Jakob C.,FRC LR |
Ponce-Boutin F.,CNERA PFSP |
Besnard A.,CNRS Center of Evolutionary and Functional Ecology |
European Journal of Wildlife Research | Year: 2010
Successful management practices for declining bird species depend often on long-term surveys acquired by point counts. Despite high standardization of field protocols, uncertain detection probability remains an important source of variability and bias in point-count data. This effect is of main importance in low-responsive species as the Red-legged partridge (Alectoris rufa), but it can be counterbalanced, increasing detection probability. In this 2-year study, we sampled using traditional point-count methods, followed by playback sessions for each repetition. We measured detection probability and the efficiency of playback for detectability in the context of a feasibility study on long-term point-count surveys for a harvested game bird, the Red-legged partridge. The results for both study years show a distinct increase in detection probability (23% and 45%, respectively) when using playback vs. the traditional point-count method. We also tested our results for heterogeneity, trap dependence, and time dependence, and no effect was detected. Thus, we suggest that the future design of long-term surveys on Red-legged partridges should consider abundance indices using playback sessions. © 2010 Springer-Verlag.
Plantard O.,French National Institute for Agricultural Research |
Plantard O.,University of Nantes |
Bouju-Albert A.,French National Institute for Agricultural Research |
Bouju-Albert A.,University of Nantes |
And 6 more authors.
PLoS ONE | Year: 2012
The identification of micro-organisms carried by ticks is an important issue for human and animal health. In addition to their role as pathogen vectors, ticks are also the hosts for symbiotic bacteria whose impact on tick biology is poorly known. Among these, the bacterium Wolbachia pipientis has already been reported associated with Ixodes ricinus and other tick species. However, the origins of Wolbachia in ticks and their consequences on tick biology (known to be very diverse in invertebrates, ranging from nutritional symbionts in nematodes to reproductive manipulators in insects) are unknown. Here we report that the endoparasitoid wasp Ixodiphagus hookeri (Hymenoptera, Chalcidoidea, Encyrtidae) - strictly associated with ticks for their development - is infested at almost 100% prevalence by a W. pipientis strain belonging to a Wolbachia supergroup that has already been reported as associated with other hymenopteran parasitoids. In a natural population of I. ricinus that suffers high parasitism rates due to I. hookeri, we used specific PCR primers for both hymenopteran and W. pipientis gene fragments to show that all unfed tick nymphs parasitized by I. hookeri also harbored Wolbachia, while unparasitized ticks were Wolbachia-free. We demonstrated experimentally that unfed nymphs obtained from larvae exposed to I. hookeri while gorging on their vertebrate host also harbor Wolbachia. We hypothesize that previous studies that have reported W. pipientis in ticks are due to the cryptic presence of the endoparasitoid wasp I. hookeri. This association has remained hidden until now because parasitoids within ticks cannot be detected until engorgement of the nymphs brings the wasp eggs out of diapause. Finally, we discuss the consequences of this finding for our understanding of the tick microbiome, and their possible role in horizontal gene transfer among pathogenic and symbiotic bacteria. © 2012 Plantard et al.
Jakob C.,ONCFS |
Ponce-Boutin F.,ONCFS |
Besnard A.,CNRS Center of Evolutionary and Functional Ecology
Journal of Wildlife Management | Year: 2014
The reliability of long-term population estimates is crucial for conservation and management purposes. Most game species population monitoring programs assume that count indices are proportionally related to abundance. However, this assumption is untenable when detection varies spatially and temporally. We assessed whether N-mixture models, which allow detection modeling using spatially and temporally repeated count data, were relevant for monitoring the population of red-legged partridge (Alectoris rufa). Unbiased estimates are needed for calculating hunting quotas for this game species. We used the simple aural playback point-count method and a dataset of 121 point-transects (n=16,288 counts) collected from 1992 to 2010. Covariates such as date, hour, wind, rain, and vegetation density influenced detection probability. Estimated abundance ranged from 0 to 15 males per point and exhibited variable coefficients of variation depending on sites (range: 0.14-1.31, mean: 0.44). We found a positive and linear relationship between the abundance estimated by the N-mixture model and the densities provided by 2 other counting methods, square sampling and kilometric abundance index, but not with blank beat. We established a maximum detection radius for the playback surveys, which enabled conversion of abundance at the points into density. The N-mixture modeling approach is more cost-effective for game species monitoring than capture-recapture methods or square sampling, and more reliable than indices of relative abundances. © 2014 The Wildlife Society.
Bonnot N.,French National Institute for Agricultural Research |
Morellet N.,French National Institute for Agricultural Research |
Verheyden H.,French National Institute for Agricultural Research |
Cargnelutti B.,French National Institute for Agricultural Research |
And 3 more authors.
European Journal of Wildlife Research | Year: 2013
Wildlife populations are subjected to increasing pressure linked to human activities, which introduce multiple stressors. Recently, in addition to direct effects, it has been shown that indirect (non-lethal) effects of predation risk are predominant in many populations. Predation risk is often structured in space and time, generating a heterogeneous "landscape of fear" within which animals can minimize risks by modifying their habitat use. Furthermore, for ungulates, resource quality seems to be positively correlated with human-related sources of risk. We studied the trade-off between access to resources of high-quality and risk-taking by contrasting habitat use of roe deer during daytime with that during nighttime for 94 roe deer in a hunted population. Our first hypothesis was that roe deer should avoid human disturbance by modifying their habitat use during daytime compared to nighttime. Our results supported this, as roe deer mainly used open fields during nighttime, but used more forested habitats during daytime, when human disturbance is higher. Moreover, we found that diel patterns in habitat use were influenced by hunting disturbance. Indeed, the roe deer decreased their use of high-crops during daytime, an important source of cover and food, during the hunting season. The proximity of roads and dwellings also affected habitat use, since roe deer used open fields during daytime to a greater extent when the distance to these sources of disturbance was higher. Hence, our results suggest that roe deer resolve the trade-off between the acquisition of high-quality resources and risk avoidance by modifying their habitat use between day and night. © 2012 Springer-Verlag Berlin Heidelberg.
Dewas M.,ONCFS |
Herr J.,Administration de la Nature et des Forets |
Schley L.,Administration de la Nature et des Forets |
Angst C.,Center Suisse Of Cartographie Of La Faune Cscf |
And 3 more authors.
Mammal Review | Year: 2012
1 The Eurasian beaver Castor fiber suffered a drastic reduction in both geographical range and population size, due to human persecution, until the end of the 19th century. After the adoption of protection measures, natural expansion and reintroductions led to the recovery of this species over much of its European range. 2 We review historical events that led to the recovery of beavers in France, and summarize the status of beavers in various river systems. Beaver establishment in France is a story of overall success: several major river systems are presently occupied, so that the species is no longer at risk in France. 3 However, beaver recolonization took place in parallel with increasing human impacts on the environment. In addition to natural limiting factors, anthropogenic factors impeded beaver settlement in many areas. Today, beavers often occupy suboptimal habitats and, as a consequence, come into conflict with human activities. Effective solutions for preventing beaver damage include the restoration of riparian habitats to discourage crop damage and the provision of physical barriers to protect crops. 4 Beaver populations reintroduced into France all originate from the relict Rhône population. However, in recent years, beavers from populations in neighbouring countries have been expanding into north-eastern France. Therefore, our review of beaver origin and distribution in these countries may contribute to the development of appropriate national management strategies and towards important decisions, e.g. the decision to try to keep Rhône beavers genetically isolated, or to allow populations to mix. 5 The recently discovered presence of North American beavers Castor canadensis in three countries surrounding France has raised an important issue. This species may out-compete C. fiber in places where the species come into contact. A programme based on field-trapping sessions and genetic analyses has recently been initiated in some western countries in order to eradicate this non-native species. © 2011 The Author. Mammal Review © 2011 Mammal Society/Blackwell Publishing.
Toigo C.,ONCFS |
Gaillard J.-M.,University Claude Bernard Lyon 1 |
Loison A.,CNRS Alpine Ecology Laboratory
Oecologia | Year: 2013
Large horns or antlers require a high energy allocation to produce and carry both physiological and social reproductive costs. Following the principle of energy allocation that implies trade-offs among fitness components, growing large weapons early in life should thus reduce future growth and survival. Evidence for such costs is ambiguous, however, partly because individual heterogeneity can counterbalance trade-offs. Individuals with larger horns or antlers may be of better quality and thus have a greater capacity to survive. We investigated trade-offs between male early horn growth and future horn growth, baseline mortality, onset of actuarial senescence, and rate of ageing in an Alpine ibex (Capra ibex ibex) population. Horn growth of males in early life was positively correlated to their horn length throughout their entire life. Cohort variation and individual heterogeneity both accounted for among-individual variation in horn length, suggesting both long-lasting effects of early life conditions and individual-specific horn growth trajectories. Early horn growth did not influence annual survival until 12 years of age, indicating that males do not invest in horn growth at survival costs over most of their lifetime. However, males with fast-growing horns early in life tended to have lower survival at very old ages. Individual heterogeneity, along with the particular life-history tactic of male ibex (weak participation to the rut until an old age after which they burn out in high mating investment), are likely to explain why the expected trade-off between horn growth and survival does not show up, at least until very old ages. © 2013 Springer-Verlag Berlin Heidelberg.
Cappelle J.,CIRAD - Agricultural Research for Development |
Girard O.,ONCFS |
Fofana B.,Direction Nationale des Eaux et Forets du Mali |
Gaidet N.,CIRAD - Agricultural Research for Development |
Gilbert M.,Roosevelt University
EcoHealth | Year: 2010
Predicting areas of disease emergence when no epidemiological data is available is essential for the implementation of efficient surveillance programs. The Inner Niger Delta (IND) in Mali is a major African wetland where >1 million Palearctic and African waterbirds congregate. Waterbirds are the main reservoir of Avian Influenza Viruses (AIV). Our objective was to model their spatial distribution in order to predict where these viruses would be more likely to circulate. We developed a generalized linear model (GLM) and a boosted regression trees (BRT) model based on total aerial bird counts taken in winter over 6 years. We used remotely sensed environmental variables with a high temporal resolution (10 days) to predict the spatial distribution of four waterbird groups. The predicted waterbird abundances were weighted with an epidemiological indicator based on the prevalence of low pathogenic AIV reported in the literature. The BRT model had the best predictive power and allowed prediction of the high variability of waterbird distribution. Years with low flood levels showed areas with a higher risk of circulation and had better spatial distribution predictions. Each year, the model identified a few areas with a higher risk of AIV circulation. This model can be applied every 10 days to evaluate the risk of AIV emergence in wild waterbirds. By taking into account the IND's ecological variability, it allows better targeting of areas considered for surveillance. This could enhance the control of emerging diseases at a local and regional scale, especially when resources available for surveillance programs are scarce. © 2010 International Association for Ecology and Health.
Montadert M.,Les Granges Michel |
Alauda | Year: 2011
Breeding biology of 29 radio-tracked Hazel Grouse hens was investigated from 1999 to 2008 in the south-eastern part of French Alps. Spring home range of females up to incubation sized from 7.6 to 31.1 ha (50% activity range covered 2.5-9.4 ha, Kernel method). First clutches were 7.3 (range: 6-9) eggs and second clutches were 3.7 (range: 3-4) eggs in average. Hatching period extended from 23 May to 4 July, the median date for first clutches was 4 June and that for second clutches was 25 June. Nesting success was estimated by the Mark software capture-recapture method. Breeding success from the beginning of laying to hatching was 0.34 for all nests (first and second clutches together) and 0.46 during the incubation period. Nest loss was mainly, if not entirely, due to predation, probably by carnivores. 15% of the hens did not initiate a clutch but this rate was probably biased by undetected early destroyed clutches. If these hens were taken into account, breeding success was 0.28. Nest loss was not influenced by hen's age, nest visibility, distance to roads and laying date. Breeding success was significantly higher in the first study years (0.55 in 1999-02) than subsequently (0.22 in 2004-08). Reproduction traits (clutch size, nesting success) of this population appeared relatively low when compared to other studies on Hazel Grouse. Results are discussed in relation to the adaptive value of clutch size and to the role of environmental factors on breeding success.
Clignasse J.-M.,ONCFS |
Alauda | Year: 2012
Breeding Peregrine Falcons usually nest on cliffs offering a wide open view and easy flying off. Breeding Northern Ravens are less specialized. Despite the plasticity shown by these two species, nesting below ground is unknown so far in the first and exceptional in the second. We describe the nesting of a Peregrine Falcon pair in a swallow hole (aven) some 10-12m below ground and three new cases in the Northern Raven. We present arguments that the choice of these nesting sites was neither determined by environmental (nesting site availability, intraspecific competition, prédation pressure) nor anthropogenic factors (disturbance) but its generalization is doubtful.
Alauda | Year: 2013
Distribution and population status of the Capercaillie were updated in 2010 in the French Jura mountains (Northeast France). In comparison with a first regional overview in 1995, distribution range covers 21 585 ha in 2010, thus showing a decrease of 21% of the range regularly occupied. Total population is estimated to amount 340 adults in 2010 indicating a decrease of 27%. Population trend was assessed by counts of displaying cocks at 20 leks and was analysed with log linear model between 1991 and 2012. Only 3 out of 20 leks remained stable at a low level. Ten leks showed marked decline between 1991 and 2004 leading to complete disappearance of 6 leks. Seven leks steadily decreased until 2004 and subsequently showed marked increase. Overall cock numbers decreased by 73% between 1991 and 2004 and then was multiplied by 3 from 2004 to 2012. Despite this increase displaying cock numbers are still 13% lowerthanin 1991. The marked instability of this population associated with a complete isolation represents a serious threat for its long term survival. Several small populations in that region have vanished during the last 30 years and only those occupying large tracks of forest at higher altitude seem to be able restoring after a steep decline. Local trends can hardly be associated with evident change in habitat quality or human disturbance. They can rather be related with change in breeding success which remained low in general (0.34 juvenile/hen in July on 3 sites) but seems to have increased since 2003 explaining the observed partial recovery. However, without a comprehensive knowledge of the role played by environment on the demographic parameters it is difficult to promote specific and efficient conservation measures.