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Population dynamics of fossorial Water Vole (Arvicola terrestris Scherman): a land use and landscape perspective
Abstract
This study investigates the effect of land use, and landscape composition and structure on the population dynamics of fossorial water vole (Arvicola terrestris scherman Shaw). Water vole populations were monitored from 1989 to 1994 in the Doubs department, France, by using index methods. Land use patterns were studied based on agriculture and forestry data from the French Ministry of Agriculture collected in 1956, 1970, 1979 and 1988. Grassland quality and landscape structure were studied based on field transects, combined with the assessment of landscape structure from maps at 1:25,000 scale. Outbreaks of water vole populations occurred as a wave, spreading from epicentres over more than 2500 km2. The propagation speed was in excess of 10 km/yr. On a regional level (n × 10 km) and over 5 years and more, density variation patterns of water vole were linked to the ratio of ploughed land and of permanent grassland to farmland. At a sectional scale (n × 1 km), forests and uncultivated lands had a dampening effect both on the outbreaks and on their duration. The evolution of farmlands from 1956 to 1988 was apparently the major cause of increase in density variations of water vole. Therefore, land use and landscape management could be a way to control water vole outbreaks, and their effects are discussed.
... Small mammal species form a key role in terrestrial ecosystem functioning in many parts of the world. In addition to their important role in food chains and ecosystem functioning [1][2][3][4][5][6], understanding their distributions and population dynamics is important for other fields including agriculture [7][8][9][10], and public health and disease transmission [11][12][13]. Many small mammal species exhibit specific habitat preferences which drive the distribution and population dynamics of those species [14][15][16][17][18][19]. ...
... Many small mammal species exhibit specific habitat preferences which drive the distribution and population dynamics of those species [14][15][16][17][18][19]. Understanding the linkages between landscape and small mammal ecology is therefore key [11,20,21]; when optimal conditions are met, small mammal populations of some species can reach peaks of several hundred individuals per hectare [2,7,8,22]. Therefore, key to understanding the potential impacts of small mammal population dynamics is identifying the distributions and abundances of the species involved [23][24][25]. ...
... Similarly, for other species, the variables ranked as important comprised a mix of land cover and vegetation and water index metric variables. This advances the findings of previous studies, for example [7,8,21], that have modelled small mammal distributions based on only the ratio of optimal to marginal patch area (ROMPA) for a specific species within the broader landscape [65], using a pre-defined decision of what is considered key habitat type for a species. Characterising ROMPA simply through the extent of a discrete land cover type across an area of interest precludes examination of how variability within land cover classes drives small mammal distributions and abundances, and so offers a restricted understanding of the mechanics driving those patterns. ...
Small mammal species play an important role influencing vegetation primary productivity and plant species composition, seed dispersal, soil structure, and as predator and/or prey species. Species which experience population dynamics cycles can, at high population phases, heavily impact agricultural sectors and promote rodent-borne disease transmission. To better understand the drivers behind small mammal distributions and abundances, and how these differ for individual species, it is necessary to characterise landscape variables important for the life cycles of the species in question. In this study, a suite of Earth observation derived metrics quantifying landscape characteristics and dynamics, and in-situ small mammal trapline and transect survey data, are used to generate random forest species distribution models for nine small mammal species for study sites in Narati, China and Sary Mogul, Kyrgyzstan. These species distribution models identify the important landscape proxy variables driving species abundance and distributions, in turn identifying the optimal conditions for each species. The observed relationships differed between species, with the number of landscape proxy variables identified as important for each species ranging from 3 for Microtus gregalis at Sary Mogul, to 26 for Ellobius tancrei at Narati. Results indicate that grasslands were predicted to hold higher abundances of Microtus obscurus, E. tancrei and Marmota baibacina, forest areas hold higher abundances of Myodes centralis and Sorex asper, with mixed forest-grassland boundary areas and areas close to watercourses predicted to hold higher abundances of Apodemus uralensis and Sicista tianshanica. Localised variability in vegetation and wetness conditions, as well as presence of certain habitat types, are also shown to influence these small mammal species abundances. Predictive application of the Random Forest (RF) models identified spatial hot-spots of high abundance, with model validation producing R2 values between 0.670 for M. gregalis transect data at Sary Mogul to 0.939 for E. tancrei transect data at Narati. This enhances previous work whereby optimal habitat was defined simply as presence of a given land cover type, and instead defines optimal habitat via a combination of important landscape dynamic variables, moving from a human-defined to species-defined perspective of optimal habitat. The species distribution
models demonstrate differing distributions and abundances of host species across
the study areas, utilising the strengths of Earth observation data to improve our understanding of landscape and ecological linkages to small mammal distributions and abundances.
... Vole density thus varies from a few individuals per hectare to more than 500 individuals per hectare during outbreak phases. Each cycle lasts between 5 and 7 years on average in this species [2,[5][6][7]. ...
... Regarding the population dynamics of the water vole, several studies have notably examined predation, landscape influence, agricultural practices, parasitism and pathogen-induced stress [6,[11][12][13][14][15][16]. However, the impact of vole population density on reproductive physiology is still poorly documented. ...
... In water voles, seasonal breeding cycles overlap with pluriannual cycles of population fluctuation [6]. In this study, we explored whether population density affects the reproductive function of male water voles. ...
Most small rodent species display cyclic fluctuations in their population density. The mechanisms behind these cyclical variations are not yet clearly understood. Density-dependent effects on reproductive function could affect these population variations. The fossorial water vole ecotype, Arvicola terrestris , exhibits multi-year cyclical dynamics with outbreak peaks. Here, we monitored different water vole populations over 3 years, in spring and autumn, to evaluate whether population density is related to male reproductive physiology. Our results show an effect of season and inter-annual factors on testis mass, plasmatic testosterone level, and androgen-dependent seminal vesicle mass. By contrast, population density does not affect any of these parameters, suggesting a lack of modulation of population dynamics by population density.
... Dans les prairies semi-naturelles, l'impact des perturbations par la fauche et le pâturage sur la diversité végétale est bien documenté (Critchley et al. 2007 ;Gaisler et al. 2013 ;Dengler et al. 2014 ;Dainese et al. 2015 ;Koch et al. 2017 Les perturbations causées par le campagnol terrestre dans les prairies semi-naturelles se sont fortement accentuées en France dans le massif du Jura et le massif central au cours de la seconde moitié du 20 e siècle (Giraudoux et al. 2002 ;Delattre & Giraudoux 2009). L'accentuation de ces perturbations est liée à une forte augmentation des variations de densité du campagnol terrestre, conséquence d'une conversion de la quasi-totalité de la surface agricole des exploitations en prairies (Giraudoux et al. 1997). De nos jours, les populations de campagnols terrestres connaissent des pullulations interannuelles cycliques qui ont des conséquences négatives à court terme sur la production fourragère (Quéré et al. 1999 ;Schouwey et al. 2014). ...
... Since the early 1970s, subsequent to the specialization of agriculture in dairy production in the French Jura Mountains, almost all the utilized agricultural area has been converted into permanent grasslands, resulting in an increase of montane water vole (Arvicola terrestris) densities (Giraudoux et al. 1997). Montane water voles are herbivorous small mammals feeding on plant roots. ...
... Cyclic outbreaks of montane water vole populations (200 to 1000 individuals per hectare) occur every 5 to 8 years (Berthier et al. 2014) and do considerable damage on vegetation (Delattre & Giraudoux 2009), resulting in an important loss of forage production (Quéré et al. 1999;Schouwey et al. 2014). Many studies have been conducted to understand the determinism of these outbreaks (Giraudoux et al. 1997;Morilhat et al. 2007;Morilhat et al. 2008) and to limit their intensity (Couval & Truchetet 2014;Foltête et al. 2016). However, the impact of montane water vole disturbances on plant diversity and composition in grassland ecosystems have not been assessed yet. ...
En Europe, les prairies semi-naturelles de moyenne montagne sont principalement des écosystèmes ayant évolués au cours de plusieurs décennies d’activité humaine. Ces écosystèmes présentent une biodiversité remarquable et dépendent de régimes traditionnels de perturbations par la fauche ou le pâturage. Cependant, dans l’objectif d’augmenter leur production de fourrage, les prairies semi-naturelles sont soumises à des régimes de perturbations de plus en plus importants ainsi qu’à de nouveaux types de perturbations. Ce travail de thèse propose d’apporter de nouveaux éléments pour suivre et comprendre l’impact des perturbations sur la diversité des communautés végétales des prairies semi-naturelles.Dans un premier temps, la comparaison de relevés de végétation anciens (2005 à 2009) avec des relevés récents (2019) a été réalisée dans des prairies de fauche de moyenne montagne. Cette comparaison a permis de mettre en évidence des évolutions contrastées de la diversité végétale et des régimes de perturbations entre deux massifs. Dans le massif des Vosges, la diversité végétale ainsi que les régimes de perturbations ne semblent pas avoir évolué. A l’inverse, dans le massif du Jura, la diversité végétale a fortement diminué, probablement en association avec une augmentation de la fréquence des régimes de perturbations et de la fertilisation.Dans un second temps, l’impact de perturbations de forte intensité sur la diversité végétale a été évalué. Dans les prairies de fauche, les perturbations par les pullulations de campagnols terrestres semblent permettre une augmentation de la richesse spécifique par la réduction de la compétition pour la lumière. A l’inverse, ces perturbations semblent favoriser des espèces proches phylogénétiquement et entraîner une diminution de l’équitabilité phylogénétique. Dans les pelouses sèches, les perturbations par l’utilisation de broyeurs de pierres ne semblent pas impacter la diversité végétale. En revanche, la composition en espèces des milieux perturbés évolue vers des végétations de prairies productives suite à la perte des espèces typiques des pelouses.Dans un troisième temps, l’utilisation d’espèces diagnostiques comme indicateurs des régimes de perturbations et de la diversité végétale dans les prairies pâturées du massif du Jura a été testée. Le nombre d’espèces diagnostiques dans un relevé de végétation s’est révélé être un bon indicateur de la diversité végétale et des régimes de fertilisation. Cependant, les espèces diagnostiques ne semblent pas être de meilleurs indicateurs que des espèces généralistes des prairies pour évaluer l’intensité des régimes de perturbations.Nos résultats confirment que les changements de pratiques agricoles sont une menace majeure pour la diversité végétale des prairies semi-naturelles de moyenne montagne, en particulier dans le massif du Jura. Nos travaux mettent également en avant que l’augmentation de la fréquence des régimes de perturbations est susceptible d’avoir davantage d’effets négatifs sur la diversité végétale que des perturbations de forte intensité mais peu fréquentes. Néanmoins, certaines perturbations de forte intensité, comme l’utilisation de broyeurs de pierres, peuvent entraîner des modifications très importantes et irréversibles de la composition en espèces des milieux perturbés. Dans l’objectif de concilier enjeux sociétaux et environnementaux, il convient de maintenir des parcelles productives ou les régimes de perturbations par la fauche ou le pâturage sont fréquents, ce qui permet d’assurer une production fourragère importante. Cependant, Il est également nécessaire de limiter la fréquence et l’intensité des perturbations dans des parcelles encore peu intensifiées afin de protéger leur composition en espèces ainsi que leur diversité végétale.
... In Western Europe, a general trend for agricultural intensification since the middle of the last century has resulted in a loss of habitat heterogeneity with serious implications for biodiversity and ecosystem functions in agricultural areas [28,29]. The homogenization of agricultural landscapes has increased the occurrence and the severity of grassland vole species such as common voles, Microtus arvalis, and fossorial water voles, Arvicola scherman (formerly fossorial form of A. terrestris [30], which may spread unimpeded and reach population averages of 500 individuals per hectare, and up to 1000 voles/ha during population peaks [31,32]. Both cyclic vole species are considered serious agricultural pests and a human health hazard in much of their range, and they have consequently received much attention from rodent control organizations [33][34][35]. ...
... Spatial demographic and genetic structural analyses of fossorial water voles have shown that there is often unimpeded dispersal and hence merged and synchronised populations in these homogeneous landscapes [4,18,38]. Consequently, the multiannual fluctuations in the density and the outbreaks of this species may occur at the regional scale [4,32]. ...
... Information on landscape-level processes in A. scherman should be considered to assess link probabilities between demes [6,54]. In that sense, and according to the Ratio of Optimal to Marginal Patch Area (ROMPA) hypothesis, the higher the ratio of suitable habitats (meadows, orchards and grasslands) to the total land area (SH/TL), the higher the link probabilities between demes [32,57]. Thus, the SH/TL ratio was calculated for the area of intersection between two circular buffers around each orchard that considered the centre of the plot as the origin and the Euclidean distance between them as the radius. ...
The population dynamics of most animal species inhabiting agro-ecosystems may be determined by landscape characteristics, with agricultural intensification and the reduction of natural habitats influencing dispersal and hence limiting gene flow. Increasing landscape complexity would thus benefit many endangered species by providing different ecological niches, but it could also lead to undesired effects in species that can act as crop pests and disease reservoirs. We tested the hypothesis that a highly variegated landscape influences patterns of genetic structure in agricultural pest voles. Ten populations of fossorial water vole, Arvicola scherman, located in a bocage landscape in Atlantic NW Spain were studied using DNA microsatellite markers and a graph-based model. The results showed a strong isolation-by-distance pattern with a significant genetic correlation at smaller geographic scales, while genetic differentiation at larger geographic scales indicated a hierarchical pattern of up to eight genetic clusters. A metapopulation-type structure was observed, immersed in a landscape with a low proportion of suitable habitats. Matrix scale rather than matrix heterogeneity per se may have an important effect upon gene flow, acting as a demographic sink. The identification of sub-populations, considered to be independent management units, allows the establishment of feasible population control efforts in this area. These insights support the use of agro-ecological tools aimed at recreating enclosed field systems when planning integrated managements for controlling patch-dependent species such as grassland voles.
... Il est aujourd'hui établi que ces vagues sont plus qu'une curiosité mathématique issue des modèles théoriques. Elles ont ainsi été décrites pour des populations cycliques de rongeurs, d'oiseaux, d'insectes ainsi que pour les pathogènes responsables, chez l'homme, de la dengue et de la rougeole (GIRAUDOUX et al., 1997 ;LAM-BIN et al., 1998 ;MOSS et al., 2000 ;MCKINNON et al., 2001 ;GRENFELL et al., 2001 ;BJØRNSTAD et al., 2002 ;JOHNSON et al., 2004 ;CUMMINGS et al., 2004 ;TENOW et al., 2013 ;BERTHIER et al., 2014). La particularité de ces vagues d'abondance est d'émerger en l'absence de propagation nette des individus impliqués dans la dynamique cyclique. ...
... Dans le massif du Jura, en France et en Suisse, la dynamique cyclique des populations de campagnols terrestres est caractérisée par une période de 5 à 8 ans (SAUCY, 1994 ;GIRAUDOUX et al., 1997 ;BERTHIER et al., 2014). Au cours d'un cycle, les densités des populations peuvent varier de moins d'un individu à l'hectare, en phase de faible densité, à plus de 500 individus à l'hectare lors des pics de pullulations. ...
... Plusieurs études, dans le massif du Jura mais aussi en Auvergne, ont permis de mettre en évidence des relations entre les pullulations, les types de paysage et les pratiques agricoles (GIRAUDOUX et al., 1997 ;FICHET-CALVET et al., 2000). Dans les paysages hétérogènes où se mêlent cultures, prairies, haies et bosquets, on trouve des populations de campagnols stables en densité relativement faible. ...
Certaines populations de campagnol terrestre connaissent des variations cycliques de leurs effectifs. La désynchronisation dans l'espace de ces fluctuations peut conduire à l'émergence de "vagues voyageuses" d'abondance. L'hétérogénéité paysagère (qualité d'habitat et obstacles à la dispersion) est l'hypothèse la plus probable pour expliquer ce phénomène. Dans le massif du Jura, l'analyse de données d'abondance du campagnol terrestre, collectées depuis 1989 dans les communes du Doubs, a révélé l'existence d'une vague d'abondance se propageant à la vitesse de 7 km/an le long d'un axe orienté nord-ouest / sud-est, perpendiculairement à l'un des obstacles majeurs à la dispersion. A une échelle plus locale, la vague est freinée par la présence de haies et de massifs boisés, milieux défavorables aux campagnols.
... Therefore, determining the environmental drivers influencing these small mammal distributions is critical to understanding Em transmission dynamics. Small mammal distributions are influenced by the availability of key favourable habitats [14,15], with landscape modification impacting these habitats, so that small mammal presence and transmission varies spatio-temporally [16,17]. Despite its importance, and due in part to its complexity, knowledge is lacking as to the specific landscape mechanisms that are driving these small mammal host distributions. ...
... This could result in inappropriate conclusions being drawn on the influences of the landscape on small mammal distributions. For example, in the case of M. arvalis and A. terrestris in France, absence is typically determined by bare ground in winter as a result of tilling, where populations cannot be sustained due to the lack of vegetation [16,29]. If single-date remote sensing data acquired in the spring or the summer is used to characterise vegetation in these locations, then these areas will, misleadingly, be characterised by cereal crops, which are considered a favourable habitat for these species. ...
... If single-date remote sensing data acquired in the spring or the summer is used to characterise vegetation in these locations, then these areas will, misleadingly, be characterised by cereal crops, which are considered a favourable habitat for these species. The only way to map the permanent presence of favourable habitats and vegetation conditions such as the permanent grassland shown to be key factors for species such as M. arvalis and A. terrestris [16,29] is to use a time-series of data. The importance of seasonal differences in vegetation condition for small mammal studies has also been illustrated by Reference [28], which determined relationships between Ochotona spp. ...
1) Background: Echinococcus multilocularis (Em), a highly pathogenic parasitic tapeworm, is responsible for a significant burden of human disease. In this study, optical and time-series Synthetic Aperture Radar (SAR) data is used synergistically to model key land cover characteristics driving the spatial distributions of two small mammal intermediate host species, Ellobius tancrei and Microtus gregalis, which facilitate Em transmission in a highly endemic area of Kyrgyzstan. (2) Methods: A series of land cover maps are derived from (a) single-date Landsat Operational Land Imager (OLI) imagery, (b) time-series Sentinel-1 SAR data, and (c) Landsat OLI and time-series Sentinel-1 SAR data in combination. Small mammal distributions are analyzed in relation to the surrounding land cover class coverage using random forests, before being applied predictively over broader areas. A comparison of models derived from the three land cover maps are made, assessing their potential for use in cloud-prone areas. (3) Results: Classification accuracies demonstrated the combined OLI-SAR classification to be of highest accuracy, with the single-date OLI and time-series SAR derived classifications of equivalent quality. Random forest analysis identified statistically significant positive relationships between E. tancrei density and agricultural land, and between M. gregalis density and water and bushes. Predictive application of random forest models identified hotspots of high relative density of E. tancrei and M. gregalis across the broader study area. (4) Conclusions: This offers valuable information to improve the targeting of limited-resource disease control activities to disrupt disease transmission in this area. Time-series SAR derived land cover maps are shown to be of equivalent quality to those generated from single-date optical imagery, which enables application of these methods in cloud-affected areas where, previously, this was not possible due to the sparsity of cloud-free optical imagery.
... The focus of this thesis is on the fossorial form of the water vole, Arvicola terrestris in the Doubs and Jura departments of Franche-Comté, eastern France (see Box 1.1 for a discussion of the taxonomy of this genus). In this region, A. terrestris are found primarily in grasslands above 400 m above sea level (Giraudoux et al., 1997). Adults range in mass from 80-160 grams, and measure between 12 and 18 cm from head to anus (Delattre and Giraudoux, 2009). ...
... Population densities of A. terrestris in Franche-Comté fluctuate dramatically, with outbreaks characterized by densities of over 200 individuals/ha and forage production losses of over 1000 kg/ha/year occurring every 5-8 years (mean period, 6 years, Berthier et al., 2014). Fluctuations in A. terrestris density have been documented in neighbouring Switzerland as early as the 16th century (Korner, 1993;Saucy, 1994b), but current outbreaks of such magnitude emerged in the late 1960s in Franche-Comté in conjunction with significant land-use changes; agricultural policy at the time encouraged specialization in milk production which led farmers to convert ploughed fields to permanent grassland (Giraudoux et al., 1997) and remove hedges to create larger homogeneous patches. ...
... From Berthier et al. (2014) tunnel networks when A. terrestris density is low Fritschy and Meylan, 1980). At the regional scale (~2500 km 2 ), risk of outbreak is highest when the ratio of permanent grassland to agricultural land is >90 % but outbreaks still occur at ratios as low as 40% (Giraudoux et al., 1997). At the commune scale (~25 km 2 ), outbreaks tend to occur in areas of homogeneous grassland as opposed to areas broken up with hedge networks and forest patches (Duhamel et al., 2000). ...
Context In France, during cyclic population surges, water voles, Arvicola terrestri, cause extensive damage to mountain grassland. A working group consisting of researchers from the University of Franche-Comté (UFC), INRA (Centre de Biologie et de Gestion des Populations) agricultural organizations (Fédération Régionale de Défense contre les Organismes Nuisibles de Franche-Comté, FREDON) are working on systems approach in which interactions between voles, their habitat (landscape, predators) and agricultural practices are analysed hierarchically (in space and time). One of the objectives is to highlight the largest possible number of control factors on which it is possible to act, and the scale at which these actions are relevant. These studies have helped initiate a strategy, successfully tested in Franche-Comté and in Auvergne, which promotes the integrated control of water vole populations. Nevertheless, there are still grey areas in the understanding of the cycle, particularly on the determinants of the decline phase. The role of pathogen communities (some species may even be transmitted to humans) so far remains the subject of debate in the scientific literature. The understanding of the key factors determining this phase should allow farmers to better anticipate economic impacts and to adopt optimal strategies for vole population control Objectives: (1) To test the pathogens and senescence hypotheses in order to explain the population decline. (2) To look for biological indicators (diversity of pathogens and / or immune indicators) that may predict the decline phase in order to anticipate appropriate measures to restore grasslands. (3) To assess the role of the transition between high population density phase and the decline phase for the emergence of pathogens in vole populations that may cause human diseases.General Methodology Population monitoring with regular (monthly) sampling will be made on several populations (replicates) in the period that brackets the vole population declines. Methods based on Next Generation Sequencing (NGS) makes it possible to establish extensive catalogues of pathogens (viruses, bacteria, other parasites) hosted by vole populations and to measure the prevalence.
... Farming areas were converted into grasslands for milk production in the 1960s, which has favored outbreaks of water voles (WVs, Arvicola scherman S.) since the 1970s. 11 To reduce WV damage, bromadiolone was applied during the 1980s and 1990s during WV outbreaks as previous studies indicated a low risk to non-target species. 9 Unfortunately, bromadiolone applications in conditions of high WV density produced numerous poisonings and mortality in non-target species. ...
... The sites were located on the second Jura Plateau in a mid-mountain zone (range = 688-1028 m altitude), where WV populations show 6-year cycles moving in traveling waves. 11,28 WVs can reach 800 individuals ha −1 in the Jura Mountains, and WVs normally disperse short distances, with a mean of less than 100 m (WV home range = 100-200 m 2 ). 7,29 For each site, all surveys (i.e. the field work in Sections 2.2, 2.3 and 2.4) were conducted within a circular area of approximately 450 ha (i.e. a radius of 1.2 km). ...
... The parcels were primarily grasslands used by farmers to feed their cows. 7,11 The mean area of the parcels was 6.64 ha (range = 0.09-49.72 ha). ...
BACKGROUND
The use of pesticides can affect non‐target species by causing population declines through indirect intoxication. Small mustelids (SMs; weasels, Mustela nivalis L.; stoats, Mustela erminea L.) consume water voles (WVs, Arvicola scherman S.) and can be exposed to bromadiolone, an anticoagulant rodenticide used in some countries to reduce WV damage to grasslands. Here, we investigated whether bromadiolone affected SM abundance.
RESULTS
We monitored SM abundance using footprint tracking tunnels in spring and autumn at 10 sites. Among these sites, 4 were treated with bromadiolone, while 6 were not treated. We found reduced SM abundance at these 4 sites from spring to autumn (treated sites, mean±SE SM abundance change=‐1.68±0.42; untreated sites, 0.29±0.25). Using a linear model, we observed that SM abundance decreased as a function of the quantity of bromadiolone applied during the 3 months before the autumn estimate. We found that WV abundance increased at treated sites (linear model, treated sites, mean±SE WV abundance change=1.4±0.4; untreated sites, 0.33±0.25). Thus, at treated sites, SM abundance declined despite increased food availability. By analyzing residues in vole livers and SM scats we showed that SMs may be exposed to bromadiolone at the sites where this compound was used.
CONCLUSION
This study is the first to document the relationship between SM abundance and bromadiolone usage for small mammal control. Declines in SM abundance were observed at treated sites, where bromadiolone residue was found in SM scats. This correlative approach suggests that bromadiolone treatment may lead to seasonal SM declines and associated WV increases.
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... Here, we propose coupling ABM and EBM in a multiscale model to overcome these limits, and as an example, we seek to build a model to simulate the spread of a montane water vole, Arvicola scherman, population in the Haute-Romanche valley (France). The population surges of montane water voles have been studied in a number of mountain ranges in France (Giraudoux et al., 1997;Fichet-Calvet et al., 2000;Delattre and Giraudoux, 2009;Berthier et al., 2014;Michelin et al., 2014;Halliez et al., 2015). This work provides basic knowledge on the ecology of this species and its population dynamics. ...
... Given the proximity of the Parc National des Écrins and considering the potential risk to wildlife posed by the side effects of vole control, the staff of the park carefully mapped the annual progress of the colonization from 1998 to 2010 until it reached the Col du Lautaret and stopped in the 13th year. Mapping was based on the observation of surface activity indices after the snowmelt, which is a reliable indicator of variations in vole abundance (Giraudoux et al., 1995(Giraudoux et al., , 1997Berthier et al., 2014). This unique situation of primary colonization made it possible to know the characteristics of an invasion pattern of a valley from a known starting point (the end of the Buffe valley) over a surface area of approximately 2500 ha constrained by the relief of valleys. ...
... This approach might help field ecologists determine which parameter configuration corresponds to what actually occurs in the field by developing hypothesisdriven observations/experiments in an explicitly spatial and temporal context. Such a method is of prime importance in, for example, landscape ecology, where one of the main direct and indirect drivers of population dynamics is the spatial arrangements of species habitats (Delattre et al., 1992(Delattre et al., , 1999Giraudoux et al., 1997;Berthier et al., 2014). Fig. 7. Parameter values of the 27 simulations selected (B = 6059). ...
The incorporation of the spatial heterogeneity of real landscapes into population dynamics remains extremely difficult. We propose combining equation-based modelling (EBM) and agent-based modelling (ABM) to overcome the difficulties classically encountered. ABM facilitates the description of entities that act according to specific rules evolving on various scales. However, a large number of entities may lead to computational difficulties (e.g., for populations of small mammals, such as voles, that can exceed millions of individuals). Here, EBM handles age-structured population growth, and ABM represents the spreading of voles on large scales. Simulations applied to the spreading of a montane water vole population demonstrated that our model is quite efficient in representing the pattern observed and might help to highlight some key parameters during population expansion. This method paves the way for further developments, including the introduction of density-dependent parameters (predation, diseases, etc.) capable of triggering population declines in an explicitly spatial context.
... The achievement of successful dispersal and subsequent settlement supposes effective movements, nevertheless, landscape characteristics can influence this process in A. scherman (Fichet-Calvet et al. 2000;Foltête & Giraudoux 2012;Foltête et al. 2016). On the one hand, homogeneous landscapes, such as large meadow areas, allow connectivity among favourable habitats and hence effective movements in this species (Giraudoux et al. 1997;Fichet-Calvet et al. 2000;Foltête & Giraudoux 2012). On the other hand, heterogeneous landscapes can prevent colonisation of fossorial water voles directly by slowing their dispersion and indirectly by favouring predation (Giraudoux et al. 1997;Fichet-Calvet et al. 2000;Foltête et al. 2016). ...
... On the one hand, homogeneous landscapes, such as large meadow areas, allow connectivity among favourable habitats and hence effective movements in this species (Giraudoux et al. 1997;Fichet-Calvet et al. 2000;Foltête & Giraudoux 2012). On the other hand, heterogeneous landscapes can prevent colonisation of fossorial water voles directly by slowing their dispersion and indirectly by favouring predation (Giraudoux et al. 1997;Fichet-Calvet et al. 2000;Foltête et al. 2016). Connected favourable habitats lead to merged populations of A. scherman and a synchronization of their population densities (Giraudoux et al. 1997;Morilhat et al. 2008;Berthier et al. 2013). ...
... On the other hand, heterogeneous landscapes can prevent colonisation of fossorial water voles directly by slowing their dispersion and indirectly by favouring predation (Giraudoux et al. 1997;Fichet-Calvet et al. 2000;Foltête et al. 2016). Connected favourable habitats lead to merged populations of A. scherman and a synchronization of their population densities (Giraudoux et al. 1997;Morilhat et al. 2008;Berthier et al. 2013). For example, fossorial water voles from France and Switzerland show well-marked multiannual fluctuations of density, commonly named cycles, every 5 to 9 years (Saucy 1988; Giraudoux et al. 1997;Fichet-Calvet et al. 2000). ...
The montane water vole Arvicola scherman occurs in mountainous areas of Europe, living in underground burrow systems located in grasslands and fruit orchards. This species feeds on the root system of plants, including fruit trees. Specifically, the subspecies A. scherman cantabriae is nowadays one of the main causes of economical loss in apple orchards of Asturias (northwestern Spain). An official control program in Spain considers all sustainable phytosanitary measures that can reduce population growth of this species. Since the pest condition of A. scherman depends on its biology and ecology, a deep knowledge of these aspects is needed to set up specific and suitable control strategies. Thus, the aim of this research is to obtain essential information on the reproductive biology and population genetics of this species in the agricultural landscape of Asturias.
More than 800 individuals of A. scherman cantabriae were gathered in apple orchards located at low altitude in Villaviciosa and Nava municipalities during two annual cycles (from February 2011 to January 2013). Sexual characteristics, body measurements and relative age class of each specimen were recorded. Body condition of females, which indicates energy provision, and the number of embryos of each one were also wrote down. Skeletal muscle samples of 137 specimens from ten demes were used to conduct a microsatellite-based analysis (12 microsatellite loci). These orchards are placed in a landscape conformed by a mosaic of small and different land-use plots, which was assessed in a vector based geographic information system and it was focused on soil-occupancy categories.
Pregnant females and young specimens were detected over the whole year, which mean that A. scherman cantabriae showed a continuous breeding pattern during the study period. Intra-annual changes in body mass and size of sexual organs of males did not affect significantly reproduction at a population scale. Thus, primary demands of these voles seem to be properly fulfilled during the whole year and hence energy budgets can be destined to cop continuous reproduction. To our knowledge, no other A. scherman population shows regularly this reproductive pattern. Females were able to produce a high number of litters per year (7.30) although litter size was relatively moderate (embryos/female: first year: 3.87; second year: 3.63). Each female was able to produce 28.25 pups per year. The reproductive potential showed by Cantabrian voles is, to our knowledge, the highest one reported to date for this species; probably because the breeding season does not entail a critical factor in this area. A positive correlation between litter size and the body condition of the mother was observed. Therefore, the body condition of females seems to be one of the main factors involved in the variation of the reproductive potential in A. scherman cantabriae.
These studied demes showed relatively low level of genetic diversity (HE = 0.621; HO = 0.601; AR = 4.42) probably due to both the inbreeding and genetic drift effects. Significant genetic differentiation appeared among demes, which revealed a strong pattern of significant isolation-by-distance both for Euclidean distances (r = 0.790) and effective distances (r = 0.780). The spatial autocorrelation analysis detected four genetic clusters or populations in this study area (120 km2). Thus, this mosaic of different land-use plots decreases connectivity among suitable habitats even at local scale, in which A. scherman populations mainly depend on birth and death rates. An estuary and a four-lane road did not suppose a barrier for gene flow of this species. Less seasonal environment and highly patched landscape would suggest that this species does not show well marked multiannual fluctuations of density at large scale in this area.
Control strategies for A. scherman cantabriae at a regional scale can be discarded. The monitoring of each population, or management unit, will be essential to know the population dynamic and to establish coordinated control strategies. Preserving and promoting this patchy landscape would favour the presence of predators and hamper dispersion of this species. A continuous population control throughout the year would be advisable, using sustainable methods, such as traps, the installation of barriers and/or coordinated manipulation of habitat.
... Estos parámetros están muy relacionados entre sí, ya que las parcelas de mayor tamaño son aquellas obtenidas tras los procesos de concentración parcelaria en los cuales se unen varias parcelas más pequeñas, con la consiguiente eliminación de linderos existentes entre las mismas, y se redefinen los límites de las fincas buscando formas más regulares que faciliten el laboreo, con lo que la sinuosidad también se ve reducida (Rodríguez y Wiegand 2009). Esta simplificación del hábitat favorece tanto la aparición de los daños por rata topera (Giraudoux et al. 1995(Giraudoux et al. , 1997Duhamel et al. 2000;Morilhat et al. 2008), como la expansión hacia nuevas zonas (Giraudoux et al. 1997;Berthier et al. 2013Berthier et al. , 2014, y podría estar detrás de la reciente aparición de los daños por rata topera en la zona, que eran prácticamente inexistentes en la década de los 80 (Castién 1993). ...
... Estos parámetros están muy relacionados entre sí, ya que las parcelas de mayor tamaño son aquellas obtenidas tras los procesos de concentración parcelaria en los cuales se unen varias parcelas más pequeñas, con la consiguiente eliminación de linderos existentes entre las mismas, y se redefinen los límites de las fincas buscando formas más regulares que faciliten el laboreo, con lo que la sinuosidad también se ve reducida (Rodríguez y Wiegand 2009). Esta simplificación del hábitat favorece tanto la aparición de los daños por rata topera (Giraudoux et al. 1995(Giraudoux et al. , 1997Duhamel et al. 2000;Morilhat et al. 2008), como la expansión hacia nuevas zonas (Giraudoux et al. 1997;Berthier et al. 2013Berthier et al. , 2014, y podría estar detrás de la reciente aparición de los daños por rata topera en la zona, que eran prácticamente inexistentes en la década de los 80 (Castién 1993). ...
La rata topera (Arvicola scherman) es una especie de gran interés, tanto por su papel como presa de multitud de depredadores, como por el impacto de sus daños sobre la agricultura. Las variaciones en su abundancia poblacional y el papel de los factores que la modulan han sido ampliamente estudiadas en el norte de Europa, pero hasta el momento, se carecía de esta información para las poblaciones del Pirineo. En el presente trabajo se exponen los resultados obtenidos en el plan de monitorización de la especie en Navarra desde 2016 hasta 2020, describiendo tanto los cambios de abundancia registrados, como la influencia de los factores ambientales y de gestión agroganadera analizados. Describimos una variación de la abundancia a lo largo del año, con valores significativamente mayores en primavera que en verano; y entre los 5 años de muestreo, con una abundancia significativamente mayor en 2016 y 2020. La pluviometría acumulada en los meses previos al censo y el pastoreo con ovejas han sido los factores retenidos en los modelos con influencia significativa. Ambos han ejercido un efecto positivo sobre la rata topera, aumentando su abundancia al incrementarse la pluviometría y con el aprovechamiento con ganado ovino. Se discute el papel de estos factores y otras variables de estructura del paisaje y de gestión agrícola en los cambios de abundancia poblacional de la rata topera.
... We obtained information on Arvicola abundance for 196 scats. As Arvicola monticola cycles last at least one year (Giraudoux et al., 1997), we considered the cycles (i.e. years) to last from spring to the end of winter of the next year. ...
... Following our expectations, prey consumption varied seasonally, with higher consumption of Arvicola during summer and autumn, when its abundance and accessibility to predators in pastoral areas may be higher (Weber & Aubry, 1993;Butler & Gillings, 2004). Seasonal variations in abundance of Arvicola respond to reproductive cycles of the species, with demographic peaks occurring between spring and the end of summer (Giraudoux et al., 1997). ...
Traditional agro-pastoral practices are more beneficial for biodiversity than intensified agricultural systems. Promotion of growth of natural herbaceous vegetation in pastoral fields can enhance rodent populations and consequently influence ecological aspects of carnivores with rodent-based diets, like prey consumption in the European wildcat (Felis silvestris). In this article, we investigated the effects of pastoral field extent, season and prey abundance on wildcat consumption of several prey species in the Cantabrian Mountains (NW Spain). Prey consumption in areas with presence of pastoral fields (even in low proportions) was dominated by profitable field-dwelling rodent species such as Arvicola monticola. Consumption of Arvicola was not correlated with its abundance and was higher during summer and autumn. Apodemus dominated wildcat diet in areas with higher forest proportion and far from pastoral fields particularly during spring. Our results suggest that varying habitat use and seasonal changes in prey accessibility may determine wildcat prey consumption in pastoral landscapes. Our results can contribute to highlight the potential benefits of traditional and sustainable pastoral activities for the conservation of the European wildcat across its distribution range.
... In upland regions of Europe, water vole (Arvicola amphibius) populations widely fluctuate, and periodic outbreaks move in waves from epicenters, devastating orchards, grasslands and young tree plantations [34]. Population cycles last six to seven years [35] with alternating phases of low-density and outbreaks, the latter of which can last two to four years [36], causing severe damage and economic losses [37]. ...
... Population cycles last six to seven years [35] with alternating phases of low-density and outbreaks, the latter of which can last two to four years [36], causing severe damage and economic losses [37]. According to Giradoux et al. [34], land use and landscape management could be a way to control water vole outbreaks. Cultivation practices strongly affected voles' presence, especially in orchards [38]. ...
Rodent bark gnawing is common during winter in times of low or unavailable food supply. During the growing season, it is a rare phenomenon, but can occur due to low food supply and/or poor food quality resulting from climatic influence. We evaluated this unusual damage of apple tree (Malus domestica) orchards by rodents in two localities in the Czech Republic. In 2019, 24% of trees in the orchard in Brno were gnawed by the common vole (Microtus arvalis) population. Damage in the Holovousy orchard by water vole (Arvicola amphibius) was inspected in 2020 and showed that 15% of trees were damaged with massive root gnawing. These findings were compared with gnawing in forest beech plantations in 2019, with up to 13% of trees damaged. Three rodent species (Microtus agrestis, M. arvalis and Clethrionomys glareolus) participated in the damage. Detailed description of the various vole species’ damage in vegetation period, which somehow differs from winter time damage, may help in the future in early recognition and early application of plant protection in times when this phenomenon may reappear.
... Small mammals (Rodentia and Eulipotyphla) are considered keystone species in agro-ecosystems [16], including olive groves, where they play crucial ecological functions promoting plant community productivity and diversity, including soil aeration, organic turn-over and mineralization, seed dispersal, and the maintenance of ectomycorrhizal fungi (e.g., [17]). Small mammals also contribute to support trophic networks, for instance, by consuming insects [18] and by affecting the diversity of higher trophic levels as prey species for mammalian and avian predators [19][20][21]. However, small mammals may also contribute to spreading zoonotic diseases, and in the case of rodents, they may also become agricultural pests (e.g., [17,22,23]). ...
... We surveyed a total of 613 transects across the 51 sampling units, with a mean ± SE (range) of 12 ± 0.38 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) per sampling unit. In each sampling unit, 2.65 ± 0.14 (1-5) of the transects were located within the focal olive grove, and 9.00 ± 0.28 (6)(7)(8)(9)(10)(11)(12)(13)(14)(15) were located at surrounding semi-natural areas. ...
Understanding how small mammals (SM) are associated with environmental characteristics in olive groves is important to identify potential threats to agriculture and assess the overall conservation value and functioning of agro-ecosystems. Here, we provide first insights on this topic applied to traditional olive groves in northeast (NE) Portugal by assessing the landscape attributes that determine SM occurrence, focusing on one species of conservation concern (Microtus cabrerae Thomas 1906) and one species often perceived as a potential pest of olives (Microtus lusitanicus Gerbe 1879). Based on SM genetic non-invasive sampling in 51 olive groves and surrounding habitats, we identified seven rodent species and one insectivore. Occupancy modelling indicated that SM were generally less detected within olive groves than in surrounding habitats. The vulnerable M. cabrerae reached a mean occupancy (95% CI) of 0.77 (0.61–0.87), while M. lusitanicus stood at 0.37 (0.24–0.52). M. cabrerae was more likely to occur in land mosaics with high density of agricultural field edges, while M. lusitanicus was more associated with high density of pastureland patches. Overall, our study suggests that the complex structure and spatial heterogeneity of traditionally managed olive grove agro-ecosystems may favor the occurrence of species-rich SM communities, possibly including well-established populations of species of conservation importance, while keeping potential pest species at relatively low occupancy rates.
... Estos parámetros están muy relacionados entre sí, ya que las parcelas de mayor tamaño son aquellas obtenidas tras los procesos de concentración parcelaria en los cuales se unen varias parcelas más pequeñas, con la consiguiente eliminación de linderos existentes entre las mismas, y se redefinen los límites de las fincas buscando formas más regulares que faciliten el laboreo, con lo que la sinuosidad también se ve reducida (Rodríguez y Wiegand 2009). Esta simplificación del hábitat favorece tanto la aparición de los daños por rata topera (Giraudoux et al. 1995(Giraudoux et al. , 1997Duhamel et al. 2000;Morilhat et al. 2008), como la expansión hacia nuevas zonas (Giraudoux et al. 1997;Berthier et al. 2013Berthier et al. , 2014, y podría estar detrás de la reciente aparición de los daños por rata topera en la zona, que eran prácticamente inexistentes en la década de los 80 (Castién 1993). ...
... Estos parámetros están muy relacionados entre sí, ya que las parcelas de mayor tamaño son aquellas obtenidas tras los procesos de concentración parcelaria en los cuales se unen varias parcelas más pequeñas, con la consiguiente eliminación de linderos existentes entre las mismas, y se redefinen los límites de las fincas buscando formas más regulares que faciliten el laboreo, con lo que la sinuosidad también se ve reducida (Rodríguez y Wiegand 2009). Esta simplificación del hábitat favorece tanto la aparición de los daños por rata topera (Giraudoux et al. 1995(Giraudoux et al. , 1997Duhamel et al. 2000;Morilhat et al. 2008), como la expansión hacia nuevas zonas (Giraudoux et al. 1997;Berthier et al. 2013Berthier et al. , 2014, y podría estar detrás de la reciente aparición de los daños por rata topera en la zona, que eran prácticamente inexistentes en la década de los 80 (Castién 1993). ...
Resumen: La rata topera (Arvicola scherman) es una especie de gran interés, tanto por su papel como presa de multitud de depredadores, como
por el impacto de sus daños sobre la agricultura. Las variaciones en su abundancia poblacional y el papel de los factores que la modulan han sido
ampliamente estudiadas en el norte de Europa, pero hasta el momento, se carecía de esta información para las poblaciones del Pirineo. En el presente
trabajo se exponen los resultados obtenidos en el plan de monitorización de la especie en Navarra desde 2016 hasta 2020, describiendo
tanto los cambios de abundancia registrados, como la influencia de los factores ambientales y de gestión agroganadera analizados. Describimos
una variación de la abundancia a lo largo del año, con valores significativamente mayores en primavera que en verano; y entre los 5 años de muestreo,
con una abundancia significativamente mayor en 2016 y 2020. La pluviometría acumulada en los meses previos al censo y el pastoreo con
ovejas han sido los factores retenidos en los modelos con influencia significativa. Ambos han ejercido un efecto positivo sobre la rata topera, aumentando
su abundancia al incrementarse la pluviometría y con el aprovechamiento con ganado ovino. Se discute el papel de estos factores y otras
variables de estructura del paisaje y de gestión agrícola en los cambios de abundancia poblacional de la rata topera.
Abstract: The Fossorial Water Vole (Arvicola scherman) is a species of great interest, both because of its role as prey for a wide variety of predators,
and the damages on agriculture. The variation in its population abundance and the factors that modulate it have been widely studied in northern Europe,
but they are rather unknown for Pyrenean populations. Here we show the results obtained in the monitoring plan for the species in Navarra
from 2016 to 2020, describing both the inter- and intra-annual changes in population abundance, as well as the effect of environmental factors and
agricultural management. We found intra-annual variation in its abundance, with significantly higher values in spring than in summer. Interannually,
there was a significantly higher abundance both in 2016 and 2020. The accumulated rainfall in the three months prior to sampling and grazing with
sheep were the two most important factors that explain variation in population abundance. Both factors had a positive effect on the Fossorial Water
Vole, so that its abundance increased with wetter months before sampling and in areas where sheep were present. The role of these factors and
other variables of landscape and agricultural management in the changes of abundance of this rodent are also discussed.
... In the same area, outbreaks of the common vole (>1,000 ind.ha −1 ), another grassland vole, also occur; however, they are noncyclic in this area (Giraudoux et al., 2019). Previous studies have shown that the population dynamics of the two species are shaped by landscape features, with hedgerow networks and wood patches dampening the population dynamics and by contrast open grassland landscapes amplifying the outbreaks (Delattre et al., 1996;Duhamel et al., 2000;Foltête et al., 2016;Foltête & Giraudoux, 2012;Giraudoux et al., 1997;Morilhat et al., 2008). Those outbreaks provide regularly massive quantities (up to >80 kg.ha −1 ) of prey for many species of carnivorous mammals and birds in grassland and by contrast low densities of secondary prey resources that are less accessible (vegetation and/or antipredation behavior) such as forest, marsh and fallow small mammals (maximum about 3 kg.ha ...
... In our study area, the population of the main prey species varied between 0 and approximately 1,000 ind.ha −1 on a scale of tens of km 2 (Berthier et al., 2014;Giraudoux et al., 1997) and an amplitude 5-100 times larger than those observed on a similar scale in different areas worldwide (Dupuy et al., 2009;Erlinge, 1983;Gilg et al., 2006;Lambin et al., 2000). A similar amplitude has been reported locally for M. arvalis in alfalfa semi-permanent plots of some ha in an intensive agriculture matrix of plowed fields of western France (50-1,500 ind.ha −1 ) (Pinot et al., 2016). ...
Voles can reach high densities with multiannual population fluctuations of large amplitude, and they are at the base of predator communities in Northern Eurasia and Northern America. This status places them at the heart of management conflicts wherein crop protection and health concerns are often raised against conservation issues. Here, a 20‐year survey describes the effects of large variations in grassland vole populations on the densities and the daily theoretical food intakes (TFI) of vole predators based on roadside counts. Our results show how the predator community responded to prey variations of large amplitude and how it reorganized with the increase in a dominant predator, here the red fox, which likely negatively impacted hare, European wildcat, and domestic cat populations. This population increase did not lead to an increase in the average number of predators present in the study area, suggesting compensations among resident species due to intraguild predation or competition. Large variations in vole predator number could be clearly attributed to the temporary increase in the populations of mobile birds of prey in response to grassland vole outbreaks. Our study provides empirical support for more timely and better focused actions in wildlife management and vole population control, and it supports an evidence‐based and constructive dialogue about management targets and options between all stakeholders of such socio‐ecosystems.
... Outbreaks, crop damage, and zoonosis.-Changes in agricultural practices throughout Europe have led to an increase in connectivity of grasslands, resulting in outbreaks of grassland rodents, such as the fossorial water vole (Arvicola terrestris scherman), whose populations undergo travelling waves on a multiyear cycle (Giraudoux et al. 1997). High population densities of A. t. scherman cause severe crop damage, substantial economic losses (Meylan 1977;Jacob and Tkadlec 2010), and a greater prevalence of alveolar echinococcosis in humans, which is a lethal parasitic disease transmitted via a fox-small mammal cycle (Viel et al. 1999). ...
... High population densities of A. t. scherman cause severe crop damage, substantial economic losses (Meylan 1977;Jacob and Tkadlec 2010), and a greater prevalence of alveolar echinococcosis in humans, which is a lethal parasitic disease transmitted via a fox-small mammal cycle (Viel et al. 1999). At a regional scale (~2,500 km 2 ), percent grassland is the primary driver of fluctuations in population densities and outbreaks of A. t. scherman (Giraudoux et al. 1997), whereas at the landscape scale (~25 km 2 ) differences in landscape structure exist between outbreak epicenters and diffusion areas (locations of minor outbreaks that occur in years following the initial outbreak). Epicenters occur in open landscapes with little forest and in unfragmented grasslands, whereas diffusion areas have more woodland patches and hedgerow networks that fragment grasslands, suggesting a negative effect of fragmentation on rodent breakouts (Duhamel et al. 2000). ...
Recognition of the Anthropocene epoch formally acknowledges the pervasive and increasingly dominant effects of human activities on the world’s biomes. A defining characteristic of the Anthropocene is habitat conversion (land-use change) for agricultural and urbanized land uses. Within this context, landscape ecology is of critical importance as it examines the influence of spatial heterogeneity on ecological patterns and processes at spatial and temporal extents that are larger than those traditionally studied in ecology. The application of landscape ecological approaches to mammalian populations, communities, and metacommunities began in and has increased steadily since the 1990s. Non-volant small mammals or bats are often the focus of landscape studies of communities, whereas carnivores or artiodactyls are commonly the focus of population-level studies cast within the domains of conservation or wildlife management. Research on the landscape ecology of mammals has primarily been conducted in Europe and North America, but with increasing frequency has been explored on other continents. Mammalian research has contributed significantly to the development of landscape ecology, demonstrating that responses to landscape structure are often taxon-, scale-, or context-dependent. Future research should consider hierarchical approaches that are scale-sensitive, with explicit linkage to contemporary hypotheses, thereby advancing theoretical understanding and informing management and conservation action.
... Since the early 1970s, subsequent to the specialization of agriculture in dairy production in the French Jura Mountains, almost all the utilized agricultural area has been converted into permanent grasslands, resulting in an increase of montane water vole (Arvicola terrestris) densities (Giraudoux et al., 1997). Montane water voles are herbivorous small mammals feeding on plant roots. ...
... Cyclic outbreaks of montane water vole populations (200-1000 individuals per hectare) occur every 5-8 years (Berthier et al., 2014) and do considerable damage on vegetation (Delattre and Giraudoux, 2009), resulting in an important loss of forage production (Quéré et al., 1999;Schouwey et al., 2014). Many studies have been conducted to understand the determinism of these outbreaks (Giraudoux et al., 1997;Morilhat et al., 2007Morilhat et al., , 2008 and to limit their intensity (Couval and Truchetet, 2014;Foltête et al., 2016). However, the impact of montane water vole disturbances on plant diversity and composition in grassland ecosystems have not been assessed yet. ...
It is recognized that disturbances by fossorial small mammals are important factors determining plant community diversity, especially in grasslands. However, although information about the effects of disturbances by fossorial small mammals on species richness are starting to accumulate, we know little about the impact of these disturbances on the functional and phylogenetic facets of plant community diversity in grasslands.
In a study site located in the French Jura Mountains, we compared taxonomic, functional and phylogenetic diversity of plant communities in areas highly disturbed by montane water vole (Arvicola terrestris) with areas lowly disturbed by this small mammal. In accordance with previous studies, we found that species richness was higher in highly disturbed communities. Indeed, competitive species unable to withstand disturbances were less abundant in disturbed communities, allowing species less adapted to competition for light to survive. Because these species have different trait values in comparison to strong competitors, functional richness was also higher in highly disturbed communities. Results were similar for phylogenetic richness, maybe due to the fact that the used metric was not independent from species richness. Although species composition differed between highly and lowly disturbed communities, functional composition was very similar. Thereby, the studied disturbances were probably not strong enough to affect plant community functioning. Rao functional diversity and functional evenness were not different between both community types. Interestingly, phylogenetic evenness was lower in highly disturbed areas, supporting the idea that disturbances might select for disturbance tolerance traits that are phylogenetically conserved.
Though correlational, our results suggest that water vole disturbances may modify multiple facets of plant community diversity, while ecosystem functioning is maintained across disturbance levels. Further research is needed to understand causal mechanisms in this system and the ecological repercussions of small mammal disturbances more broadly.
... In Franche-Comté, farmers shifted from polyculture to almost exclusively grass production for milk used to produce cheese from the early 1970s (Giraudoux et al., 1997). Due to recurrent vole outbreaks and damages to grasslands, massive rodenticide treatments were implemented from the early 80s with consequences on non-target wildlife. ...
... We considered a tri-trophic system described in Figure 1 and Equations (1-5); parameterization is provided in Table 1 The vole population followed a logistic growth rate, with r V the maximal reproduction rate, fixed at r V = ln(2 × 600)/365 per day, since montane water vole populations can increase from 0 to 600 individuals/ha or more (Giraudoux et al., 1997), resulting in the equilibrium density being fixed at K V = 600 individuals. The vole population was preyed upon by mustelid and fox populations. ...
Understanding pesticide impacts on populations of target/non‐target species and communities is a challenge to applied ecology. When predators that otherwise regulate pest densities ingest prey contaminated with pesticides, this can suppress predator populations by secondary poisoning. It is, however, unknown how species relationships and protocols of treatments (e.g. anticoagulant rodenticide [AR]) interact to affect pest regulation.
To tackle this issue, we modelled a heuristic non‐spatialized system including montane water voles, specialist vole predators (stoats, weasels) and a generalist predator (red fox) which consumes voles, mustelids and other prey. By carrying out a broad‐range sensitivity analysis on poorly known toxicological parameters, we explored the impact of five farmer functional responses (defined by both AR quantity and threshold vole density above which AR spreading is prohibited) on predator–prey interactions, AR transfer across the trophic chain and population effects.
Spreading AR to maintain low vole densities suppressed mustelid and fox populations, leading to vole population dynamics being entirely regulated by AR use. Such vole‐suppression treatment regimes inhibited predation ecosystem services and promoted pesticide dependence.
Keeping vole density below acceptable bounds by spreading AR while maintaining sufficient voles as prey resources led to less AR being applied and extended periods without AR in the environment, benefiting predators while avoiding episodes with high vole density. This may meet farm production interests while minimizing the impact on mustelid and fox populations and associated ecosystem processes. These alternating phases of mustelids and farmer regulation highlight the consequence of intraguild relationship where mustelids may rescue foxes from poisoning. Both global and wide‐range sensitivity analysis illustrate the tightrope between predator–prey regulation and pesticide–pest regulation.
Synthesis and applications . Different pesticide protocols lead to a rich variety of predator–prey dynamics in agro‐ecosystems. Our model reveals the need to maintain refuges with sufficient non‐poisoned voles for sustaining specialist mustelids, to conserve the predator community given the potential of secondary poisoning with rodenticides. We suggest that long periods without pesticide treatment are essential to maintain predator populations, and that practices of pesticides use that attempt to permanently suppress a pest over a large scale are counterproductive.
... Dans le cas du campagnol, sa pullulation est fortement corrélée avec l'occupation des sols. Les valeurs élevées du rapport entre les surfaces en prairies et les zones cultivées indiquent un risque élevé de pullulation (Giraudoux et al., 1997). Millán de la Peña et al. (2003b) ont montré qu'un territoire avec une connectivité élevée permet une diversité de rongeurs par rapport à un paysage d'openfield. ...
... Par rapport à l'indicateur général de résistance aux stress biotique (Chapitre 2), même s'il reste à préciser et valider les autres sous-indicateurs, certains, comme l'indicateur « pression des adventices » ( § 2.2.1.c.) existe et a été éprouvé pour le piétin verse par le Service de Protection des Végétaux (SRPV). Un autre indicateur comme l'indicateur « pression des ravageurs à déterminisme territorial » ( § 2.3.2.b.) sur le modèle des campagnols (Microtinus arvalis) peut être finalisé rapidement étant donné la présence d'un certain nombre de publications sur le sujet, notamment en France (Delattre et al., 1992;Giraudoux et al., 1995;Delattre et al., 1996;Giraudoux et al., 1997;Delattre et al., 1999). ...
Des outils d'évaluation pertinents sont nécessaires pour évaluer l'impact des pratiques agricoles sur les fonctions assurées par la biodiversité de l'échelle de la parcelle à l'échelle du territoire. L'objectif et l'innovation du présent travail a été d'explorer une nouvelle méthode de création d'un outil d'évaluation des fonctions de la biodiversité. Nous avons choisi comme méthode d'évaluation les indicateurs agri-environnementaux, qui permettent d'évaluer l'impact des pratiques agricoles sur les compartiments de l'environnement (eau, sol, air, faune et flore) et aident à la prise de décisions. Nous proposons donc une architecture générale d'un indicateur de biodiversité fonctionnelle et le détail d'un indicateur de fonction agronomique d'importance: la résistance aux stress biotiques. Au sein de cet indicateur se trouve un sous-indicateur : le « rôle des auxiliaires terrestre ». Les carabes seront utilisés comme auxiliaire modèle pour la construction de ce sous-indicateur. Deux méthodes de construction d'indicateurs sont comparées: une méthode à dire d'expert et une méthode par fouille de données, cette deuxième méthode représentant une innovation de la thèse. Les résultats de ces méthodes sont ensuite comparés à des mesures de terrain conduit sur le territoire de Vittel. Les mesures de terrain ont concerné le suivi des populations de carabes, et l'organisation du territoire agricole. Un traitement par un système d'information géographique a permis la validation des indicateurs obtenus
... The Chinese government is implementing a series of extensive landscape regeneration projects to restore the country's degraded ecological landscape [19,20]. Studies conducted in various echinococcosis-endemic regions have documented that land cover transformations are related to higher population densities of key intermediate hosts for E. multilocularis, which has increased the risk of human AE infection [21][22][23][24][25][26][27][28]. Hence, research also needs to be conducted to better describe the ecological processes that may lead to variations in the transmission patterns of E. granulosus and E. multilocularis based on shifting environmental factors [29]. ...
... Landscape change and fragmentation have been identified as important determinants of the population dynamics of several species of wild mammals that are common intermediate host of E. multilocularis [87][88][89][90]. In eastern France, population outbreaks of Microtus arvalis and Arvicola terrestris were reported in areas where ploughed fields were converted into permanent grassland [21,22]. Significant positive associations of E. multilocularis infection in humans and foxes with the extent of grassland were also reported in the same region [21,91,92]. ...
Background:
Human echinococcoses are parasitic helminth infections that constitute a serious public health concern in several regions across the world. Cystic (CE) and alveolar echinococcosis (AE) in China represent a high proportion of the total global burden of these infections. This study was conducted to predict the spatial distribution of human seropositivity for Echinococcus species in Xiji County, Ningxia Hui Autonomous Region (NHAR), with the aim of identifying communities where targeted prevention and control efforts are required.
Methods:
Bayesian geostatistical models with environmental and demographic covariates were developed to predict spatial variation in the risk of human seropositivity for Echinococcus granulosus (the cause of CE) and E. multilocularis (the cause of AE). Data were collected from three cross-sectional surveys of school children conducted in Xiji County in 2002-2003, 2006-2007 and 2012-2013. Environmental data were derived from high-resolution satellite images and meteorological data.
Results:
The overall seroprevalence of E. granulosus and E. multilocularis was 33.4 and 12.2%, respectively, across the three surveys. Seropositivity for E. granulosus was significantly associated with summer and winter precipitation, landscape fragmentation variables and the extent of areas covered by forest, shrubland, water and bareland/artificial surfaces. Seropositivity for E. multilocularis was significantly associated with summer and winter precipitations, landscape fragmentation variables and the extent of shrubland and water bodies. Spatial correlation occurred over greater distances for E. granulosus than for E. multilocularis. The predictive maps showed that the risk of seropositivity for E. granulosus expanded across Xiji during the three surveys, while the risk of seropositivity for E. multilocularis became more confined in communities located in the south.
Conclusions:
The identification of high-risk areas for seropositivity for these parasites, and a better understanding of the role of the environment in determining the transmission dynamics of Echinococcus spp. may help to guide and monitor improvements in human echinococcosis control strategies by allowing targeted allocation of resources.
... being higher in communities where pastoralism and poor socio-economic conditions are predominant [9,10]. The patchy AE endemicity distribution has been associated with landscape characteristics and climatic factors that determine habitat suitability for the definitive and intermediate hosts [11][12][13][14][15][16][17]. Hence, understanding how environmental and social factors interact to determine parasite transmission is essential for the design and implementation of effective strategies against echinococcosis, and to target resources to the communities most in need. ...
... Similarly, the percentage of area covered by grassland and E. multilocularis infection in humans and foxes had a positive relationship in Eastern France [13,83,84]. In this area various studies also reported regular outbreaks of Microtus arvalis and Arvicola terrestris, key intermediate hosts for E. multilocularis [13,17]. However, the picture is complex, given that in Sichuan Province, a negative cross-sectional association was observed between Ochonta spp. ...
Background:
Human cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations. We aimed to assess and quantify the spatiotemporal patterns of human echinococcoses in Ningxia Hui Autonomous Region (NHAR), China between January 1994 and December 2013, and examine associations between these infections and indicators of environmental variability and change, including large-scale landscape regeneration undertaken by the Chinese authorities.
Methods:
Data on the number of human echinococcosis cases were obtained from a hospital-based retrospective survey conducted in NHAR for the period 1 January 1994 through 31 December 2013. High-resolution imagery from Landsat 4/5-TM and 8-OLI was used to create single date land cover maps. Meteorological data were also collected for the period January 1980 to December 2013 to derive time series of bioclimatic variables. A Bayesian spatio-temporal conditional autoregressive model was used to quantify the relationship between annual cases of CE and AE and environmental variables.
Results:
Annual CE incidence demonstrated a negative temporal trend and was positively associated with winter mean temperature at a 10-year lag. There was also a significant, nonlinear effect of annual mean temperature at 13-year lag. The findings also revealed a negative association between AE incidence with temporal moving averages of bareland/artificial surface coverage and annual mean temperature calculated for the period 11-15 years before diagnosis and winter mean temperature for the period 0-4 years. Unlike CE risk, the selected environmental covariates accounted for some of the spatial variation in the risk of AE.
Conclusions:
The present study contributes towards efforts to understand the role of environmental factors in determining the spatial heterogeneity of human echinococcoses. The identification of areas with high incidence of CE and AE may assist in the development and refinement of interventions for these diseases, and enhanced environmental change risk assessment.
... For example, it has been shown in the Massif Central, France, that the risk for outbreaks of A. scherman populations is high in regions where the proportion of permanent grassland exceeds 90% and low in regions where this proportion is <80% (Fichet-Calvet et al., 2000). It is, therefore, worth considering how agricultural practices and landscape management sustain high densities of known or potential intermediate hosts (Giraudoux et al., 1997). Altering the habitat and reducing its potential for maintaining populations of relevant small mammal intermediate host species near human settlements could play an important role in the framework of integrated control programmes Giraudoux et al., 2013b). ...
... An important baseline for the implementation of an integrated control strategy is a detailed knowledge about the occurrence and ecology of the intermediate and final hosts Liccioli et al., 2015;Raoul et al., 2015). Knowing the importance of different intermediate and final host species for parasite transmission in a given region and an understanding how their population dynamics are affected by wildlife management measures and agricultural practices are fundamental to develop regionally adapted control and prevention measures (Giraudoux et al., 1997. ...
Human cystic echinococcosis (CE) has been eliminated or significantly reduced as a public health problem in several previously highly endemic regions. This has been achieved by the long-term application of prevention and control measures primarily targeted to deworming dogs, health education, meat inspection, and effective surveillance in livestock and human populations. Human CE, however, remains a serious neglected zoonotic disease in many resource-poor pastoral regions. The incidence of human alveolar echinococcosis (AE) has increased in continental Europe and is a major public health problem in parts of Eurasia. Better understanding of wildlife ecology for fox and small mammal hosts has enabled targeted anthelmintic baiting of fox populations and development of spatially explicit models to predict population dynamics for key intermediate host species and human AE risk in endemic landscapes. Challenges that remain for echinococcosis control include effective intervention in resource-poor communities, better availability of surveillance tools, optimal application of livestock vaccination, and management and ecology of dog and wildlife host populations.
... Outbreaks of water vole populations occur every 6 years on average, with densities peaking at 500-1000 individuals/hectare for 1-3 years [32,33]. If a vole population is headed toward an outbreak and is hosting a pathogenic Leptospira species, humans, livestock, and other animals in the same environment may be at risk [34]. ...
Rodents are the primary reservoirs for pathogenic Leptospira species, which cause leptospirosis. Among the key potential carriers are water voles, whose population outbreaks can consequently pose a major threat to human and animal health. We studied the prevalence, prominence, and epidemiology of pathogenic Leptospira species in water voles in central France. First, 46 voles were captured, and DNA was extracted from kidney, lung, liver, blood, and urine and tested for the presence of Leptospira using three molecular methods: PCR, O-antigen typing, and variable number tandem repeat (VNTR) typing. We also attempted to culture leptospires from kidney and urine samples. In addition, we investigated leptospiral antibodies in serum samples from 60 sheep using microscopic agglutination testing. These animals co-occurred with the voles, so we sought to assess their degree of exposure and involvement in pathogen dynamics. The overall prevalence of infection was 76.1% (CI95% [61.2%, 87.4%]). The only strain found was L. kirschneri serogroup Grippotyphosa and a similar VNTR profile was acquired. Leptospires were successfully cultured from kidney and urine samples for four voles. Three sheep had low antibody titers against the Leptospira serogroup Grippotyphosa. Taken together, our results suggest the exclusive carriage of L. kirschneri serogroup Grippotyphosa among water voles in central France. Nevertheless, their ability to act as reservoir hosts that transmit the pathogen to co-occurring livestock remains unclear and merits further research.
... Le pâturage provoque la destruction en partie les galeries grâce au piétinement provoqué par le bétail et favorise la compétition alimentaire entre les ruminants et les campagnols. En plus, un travail du sol par le labour ou le hersage imite le piétinement du bétail détruisant ainsi une partie des galeries et exposant le reste à l'extérieur ou aux prédateurs (Fichet-Calvet et al., 2000;Giraudoux et al., 1997). Pour avoir plus d'effet contre le développement des campagnols le travail du sol peut être associé à une implantation et rotation de culture qui réduit la surface agricole toujours en herbes par rapport à la surface agricole utile (le ratio STH/SAU). ...
Les pullulations de campagnols terrestres sont à l’origine de nombreux problèmes. Leur gestion implique différentes mesures mais surtout une lutte chimique par les antivitamines K (AVK). Ces molécules ciblent l’enzyme VKOR codée par le gène VKORC1. L’inhibition de cette enzyme provoque des hémorragies mortelles. L’utilisation intensive des AVK a mené à l’émergence d’une résistance de cible ainsi que des ecotoxicités documentées par plusieurs études. Au cours de ce travail, nous avons étudié la pharmacocinétique de la chlorophacinone et de la bromadiolone chez le campagnol. Nous tenons à préciser que le mélange actuel de bromadiolone utilisé dans la lutte est composé de 85% de l’isomères trans et de 15% de l’isomères cis. Notre étude nous a permis d’identifier une longue demi-vie de l’isomère trans de la bromadiolone contre une demi-vie beaucoup plus réduite pour la cis-bromadiolone et la chlorophacinone. Par conséquence, l’isomère trans est responsable de la persistance de la molécule chez le campagnol et ensuite de l’intoxication des espèces non cible. Nous nous sommes ensuite intéressés au phénomène de la résistance de cible aux AVK.Nous avons tout d’abord, participé à une étude de la résistance sur différents rongeurs piégés en Martinique. Cette étude a permis de mettre en évidence plusieurs mutations dans le gène vkorc1 des rats et des souris. Parmi les souris séquencées, 5 mutations ont été trouvées seules ou en combinaison. Toutes ces mutations étaient des mutations faux-sens A26T, A48T, R61L, Y139C et S149N. La résistance de cible des souris domestiques aux AVK de première génération et même aux AVK de deuxième génération a été clairement démontrée en Martinique surtout avec la détection de la mutation Y139C à une fréquence allélique de 40% et de la double mutation A26T / Y139C à une fréquence allélique de 0,9%. Chez le rat noir, le rongeur le plus répandu en Martinique, 3 nouvelles mutations codantes ont été détectées, les mutations H68N, A115T et S149N associées à une résistance modérée aux AVK de première génération. Parmi les Rattus norvegicus séquencés, une seule mutation silencieuse H68H a été détectée avec une fréquence allélique de 93,3%. Dans un second temps, dans le cadre d’une étude sur le campagnol, nous avons détecté 2 mutations faux-sens (G71R et S149I mutation) avec une très faible prévalence aux seins des populations. Nous avons caractérisé les conséquences catalytiques de ces deux mutations trouvées. Les mutations semblent n’avoir aucun effet sur la résistance aux AVK. Ensuite, nous nous sommes intéressés à la vitamine K chez les campagnols. Le régime alimentaire de ces herbivores est très riche en vitamine K (l’antidote naturel des troubles de coagulation liés à l’utilisation des AVK) et pourrait être responsable de la résistance des campagnols. Ainsi, les campagnols ont montré des concentrations en vitamine K beaucoup plus grandes que celles trouvées chez le rat. En outre, les concentrations de vitamine K chez les campagnols varient avec les saisons, elles sont plus abondantes en été qu’en hiver. Cette variation est liée à la disponibilité de la nourriture qui dépend à son tour des saisons. Il s’agit donc d’une résistance alimentaire. Enfin, nous avons étudié un troisième problème lié aux pullulations des campagnols en évaluant la capacité des campagnols terrestres à participer à la transmission et au maintien du cycle du pathogène dans l’environnement. Ainsi, nous avons cherché à identifier le portage des leptospires par les campagnols dans deux régions de la France touchées par les pullulations (l’Auvergne et la Franche comté). Nous avons identifié la présence, avec une faible prévalence, de L. borgpetersenii et L. kirschneri dans le Cantal et L. borgpetersenii, L. interrogans et L. kirschneri dans le Puy De Dôme. Alors que seule L. kirschneri a été trouvée en Franche comté avec une prévalence beaucoup plus alarmante qu’en Auvergne.
... agriculture landscapes should also be carried out on the long term, given that vole expansion is partly the result of agricultural intensification at landscape level (Giraudoux 1997, Santamaría et al. 2019 ...
El control biológico de roedores por depredación en ecosistemas agrícolas, se ha sugerido desde hace varias décadas como una alternativa sostenible al uso generalizado de rodenticidas
anticoagulantes por su menor impacto ambiental.
La depredación es un componente clave en la dinámica poblacional de muchas especies de micromamíferos y su utilización como agente de control biológico agrícola, requiere seleccionar depredadores cuyas poblaciones puedan ser atraídas con facilidad y que a su vez por su respuesta funcional sean capaces de estabilizar las poblaciones de
micromamíferos para reducir los daños agrícolas.
Las aves rapaces que nidifican en cavidades pueden ser considerados óptimos agentes biológicos, ya que sus abundancias tienden a incrementarse rápidamente mediante la instalación de cajas nido y posaderos, especialmente en ambientes agrícolas donde la disponibilidad de cavidades naturales para nidificar suele ser escasa.
En esta tesis doctoral, evaluamos la capacidad del control biológico del topillo campesino (Microtus arvalis), favoreciendo la presencia de dos depredadores, uno generalista y otro especialista, con alta capacidad de movilidad: el cernícalo vulgar (Falco tinnunculus) y la lechuza común (Tyto alba), en regiones de la península Ibérica donde se han registrado explosiones demográficas recurrentes de topillos campesinos, que han estado asociadas con daños agrícolas y en algunas regiones con problemas sanitarios por tularemia.
El control biológico por depredación puede ser considerado como una técnica prometedora dentro de los planes de manejo ecológico de plagas de roedores, Ecologically-based rodent pest
management (EBRM), basados en la búsqueda de tratamientos donde se prioriza el conocimiento ecológico de la especie que causa el daño, dentro de un marco de aplicación ambiental, cultural y
económicamente sostenible. Sin embargo, es necesario tener en cuenta que los depredadores pueden producir efectos adversos sobre otras especies no diana, incluyendo especies cinegéticas,
bien por depredación directa o por que la especie presa modificaomportamiento para compensar el aumento en el riesgo de depredación.
Los depredadores pueden también ser un componente clave en la dinámica de trasmisión de numerosas enfermedades, aunque por dos mecanismos principales excluyentes. Por un lado, los depredadores pueden extraer individuos enfermos de las poblaciones, lo que reduciría la prevalencia de la enfermedad, pero por otro lado también pueden inducir estres e inmunosupresión
a sus presas, lo que podría favorecer la trasmisión del patógeno. En la península Ibérica, las plagas de topillo campesino están asociadas a un aumento en el número de casos de tularemia en seres humanos. En esta tesis evaluamos que papel podría ejercer la depredación la dinámica de trasmisión de la tularemia en unos de sus principales reservorios, el topillo campesino.
Nuestros resultados mostraron que la instalación de cajas nido para cernícalos y lechuzas en ambientes agrícolas, tuvo la capacidad de reducir significativamente la abundancia tanto del topillo campesino como del topillo mediterráneo (Microtus duodecimcostatus), en cultivos de alfalfa y frutales. También hallamos una menor abundancia de topillos campesinos en las proximidades de las cajas nido ocupadas, siendo el efecto más intenso a mayor proximidad a la caja. Respecto a efectos sobre otras especies de aves, encontramos que la instalación de cajas nido produjo una disminución
en las abundancias dos especies de aves comunes en ambientes agrícolas, la lavandera boyera (Motacilla flava) y la lavandera blanca (Motacilla alba). También observamos un crecimiento
poblacional más lento en el caso de la urraca común (Pica pica), en las zonas con cajas nido respecto de las zonas control. Es recomendable que estos resultados se tengan en cuenta cuando se considera la aplicación de esta técnica de control de roedores, en áreas donde puedan aparecer presas potenciales de las aves rapaces que estén catalogadas como especies amenazadas, como el
caso de la alondra de Dupont (Chersophilus duponti). Sin embargo, conviene mencionar que el control biológico puede ser considerado como una estrategia de control mucho menos dañina sobre otras especies que los rodenticidas anticoagulantes, cuyo impacto negativo sobre la comunidad de
depredadores es muy elevado.
Considerando los posibles efectos del control biológico sobre una especie cinegética, en esta tesis estudiamos los efectos de la depredación sobre la detectabilidad de la perdiz roja (Alectoris rufa), considerando tres métodos de censo, puntos de conteo y escucha,
transectos lineales por vehículo y transectos lineales a pie. Nuestros resultados mostraron que en aquellos casos donde la presión depredatoria sobre las perdices fue mayor, la detectabilidad de la especie se vio afectada, siendo este efecto mayor cuando el método de censo utilizado no permite contabilizar individuos por señales acústicas.
Respecto a la dinámica de la trasmisión de la tularemia, nuestros resultados mostraron que, durante un periodo de alta densidad de topillos, los depredadores no seleccionaron favorablemente topillos infectados. Sin embargo, la prevalencia de tularemia fue mayor en las proximidades de las cajas
nido, siendo este estudio la primera vez que se observa que la depredación favorece la prevalencia de la tularemia en poblaciones cíclicas de roedores.
No se registraron caso de tularemia en humanos en los municipios con mayor prevalencia en topillos, lo que sugiere que otros factores como la abundancia de vectores, la presencia de topillos muertos en el paisaje o la propagación a través de
aerosoles o red hidrográfica podrían estar involucrados en la epidemiología de la tularemia en humanos
... The proliferation of this rodent shows cyclical variations over a period of about 5 to 6 years, with densities ranging from 50-100 animals/hectare to more than 1000 during outbreaks [2,3]. The excessive cyclical proliferation and expansion of ATS colonization areas, since the 1970s, mainly in mid-mountain agronomic and tourist ecosystems, is an increasingly important problem with strong environmental and economic impacts [4][5][6]. At high densities, ATS affects the botanical composition of grasslands, causing the regression of legumes and the increase of poor-quality grass and undesirable plants. ...
The cyclical proliferation of the wild fossorial rodent Arvicola terrestris scherman (ATS) is critical in mid-mountain ecosystems of several European countries. Our goal is to develop an immunocontraceptive vaccine to control their fertility, as a sustainable alternative to chemical poisons currently used. Indeed, these chemicals cause the death of ATS predators and animals sharing their ecosystem, and current laws progressively limit their use, making the development of a targeted vaccination strategy an interesting and efficient alternative. In order to identify species-specific sperm antigens, male and female ATS received subcutaneous injections of whole ATS spermatozoa to elicit an immune response. The analysis of the immune sera led to the identification of 120 immunogenic proteins of sperm cells. Of these, 15 were strictly sperm-specific and located in different regions of the male gamete. Some of these antigens are proteins involved in molecular events essential to the reproductive process, such as sperm–egg interaction, acrosomal reaction, or sperm motility. This approach not only identified a panel of immunogenic proteins from ATS sperm cells, but also demonstrated that some of these proteins trigger an immune response in both male and female ATS. These spermatic antigens are good candidates for the development of a contraceptive vaccine.
... While most individuals spend almost all of their lives in burrows, where they also breed, some of the juveniles have a significant spatial dynamics during dispersals. The mechanism triggering dispersal is still not completely understood and it is most probably related to the interaction of several factors (see for instance [1,2,3,5,7,9,10,18,19] and references therein). However, for modeling purposes, it is reasonable to link stress conditions to overcrowding, and say that dispersal begins when the total number of individuals in a colony reaches a threshold value, fixed as a fraction of the carrying capacity of the environment, R. ...
In this paper, we propose two models to describe the spatial dynamic of vole populations together with their finite volumes discretization. The models are based on age-structured transport equations set on a graph. The local evolution of the population occurs at the nodes, while transmission between nodes represents spatial dynamics and is a gradual process in the first model, an instantaneous one in the second. The parameters in the reproduction and mortality rates allows to reproduce the characteristics of different landscapes.
... Ces pullulations sont d'origine multifactorielle mais à l'échelle régionale, la part des prairies permanentes dans la surface agricole utile (SAU) augmente significativement le risque lorsque ce ratio dépasse 80 à 85 % (Giraudoux et al., 1997). ...
La surveillance biologique des micromammifères est un pilier de la lutte raisonnée qui permet de conserver l’autonomie fourragère des exploitations agricoles en minimisant les impacts environnementaux. Actuellement, les méthodes existantes à l’échelle du territoire («scoring communal») et à l’échelle de la parcelle (diagonale indiciaire) permettent d’établir un diagnostic des populations et de définir la stratégie de lutte à adopter en fonction des niveaux de populations. Ces méthodes sont très consommatrices de temps et exigent des observateurs confirmés pour bien différencier les indices de taupes de ceux de campagnols. L’utilisation d’un drone, couplée à l’expertise d’un technicien de terrain, peut aider à la détection précoce des indices de micromammifères. Il reste à définir les modalités de son intégration dans les stratégies de lutte collective et dans les dispositifs d’accompagnement des agriculteurs.
... Il était important de pouvoir concentrer les observations sur les secteurs subissant régulièrement des pullulations et générant des crises majeures tout en maintenant l'objectif de mettre en place une surveillance fine, exhaustive et régulière à l'échelle départementale. Le risque de pullulation est d'autant plus fort que la part de STH / SAU augmente au-dessus de 75 %(Giraudoux et al., 1997) et que le paysage est plus ouvert et peu fragmenté par des haies et des bois. Nous inspirant du travail réalisé par Note ...
Nous avons le plaisir de vous présenter l’ouvrage numérique « Comment adapter et hybrider les démarches participatives dans les territoires ? »
Vous y trouverez des outils qui impulsent, encouragent, fondent et favorisent le « décider ensemble » autour des processus de participation et d’apprentissage collectif.
Cette production est elle-même collective, participative et interactive dans sa réalisation et son contenu :
Collective, car elle a nécessité la conjugaison de compétences de Sylvie Lardon, Sabine Nguyen Ba et Grégoire Rouchit.
Participative, car elle rassemble l’ensemble des contributions des participants, les débats en plénier et les enseignements tirés de quatre ateliers participatifs.
Interactive, car échanges, discussions et témoignages des participants permettent de revivre les moments forts du colloque.
Vous pourrez parcourir cet ouvrage en couleur et en musique... Bonne lecture et bonne écoute ! Sabine Nguyen Ba et Sylvie Lardon.
Lien vers l’ouvrage numérique : https://www.iadt.fr/editions-webtv/psdr-opde .
Cet ouvrage numérique est issu du colloque éponyme qui s’est déroulé les 15 et 16 octobre 2019 à Clermont-Ferrand, dans les locaux d’AgroParisTech. Organisé en coordination avec deux réseaux scientifiques, le réseau OPDE « Des Outils Pour Décider Ensemble » et le Groupe Transversal « Systèmes alimentaires et forestiers, circuits et circularités » du Programme de Recherche National PSDR « Pour et Sur le Développement Régional », cet ouvrage numérique constitue un livrable du projet PSDR INVENTER – Inventons nos territoires de demain.
... To lay groundwork for understanding how parasite communities change in fluctuating host populations, we considered the bacterial parasite community of the fossorial form of the water vole Arvicola terrestris in the Doubs and Jura departments of Franche-Comté, eastern France. In this region, A. terrestris are found primarily in grasslands ≥400 m above sea level 23 , and population densities fluctuate dramatically, peaking at over 200 individuals/ ha every 5-8 years (mean period, 6 years) with concomitant forage production losses of over 1000 kg/ha/year 24 . Such peaks are followed by a decline phase which can be quite rapid, with a catastrophic decline in abundance during the winter months after the peak and a lack of recovery in population abundance the following spring. ...
Understanding the driving forces that control vole population dynamics requires identifying bacterial parasites hosted by the voles and describing their dynamics at the community level. To this end, we used high-throughput DNA sequencing to identify bacterial parasites in cyclic populations of montane water voles that exhibited a population outbreak and decline in 2014–2018. An unexpectedly large number of 155 Operational Taxonomic Units (OTUs) representing at least 13 genera in 11 families was detected. Individual bacterial richness was higher during declines, and vole body condition was lower. Richness as estimated by Chao2 at the local population scale did not exhibit clear seasonal or cycle phase-related patterns, but at the vole meta-population scale, exhibited seasonal and phase-related patterns. Moreover, bacterial OTUs that were detected in the low density phase were geographically widespread and detected earlier in the outbreak; some were associated with each other. Our results demonstrate the complexity of bacterial community patterns with regard to host density variations, and indicate that investigations about how parasites interact with host populations must be conducted at several temporal and spatial scales: multiple times per year over multiple years, and at both local and long-distance dispersal scales for the host(s) under consideration.
... It is commonly assumed that the composition and distribution of a given predator community is influenced by landscape configuration (Delattre et al., 1992;Giraudoux et al., 1997;Lidicker, 2000). The spatial distribution of small carnivores within oil palm plantations and its correlation to habitats was thus further investigated, with a view to suggesting appropriate land use for small carnivore persistence within oil palm plantations. ...
... The montane water vole, Arvicola scherman (Shaw, 1801), mainly inhabits meadows, grasslands and fruit orchards (Giraudoux et al. 1997, Fichet-Calvet et al. 2000 of the main mountainous areas of Europe (Kryštufek et al. 2015 and reference therein). This species lives underground in extensive burrow systems (Airoldi 1976), consuming both epigeic and hipogeic parts of plants (Airoldi 1976, Kopp 1993). ...
The presence of montane water voles in the NW Iberian Peninsula goes back to the Mousterian (Middle Palaeolithic, about 39,110 years BP) as showed the dentitions of several specimens found in Cueva del Conde, an archaeo-palaeontological deposit located in Asturias. In Upper Paleolithic, this species seemed to be present along NW coastal Spain, from Donostia to at least Oviedo. Nevertheless, there seems to be no information on agricultural damages caused by montane water voles until the beginning of the XVIIth-century. In that sense, the first reported case encountered to date which suggests crop losses arguably caused by montane water voles occurred in uplands from Villaviciosa (Asturias) between 1616 and 1622 .
... The above observations are consistent with the Trophic ROMPA (Ratio of Optimal to Marginal Patch habitat) Integrated Model (TRIM) (Krebs, 2013;Lidicker, 2000), which combines the exploitation ecosystems hypothesis (Oksanen and Oksanen, 2000) with the effect of spatial arrangements of habitats on vole dispersal and predator communities. Briefly, TRIM predicts that from low to high ROMPA in a given landscape, population dynamics of small mammals will shift from stochastic fluctuations of very low amplitude through larger-amplitude fluctuations and increasing cyclicity with longer peak duration, up to permanent high density with only seasonal variation and no cyclicity Giraudoux et al., 1997). One of the consequences is that a given species of small mammal can undergo various types of population dynamics depending on ecosystem productivity and the spatial arrangement of their optimal habitat in a landscape. ...
Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.
... As áreas seminaturais albergam uma grande quantidade de fauna útil (Clergue, et al, 2009). A manutenção do habitat é muito importante do ponto de vista ecológico, por exemplo surtos de ratazanas podem estar associados a determinados tipos de uso do solo, e muitas vezes estes animais representam graves pragas para algumas culturas, como é o caso dos pomares de maçã (Giraudoux, et al., 1997). FCUP Desenvolvimento de indicadores da componente fauna-terrestre em contexto agrícola: reunião de uma metodologia de avaliação da sustentabilidade Figura 3: Escala hierárquica dos serviços de ecossistema que a biodiversidade presta aos sistemas agrícolas (Gurr, et al., 2003). ...
The agrossystems’ sustainability concept approaches tree strands: economic, social
and environmental. In the environmental context, the rural space is considered an
important habitat of an important diversity of fauna that provide essential ecosystem’s
services. To evaluate this sustainability it becomes indispensable an assessment of the
farms through an appropriate methodology. The literature suggests the use of two
integrated methods: sustainability indicators and assessment models. The main goal of
this study is to find a simple methodology that allows to understanding the level of
sustainability of the different farms, and in the other hand, allows to identifying positive
or negative aspects of the productive systems due the conservation of terrestrial fauna.
For that three Portuguese regions were chosen different types of crops and productive
systems: strawberry, apple, lettuce and courgette. The richness of the following groups
was measured: mammals, birds, amphibian reptiles and insects. The species data was
collected using transects, listening spots and pan-traps (for insects) on the field and
using bibliographic information. The indicators were chosen taking into account the
characteristics of the farms. Finally all the data was analysed and the indicators for the
species richness were calculated: species richness, percentage of occurrence for each
one of the taxa above indicated, Margalef Index (DMg) modified and Shannon-Wiener
index for insect’s pan-traps and transects. To obtain a new indicator characterising the
farms all values of the indicators were standardised into a 1-5 scale and them the
unweighed mean was obtained for each farm. Finally a PCA analysis was constructed
taking onto account the indicators for the four environmental components: fauna, flora,
agriculture, and water.
Our preliminary results show what farms are closer to be environmentally friends.
However, regardless of the production type, all of the farms present close values for
our index, varying from 2 to 3. This results points that the productive system isn’t the
most influent factor, so de PCA analysis showed that the surrounding habitat diversity
and land cover should be the most important variables to explain the specie richness
distribution. Although specific groups of fauna react differently to the different
environmental indicators.
Keywords: sustainability, agrossystems, ecosystem services, terrestrial fauna,
indicators and models.
... scat counts, snow tracking, counts on dens, camera trapping, etc.) to verify their relative value is recommended (Beltran et al. 1991, Gompper et al. 2006. In some cases, observations of indices along transects have provided efficient ways for monitoring seasonal and inter-annual fine changes in population densities on multiple scales from local up to regional as shown for grassland voles (Delattre et al. 1992, 1999, Giraudoux et al. 1997, Berthier et al. 2014. ...
Studying elusive species of conservation concern might be difficult for technical and ethical reasons. However, censuses can be based on the observation of activity indices. When coupled to non-invasive genetic methods this approach can provide extremely precise information about population size, individual movements and diseases. However, the design of optimal sampling is dependent on a knowledge on group distribution and possible variations of detectability of index targets. The aim of this study was to document the distribution of Yunnan snub-nosed monkey indices in space and time in that perspective. Based on transects carried out across the range of a fed population and on counts along the trail across the range of a wild group, we show that 2–3 day stays of a group in a place of some hectares were sufficient to get an homogeneous distribution of indices. Furthermore, the number of indices found were dependent on both pig presence and season. On the other hand, on a large scale of 100 km ² indices were spatially distributed as nested clusters. Indices distribution indicated a strong preference towards southern slopes and altitudes ranging between 2900 and 3400 m. Those observations pinpoint the importance of considering spatial scale to organise sampling designed to estimate population distribution.
... Les pullulations causent des dégâts aux prairies et bouleversent le fonctionnement des exploitations agricoles. Le phénomène est multifactoriel, mais la part des prairies permanentes dans la Surface Agricole Utile (SAU) augmente le risque de pullulation lorsque ce ratio dépasse 70 à 80 % (Giraudoux et al., 1997). ...
... Les pullulations causent des dégâts aux prairies et bouleversent le fonctionnement des exploitations agricoles. Le phénomène est multifactoriel, mais la part des prairies permanentes dans la Surface Agricole Utile (SAU) augmente le risque de pullulation lorsque ce ratio dépasse 70 à 80 % (Giraudoux et al., 1997). ...
... Landscapes with intermediate ROMPA would favour multiannual cycles. Population dynamic patterns of vole pest species fit well with the ROMPA hypothesis, multiannual cycles of common voles or water voles occurred in areas of several km 2 where ROMPA (i.e., ratio of permanent grassland to farmland) was over 50% or 85% respectively (Delattre et al. 1992;Giraudoux et al. 1997Giraudoux et al. , 2003Raoul et al. 2001). More locally (~1 km 2 ), dense hedgerow networks and/or vicinity to forest may dampen the amplitude of the common vole (Delattre et al. 1999) and the water vole (Duhamel et al. 2000;Morilhat et al. 2008) fluctuations. ...
... By contrast, researches conducted on the montane water vole (Arvicola scherman, ex terrestris) have well illustrated how population genetics, demography, life history traits and parasitology may help to understand how immune genes evolve at the contemporary scale. This rodent species exhibits pluri-annual demographic cycles, with density varying from less than one to several hundred individuals per hectare over 5-6 years (Giraudoux et al. 1997;Saucy 1994) in the East of France. Berthier et al. (2006) emphasized that drift operating during low density populations (small size and geographical isolation of demes) and migration occurring principally while population size increased closely interacted to maintain high genetic diversity at neutral microsatellites. ...
Molecular epidemiology has recently broaden its focuses due to the development of molecular tools but also by incorporating advances of other fields such as mathematical epidemiology, molecular ecology, population genetics and evolution. Facing new risks of emerging and re-emerging infectious diseases that are threats for humans and their livestock, the objectives of molecular epidemiology include: - the development of molecular tools, genotyping and gene expression - the incorporation of concepts and results of population genetics of infectious diseases - the integration of recent advances in theoretical epidemiology and evolutionary ecology of diseases - a better understanding of transmission for the development of risk factors analyses. This book will demonstrate how the latest developments in molecular tools and in epidemiology can be integrated with studies of host-pathogen interactions. Besides a strong theoretical component, there will also be an emphasis on applications in the fields of epidemiology, public health, veterinary medicine, and health ecology. Students and researchers in the fields of epidemiology, animal and human health, evolutionary ecology, parasitology are the main potential readers of the book, as well as a broader audience from veterinary medicine and conservation.
... Landscapes with intermediate ROMPA would favour multiannual cycles. Population dynamic patterns of vole pest species fit well with the ROMPA hypothesis, multiannual cycles of common voles or water voles occurred in areas of several km 2 where ROMPA (i.e., ratio of permanent grassland to farmland) was over 50% or 85% respectively (Delattre et al. 1992;Giraudoux et al. 1997Giraudoux et al. , 2003Raoul et al. 2001). More locally (~1 km 2 ), dense hedgerow networks and/or vicinity to forest may dampen the amplitude of the common vole (Delattre et al. 1999) and the water vole (Duhamel et al. 2000;Morilhat et al. 2008) fluctuations. ...
Both target and non-target small mammals are exposed to rodenticides (AR). A better understanding of the drivers controlling this exposure is critical for the conservation of threatened small mammal species but also because they may represent important pathways of poisoning for birds of prey and carnivore mammals. Here, we consider the spatial components involved in the process of small mammal exposure to ARs with the aim to address how these can be used in spatially explicit risk assessment. We present how various drivers operate on multiple spatial scales. On continental and/or regional scales, both biogeographical distribution of small mammals and other species of conservation value and international/national regulations of AR applications (indoor vs outdoor…) could be used to identify some countries or states where exposure is more likely. For application at the local scale (i.e. few km²), we reviewed published studies that analysed the spatial pattern of small mammal exposure to ARs according to species and distance to treatments. We evidence that most of the small mammals exposed to AR are found in the immediate vicinity of treatment areas, i.e., within 100 m. Over 100 m, exposed rodents are rare but can be found until 750 m distance from treatment areas. Species traits related to spatial dimension such as habitat preferences, home range size and mobility also influence exposure. Exposure is variable, in terms of proportion of contaminated individuals and levels of residues, for species showing small home-range size and a limited spatial mobility. The level of exposure depends on whether the main habitat of the given species is similar or not to the one of the target rodent. For instance, exposure of the common vole, a grassland species, is low when ARs are used indoor while it can be highly exposed when bromadiolone is applied outdoor to control the water vole, a sympatric species. For small mammals exhibiting a relatively large home-range size and a high spatial mobility such as the wood mouse and the bank vole, the exposure is commonly reported within a lower range than target species. Although this has not been studied in details, we also address how landscape and/or habitat features may modulate exposure, suggesting that landscape management may help to mitigate the risk of ARs to small mammals. Finally, we discuss both the advantages and disadvantages of statistical, analytical or simulation models to assess potential or actual exposure of NTSM to AR in a spatially explicit way. We conclude that in order to analyse global patterns in usage and exposure risks, large scale statistical modelling should be used while for detailed site specific assessments, simulation models may be more appropriate.
Rodent outbreaks have, in historical memory and at more or less regular intervals, massively affected crops and stored goods locally and sometimes even regionally. The Jura Massif is known, among other things, for its cheese specialties with several emblematic protected designations of origin (PDO), such as Comté, Morbier, Mont‐d'or and Bleu de Gex. In the 1950s, in this region of medium‐altitude mountains, grassland covered between 20% and almost 75% of farmland, regardless of altitude. From the early 1980s to the mid‐1990s, population demographic monitoring of small mammals was carried out in the Septfontaines and Le Souillot area, covering nearly 20,000 hectares. It has been suggested that predation is a major driver of fluctuations in rodent populations. It has taken about 30 years to describe and understand the factors that determine vole outbreaks in the Jura Massif in PDO grassland areas and to establish the basis for controlling them.
We prove existence and stability of entropy solutions for a predator-prey system consisting of an hyperbolic equation for predators and a parabolic-hyperbolic equation for preys. The preys' equation, which represents the evolution of a population of voles as in [2], depends on time, t, age, a, and on a 2-dimensional space variable x, and it is supplemented by a nonlocal boundary condition at a=0. The drift term in the predators' equation depends nonlocally on the density of preys and the two equations are also coupled via classical source terms of Lotka-Volterra type, as in [4]. We establish existence of solutions by applying the vanishing viscosity method, and we prove stability by a doubling of variables type argument.
In: Lardon S. & Nguyen Ba S. (2020). Comment adapter et hybrider les démarches participatives dans les territoires ?
The main objective of the thesis is to propose and analyze mathematical models based on partial differential equations (PDE) to describe the spatial dynamics of two species of voles (Microtus arvalis and Arvicola terrestris), which are particularly monitored in Eastern France. The models that we have proposed are based on PDE which describe the evolution of the density of the population of voles as a function of time, age and position in space. We have two complementary approaches to represent the dynamics. In the first approach, we propose a first model that consists of a scalar PDE depending on time, age, and space supplemented with a non-local boundary condition. The flux is linear with constant coefficient in the direction of age but contains a non-local term in the directions of space. Moreover, the equation contains a second order term in the spatial variables only. We have demonstrated the existence and stability of weak entropy solutions for the model by using, respectively, the Panov's theorem of the multidimensional compensated and a doubling of the variables type argument. In the second approach we were inspired by a Multi Agent model proposed by Marilleau-Lang-Giraudoux, where the spatial dynamics of juveniles is decoupled from local evolution in each plot. To apply this model, we have introduced a directed graph whose nodes are the plots. In each node, the evolution of the colony is described by a transport equation with two variables, time and age, and the movements of dispersion, in space, are represented by the passages from one node to the other. We have proposed a discretization of the model, by finite volume methods, and noticed that this approach manages to reproduce the qualitative characteristics of the spatial dynamics observed in nature. We also proposed to consider a predator-prey system consisting of a hyperbolic equation for predators and a parabolic-hyperbolic equation for preys, where the prey's equation is analogous to the first model of the vole populations. The drift term in the predators' equation depends nonlocally on the density of prey and the two equations are also coupled via classical source terms of Lotka-Volterra type. We establish existence of solutions by applying the vanishing viscosity method, and we prove stability by a doubling of variables type argument. Moreover, concerning the numerical simulation of the first model in one-dimensional space, we obtain a finite volume discretization by using the upwind scheme and then validate the numerical scheme.The last part of my thesis work is a project in which I participated during a Summer school CEMRACS. The project was on a subject of biomathematics different from that of the thesis (an epidemiological model for salmonellosis). A new generic multi-scale modeling framework for heterogeneous transmission of pathogens in an animal population is suggested. At the intra-host level, the model describes the interaction between the commensal microbiota, the pathogen and the inflammatory response. Random fluctuations in the ecological dynamics of the individual microbiota and transmission at the inter-host scale are added to obtain a PDE model of drift-diffusion of pathogen distribution at the population level. The model is also extended to represent transmission between several populations. Asymptotic behavior as well as the impact of control strategies, including cleaning and administration of antimicrobials, are studied by numerical simulation.
La gestion de populations de rongeurs est importante car ils peuvent causer divers problèmes économiques, écologiques et sanitaires. Cette gestion s'appuie sur des méthodes de prévention, celles-ci étant des mesures architecturales, hygiéniques et des pratiques agricoles. Elle s'appuie également sur des méthodes de lutte biologique, chimique et mécanique. La lutte chimique se fait principalement avec l'utilisation de rodenticides anticoagulants qui agissent plusieurs heures après ingestion permettant d'éviter l'éviction alimentaire. L'utilisation excessive de ces molécules a entrainé la sélection de résistance chez certains individus rendant leur utilisation peu efficace. Il y a alors eu le développement de nouvelles molécules, mais celles-ci sont plus écotoxiques. Nous nous sommes intéressés dans ces travaux de thèse à la gestion de populations de rongeurs dans un cadre de risque sanitaire leptospirosique. Les rongeurs sont les principaux réservoirs de leptospires pathogènes, des bactéries Spirochètes responsables de la leptospirose. La leptospirose est une zoonose ré-émergeante à répartition mondiale dont le nombre de cas annuel est évalué à approximativement un million et dont il y a eu une augmentation du nombre de cas ces dernières années. Elle est endémique en régions tropicales. C'est une maladie dont l'incidence réelle est sous-estimée en raison notamment de la grande variabilité de symptômes possibles allant du syndrome grippal à des formes rénales. Le taux de mortalité est élevé aux alentours de 10% mais pouvant aller jusqu'à 50% dans certains cas avec des complications pulmonaires. De nombreux facteurs influent sur le cycle complexe de transmission de la leptospirose. Il peut y avoir un risque sanitaire lié à la présence de rongeurs porteurs de leptospires pathogènes, qui peut être difficile à contrôler si les rongeurs sont résistants aux rodenticides anticoagulants utilisés pour réguler leurs populations. De plus, il peut y avoir des problèmes d'exposition à des risques écotoxiques lors de mise en place de traitements chimiques. Nous avons étudié plusieurs cas concrets montrant la difficulté dans la prise de décision liée à la gestion des rongeurs dans des contextes divers. Dans un contexte de problèmes économiques, nous avons analysé le portage de leptospires pathogènes par des campagnols des champs et des campagnols terrestres ainsi que la résistance de cible à la bromadiolone, molécule utilisée en lutte chimique à basse densité de population. Nous nous sommes intéressés à l'influence de la perception sociétale sur le risque sanitaire lié à des souris dans un élevage bovin dans lequel il y a des cas de leptospirose humaine et de leptospirose bovine. Dans le cadre d'un projet visant à étudier l'efficacité de gestion de populations de rongeurs commensaux en Martinique dans un contexte leptospirosique, nous avons regardé l'exposition des rongeurs aux AVKs et la résistance de cible aux AVKs. Pour le portage de leptospires pathogènes par les campagnols nous avons trouvé des prévalences allant de 3% à 53% selon la zone étudiée. Il y avait 3 mutations sur le gène vkorc1 amenant peu de résistance de cible à la bromadiolone. Dans l'élevage bovin nous avons notamment trouvé que la perception sociétale de l'éleveur sous-estimait le risque lié aux souris dont 41% étaient porteuses de leptospires pathogènes et 50% étaient porteuses de mutations du gène vkorc1 amenant de la résistance de cible aux AVKs. En Martinique nous avons trouvé que 54% des individus analysés avaient été exposé à au moins une molécule AVKs et qu'il y avait plusieurs mutations du gène vkorc1 dont certaines pas encore caractérisées amenant de la résistance de cible aux AVKs. La gestion des rongeurs est un problème complexe avec plusieurs facteurs à prendre en compte que ce soient les risques liés à l'exposition aux rongeurs ou ceux liés à l'utilisation de rodenticides anticoagulants [etc...]
We prove existence and stability of entropy weak solutions for a macroscopic PDE model for the spatial dynamics of a population of voles structured in age. The model consists of a scalar PDE depending on time, t, age, a, and space x=(x1,x2), supplemented with a non-local boundary condition at a=0. The flux is linear with constant coefficient in the age direction but contains a non-local term in the space directions. Also, the equation contains a term of second order in the space variables only. Existence of solutions is established by compensated compactness, see Panov (2009), and we prove stability by a doubling of variables type argument.
Der Einfluss von Landschaftsfaktoren auf die Prävalenz von Echinococcus multilocularis bei Rotfüchsen (Vulpes vulpes) wurde am Beispiel Baden-Württembergs (35 900 km2) geprüft. Die Untersuchung von 7218 Füchsen mit der Darmabstrichmethode ergab 1995 - 2000 eine Prävalenz von 37%. Ein landesweites Monitoring-Programm des Ministeriums für Ernährung und Ländlichen Raum mit einem kommerziellen Koproantigen-ELISA (Chekit Echinotest, Dr. Bommeli-AG) 2002 - 2003 zeigte bei 5794 Füchsen eine korrigierte Prävalenz von 48%. Zwar sind die Prävalenzen der beiden Zeiträume aufgrund der unterschiedlichen Nachweismethoden nicht direkt vergleichbar, jedoch war eine räumliche Verlagerung der Hochendemiegebiete von Süden nach Norden feststellbar. Der Vergleich mit der Landnutzung basierte auf den Daten einer europäischen CORINE-Landnutzungskarte, deren Eignung für großräumige Analysen durch die Kartierung einer Gemeinde (4600 ha) validiert wurde. Für die Studie 1995 - 2000 ergaben sich signifikante Prävalenzunterschiede zwischen Gras- (50%), Acker- (43%), Wald- (31%) und Stadtgebieten (24%), was sich in der Studie 2002 - 2003 bestätigte. Unterschiede in der Habitateignung für Zwischenwirte werden als Gründe für diese Korrelation diskutiert. Um räumliche und zeitliche, landschaftsunabhängige Fluktuationen der Prävalenz erkennen zu können, sollten Sentinel-Gebiete mit unterschiedlichen Landnutzungsarten langfristig beobachtet werden. The influence of the land use on the prevalence of Echinococcus multilocularis in red foxes (Vulpes vulpes) was studied using the German federal state of Baden- Württemberg (35 900 km²) as example. The examination of 7218 foxes 1995 - 2000 with the intestinal scraping method (IST) resulted in a prevalence of 37%. A state wide monitoring program by the Ministry for Agriculture with a commercial coproantigen-ELISA (Chekit Echinotest, Dr. Bommeli-AG) 2002 / 2003 revealed a corrected prevalence of 48%, based on 5794 foxes. Because of the different diagnostic methods a direct comparison of the prevalence levels is not possible, but a shift of high endemicity areas from south to north was recognised. The comparison with landscape data was based on the European CORINE land cover data, that was validated by a field survey of one commune (4600 ha) for analyses on a regional scale. Using data from the survey 1995 - 2000, significant differences in prevalences were revealed between foxes in grassland (50%), agriculture (43%), forest (31%) and urban zones (24%), which was confirmed with data from the study 2002 / 2003. Differences in the frequency of habitats suitable for intermediate hosts are discussed as reasons for this correlation. To recognise space, time and landscape independent fluctuations of the prevalence, sentinel areas with different landscape composition should be selected for long term monitoring.
« PRISMAL » (Perception, representation and health risk management in rural settings): a regional public health research network
The PRISMAL (Perception, representation and health risk management in rural settings) network comprises three academic research teams, two health insurance agencies, and two health care networks in the Franche-Comté region that share their expertise to study the relationship between health and the rural environment. Three main objectives guide the network’s activities and are linked to the following questions : 1) What are the epidemiological changes linked to the rural setting ; what are their causes and effects ? 2) What are the relationships between the rural environment, health risks, behaviours in seeking health care, access to health care services and quality of life ? 3) What are the perceptions and representations of the affected populations on health risks specific to the rural setting ? Research activities utilise specific diseases as examples of the result from interaction with the rural environment, such as « farmer’s lung », alveolar echinococcosis, occupational risks for farmers, lung cancer, suicide attempts, premature birth, and vascular stroke. The partnership’s framework extends well beyond the medical world and includes ecologists, geographers, sociologists, administrators and environmental technicians.
Fluctuations of barn owl populations appear to be synchronized throughout Europe, but this does not seem to be the case in rodent populations which fluctuate on a much more local scale. Suitable approaches, belonging to comparative ecology, ecoethology and ecophysiology must be carried out to understand the causality of barn owl population dynamics. -from English summary
The bank vole Clethrionomys glareolus (Schreber), was studied in enclosures and on islands in Central Finland in 1982-88. Winter breeding was observed in 1983-84 and 1986-87, both of which were years of increasing microtine populations. No mustelids were observed in the study areas during these winters. Local microtine populations peaked in 1987-88. However, when bank voles were kept in large enclosures at fairly low densities during winter, female voles were found to have perforated vaginae and males scrotal testes by February 1988. The first litters were born as late as two and a half months later. This delay between maturation and parturition could have been due to the presence in the study area of one or more weasels Mustela nivalis L. between January and March. This idea was tested in a laboratory experiment: the presence of a weasel close to the breeding pairs of bank voles suppressed the reproduction in all four cases. In the control group, without a weasel successful fertilization occurred in three females out of four. The observations indicate the importance of indirect effects that the presence of specialist predators have on the breeding behaviour of their prey.
Predation on populations of small rodents is reviewed. Various types of predators are distinguished; specialists, generalists, residents, and "nomadic" species. Their functional and numerical responses to changes in prey density, and their influence on small rodent numbers, are discussed. The shape of the functional response curve of the predators may be important for the dynamics of the predator-prey system. Generalists with access to alternative prey tend to stabilize rodent numbers, as do migrating specialists, whereas resident specialists may be destabilizing. Field studies on cyclic rodent populations point to the importance of predation during and after the decline phase, and indicate that predation may increase the amplitude and prolong the period of the cycles. Other studies indicate a strong influence of predation on rodent numbers in areas with a diversified prey and predator fauna. /// Описано хищничество на популяциях мелких грызунов. Различаются разные типы хищников:специалисты, всеядные, резиденты и "номадические" виды. Обсиждаются их функциональные реакции и колебания численности в зависимости от плотности жертв и влияние на численность мелких грызунов. Форма кривой функциональных реакций хищников может иметь значение для динамики системы хищник-жертва. У всеядных хищников при возможности выдора жертв наблюдается тенденция к стабилизации численности грызунов, как и у мигрирющих специалистов. В то то же время резидентные специалисты дестабилизируют плотность жертв. Полевые исследования цикличности популяций грызунов показывают большое значение хищничества в течение и после фазы снижения плотности; хищничество может увеличивать амплитуду колебаний численности и удлинять циклы. Другие исследования показалик сильное влияние хищничества на плотность грызунов на территории с разнобразной фауной хищников и жертв.
The holism-reductionism dichotomy continues to provoke controversy as well as useful discussion. Some of this stems from misunderstandings and/or different definitions for the terms (see also Wilson 1988). Even among holists, however, there is the intriguing question of how to mix reductionist approaches (looking into the system of interest) with holistic ones (looking out to the context of the system). My conclusion from many years of research in small mammal ecology is that the most successful ecological analyses necessarily entail both approaches; they are synergistic. Because ecologists investigate ecological systems on several levels of complexity, it is argued that the term "ecosystem" be used in its original sense to apply to all levels of ecological systems. It should not, therefore, be used for a specific level in the ecological hierarchy, as is commonly the case. The term "landscape" is proposed for systems at a level above that of communities, namely for assemblages of communities of different kinds. Finally, research on the population dynamics of the California vole, a microtine rodent, is used to illustrate the "two-directional" philosophical framework advocated here.
A frequently expressed opinion is that despite massive efforts the multi-annual cycles in density exhibited by many microtine rodents remain mysterious; moreover, understanding awaits completion of one or a few clever experiments or elegant mathematical models that will discredit all but the one true hypothesis. I contend in this brief, personal essay that, on the contrary, we are actually quite close to an adequate understanding of microtine cycles. This optimistic perspective requires that we adopt a multi-factorial model of vole demography, a position that allows us to comprehend how many extrinsic and intrinsic factors act synergistically and sequentially to produce the density changes we observe. I argue that this approach is not only supported by a modern systems view of reality, but is consistent with the extensive data base accumulated over a 60 year period. A multi-factorial perspective is illustrated by data for Microtus californicus, a well-studied species that shows considerable geographic and temporal variation in demographic pattern. At least eight key factors (four extrinsic and four intrinsic) are required to explain the multi-annual cycles in this species. The resulting model is complex, but not chaotic or non-testable.
A method to estimate the abundance of the fossorial form of the water vole Arvicola terrestris scherman (Shaw, 1801) has been developed, by using surface indices. Results are compared to the standard method of estimation using trap lines. These results show quantitatively that it is possible to differentiate reliably mole indices from water vole indices. Moreover, the two species are inclined to exclude each other. Even though water voles share the same galleries as moles, specific surface indices of the water vole occur for any density exceeding 2 ind/trap line (over 20 ind/ha). Several models of abundance estimation are put forward, all of them using linear multiple regressions. Correlations between the estimations from indices and the estimations from trap lines exceed 0.8 and the limits of using abundance classes are tested. Other limits are developed in the discussion. One of them is that the sampling intervals are saturated for densities exceeding 400 ind/ha. The index method, which is easy to carry out, offers the definite advantage of being suitable to space and time scales otherwise incompatible with estimations from trap lines. For instance, it allows distribution maps from wide transects about areas of more than 25 km(2) to be drawn, in less than two days.
Long term population fluctuations of the fossorial form of the water vole, Arvicola terrestris, can be reconstructed on the basis of the rewards given to vole trappers ("tail-return statistics"). Nine time series of at least 20 yr of continuous data recorded during the 20th century in Switzerland have been analysed using time series analysis and tested for direct and delayed density dependence. Seven of these data sets showed cyclic changes in abundance with statistically significant maxima of the periodogram for periods ranging between 5 and 7 yr. Their partial autocorrelation functions suggested the presence of both direct or delayed density dependence in the data. This was confirmed by regression analysis using the nonlinear approach advocated by Turchin. In contrast, no simple periodicity could be found in the two remaining time series, nor indication for direct or delayed density dependence in their partial autocorrelation functions. However, direct density dependence was also statistically demonstrated in these two data sets. In most cases, the analyses were complicated by the presence of trends in the data. The detection of density-dependent regulatory effects was obscured by linear and nonlinear trends in one and two cases, respectively. The data support the hypothesis that time-delayed and nonlinear mechanisms of population regulation operate in fossorial populations of A. terrestris. Furthermore, the data are consistent with regulatory mechanisms involving predator-prey interactions, while the causation of the unusually long cycle is still an open question. Finally, the presence of trends in these time series suggests that water vole populations track some long-term climatic changes in the environment.
This paper aims to answer the following question: are the fluctuations of abundance of Common Vole (Microtus arvalis) specific to different types of landscapes? The research was carried out in landscapes where grassland was dominant. The sampling method was based upon a partition in both landscape types and landscape units. Tracking of vole indices was used to evaluate their relative abundance. Six landscape transects were sampled during two successive years. Results show that population variation and diffusion of demographic states are closely related to landscape types. The possible causes of this are discussed. The landscape units can be used as global variables to assess outbreak risk and landscape design can be used to prevent them.
Un zonage d'isopotentialités fourragères est présenté pour les départements du Doubs et du Jura. Les potentialités de production de la prairie permanente sont calculées pour chaque zone à partir des données climatiques (méthode de de MONTARD, 1983). S'il existe peu de différence de production annuelle totale selon les zones, les rythmes de production sont divers : en altitude, la période de végétation est plus courte, mais en plaine, un déficit hydrique estival réduit la production. Les difficultés de récolte de l'herbe sont par ailleurs accentuées en altitude : la souplesse du pâturage est faible, les jours disponibles pour la récolte du foin peu nombreux, même après le stade épiaison, et les regains sont peu abondants car les foins sont faits tardivement, et les températures restent fraîches enfilé. Par contre, la production estivale est beaucoup plus variable dans la plaine qu'en montagne. Mais on observe une grande variété de pratiques et de résultats entre les exploitations agricoles d'un même lieu géographique : outre ces contraintes climatiques, celles qui sont liées au fonctionnement de l'exploitation ont aussi une grande importance sur la gestion des surfaces en herbe.
Variations in densities and distribution of weasel and stoat populations were studied during periods of increasing and maximum densities of water vole Arvicola terrestris. Together with the increase of water vole numbers (200 individuals/ha in August 1979, 500-1000/ha in August 1980), there was a simultaneous increase in the population densities of several species, especially that of Microtus arvalis (100rt arrow 200 individuals/ha in August 1979 and August 1980). Observations in August 1979 showed that weasel population densities were almost similar in open environments and half-open ones. This species can also be found at the border of forests. Densities increased during the course of 1979 and in October 80 reached densities ranging around 10 individuals/100ha in bocages after the summer breeding season. The disappearance of M. arvalis during winter 1980-81 is probably the cause of low reproduction rate during the following year.-from Author
Celem pracy bylo określenie powiązan troficznych M. arvalis, czyli wplywu populacji tego gatunku na roślinnośc terenu oraz presji na badaną populacje zespolu drapieznikow. Badania prowadzono na obszarze 3100 ha pol i roznego typu zadrzewien w okolicach Turwi, woj. Poznan (Tabela 1).
In northern Finnish Lapland there was a tendency for hole-nesting passerines to be preyed on by mustelids in years of low small rodent densities, whereas in other years predation rate was zero. Mustelid densities were the highest just before the "crash" of rodents. Mustelids apparently turned to birds after having preyed heavily on their favourite prey, the small rodents, which declined to very low numbers.
(1) Annual and seasonal variations in predation rates by weasels (Mustela nivalis L.) on tits were studied in Wytham Wood, Oxfordshire. Four Parus species of tits breed in the nest boxes which have been provided for them in the wood since 1947. (2) Weasels are by far the most important cause of nest failure in the wood and on average 20.8% of nests were preyed upon by them each year from 1947 to 1975. (3) There were marked annual fluctuations in predation rate, varying from 0-50%. Predation was insignificant until 1957, two years after myxomatosis cleared the wood of rabbits. This caused widespread predation pressure on small rodents and may have led weasels to explore nest boxes as an alternative source of food. (4) The nesting density of tits and the density of rodents, measured the same summer, together accounted for over 60% of the annual variation in predation rates; both prey types appear to be equally important. The possible influence of weasel density on predation rates is also discussed. (5) Because predation on tit nests is proportional to nesting density, Coal Tits Parus ater L. apparently suffer less predation than the other species by starting to breed first when few other nest boxes contain eggs. The staggered laying also results in interspecific variation in the stages (laying, incubation, nestling) at which nests are most likely to be preyed upon. (6) Using the combined nests of Blue Tits and Great Tits as a `prey population', it is shown that a high nest density hastens the onset of predation but if rodent density is high this tends to retard the rate of predation on tit nests. (7) This effect of prey density on the timing of predation accounts for seasonal variations in predation rates between 1959-63, described by Perrins (1965), and explains the decline in predation on nestlings after 1963. The relationship found here may also help to explain why Krebs (1970) found that predation on nestlings was not density dependent. (8) The breeding strategy of the tits is discussed and found to be little defence against predation by weasels. Laying date may, however, affect the incidence of adult mortality but there is insufficient information on survival to calculate overall fitness.
An analysis was made of the diet, numbers and penetration of study area by a group of predators typical of the agrocenoses of the Wielkopolska region of Poland. There was distingguished a group of predators highly specialized in capture of the common vole.This group includes species for which the vole forms the most important component of their food, which react very markedly in respect of their numbers to variations in the density of rodent and which obtain their food chiefly in fields and meadows. Estimates are given of the extent of pressure exerted by predators on field and forest rodents, and means of counteracting mass irruption of field rodents discussed. Czteroletnie badania nad drapieznymi ptakami i ssakami prowadzone przez okres pelnego cyklu zmian zageszczenia nornika zwyczajnego w okolicach Turwi pozwolily ocenic zmiennośc pokarmu, liczebności i penetracji terenu przez drapiezniki przy roznych liczebnościach nornika
We surveyed the densities of small mammals on 17 islands in Lake Inari in Finnish Lapland during 5 yr to estimate the degree of spatial synchrony in the dynamics of microtine rodents (Clethrionomys, Microtus) and shrews (Sorex). Microtine rodents have a 4-5 yr population cycle in Lapland, Most island populations of microtine rodents were in complete synchrony with the mainland populations and each other, and the same-island rodent and shrew populations showed largely synchronous population changes. The few exceptions included small and isolated populations of Microtus oeconomus fluctuating out of synchrony. The generally high level of spatial synchrony is unlikely to be caused by predation by nomadic avian predators, as has been suggested previously, because they are very scarce in the study area. We present and discuss results suggesting that the synchrony is due to predation by small mustelids, especially the stoat, which may also be the primary cause of the large-amplitude rodent oscillations.
Looking for a single, consistent cause for population regulation is not only wishful thinking, but also
hinders our efforts to understand population dynamics. Population regulation is not only multifactorial, but
interactions among those factors are important; single-factor experiments can miss important interactions.
In addition, the ecological context constantly changes, so that regulatory processes track a moving target;
experiments can have different results if the context differs. I focus on interactions among nutrition,
predation and parasites. Parasitic disease can be an important regulatory factor on its own, but indirect
effects through interactions with energy budgets or predation are likely to be more important. Disease may
act as a precipitating mortality factor when energy (and especially protein) budgets are low; under such
circumstances, disease may be important, but which disease may be immaterial. The complex interactions
involved in regulation can be understood only by using all of the tools available: field observations, field
and laboratory experimentation and dynamic modelling.
Winter nests of brown and collared lemmings were examined following melt-off in 1969 through 1973 for evidence of predation by weasels during the preceding winter. In the winter of 1968-69 heavy weasel predation (34.7% of nests examined) contributed to the decline of a breeding lemming population. Weasel and bird predation in summer 1969 then drove the lemmings to a very low density. Weasel predation remained low for the duration of the study. Lemming population changes were related to the intensity of summer and, especially, winter reproduction. Reproduction was impaired in winters of unusually shallow snow cover and cold subnivean conditions. We conclude that subnivean conditions, as they affect winter reproduction, influence the timing of the rise to a population peak, and thus influence the period of the cycle. Predation on a declining lemming population is important in sustaining the amplitude of the cycle. This crucial predation need not occur at the point of maximum prey density and need not account for the majority of post-high mortality.
(1) In the Sierra Nevada, California deep snow covers the ground from about late November to mid-April and voles (Microtus montanus) build subnivean, non-breeding nests. (2) Ermine (Mustela erminea) and long-tailed weasels (M. frenata) prey on voles under the snow and use vole nests as dens. Food habits of these carnivores and their predation on the voles were measured by examining vole nests in spring over four years. (3) Voles showed characteristics of a cyclic population; they declined in density between autumn 1965 and spring 1967, increased to peak density in mid-summer 1968, crashed in winter 1968-69 and continued to decline through summer 1969. (4) Ermine were common in summer 1966, decreased in winter 1966-67 and were scarce in summer 1967 and winter 1967-68. They increased in summer 1968 and were common in winter 1968-69. In winter 1967-68 only one ermine was present on 14 ha of meadows but the following winter four were present on the same area. Ermine territories were restricted largely to the meadows. Long-tailed weasels also varied in numbers but they could not be counted. Long-tailed weasels hunted over large areas of both meadow and forest. (5) Ermine and long-tailed weasels in winter preyed almost entirely on voles. Food habits of ermine did not vary with changes in density of voles, but evidence for long-tailed weasels was inconclusive. (6) The percentage of winter nests of voles occupied by ermine in different years varied from 4.9 to 27.7% and by long-tailed weasels from 1.5 to 3.5%. The number of voles eaten at each den (occupied nest) also varied, being highest when the percentage of nests occupied by weasels was highest. These two variables, combined as the number of voles eaten per 100 nests examined, provided an estimate of the minimum percentage of the vole population eaten by weasels. (7) Ermine ate 21.2% of the population in winter 1965-66, 54.3% in 1966-67, 5.9% in 1967-68 and 28.3% in 1968-69. Predation was heaviest when voles were at lowest density and very light as voles increased again to peak density. Predation by long-tailed weasels was always light reaching its highest level after the vole population peaked, when 11.4% of the voles were eaten. (8) In winter 1966-67 all losses of voles from the population between autumn and spring could be accounted for by predation, almost entirely by ermine, but in subsequent winters as voles increased and were at higher densities fewer of the losses were accounted for. (9) These results support Pearson's hypothesis that predation during and following the crash is responsible for the timing and amplitude of the microtine cycle including that of lemmings. Small weasels (M. nivalis or M. erminea) are present throughout almost the entire range of cyclic microtines and may be the main carnivores responsible for the cyclic changes in density of microtine populations.