Water Vole Research Articles

INVESTIGATING THE EVOLUTIONARY HISTORY OF THE PACIFIC NORTHWEST MESIC FOREST ECOSYSTEM: HYPOTHESIS TESTING WITHIN A COMPARATIVE PHYLOGEOGRAPHIC FRAMEWORK

We examine the evolution of mesic forest ecosystems in the Pacific Northwest of North America using a statistical phylogeography approach in four animal and two plant lineages. Three a priori hypotheses, which explain the disjunction in the mesic forest ecosystem with either recent dispersal or ancient vicariance, are tested with phylogenetic and coalescent methods. We find strong support in three amphibian lineages (Ascaphus spp., and Dicampton spp., and Plethodon vandykei and P. idahoensis) for deep divergence between coastal and inland populations, as predicted by the ancient vicariance hypothesis. Unlike the amphibians, the disjunction in other Pacific Northwest lineages is likely due to recent dispersal along a northern route. Topological and population divergence tests support the northern dispersal hypothesis in the water vole (Microtus richardsoni) and northern dispersal has some support in both the dusky willow (Salix melanopsis) and whitebark pine (Pinus albicaulis). These analyses demonstrate that genetic data sampled from across an ecosystem can provide insight into the evolution of ecological communities and suggest that the advantages of a statistical phylogeographic approach are most pronounced in comparisons across multiple taxa in a particular ecosystem. Genetic patterns in organisms as diverse as willows and salamanders can be used to test general regional hypotheses, providing a consistent metric for comparison among members of an ecosystem with disparate life-history traits.

An assessment of the local impact of native predators on an established population of British water voles ( Arvicola terrestris )

There is a considerable amount of literature on the diet and effect of feral American mink Mustela vison on the distribution and abundance of water voles Arvicola terrestris in Britain. Few recent studies, however, have attempted to examine the occurrence of water voles in the diets of native predators. Fox Vulpes vulpes scat and grey heron Ardea cinerea pellets were collected during winter 2003–2004 at a location known to contain a large number of water voles. These scats and pellets were subsequently analysed to determine the frequency of water vole occurrence in the diet of these opportunistic predators. Water vole remains were found in 30% of fox scats analysed and accounted for 13% of the total weight of scats. A total of 18% of heron pellets contained the fur of water voles in addition to the fur of four other rodent species. The potential role of native predators in the loss and fragmentation of site-specific populations of water voles in Britain is further discussed.

Diet composition and food consumption of the grey heron (Ardea cinerea) from breeding colonies in northern Poland

The diet of the grey heron (Ardea cinerea) was investigated in three colonies in northern Poland (Mosty, Kiersity and Kąty Rybackie) varying in size, habitat type and composition of feeding areas used by birds. The diet was assessed during the breeding season on the base of pellets and regurgitated food. Pellets from all studied colonies consisted mainly of mammal hair (almost 100% of samples), bone remains (20–24%) and invertebrate remains (26–51%, mainly water beetle, Dytiscus marginalis). Bones and hair of water vole (Arvicola terrestris) and Microtus voles were the most common remains of mammals recorded in pellets. Remains of other animal taxa were found sporadically. In the colonies at Mosty and Kiersity, fish composed more than 95% of collected regurgitated prey items. Food consumption of herons from the biggest colony at Kąty Rybackie was estimated to exceed 100 t per season. Herons from Mosty consumed ca 46–52 t, from Kiersity 30–38 t of food per season. The impact of herons on fish communities was much lower than other losses due to predation (herons from Kąty Rybackie caught only 6% of fishermen bycatch, birds from Mosty took 10–14% of round gobies eaten by cormorants).

Genetic structure of the cyclic fossorial water vole (Arvicola terrestris): landscape and demographic influences

Genetic structure can be strongly affected by landscape features and variation through time and space of demographic parameters such as population size and migration rate. The fossorial water vole (Arvicola terrestris) is a cyclic species characterized by large demographic fluctuations over short periods of time. The outbreaks do not occur everywhere at the same time but spread as a wave at a regional scale. This leads to a pattern of large areas (i.e. some hundreds of km2), each with different vole abundances, at any given time. Here, we describe the abundance and genetic structures in populations of the fossorial water vole. We use the data to try to understand how landscape and demographic features act to shape the genetic structure. The spatial variability of vole abundance was assessed from surface indices, collected in spring 2002 (April) in eastern central France. Genetic variability was analysed using eight microsatellite loci at 23 localities sampled between October 2001 and April 2002. We found some congruence between abundance and genetic structures. At a regional scale, the genetic disruptions were associated with both sharp relief and transition between an area of low abundance and another of high abundance. At a local scale, we observed a variation of the isolation-by-distance pattern according to the abundance level of vole populations. From these results we suggest that the dispersal pattern in cyclic rodent populations varies throughout the demographic cycle.

Cluster of Capillaria hepatica infections in non-commensal rodents from the canton of Geneva, Switzerland

We trapped 664 rodents belonging to five non-commensal species in the canton of Geneva, Switzerland, and found a significant cluster of Capillaria hepatica infections in three species in rural and urbanized areas of the northern part of the canton. C. hepatica infections were discovered in the yellow-necked mouse Apodemus flavicollis (n=99) with an overall prevalence (OP) of 7.0% and a clustered prevalence (CP) of 20%, in the bank vole Clethrionomys glareolus (n=58, OP 5.2%; CP 19%), and in the water vole Arvicola terrestris scherman (n=466; OP 0.2%; CP 4%). The estimated numbers of C. hepatica eggs isolated from infected livers ranged from 1,914 to 938,000 per animal.

Phylogeographic structure and postglacial evolutionary history of water voles (Arvicola terrestris) in the United Kingdom

The phylogeographic pattern of mitochondrial DNA variation in water voles (Arvicola terrestris) from 57 localities across the United Kingdom and representative samples from Spain, France, Switzerland and Finland was determined from sequence variation in the central portion of the control region. Twenty-seven different haplotypes were resolved which formed two distinct phylogenetic clades. This major division separated haplotypes found in Scotland from those found in England and Wales. Nested clade analysis of haplotypes indicated that such a division was a consequence of allopatric fragmentation. The haplotypes found in Switzerland, France and Spain clustered with Scottish haplotypes, whereas the haplotype from Finland clustered with the English/Welsh haplotypes. These patterns indicate that contemporary Scottish populations are derived from an Iberian glacial refugium, whereas English and Welsh populations are derived from an eastern European refugium. As such, the postglacial recolonization of the United Kingdom must have involved two colonization events, either in different localities with no subsequent contact, or as two waves separated over time, with the second wave of colonizers displacing the first. An analysis of molecular variance (AMOVA) identified significant population genetic divergence within both the major clades, indicative of restricted gene flow and regional population isolation. The implications of both phylogeographical and population genetic structure are discussed in context with the conservation of water voles in Britain.

Les actualités sur les pneumopathies d'hypersensibilité en milieu rural

Hypersensitivity pneumonitis (HP) occurring in the rural environment is most often the consequence of exposure to fungi and bacteria. Recently, there have been a number of reports dealing with this problem, most of which fall under the heading of farmer's lung. Some new pathogens have been identified as etiological agents of farmer's lung, based on evidence obtained with serological tests. Environmental and occupational factors associated with the proliferation of these pathogens and with the risk of developing this condition have been identified, or at least suspected of being important. For example, the density of water voles (Arvicola terrestris scherman) appears to be one of the principal predictors of the development of HP. Concerning the diagnosis of these conditions, the results of a large international study provides important evidence on the relative value of clinical and laboratory data, especially for epidemiological studies; these data allow one to limit the use of invasive and expensive examinations. The significance of precipitins and the results of chest HRCT in the differential diagnosis of diffuse infiltrative lung diseases have been defined. Finally, the follow-up of cohorts of farmer's lung has confirmed the frequent evolution of these conditions to obstructive pulmonary disease with emphysema, especially when exposure to the responsible pathogen is not permanent.

Indirect negative impacts of radio‐collaring: sex ratio variation in water voles

SummaryRadio‐tracking is used ubiquitously in studies of wild vertebrates, a fundamental assumption being that tagged animals do not significantly differ, behaviourally or otherwise, from untagged animals.We studied two populations of water volesArvicola terrestris: one population was live‐trapped from April to September for 2 years (2000, 2001) and then concurrently radio‐tracked and trapped in a third year (2002). The second population was trapped only during 2002.During 2002, a substantial decline in female numbers in the radio‐collared population was recorded, apparently resulting from a male skew in the sex ratios of offspring born to this population. The mean numbers of males and females born duringtrappingonly were 25·7 (SD 2·1) and 29·0 (SD 7·0), respectively. Recruits to theradio‐trackedpopulation were skewed heavily in favour of males (43 : 13).Both hypotheses commonly invoked to explain mammalian sex‐ratio manipulation refer to the condition of mothers. The altered sex ratio resulted from a 48% decrease in numbers of females born, a decrease similar to the proportion (0·49) of the female population that was collared. No similar decline in male births occurred. This suggests that radio‐collaring of females caused male‐skewed sex ratios.Synthesis and applications. We conclude that the observed decline in female numbers resulted from male‐skewed recruitment sex ratios due to the attachment of radio‐collars to female water voles. These results question the assumption that the use of radio‐collars does not fundamentally affect the biology of collared water voles.

Predator–induced synchrony in population oscillations of coexisting small mammal species

Comprehensive analyses of long-term (1977-2003) small-mammal abundance data from western Finland showed that populations of Microtus voles (field voles M. agrestis and sibling voles M. rossiaemeridionalis) voles, bank (Clethrionomys glareolus) and common shrews (Sorex araneus) fluctuated synchronously in 3 year population cycles. Time-series analyses indicated that interspecific synchrony is influenced strongly by density-dependent processes. Synchrony among Microtus and bank voles appeared additionally to be influenced by density-independent processes. To test whether interspecific synchronization through density-dependent processes is caused by predation, we experimentally reduced the densities of the main predators of small mammals in four large agricultural areas, and compared small mammal abundances in these to those in four control areas (2.5-3 km(2)) through a 3 year small-mammal population cycle. Predator reduction increased densities of the main prey species, Microtus voles, in all phases of the population cycle, while bank voles, the most important alternative prey of predators, responded positively only in the low and the increase phase. Manipulation also increased the autumn densities of water voles (Arvicola terrestris) in the increase phase of the cycle. No treatment effects were detected for common shrews or mice. Our results are in accordance with the alternative prey hypothesis, by which predators successively reduce the densities of both main and alternative prey species after the peak phase of small-mammal population cycles, thus inducing a synchronous low phase.

Vilnius City Theriofauna

Mammal diversity investigations in Vilnius were carried out in 1992, 1998–2004. The following 51 mammal species were registered in the city: five species of insectivores (Insectivora), 11 of bats (Chiroptera), 18 of rodents (Rodentia), two of hares (Lagomorpha), 11 of carnivores (Carnivora) and four of ungulates (Artiodactyla). Fourteen mammal species are included into the Red Data Book of Lithuania, namely pond bat, Brandt's bat, barbastelle, brown long-eared bat, noctule, Leisler's bat, serotine bat, northern bat, particoloured bat, northern birch mouse, mountain hare, stoat, brown bear and otter. All insectivorous mammals in the city are common. During the warm span of the year we registered nine, and in hibernacula seven species of bats. The most widely spread and the most abundant small rodents of Vilnius were bank and common voles and yellow-necked mice, whereas muskrats and water voles were less frequent. The most numerous city carnivores were pine martens, with otters and badgers, and in particula...

INVESTIGATING THE EVOLUTIONARY HISTORY OF THE PACIFIC NORTHWEST MESIC FOREST ECOSYSTEM: HYPOTHESIS TESTING WITHIN A COMPARATIVE PHYLOGEOGRAPHIC FRAMEWORK

We examine the evolution of mesic forest ecosystems in the Pacific Northwest of North America using a statistical phylogeography approach in four animal and two plant lineages. Three a priori hypotheses, which explain the disjunction in the mesic forest ecosystem with either recent dispersal or ancient vicariance, are tested with phylogenetic and coalescent methods. We find strong support in three amphibian lineages (Ascaphus spp., and Dicampton spp., and Plethodon vandykei and P. idahoensis) for deep divergence between coastal and inland populations, as predicted by the ancient vicariance hypothesis. Unlike the amphibians, the disjunction in other Pacific Northwest lineages is likely due to recent dispersal along a northern route. Topological and population divergence tests support the northern dispersal hypothesis in the water vole (Microtus richardsoni) and northern dispersal has some support in both the dusky willow (Salix melanopsis) and whitebark pine (Pinus albicaulis). These analyses demonstrate that genetic data sampled from across an ecosystem can provide insight into the evolution of ecological communities and suggest that the advantages of a statistical phylogeographic approach are most pronounced in comparisons across multiple taxa in a particular ecosystem. Genetic patterns in organisms as diverse as willows and salamanders can be used to test general regional hypotheses, providing a consistent metric for comparison among members of an ecosystem with disparate life-history traits.

Analysis of major histocompatibility complex class II gene in water voles using capillary electrophoresis‐single stranded conformation polymorphism

AbstractAnalysis of a single strand conformation polymorphism (SSCP) using capillary electrophoresis (CE) is a novel method to study polymorphism of DNA sequences in large scale population studies. We optimized CE‐SSCP analysis to study the major histocompatibility complex (MHC) class II alpha gene (DQA) polymorphism. Short‐chain linear polyacrylamide (6%) as sieving matrix, TrisCl (pH 8.5) as buffer for sample dilution, and 27 °C, 9 kV as electrophoresis parameters were suitable for sufficient resolution of all alleles. We found that almost 25% of clones contained a PCR (polymerase chain reaction) artefact and strict criteria have to be applied when using cloning and sequencing to analyse the allelic diversity of MHC genes.

Frenkeliaparasites in a small mammal community. Dynamics of infection and effect on the host

A community of small mammals, Clethrionomys glareolus, Arvicola terrestris, Microtus arvalis, M. agrestis, M. subterraneus, Apodemus spp. and Sorex spp., was studied as hosts of Frenkelia glareoli and F. microti in Fronche-Comté (France). They were monitored in spring, summer and autumn on an area of about 1,350 ha comprising open field, hedgerow network and forest. Among 1,714 small mammals examined between July 1992 and October 1993, 47% (178/376) of C. glareolus, 9.9% (14/139) of A. terrestris and 1.3% (4/311) of Apodemus spp. were infected by F. glareoli. The prevalence of infection with F. microti was 9.2% (66/716) in M. arvalis and 8.2% (6/73) in M. agrestis. M. subterraneus and Sorex spp. were not infected. The maintenance of each parasite in a rural landscape is assured both by a forest and a grassland host. Multiple logistic regression showed that prevalence was highly age-dependent, with an apparent seasonal pattern. Prevalence varied between 30% in summer and 60% in early spring for F. glareoli in C. glareolus and between 3% in autumn to 30% in early spring for F. microti in M. arvalis. The year, habitat, host sex, relative density had no impact on prevalence. In M. arvalis only, sexually active voles were preferentially uninfected, indicating a possible impact of this parasitism on fertility.

Natural infection of the water vole Arvicola terrestris with Toxoplasma gondii, on the Jura plateau, eastern France.

102 A. terrestris (all juveniles) were caught between July 1992 and July 1993 from an area near the French village of Le Souillot, dissected and examined for coccidian tissue cysts. Five of the animals were found to have tissue cysts in their brains. Although histological sections of the 5 infected brains all revealed round cysts, each measuring <150 micro m in diameter, 2 of the brains had cysts that were morphologically similar to those of T. gondii, with crescent-shaped zoites. The cysts in the other three brains had spherical zoites, each with a central nucleus. Immunoperoxidase labelling confirmed the two brains had T. gondii cysts (2%). The cysts in the other 3 infected brains, which showed no reaction with the anti-Toxoplasma or anti-Neospora sera, were assumed to be young cysts of Frenkelia.

An experimental field approach to parasitism and immune defence in voles

The fox tapeworm Echinococcus multilocularis is typically perpetuated in a cycle with red foxes as definitive hosts and various rodent species as intermediate hosts. In this study, foxes were baited with a highly efficient drug against cestodes (praziquantel) in 5 blocks of 1 km2. Voles, Arvicola terrestris, the most abundant intermediate host species, were trapped in the 5 baited blocks and in 5 non-baited control blocks. Baiting the foxes reduced the prevalence of E. multilocularis in fox faecal samples in the baited blocks, but voles trapped in the two blocks did not differ in their infection rates. However, voles from the baited blocks had significantly smaller spleen masses and were more likely to be infested with mites than those from the control blocks, possibly reflecting different immunological activities. Our study suggests that the environmental contamination with E. multilocularis eggs, and perhaps those of other tapeworms, influences the immune system of the intermediate host species A. terrestris in the wild.

Competition, predation and interspecific synchrony in cyclic small mammal communities

Although competition and predation are considered to be among the most important biotic processes influencing the distribution and abundance of species in space and time, the relative and interactive roles of these processes in communities comprised of cyclically fluctuating populations of small mammals are not well known. We examined these processes in and among populations of field voles, sibling voles, bank voles and common shrews in western Finland, using spatially replicated trapping data collected four times a year during two vole cycles (1987–1990 and 1997–1999). Populations of the four species exhibited relatively strong interspecific temporal synchrony in their multiannual fluctuations. During peak phases, we observed slight deviations from close temporal synchrony: field vole densities peaked at least two months earlier than those of either sibling voles or bank voles, while densities of common shrews peaked even earlier. The growth rates of all four coexisting small mammal species were best explained by their own current densities. The growth rate of bank vole populations was negatively related to increasing densities of field voles in the increase phase of the vole cycle. Apart from this, no negative effects of interspecific density, direct or delayed, were observed among the vole species. The growth rates of common shrew populations were negatively related to increasing total rodent (including water voles and harvest mice) densities in the peak phase of the vole cycle. Sibling voles appeared not to be competitively superior to field voles on a population level, as neither of these Microtus voles increased disproportionately in abundance as total rodent density increased. We suggest that interspecific competition among the vole species may occur, but only briefly, during the autumn of peak years, when the total available amount of rodent habitat becomes markedly reduced following agricultural practices. Our results nonetheless indicate that interspecific competition is not a strong determinant of the structure of communities comprised of species exhibiting cyclic dynamics. We suggest that external factors, namely predation and shortage of food, limit densities of vole populations below levels where interspecific competition occurs. Common shrews, however, appear to suffer from asymmetric space competition with rodents at peak densities of voles; this may be viewed as a synchronizing effect.

CONSERVING WATER VOLES: BRITAIN'S FASTEST DECLINING MAMMAL

ABSTRACTIn Britain, the water vole is a declining species because of habitat loss and land‐use change associated with the intensification of agriculture and urban encroachment. During recent years, this decline has accelerated due to predation by feral American Mink (escapees from fur farms) and population fragmentation. Legal protection and planning policy has allowed for conservation action to be incorporated into waterside developments. This paper examines the various options to maintain and enhance water‐vole populations through planning design, sensitive mitigation procedures and strategic habitat restoration.

The micromammal fauna of the Dnieper modern channel alluvium: taphonomic and biostratigraphic implications [ La faune des petits mammifères des alluvions du lit fluvial actuel du Dniepr : implications taphonomiques et biostratigraphiques.

Cet article présente une étude des restes des petits mammifères des alluvions du lit fluvial actuel du Dniepr. L'obtention d'une information pertinente à partir de cette taphocénose mixte est rendue possible grâce à l'existence d'une relation entre le degré de fossilisation des os et leur âge géologique relatif. II existe ainsi trois stades de fossilisation selon l'âge géologique des restes. Les âges des groupes de fossiles déterminés sur la base des indices du niveau d'évolution des Arvicolidés sont rapportés à l'Eémien et au Weichselien ancien, au Weichselien moyen et récent et à l'Holocène. Quoique les fossiles holocènes soient les plus proches de la période de formation des alluvions, les fossiles les plus anciens (première moitié du Pléistocène supérieur) dominent dans la structure de cette taphocénose. Il est évident qu'ils ont été redéposés dans l'actuelle plaine d'inondation à partir de terrasses du Pléistocène récent (Ie, IIe, et peut-être IIIe). Cela permet d'espérer trouver de petits mammifères dans les dépôts de ces terrasses qui jusqu'à présent n'ont pratiquement pas fourni de caractérisation microthériologique. II est à supposer que la composition des associations et les mécanismes de leur formation sont communs à la plupart des taphocénoses mixtes. Ainsi dans leur étude il faut attacher une grande attention à la partie la plus jeune de l'ensemble général des fossiles, la plus avancée du point de vue d'évolution. C'est elle qui sera synchrone au moment de la formation de la séquence alluviale , les fossiles plus anciens seront considérés comme redéposés même s'ils dominent quantitativement. En outre, l'analyse morphotypique des fossiles de Arvicola terrestris de la taphocénose des alluvions actuelles du Dniepr et l'étude des Arvicola récents des diverses zones climatiques de l'Europe orientale démontrent la possibilité de certaines fluctuations des indices du niveau d'évolution chez les Arvicolidae sous l'influence des changements de l'environnement. Ce phénomène doit ainsi influer sérieusement sur la précision de la date des sédiments, sur la base des indices du niveau d'évolution des Arvicolidae.

Chichester emergency flood alleviation project, winter 2000/2001

The River Lavant is a small ephemeral chalk stream, which is culverted through the city of Chichester. In 1994 widespread flooding resulted when the capacity of the culverts was exceeded and the river overtopped its bank. Subsequently a local multi-agency Strategic Coordinating Group was formed, and a permanent flood alleviation scheme was developed through the planning process. In November 2000, after a period of very heavy rain, the River Lavant again threatened flooding. A large-scale pumping operation to divert some water around the city was brought into place by the Fire Brigade. Additional alleviation capacity was urgently needed, and local design resources were committed to adapt the permanent scheme for rapid implementation. The project comprised several major pumping operations and open channels over 5 km long with a choked diversion to protect the village of Merston. The A27 trunk road and the railway embankment carrying the mainline along the south coast lie across the route. Piped crossings were designed involving liaison with Railtrack and the Highways Agency. Documents for the whole scheme were put together while funding approval was sought. Despite the emergency conditions, both archaeological and ecological studies were undertaken, particularly for water vole, bat and badger habitats. On 4 December 2000 construction commenced in three packages costing a total of £1·3 million, with a programme to complete all but the main rail crossing before Christmas. However, further bad weather intervened, and the partially completed works were brought into use carrying floodwater less than two weeks later. In the New Year the rail crossing was constructed during a weekend possession. The paper focuses on the implementation of the project, including emergency response, multi-agency cooperation, team working, fast-tracking approvals, unique technical solutions, and rapid construction while ensuring compatibility with the full scheme.

Chichester emergency flood alleviation project, winter 2000/2001

The River Lavant is a small ephemeral chalk stream, which is culverted through the city of Chichester. In 1994 widespread flooding resulted when the capacity of the culverts was exceeded and the river overtopped its bank. Subsequently a local multi-agency Strategic Coordinating Group was formed, and a permanent flood alleviation scheme was developed through the planning process. In November 2000, after a period of very heavy rain, the River Lavant again threatened flooding. A large-scale pumping operation to divert some water around the city was brought into place by the Fire Brigade. Additional alleviation capacity was urgently needed, and local design resources were committed to adapt the permanent scheme for rapid implementation. The project comprised several major pumping operations and open channels over 5 km long with a choked diversion to protect the village of Merston. The A27 trunk road and the railway embankment carrying the mainline along the south coast lie across the route. Piped crossings were designed involving liaison with Railtrack and the Highways Agency. Documents for the whole scheme were put together while funding approval was sought. Despite the emergency conditions, both archaeological and ecological studies were undertaken, particularly for water vole, bat and badger habitats. On 4 December 2000 construction commenced in three packages costing a total of £1·3 million, with a programme to complete all but the main rail crossing before Christmas. However, further bad weather intervened, and the partially completed works were brought into use carrying floodwater less than two weeks later. In the New Year the rail crossing was constructed during a weekend possession. The paper focuses on the implementation of the project, including emergency response, multi-agency cooperation, team working, fast-tracking approvals, unique technical solutions, and rapid construction while ensuring compatibility with the full scheme.