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Landscape effects on the population dynamics of small mammal communities: A preliminary analysis of prey-resource variations
Abstract
L’objectif de cette étude est d’estimer l’effet de la composition du paysage sur les variations de disponibilité en biomasse de micro-mammifères pour les prédateurs, à l’échelle sectorielle (n x 1 km2). Quatre sites d’étude représentatifs d’un gradient d’intensification agricole ont été choisis dans l’est de la France en fonction de la composition du paysage.
Les fluctuations de biomasses de Microtus arvalis et Arvicola terrestris (espèces prairiales), de Clethrionomys glareolus et Apodemus sp. (espèces de milieux fermés) ont été suivies de 1992 à 1996 par méthodes indiciaires et piégeage. Les synchronies entre les populations de M. arvalis et celles de rongeurs de milieux fermés ont été recherchées.
Les fluctuations de biomasse de M. arvalis et A. terrestris sont stables dans les sites où la proportion de prairie permanente est la plus faible. Les populations de M. arvalis présentent les plus larges amplitudes de variation de biomasse et les déclins les plus prononcés dans les sites où la proportion de prairie permanente sur la surface agricole est supérieure à 50 %. Les populations d’A. terrestris ne sont instables que dans un site, là où la proportion de prairie permanente sur surface agricole est supérieure à 85 %. Les déclins de populations de rongeurs de milieux fermés (Clethrionomys glareolus et Apodemus sp.) sont concomitants de ceux de M. arvalis dans les sites à fortes variations de biomasse de cette dernière espèce.
Ces résultats suggèrent deux types de fonctionnement, en terme de variation de disponibilité en proies pour les prédateurs : (i) stable dans les paysages à faible proportion de prairie permanente, et (ii) instable, avec des déclins prononcés et rapides des populations d’espèces prairiales, entraînant des déclins synchrones du peuplement de micro-mammifères étudié, dans les paysages à forte proportion de prairie permanente.
Aucune synchronie dans les dynamiques de population de ces micro-mammifères n’est observée entre les sites d’étude, éloignés de quelques dizaines de kilomètres seulement.
... Small mammals, including insectivores and rodents, link lower and higher trophic levels and are thereby keystone species in the ecosystem. In agricultural landscapes, the species richness of small mammals is highest in heterogeneous farmland with high compositional and configurational diversity (van Apeldoorn et al. 1992, Raoul et al. 2001, Fischer et al. 2011, Benedek & Sîrbu 2018. In forests, small mammals often depend on structural elements, such as fallen trees, decayed wood, and woody debris (Carey & Johnson 1995, Bowman et al. 2000, Carey & Harrington 2001, Ecke et al. 2002. ...
... In farmlands, small mammal species richness is highest in heterogeneous landscapes (van Apeldoorn et al. 1992, Raoul et al. 2001, Fischer et al. 2011. In our study, the importance of landscape heterogeneity was suggested by associations with ecotones and different grassland types. ...
Habitat associations of small mammals are an essential component of ecosystem functioning. We studied habitat associations of small mammals during an 8-year period in a hemiboreal forest–farmland landscape. We observed all five rodent and one shrew species in meadows, three species in forests, and two species in crop fields. Total abundance was evenly distributed across the three main habitat types but was biased towards habitat margins. The bank vole, Myodes glareolus, was associated with mature and middle-aged forests and avoided meadows; it was absent from crop fields. The yellow-necked mouse, Apodemus flavicollis, occurred in all three main habitat types, without significant associations. However, its relative abundance was
significantly higher in dry natural meadows and mid-successional forests, and it also favored ecotones. The striped field mouse Apodemus agrarius preferred crop fields and unmanaged meadows over forests. The vital hemiboreal small mammal community requires the preservation of heterogeneous forest–farmland complexes.
... Small mammals, including insectivores and rodents, link lower and higher trophic levels and are thereby keystone species in the ecosystem. In agricultural landscapes, the species richness of small mammals is highest in heterogeneous farmland with high compositional and configurational diversity (Van Apeldoorn et al. 1992;Raoul et al. 2001;Fischer et al. 2011;Benedek & Sîrbu 2018). In forests, small mammals often depend on structural elements, such as fallen trees, decayed wood, and woody debris (Carey & Johnson 1995;Bowman et al. 2000;Carey & Harrington 2001;Ecke et al. 2002). ...
... In farmland, small mammal species richness is highest in heterogeneous landscapes (Van Apeldoorn et al. 1992;Raoul et al. 2001;Fischer et al. 2011). In the current study, the importance of landscape heterogeneity was suggested by the associations with ecotones and different grassland types. ...
Habitat associations of small mammals are an essential component of ecosystem functioning. We studied habitat associations of small mammals over an 8-year period in a hemiboreal forest-farmland landscape. We observed all five rodents and one shrew species in meadows, three species in forests, and two species in crop fields. Total abundance was evenly distributed across the three main habitat types but was biased towards habitat margins. The bank vole Myodes glareolus was associated with mature and middle-aged forests and avoided meadows; it was absent from crop fields. The yellow-necked mouse Apodemus flavicollis occurred in all three main habitat types, without significant associations. However, its relative abundance was significantly higher in dry natural meadows and mid-successional forests, and it also favored ecotones. The striped field mouse Apodemus agrarius preferred crop fields and unmanaged meadows over forests. The vital hemiboreal small mammal community requires the preservation of heterogeneous forest-farmland complexes.
... We used a Bayesian framework developed in Smout et al. (2010) to fit field data of those two generalist predators collected in the Jura mountains of eastern France. In this region, landscape composition and structure are favorable to population outbreaks of the water vole (Arvicola scherman) and the common vole (Microtus arvalis), two grassland rodents whose population biomasses are dominant in the landscape (Raoul et al. 2001, Berthier et al. 2014. Population declines of other small mammals species living in grassland and other habitats (e.g., the wood mouse Apodemus sylvaticus or the bank vole Myodes glareolus) are synchronous with the declines of grassland species (Raoul et al. 2001, Bernard et al. 2010, strengthening the interest for the predator's diet response to variation of total density of prey. ...
... In this region, landscape composition and structure are favorable to population outbreaks of the water vole (Arvicola scherman) and the common vole (Microtus arvalis), two grassland rodents whose population biomasses are dominant in the landscape (Raoul et al. 2001, Berthier et al. 2014. Population declines of other small mammals species living in grassland and other habitats (e.g., the wood mouse Apodemus sylvaticus or the bank vole Myodes glareolus) are synchronous with the declines of grassland species (Raoul et al. 2001, Bernard et al. 2010, strengthening the interest for the predator's diet response to variation of total density of prey. As a consequence, this system offers a well-suited setting to comprehensively model functional responses of generalist predators in a context of fluctuating multi-prey dynamics. ...
The ability for a generalist consumer to adapt its foraging strategy (the
multi-species functional response, MSFR) is a milestone in ecology as it contributes to
the structure of food webs. The trophic interaction between a generalist predator, as the
red fox or the barn owl, and its prey community, mainly composed of small mammals,
has been empirically and theoretically widely studied. However, the extent to which these
predators adapt their diet according to both multi-annual changes in multiple prey species
availability (frequency dependence) and the variation of the total prey density (density
dependence) is unexplored.We provide a new general model of MSFR disentangling changes
in prey preference according to variation of prey frequency (switching) and of total prey
density (we propose the new concept of “rank switching”). We apply these models to two
large data sets of red fox and barn owl foraging. We show that both frequency-dependent
and density-dependent switching are critical properties of these two systems, suggesting
that barn owl and red fox have an accurate image of the prey community in terms of
frequency and absolute density. Moreover, we show that negative switching, which can
lead to prey instability, is a strong property of the two systems.
... 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. ...
... 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.
... Aux échelles régionales et sectorielles, l'influence de la structuration des paysages explique largement les variations d'abondance des populations (DELATTRE et al., 1996(DELATTRE et al., , 1999RAOUL et al., 2001). En revanche, l'influence des facteurs s'exerçant à l'échelle parcellaire (pratiques agricoles, conduites pastorales, nature du couvert herbacé...) reste peu étudiée malgré son intérêt pour la mise en place de stratégies de lutte. ...
Les réponses démographiques des populations de campagnols des champs à l'échelle parcellaire dépendent des itinéraires techniques et des pratiques agricoles. Plusieurs catégories de prairies sont différenciées et mettent en valeur que les prairies fauchées, permanentes et temporaires, présentent les densités de campagnols les plus élevées dues à un milieu plus favorable (quiétude et prolificité supérieures et meilleure protection contre la prédation). Pour maintenir ces populations à un niveau de densité non dommageable à la production fourragère, quelques préconisations sont énoncées concernant aussi bien l'entretien des milieux herbacés, la protection de la faune prédatrice (rapaces et carnivores) que l'aménagement des territoires.
The European Food Safety Authority (EFSA) was required to support the European Commission in preparing the review of Regulation (EU) No 1152/2011. In Europe, red fox (Vulpes vulpes) is the main definitive host of the Echinococcus multilocularis (EM) lifecycle. There is no evidence that any other carnivore species can maintain the lifecycle in the absence of red fox, and this makes it to most relevant target species for surveillance. Movement of infected definitive hosts is an important introduction pathway. The knowledge on the geographical distribution of the environmental factors for the persistence of the lifecycle is scarce. In areas where no suitable autochthonous wild canid hosts and no highly suitable intermediate hosts are present, e.g. Malta, establishment of the EM cycle is considered close to impossible. Such countries do not need to carry out surveillance on domestic dogs to substantiate absence of EM in the relevant animal population. Reconsideration of some aspects of the current legislation regarding surveillance activities might be relevant; for example the identification of epidemiologically relevant units should be independent from political borders. Studies to improve the knowledge on epidemiological risk factors should be encouraged to enable risk-based sampling. Echinococcus notification should always be done at species level in order to discriminate between the more severe alveolar echinococcosis and the cystic echinococcosis. Praziquantel is the substance of choice for the treatment of dogs. However, the treatment window should be reconsidered to reduce the risk of re-infection: a general rule is to treat as close as possible to entry into a non-infected country. There is a lack of standardization of the diagnostic methods between laboratories. The diagnostic sensitivity of the tests should be established in accordance to the World Organisation for Animal Health (OIE) standards for validation. For the time being, the diagnostic sensitivity can be set conservatively to 78%.
La structure et l’intensité des interactions ressources-consommateurs qui forment les réseaux trophiques régulent une très grande partie des transferts de biomasse mais aussi de contaminants biologiques et chimiques dans les écosystèmes. L’objectif de la thèse est de développer des modèles permettant d’étudier les mécanismes de transport des contaminants et d’évaluer ainsi d’une part la dynamique des maladies infectieuses et des pollutions chimiques, et d’autre part les réponses des réseaux trophiques soumis à ces contaminations.[...] À l’issue de ces travaux, une quatrième étape de la thèse a été d’intégrer les interactions trophiques, les dynamiques des parasites et les impacts des pollutions dans des méta-écosystèmes (i.e. avec dispersions d’individus entre écosystèmes). En utilisant la théorie des matrices aléatoires nous avons établi des mesures des risques d’émergence de parasites que nous avons évalués en fonction des perturbations extérieures.L’étude a ainsi montré que ces perturbations augmentent les risques épidémiques, mais que ces risques pouvaient être réduits par la dispersion des individus (sains et infectés) sous certaines conditions qui sont,par exemple pour les TTP, un nombre d’espèces plus grand que le nombre d’écosystèmes connectés, et un taux de virulence plus faible que le taux de contagion.Ainsi, dans un contexte planétaire d’augmentation des pressions anthropiques sur les écosystèmes,cette thèse de modélisation apporte un ensemble d’outils et de développements conceptuels permettant d’analyser quantitativement et qualitativement les transferts et les impacts des contaminants sur les écosystèmes.
— Small mammal communities on four sown wild flower areas in western Switzerland were studied from spring to autumn 2005 using the capture-recapture method. We trapped 666 animals belonging to Microtus arvalis, Apodemus sylvaticus, Apodemus flavicollis and Crocidura russula. M. arvalis, the most abundant species, reached a peak of 581 animals/ ha known to be alive (MNA ) on one area in late
September. Spring populations of M. arvalis were very low on all fields. A preliminary study in 2003-2004 showed a very low number of animals known to be alive during the winter months and a similar population growth in spring. Population turnover was generally high with up to 81 % of the population renewed in a one-week period (August). On all fields, there was a surplus of female M. arvalis. In August and September, the difference from 1 : 1 ratio was significant in one field, apparently a result of differential survival rate and recruitment between sexes. There was no significant difference in body mass between adult females and adult males. The second most frequent species, A. sylvaticus reached densities of up to 225 animals/ ha on one area, but only 60-100 animals/ ha, on the other three sites.
Hunting ground and habitat selection of breeding Kestrels were studied on 26 pairs breeding in marshlands of Western France. Data were collected both by direct observations and radio-tracking over 1500 hours in 2000-2004. The mean size of hunting areas of males is 1,8 km2 (0,5-3,8 km2; and 0,5-0,6 km2 for two females) with a lot of overlap between males hunting grounds (60 %). All habitats are used by hunting Kestrels (see Tab. 1) although crop fields tend to be used less. Hunting habitat selection is linked to mammal abundance (measured by standardized method in spring) but vegetation height is also an essential factor for hunting efficiency and choice of hunting habitat. No relations were found between parental effort or breeding success and size of hunting territory; the only significant relation identified was between breeding success and proportion of grasslands within hunting territory.
I show that microtine and shrew populations in western Finland had synchronous decline phases, although the other population fluctuation phases were not regularly synchronous. The most probable reason in spring and summer is the predation by nomadic birds of prey (which frequently feed on shrews in addition to microtines) and to a smaller extent the predation by resident small mustelids, since the distaste of these mammalian predators for shrews has been shown in several studies. In winter small mustelids may play a more important role than partially migrating birds of prey. Occasionally also unfavourable weather conditions in winter may affect these synchronous declines observed in the transition zone of Fennoscandia.
In the territory of Russia and countries of the former USSR 9 species of carnivores appear to be the definitive hosts of Echinococcus multilocularis and, among them, the common fox and arctic fox play the dominant role, 30 species of mammals serve as the intermediate hosts: voles, mice, shrews, lammings, bobac marmots, jirds, muskrats, ground squirrels, jerboas, rodent-moles, hares, hamsters and man. The high morbidity of humans with alveolar hydatid disease (10 and more infected persons per 100,000 of inhabitants) is noted in Yakutia, Chukot and Korjak Autonomous Districts, Kamchatka, Omsk, Tomsk Region and Altai Territory; this index tends to be a moderate one (from 1 to 10 infected persons per 100,000 of inhabitants) in the Tuva Republic, at the south of Krasnoyarsk Territory, Magadan Region and north areas of Kazakhstan and at last it is weak (less than 1 infected person per 100,000 per inhabitants) in some zones of West Siberia, the Far East, Povolzhje, North Caucasus and Azerbaijan. Alveolar echinococcosis foci in Russia are classified in north tundra and south forest-steppe and steppe ones: in Siberia they are separated by taiga zone. Mainly arctic fox and lemmings take part in transmission of infection in the north and, in the south, foxes and corsac foxes on one hand and voles, muskrats, jirds - on the other. In Yakutia a village type of foci of alveolar echinococcosis has been revealed where.circulation follows the scheme "dog-voles" and includes house mice and man to this cycle. Thus formation of synanthropic foci of infection takes place with considerably increased risk for humans to be infected with alveolar hydatid disease.
The difficulty of monitoring population densities of the common vole on a regional scale led the authors to test the validity of some density indices. Results were compared with density estimates based on line trapping of voles in the same habitats. Correlations between the number of captures in trap line and the number of burrow openings or runways were weak or nil. The correlation with the number of droppings was strong. -from English summary
Some 32 mammals species have been recorded from an agricultural landscape near Turew, Poland. The biomasses of the trophic groups were: herbivores 3625.3, omnivores 470.5, insectivores 271.1 and carnivores 106.3 g live weight per ha. Lepus capensis, Capreolus capreolus, Microtus arvalis, Sus scrofa, Talpa europaea, Erinaceus europaeus and Vulpes vulpes made up 95.5% of the total biomass of the mammal community. Food shortage is probably responsible for crashes in populations of the common vole, small forest rodents, roe deer and carnivores. The pressure exerted by predators on the prey is inversely correlated with changes in the prey population. Intensive agriculture causes a reduction in mammal populations: mechanized harvesting affects hares and roe deer, crop rotation affects the wild boar and root vole, etc. An index of energy turnover time based on the energy value of body biomass divided by the cost of maintenance was developed. A shorter energy turnover time means higher dependence on the food supply. The average turnover time was 4.2 days in insectivores, 8.7 in herbivores, 14.3 in carnivores and 20.8 in omnivores. The mammal community studied uses energy efficiently; this is achieved by selection for bigger sizes.-from Author
Largely synchronous population fluctuations of Clethrionomys glareolus, C. rufocanus, and Microtus agrestis were monitored by snap-trapping in spring and autumn in 1971-1988 in a strongly seasonal environment near UmeA, northern Sweden. All species were cyclic in the sense that they showed fairly regular (3-4 yr) fluctuations, but amplitudes ((max)/n(min)) varied, averaging almost-equal-to 200-fold in each species. This conclusion was supported by autocorrelation and spectral analysis, and by fitting time series data to a model for phase-forgetting cycles. By contrast, data did not conform to a model for phase-remembering cycles (with fixed period and amplitude). The transition between cycles, i.e., from the low to increase phase, was characterized by a distinct shift in rate of change in numbers from low to high or markedly higher values both in summer and winter. Generally, rate of change in summer declined continuously from the increase phase through each cycle. Moreover, there was a similar decrease of rate of change in winter, although rate of change (mainly in C. rufocanus and M. agrestis) first frequently increased early in the cycle. Rate of change was delayed density dependent in all species both in summer and winter, as revealed by high negative correlations with density in previous autumn and spring for summer and winter changes, respectively. These new findings of delayed density dependence (DDD) support the suggestion that vole cycles are generated by a time-lag mechanism. Possible mechanisms of the DDD are discussed. Regression analyses of rate of change in the different voles suggest that, besides the strong dependence on previous density, rate of change in numbers was also affected by current seed supply (in C glareolus) and/or weather variables (temperature and precipitation sums) that may have affected the quantity or quality of food.
(1) Field voles, Microtus agrestis, and bank voles, Clethrionomys glareolus, are pests in Scandinavian forestry and horticulture. Damage to forest seedling or fruit trees, for example, is inflicted mainly at, or just after, population peaks. Changes in population density, using standardized trapping techniques, are laborious and expensive to follow. Therefore the value of various signs as indices of vole abundance was examined. (2) The abundance of M. agrestis on abandoned fields was correlated with grazing intensity in spring and autumn and with runway numbers in autumn. Seasonal and annual changes in catches of M. agrestis were related to various signs but variations in the latter were generally more even. The abundance of C. glareolus in mature forests was correlated with numbers of runways in spring and autumn and with grazing intensity in spring. Other signs such as earth holes or faeces did not correlate so well. Long-term predictions could not be made. (3) In order to make short term predictions, M. agrestis abundance on abandoned fields and other habitats with few other small rodent species should be assessed in terms of grazing intensity. In areas where C. glareolus is also common, e.g. reforestations, the number of runways should also be recorded.
In mosaics of forest environment the bank vole Clethrionomys glareolus (Schreber, 1780) prefers patches with dense vegetal cover like understorey or tall herbaceous plants, like ferns or sedges. The size and intensity of the space use, the rate of colonization of free space with population increases and mean home range soze are highest in habitats, or their parts, covered uniformly by this type of vegetation. Habitats with dense and uniform understorey characteristically support high vole densities, high numbers of sexual active individuals, high survival rates of individuals entering the population at the beginning of the repreductive season, a high emigration during the second half of the season and a low immigration. Vole populations in habitats of poor and clumped understorey are characterized by low densities, high immigration of individuals entering to the population during the second half of the season and a high turnover of individuals. It has been suggested that vole distribution in a mosaic of forest habitats depends upon the abundance of structural elements of the habitat thay may serve as defensive structures against predators.
Standardized plot-sampling of small mammal populations (9 species of 5 different genera) in widely-separated areas of Alaska over an eight-year period revealed synchronous fluctuations in biomass with peaks in 1954 and 1959. The synchrony apparently encompassed St Lawrence Island and most of the mainland of Alaska with the exception of the Baldwin Peninsula and perhaps the northeastern Brooks Range. The data also reveal the extreme ranges in biomass and in numbers of individuals to he expected in sampling a number of taiga and tundra vegetation types. Cyclic fluctuations in ecosystem productivity are postulated as a testable explanation of these synchronous biomass fluctuations over such a wide geographic area.