétation, car elles sont attendues conditionner celles existantes entre le chat et les oiseaux marins. J'ai analysé la dynamique spatio-temporelle de quatre populations de chats sur la Grande Terre et j'ai en particulier recherché si des conditions environnementales spatialement corrélées (effet Moran) pouvaient, en se propageant dans la chaine alimentaire, synchroniser les variations temporelles d'abondance des populations de chats. Enfin, j'ai étudié l'impact des variations spatio-temporelles d'abondance des populations de chats sur les variations spatio-temporelles de la structure génétique des populations de chats.Sub-Antarctic ecosystems are particularly vulnerable to environmental perturbations including biological invasions. The introduction of the feral cat (Felis silvestris catus) on the Grande TerreIsland of the Kerguelen archipelago has lead to detrimental effects on seabird's communities. Cat survival in this environment is possible because of the presence of the introduced rabbit (Oryctolagus cuniculus), which constitute the main prey of the cat during winter when most seabirds are offshore. Cat eradication is not a realistic solution given the size and inaccessibility of the island (6675 km2). Moreover it can lead to unwanted results such as the demographic explosion of rabbit populations. The design of appropriate management policy needs to improve our understanding of the factors that influence the spatio-temporal dynamics of cat populations. In this thesis, I explored the mechanisms of cat-rabbit-vegetation interactions, as they are expected to determine interactions existing between cats and seabirds. I analyzed the spatio-temporal dynamics of four cat populations on Grande Terre Island and I especially sought whether environmental conditions spatially correlated (Moran effect) could synchronize cat through their effect on the trophic web pathways. Finally, I studied the impact of spatio-tempora

Dynamique spatio-temporelle des populations d'un prédateur introduit sur une île sub-antarctique : l'exemple du chat (Felis silvestris catus) sur la Grande Terre de l'archipel des Kerguelen

Sub-Antarctic ecosystems are particularly vulnerable to environmental perturbations including biological invasions. The introduction of the feral cat (Felis silvestris catus) on the Grande TerreIsland of the Kerguelen archipelago has lead to detrimental effects on seabird's communities. Cat survival in this environment is possible because of the presence of the introduced rabbit (Oryctolagus cuniculus), which constitute the main prey of the cat during winter when most seabirds are offshore. Cat eradication is not a realistic solution given the size and inaccessibility of the island (6675 km2). Moreover it can lead to unwanted results such as the demographic explosion of rabbit populations. The design of appropriate management policy needs to improve our understanding of the factors that influence the spatio-temporal dynamics of cat populations. In this thesis, I explored the mechanisms of cat-rabbit-vegetation interactions, as they are expected to determine interactions existing between cats and seabirds. I analyzed the spatio-temporal dynamics of four cat populations on Grande Terre Island and I especially sought whether environmental conditions spatially correlated (Moran effect) could synchronize cat through their effect on the trophic web pathways. Finally, I studied the impact of spatio-temporalLes écosystèmes sub-Antarctiques sont particulièrement vulnérables aux perturbations environnementales et notamment aux invasions biologiques. L'introduction du Chat (Felis silvestris catus) sur la Grande Terre de l'archipel des Kerguelen a eu des effets désastreux sur les communautés d'oiseaux marins. Ce prédateur doit sa survie dans cet environnement à la présence d'une proie introduite, le Lapin (Oryctolagus cuniculus), qui constitue sa ressource principale pendant l'hiver lorsque les oiseaux marins sont repartis en mer. L'éradication du chat n'apparaît pas être une solution réaliste compte tenu de la taille de l'île (6675 km2) et son inaccessibilité. De plus elle serait susceptible de conduire à des résultats non souhaités comme par exemple une explosion démographique des populations de lapins. La mise en place d'une politique de gestion adaptée nécessite d'améliorer notre connaissance des facteurs qui conditionnent la dynamique spatio-temporelle des populations de chats. Au cours de cette thèse, j'ai cherché à identi_er les mécanismes des interactions entre le chat, le lapin et la végétation, car elles sont attendues conditionner celles existantes entre le chat et les oiseaux marins. J'ai analysé la dynamique spatio-temporelle de quatre populations de chats sur la Grande Terre et j'ai en particulier recherché si des conditions environnementales spatialement corrélées (effet Moran) pouvaient, en se propageant dans la chaine alimentaire, synchroniser les variations temporelles d'abondance des populations de chats. Enfin, j'ai étudié l'impact des variations spatio-temporelles d'abondance des populations de chats sur les variations spatio-temporelles de la structure génétique des populations de chats

The GWCT Partridge Count Scheme: A Volunteer-Based Monitoring and Conservation Promotion Scheme

The Game & Wildlife Conservation Trust’s (GWCT) Partridge Count Scheme (PCS) is a volunteer-based monitoring system serving as a means for delivering conservation and ‘best practice’ advice to participants (farmers, land managers and gamekeepers). Originally designed to monitor numbers of grey partridge (Perdix perdix) on UK shooting estates, it has been expanded to include participants primarily interested in conservation in response to the UK government’s Grey Partridge Species Action Plan. The PCS is also an invaluable tool for examining trends in partridge abundance and population parameters. We examined trends in annual Grey Partridge production (autumn counts available from 1933) and breeding abundance (spring counts available from 1952). We compared trends of production and breeding abundance from old participants to trends from recently joined participants and interpreted the results relative to the Grey Partridge Species Action Plan. We also discuss the provision of data back to PCS participants and future plans for conservation advice and collaboration with other organizations, in particular the UK government’s Department for the Environment, Farming and Rural Affairs

Data from: An R package for analyzing survival using continuous-time open capture-recapture models

Capture–recapture software packages have proven to be very powerful tools for analysing factors affecting survival in wild populations. However, all such packages are limited to discrete-time protocols. Appropriate survival analysis tools are still lacking for data acquired from continuous-time protocols. We have developed a statistical method and propose an r package for analysing such data based on an extension of classical survival analysis models incorporating an inhomogeneous Poisson process for modelling capture histories. First, data were simulated from a continuous-time protocol. These data were used to (i) compare survival estimation biases of discrete- and continuous-time approaches and (ii) investigate the performance and accuracy of our r package for four types of covariates: factors varying between individuals (like sex), in time (like climatic factors), both in time and between individuals (like physical condition) and age (as a categorical factor). Secondly, the r package has been applied to a real data set for survival analysis of cats in the Kerguelen archipelago (regrouping 682 cats over 20 years) as an illustrative example. Results of the simulated data analysis show that the method performs better than its discrete-time counterpart for analysing data acquired from continuous-time protocols. It provides unbiased parameter estimates for all parameters except those that vary both in time and between individuals – which is not surprising, since in our case, these factors were not updated in continuous time (i.e. only upon capture). When applied to the Kerguelen cat data set, the results suggest that survival is lower in juveniles than in adults and subadults, varies between study sites and increases with physical condition, and this latter effect being more important in females than in males. Sex, season, temporal linear trend in survival and the NDVI vegetation index were also tested but were not found to be significant. However, confidence intervals were too large (due to a low recapture rate) for excluding such effects. Further analyses are still needed for rigorous covariate testing in this context. In conclusion, continuous-time approaches – such as that presented in this paper – should be preferred when data acquired from continuous-time protocols is analysed

A multi-event model to study stage-dependent dispersal in radio-collared hares: when hunting promotes costly transience

International audienceBehavioral ecologists have often assumed that dispersal is costly mainly because of unfamiliarity with traversed habitats during dispersal and energy costs of the movement per se; thus, dispersers that have successfully settled should experience survival rates comparable to those of philopatric individuals. In this paper, we tested that hypothesis using 152 radio-collared European hares in a harvested population. We developed a multi-event capture-recapture model, combining telemetry data and recoveries and separately modeling the foray probability, the settlement probability, and the permanent dispersal probability. The parameterization introduced here raises the possibility of separately testing effects on survival and dispersal probabilities at each stage of dispersal (departure, transience, and settlement). In accordance with our expectations, we reveal that dispersers incur higher mortality risks during transience and the early settlement period than philopatric individuals or settled dispersers. We also found that dispersers suffer from higher risks of being shot. Those results illustrate that unfamiliarity with the habitat during transience makes dispersal costly and that settled dispersers may enjoy survival rates comparable to those of philopatric individuals. Surprisingly, we also found that individuals have a higher probability of foraying during the hunting season. We suggest that hunting and related disturbances increase dispersal costs both by increasing mortality risk during transience and (perhaps) by increasing movement rates. We emphasize the need to take human pressures into account as factors that may drive the demographics of movements in populations

Engine Test and Evaluation at NRC: Lessons Learned and the Way Ahead

NRC publication: Ye

Microsatellites and sample locations

Multilocus microsatellite genotypes, location and sampling year of n=271 feral cats on the Kerguelen Archipelag

Individual turnover in common pochards wintering in western France

International audienceStudying movements and population turnover is a prerequisite of management and conservation policies. Understanding the relative importance of known wintering sites requires estimating total number of birds using a wintering site with robust statistical methods because counts alone do not account for turnover. To study movements of common pochards (Aythya ferina) during winter (Oct to Mar) in western France, we used a combination of band-recoveries and capture-recapture data. We constructed a multi-state model to estimate monthly local survival and probability of movements between the banding site and other wintering sites, accounting for individual sex and age. We observed significant movements between sites and high population turnover even during winter. We did not detect any effect of age or sex on movement probabilities, except at the beginning of the winter when first-year individuals had a lower emigration probability. This result suggests that these inexperienced birds did not explore the wintering area like adults, at least early in the season. Combining our estimates (survival and emigration) and winter counts data, we computed the number of individuals using our study area throughout winter. This total was twice the maximum number of individuals counted in winter. Unexpectedly, low estimates for apparent survival suggest that permanent emigration occurred; although, recaptures and resightings revealed some birds traveled long distances from the capture site. We hypothesize that this permanent emigration was due to birds moving to areas where observation and hunting pressures were reduced compared to those in the French territory. If this hypothesis is true, high turnover rate would prevail not only at the scale of the wetland but also at the scale of the country. \textcopyright The Wildlife Society, 2013

Serological evidence for the presence of non-pathogenic rabbit haemorrhagic disease virus-like strains in rabbits <i>Oryctolagus cuniculus</i> of the Kerguelen archipelago

Antibodies raised against a Lagovirus were found in healthy rabbits Oryctolagus cuniculus sampled in 2003 and 2004 in the Kerguelen archipelago. The serological test we used enabled the detection of antibodies due to both pathogenic and non-pathogenic viruses related to the rabbit haemorrhagic disease virus (RHDV). The overall proportion of seropositive rabbits was 35% and differed between sites. Since previous studies have failed to detect antibodies raised against pathogenic RHDV strains, the antibodies detected in the present study were likely due to non-pathogenic strains. The interest of these strains circulating in the Kerguelen archipelago is that they have evolved independently of those detected in the other parts of the world and should derive from an ancestral RHDV precursor. Their characterization may help understanding the evolution of the virus and the emergence of the disease

The REACT study: design of a randomized phase 3 trial to assess the efficacy and safety of clazosentan for preventing deterioration due to delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

BackgroundFor patients presenting with an aneurysmal subarachnoid hemorrhage (aSAH), delayed cerebral ischemia (DCI) is a significant cause of morbidity and mortality. The REACT study is designed to assess the safety and efficacy of clazosentan in preventing clinical deterioration due to DCI in patients with aSAH.MethodsREACT is a prospective, multicenter, randomized phase 3 study that is planned to enroll 400 patients with documented aSAH from a ruptured cerebral aneurysm, randomized 1:1 to 15 mg/hour intravenous clazosentan vs. placebo, in approximately 100 sites and 15 countries. Eligible patients are required to present at hospital admission with CT evidence of significant subarachnoid blood, defined as a thick and diffuse clot that is more than 4 mm in thickness and involves 3 or more basal cisterns. The primary efficacy endpoint is the occurrence of clinical deterioration due to DCI up to 14 days post-study drug initiation. The main secondary endpoint is the occurrence of clinically relevant cerebral infarction at Day 16 post-study drug initiation. Other secondary endpoints include the modified Rankin Scale (mRS) and the Glasgow Outcome Scale-Extended (GOSE) score at Week 12 post-aSAH, dichotomized into poor and good outcome. Radiological results and clinical endpoints are centrally evaluated by independent committees, blinded to treatment allocation. Exploratory efficacy endpoints comprise the assessment of cognition status at 12 weeks and quality of life at 12 and 24 weeks post aSAH.DiscussionIn the REACT study, clazosentan is evaluated on top of standard of care to determine if it reduces the risk of clinical deterioration due to DCI after aSAH. The selection of patients with thick and diffuse clots is intended to assess the benefit/risk profile of clazosentan in a population at high risk of vasospasm-related ischemic complications post-aSAH. TRIAL REGISTRATION (ADDITIONAL FILE 1): ClinicalTrials.gov (NCT03585270). EU Clinical Trial Register (EudraCT Number: 2018-000241-39)