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Anthropogenic activities and natural events such as periodic tree masting can alter resource provisioning in the environment, directly affecting animals, and potentially impacting the spread of infectious diseases in wildlife. The impact of these additional resources on infectious diseases can manifest through different pathways, affecting host susceptibility, contact rate and host demography.To date however, empirical research has tended to examine these different pathways in isolation, for example by quantifying the effects of provisioning on host behaviour in the wild or changes in immune responses in controlled laboratory studies. Furthermore, while theory has investigated the interactions between these pathways, this work has focussed on a narrow subset of pathogen types, typically directly transmitted microparasites. Given the diverse ways that provisioning can affect host susceptibility, contact patterns or host demography, we may expect the epidemiological consequences of provisioning to vary among different parasite types, dependent on key aspects of parasite life history, such as the duration of infection and transmission mode.Focusing on an exemplar empirical system, the wood mouse Apodemus sylvaticus, and its diverse parasite community, we developed a suite of epidemiological models to compare how resource provisioning alters responses for a range of these parasites that vary in their biology (microparasite and macroparasite), transmission mode (direct, environmental and vector transmitted) and duration of infection (acute, latent and chronic) within the same host population.We show there are common epidemiological responses to host resource provisioning across all parasite types examined. In particular, the epidemiological impact of provisioning could be driven in opposite directions, depending on which host pathways (contact rate, susceptibility or host demography) are most altered by the addition of resources to the environment. Broadly, these responses were qualitatively consistent across all parasite types, emphasising the importance of identifying general trade‐offs between provisioning‐altered parameters.Despite the qualitative consistency in responses to provisioning across parasite types, we predicted notable quantitative differences between parasites, with directly transmitted parasites (those conforming to SIR and SIS frameworks) predicted to show the strongest responses to provisioning among those examined, whereas the vector‐borne parasites showed negligible responses to provisioning. As such, these analyses suggest that different parasites may show different scales of response to the same provisioning scenario, even within the same host population. This highlights the importance of knowing key aspects of host–parasite biology, to understand and predict epidemiological responses to provisioning for any specific host–parasite system. [ABSTRACT FROM AUTHOR]

DNA‐based approaches have greatly improved the applicability of dietary studies aimed at investigating ecological processes. These studies have provided direct insights into, otherwise difficult to measure, interactions between species and trophic levels, food web structure and ecosystem functioning. However, despite these advances, DNA‐based methods have struggled to accurately quantify the whole breadth of diet constituents because of methodological biases, such as amplification bias and digestive processes. The present study is, to our knowledge, the first diet study to use droplet digital PCR to quantify diet constituents. We manipulated the diet of wild‐caught wood mice (Apodemus sylvaticus) by feeding them with a known amount of small vegetable seeds (onion and carrot) and quantified the DNA traces of these diet constituents in faecal samples. The sensitivity of the technique combined with the control on the experimental design allowed mitigation of methodological bias. We were able to accurately determine DNA concentrations of small vegetable seeds in the diet of wood mice. Quantification of target DNA demonstrated significant differences in DNA content when one vs. five seeds were consumed. These differences remained significant when the age, sex and other diet constituents of the mice were altered. Different DNA markers, targeting different parts of the chloroplast, influenced onion DNA detectability. However, all onion and carrot markers showed higher DNA content for higher seed numbers. Overall, the sensitive DNA‐based approach developed in this study allows for minimally invasive quantification of small diet constituents in faeces, which would otherwise be undetectable with traditional methods. [ABSTRACT FROM AUTHOR]

Wood mouse Apodemus sylvaticus and striped field mouse A. agrarius are the most abundant mouse species in Central Europe coexisting in several habitats not only such as in forests but also in rural and urban areas. Their basic colours are similar, but the striped field mouse has a pronounced black stripe on its back. The biological function of this phenotypic difference is unexplored; therefore, our goal was to study the impact of fur pattern as well as the scent on the survival of these species. In our study, we used plasticine models mimicking wood mouse and striped field mouse. For imitating mouse scent, cotton pads saturated with mouse urine were placed under the models. In spring 2016, 200 plasticine mice divided into four types (non‐striped with scent, non‐striped without scent, striped with scent, striped without scent) were placed randomly in four sampling sites in the mid‐sized city, Pécs, Hungary. During 4 weeks of exposure, we recorded predation on 71 plasticine models. Birds (51%) and large mammals (25%) were the most common predators, and in 24% of the cases, the models disappeared. Considering predation only by large mammals, we found that the daily survival rate of both striped and non‐striped models with scent decreased in comparison to models without scent. Thus, large mammalian predators could discover plasticine models sooner than avian predators, which suggests a strong impact of scent. Despite the high rate of bird predation, we did not detect an effect of fur pattern suggesting that it may not be related to survival but might have other functional roles. With the dummy mouse experiment, we showed that fur pattern may play a minor role in mice detection by predators, thus further studies are needed to discover its ecological function. [ABSTRACT FROM AUTHOR]

Very little information exists on the growth rates of woodland rodents and the drivers of body size dynamics that are observed in British populations. In this study, we use mark–recapture data collected on two species living in sympatry, wood mice (Apodemus sylvaticus) and bank voles (Myodes glareolus). A third species of rodent, the yellow‐necked mouse (Apodemus flavicollis) was also caught occasionally. We found the density of this third species negatively impacted the growth rate of both wood mice and bank voles. No impact of conspecific population density on growth for either species was found. Previous studies have suggested high conspecific population density can impact growth for some individuals of the population, but our populations may have not reached the densities required to elucidate these effects during the study. [ABSTRACT FROM AUTHOR]

Body mass in wild animals has been suggested to be regulated by the opposing fitness consequences of variation in body size (and fat storage) for starvation and predation risk. Many studies of adult mammals and birds have broadly confirmed the predictions of this model. However, relatively few studies have addressed the potential role of such trade‐offs during early phases of development when animals are growing. Similarly, studies of the impact of high‐fat diets on wild small mammals generally show a resistance to weight gain. But whether growing animals are similarly resistant is unclear. In this study, weaned wood mice (Apodemus sylvaticus) were exposed to a high risk of predation, simulated by the broadcasting of owl calls, for 66 days during which body mass and energy intake were monitored. We hypothesized that if the risk of predation plays a role in regulating body mass during this phase then animals growing under predation risk would grow less. We found female (but not male) mice exposed to the predation risk treatment had lower growth rates and ended the experiment lighter; however, variations in energy intake and resting metabolic rate did not explain the observed differences. Feeding on high‐fat diet resulted in individuals with higher body mass. Females reached their adult size earlier than males and were more responsive to the predation risk treatment when feeding on high‐fat diet. Our data suggest males body mass to have fitness consequences on social dominance and reproductive success not accounted for in the simple starvation‐predation trade‐off model. [ABSTRACT FROM AUTHOR]

Wild populations are continuously subjected to changes in environmental factors that pose different challenges. Body condition and hormones have been commonly used as health indicators due to their potential correlation with fitness. In the present study, we analyzed whether habitats of different quality influenced body mass, food intake and physiological stress levels in wild wood mice (Apodemus sylvaticus). Field work was seasonally carried out in Holm oak woods and pine forests in central Spain. A total of 93 wood mice from 4 different populations (2 per habitat type) were live‐trapped. From each captured individual we noted body mass and food intake, measured as the amount of bait remaining in each trap. The physiological stress levels were measured non‐invasively in collected fresh feces by quantifying fecal corticosterone metabolites (FCM) with a 5a‐pregnane‐3ß,11ß, 21‐triol‐20‐one enzyme immunoassay. Wood mice abundances decreased from spring to summer, were higher in Holm oak woods than in pine forests and also resulted in different age‐class distribution between both habitats. Individuals inhabiting pine forests showed a lower body mass and increased food intake, probably because of the comparatively lower food quality and availability in this habitat. Furthermore, these individuals showed increased physiological stress levels, likely due to the lower quality habitat in relation to both food and vegetation cover availability. Overall, besides affecting local wood mouse abundance, our study underscores the effect of habitat quality on body mass, food intake and the endocrine stress response. Considering the wood mouse's pivotal position in ecosystems, these results could help in the understanding of environmental traits hampering the viability of wild populations. [ABSTRACT FROM AUTHOR]

Abstract: Mammals are mainly exposed to trace metals (TMs) via consuming contaminated food. Several studies have demonstrated relationships between metal concentrations in food and in animal tissues. However, potential effects of TMs on feeding behaviour of wildlife have been poorly documented under field conditions, despite experimental evidence showing that food selection is impacted by resource contamination. Here, we test the hypothesis that the diet of a generalist rodent, the wood mouse (Apodemus sylvaticus), is altered by soil TM contamination in the field. Wood mice were sampled in spring and in autumn along a gradient of soil contamination in the surroundings of a former smelter located in northern France. Available resources in the field were inventoried, and the diet of the animals was analysed using DNA “metabarcoding.” We demonstrated that (a) relationship between the resource richness in the diet and their richness in the field was altered by soil metal contamination. Wood mice specialized their diet along the gradient of soil metal contamination for both plant and invertebrate resources in spring. We also showed that (b) preference for Salicaceae, a plant family accumulating metals, decreased when soil contamination increased. These results suggest that environmental TM pollution could act as a force modulating trophic interactions in terrestrial food webs, thereby affecting wildlife exposure to contaminants by trophic route. [ABSTRACT FROM AUTHOR]

Abstract: Numerous studies have examined human disturbance repercussions on wildlife, mainly focused on the effects on behaviour, reproductive success and population dynamics. However, few studies have addressed the behaviour of prey species during and after human capture and handling and how this may correlate to individual characteristics or variation in their physical environment they inhabit. We explored wood mouse’s fleeing and aggressive behaviours in response to captures by human in their natural habitat. Eighty‐seven wood mice were caught using Sherman live traps. For each trapped individual, aggressiveness was measured as the total number of bites inflicted upon the investigator during handling time. Afterwards, each mouse was released in a two‐metre radius partially covered vegetation area that allowed visual mouse tracking by the observer and flight behaviour was registered by individual one‐zero focal sampling technique during 2 min. Both aggressiveness and fleeing behaviour were analysed regarding individual (sex, reproductive status, age) and environmental factors (habitat and season). Males, adults and breeding individuals showed heightened aggression levels. Higher aggressiveness levels were found in wood mice occupying scrubland and during summer and autumn. The flight response was exclusively explained by reproductive status, whereby breeding individuals spent more time on fast escape than nonbreeding ones. These results indicate that both individual and environmental factors seem to influence defensive behaviours in the wood mouse during and after being captured by a human. Since human disturbance shares many aspects with the predation risk, behavioural responses found to captures may likely be influenced by previous experience of individuals with predators as well as to seasonal and habitat features conditioning predators’ densities but also protection against them. [ABSTRACT FROM AUTHOR]

Abstract: The identification of field mice Apodemus flavicollis, Apodemus sylvaticus, and Apodemus alpicola represents a challenge for field scientists due to their highly overlapping morphological traits and habitats. Here, we propose a new fast real‐time PCR method to discriminate the three species by species‐specific TaqMan assays. Primers and probes were designed based on the alignment of 54 cyt‐b partial sequences from 25 different European countries retrieved from GenBank. TaqMan assays were then tested on 133 samples from three different areas of Italy. Real‐time PCR analysis showed 92 samples classified as A. flavicollis, 13 as A. sylvaticus, and 28 as A. alpicola. We did not observe any double amplification and DNA sequencing confirmed species assignment obtained by the TaqMan assays. The method is implementable on different matrices (ear tissues, tail, and blood). It can be used on dead specimens or on alive animals with minimally invasive sampling, and given the high sensitivity, the assay may be also suitable for degraded or low‐DNA samples. The method proved to work well to discriminate between the species analyzed. Furthermore, it gives clear results (amplified or not) and it does not require any postamplification handling of PCR product, reducing the time needed for the analyses and the risk of carryover contamination. It therefore represents a valuable tool for field ecologists, conservationists, and epidemiologists. [ABSTRACT FROM AUTHOR]

1. The study of wild bumblebee nests has been hindered by the difficulty in locating and observing them. Here, 47 wild nests were located using a sniffer dog and volunteers. The entrances to 32 nests were filmed continuously to identify successful nests (those that produced gynes) and observe vertebrate species interactions. 2. Of the 47 nests, 71% and 21% produced gynes in 2010 and 2011, respectively. 3. A total of 39 vertebrate species were filmed at entrances but the majority did not interact with the nests. Great tits (Parus major) depredated or attempted to depredate bees on 32 occasions at the entrances to 10 nests, something that has not previously been described. Small mammals were very often recorded accessing entrances to bumblebee nests, but whether they depredated bees was not known, and frequently visited nests were no less likely to produce gynes. Eight nests were entered by adult wax moths, Aphomia sociella. 4. The faeces of 1179 workers from 29 Bombus terrestris nests were screened microscopically for parasites. Crithidia bombi infections were apparent in 49% of worker bees, while Nosema bombi and Apicystis bombi were present in 5.5% and 0.68% of bees, respectively. Nests with a high prevalence of C. bombi infection were less likely to produce gynes, the first evidence of a direct impact of this common parasite on bumblebee colony reproduction in wild nests. 5. Overall, our data indicate that bumblebee nests are at the heart of a rich web of interactions between many different predator and parasite species. [ABSTRACT FROM AUTHOR]

Small mammals are key components of numerous tick-borne disease systems, as hosts for immature ticks and pathogen reservoirs. To study the factors influencing tick-borne infection in small mammals, we trapped small mammals and collected questing ticks in spring and autumn in 2012 and 2013 at 24 sites in a 10 × 15 km rural landscapes (Brittany, France). Tissue samples were screened by real-time PCR for Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato. Of the two dominant small mammal species captured, bank voles ( Myodes glareolus) had higher prevalence than wood mice ( Apodemus sylvaticus) for both infections, presumably because of specific differences in immunological defenses. Prevalence of infections was higher in 2013 than in 2012, likely because small mammals were fivefold less abundant in 2013, favouring tick aggregation. Bacterial prevalence, which was higher in autumn, was not associated to questing Ixodes ricinus nymph abundance which was six times higher in spring, but rather to the structure of the small mammal community. These findings suggest the involvement of endophilic tick species, I. trianguliceps and/or I. acuminatus, in bacterial transmission. Our study highlights that the entire community of hosts and vectors, and their interactions, should be considered to fully understand the epidemiology of vector-borne diseases. [ABSTRACT FROM AUTHOR]

'Bottom-up' influences, that is, masting, plus population density and climate, commonly influence woodland rodent demography. However, 'top-down' influences (predation) also intervene. Here, we assess the impacts of masting, climate, and density on rodent populations placed in the context of what is known about 'top-down' influences. To explain between-year variations in bank vole Myodes glareolus and wood mouse Apodemus sylvaticus population demography, we applied a state-space model to 33 years of catch-mark-release live-trapping, winter temperature, and precise mast-collection data. Experimental mast additions aided interpretation. Rodent numbers in European ash Fraxinus excelsior woodland were estimated (May/June, November/December). December-March mean minimum daily temperature represented winter severity. Total marked adult mice/voles (and juveniles in May/June) provided density indices validated against a model-generated population estimate; this allowed estimation of the structure of a time-series model and the demographic impacts of the climatic/biological variables. During two winters of insignificant fruit-fall, 6.79 g/m2 sterilized ash seed (as fruit) was distributed over an equivalent woodland similarly live-trapped. September-March fruit-fall strongly increased bank vole spring reproductive rate and winter and summer population growth rates; colder winters weakly reduced winter population growth. September-March fruit-fall and warmer winters marginally increased wood mouse spring reproductive rate and September-December fruit-fall weakly elevated summer population growth. Density dependence significantly reduced both species' population growth. Fruit-fall impacts on demography still appeared after a year. Experimental ash fruit addition confirmed its positive influence on bank vole winter population growth with probable moderation by colder temperatures. The models show the strong impact of masting as a 'bottom-up' influence on rodent demography, emphasizing independent masting and weather influences; delayed effects of masting; and the importance of density dependence and its interaction with masting. We conclude that these rodents show strong 'bottom-up' and density-dependent influences on demography moderated by winter temperature. 'Top-down' influences appear weak and need further investigation. [ABSTRACT FROM AUTHOR]

Field identification of European wood mice Apodemus spp. is challenging due to their morphological resemblance and frequent sympatry. We developed discriminant functions based on body mass and acoustic variables of distress calls to identify three cryptic species of wood mice ( Apodemus alpicola, Apodemus flavicollis and Apodemus sylvaticus) in Italy. We achieved an overall correct classification rate of 86-98%; the best results (100% correct classification) were obtained for Apodemus sylvaticus calls. This minimally invasive, effective and low-cost method highlights the potential role of bioacoustics as a powerful tool for field discrimination of cryptic species of terrestrial mammals. [ABSTRACT FROM AUTHOR]

Rodent population dynamics are predicted to respond positively to the masting of acorns, but diverging results have been published. This study tested the hypothesis that population responses to acorn masting vary depending on differences in the tolerance to tannins of different rodent species. The effects of acorn abundance on the rodent population densities were analyzed using a dataset obtained in Hokkaido, Japan. Specifically, population fluctuations of three rodent species ( Apodemus speciosus, A. argenteus, and Myodes rufocanus) and the abundance of Quercus crispula acorns have been monitored since 1992. Acorn production in previous years had a positive effect on the annual population growth rates of A. speciosus; however, this trend was not clear in the other two species. Tannin tolerance, assessed by body weight changes in an acorn feeding experiment, exhibited clear differences among the rodent species; namely, the body weight of A. speciosus increased, whereas that of the other two species decreased. The observed responses to acorn masting of populations of the three sympatric rodent species reflected tannin tolerance. It suggests that only populations of species with high tannin tolerance positively respond to acorn masting. Previous studies tend to overlook species-specific abilities of coping with tannins in acorns. Our results emphasize the necessity of evaluating the tannin tolerance of rodents and the tannin content of acorns to understand how rodent population dynamics and acorn production are related. [ABSTRACT FROM AUTHOR]

Many parasites infect multiple sympatric host species, and there is a general assumption that parasite transmission between co-occurring host species is commonplace. Such betweenspecies transmission could be key to parasite persistence within a disease reservoir and is consequently an emerging focus for disease control. However, while a growing body of theory indicates the potential importance of betweenspecies transmission for parasite persistence, conclusive empirical evidence from natural communities is lacking, and the assumption that between-species transmission is inevitable may therefore be wrong. We investigated the occurrence of between-species transmission in a well-studied multihost parasite system. We identified the flea-borne Bartonella parasites infecting sympatric populations of Apodemus sylvaticus (wood mice) and Myodes glareolus (bank voles) in the UK and confirmed that several Bartonella species infect both rodent species. However, counter to previous knowledge, genetic characterization of these parasites revealed covert host specificity, where each host species is associated with a distinct assemblage of genetic variants, indicating that between-species transmission is rare. Limited between-species transmission could result from rare encounters between one host species and the parasites infecting another and/or host-parasite incompatibility. We investigated the occurrence of such encounter and compatibility barriers by identifying the flea species associated with each rodent host, and the Bartonella variants carried by individual fleas. We found that the majority of fleas were host-generalists but the assemblage of Bartonella variants in fleas tended to reflect the assemblage of Bartonella variants in the host species they were collected from, thus providing evidence of encounter barriers mediated by limited between-species flea transfer. However, we also found several fleas that were carrying variants never found in the host species from which they were collected, indicating some degree of host-pathogen incompatibility when barriers to encounter are overcome. Overall, these findings challenge our default perceptions of multihost parasite persistence, as they show that despite considerable overlaps in host species ecology, separate populations of the same parasite species may circulate and persist independently in different sympatric host species. This questions our fundamental understanding of endemic transmission dynamics and the control of infection within natural reservoir communities. [ABSTRACT FROM AUTHOR]

Wood mice Apodemus sylvaticus are the main dispersers of acorns in highly managed Mediterranean holm-oak woodlands. Mice mobilize and cache acorns to store them for winter consumption. They carry acorns away from potential competitors, face predation risks during mobilization, and cache acorns in areas where pilfering risks are low. However, mice can act either as net predators or as moderately efficient dispersers, depending on the way landscape management affects intraspecific competition for acorns and shelter availability. To assess the influence of landscape structure and mouse behavior on acorn dispersal, we developed an agent-based model (ABM) that translates forest management into changes in key environmental factors driving mouse foraging decisions. The model was able to predict accurately acorn dispersal patterns in a wide range of forest management practices based on information on forest habitat availability, stem density and shrub cover. Sensitivity analysis revealed that caching rates emerged from the interplay between intraspecific competition for seeds and predation risk accepted during mobilization. It also showed that intraspecific competition for acorns decreased with increasing habitat loss (due to positive edge effects on acorn production) while landscape resistance to mouse movements increased. As a result, the net benefits of caching declined and acorn predation became the dominant strategy. Finally, we assessed the effects of shrub encroachment as a management practice to enhance dispersal services in savanna-like landscapes (dehesas). The model predicted non-linear responses with a 65% threshold of shrub cover needed to achieve relatively high levels of acorn dispersal. This value may not be compatible with the traditional exploitation of dehesas (livestock rearing). Our study shows that integrated approaches that combine environmental change driven by management with behavioral responses of dispersers improve our understanding of the causes of recruitment bottlenecks, and are useful tools for evaluating conservation strategies aimed at enhancing dispersal services. [ABSTRACT FROM AUTHOR]

Bat hibernacula with high numbers of bats can become high-risk areas, as they attract flying and non-flying predators. In order to protect hibernating bats effectively, more knowledge about mortality factors is needed. During the winters of 2003-2015, we found 214 dead bats in 12 hibernacula in The Netherlands province of Zuid-Holland. Most bat remains were found in December and January, with a second peak in April. Their remains showed a typical pattern of lesions consistent with those caused by predation by the wood mouse ( Apodemus sylvaticus). Trail camera surveys showed that wood mice actively searched for bats. Predation pressure seemed to vary between winters, with a peak in the winters of 2004, 2011 and 2015. The annual mortality (relative to the maximum winter population size) caused by wood mouse predation varied between 0.1 and 8.8 %, with a maximum local effect of 83.6 %. The years with high wood mouse predation pressure were characterized by a long frost period and a low mast production of common oak in the preceding autumn. The size of a hibernaculum and the population density of its bats had an effect on predation-dependent mortality. The highest predation risk occurred near the entrance of bunkers. From these results we tentatively conclude that predation is not incidental and that wood mice actively search for and kill hibernating bats or scavenge for weakened individuals. [ABSTRACT FROM AUTHOR]

Wood mouse ( Apodemus sylvaticus) populations are expected to show a peak in autumn in the year after a mast year of sessile oak ( Quercus petraea), because stored acorns increase winter survival. In Aust-Agder, South Norway, only 16 of 34 mast years from 1939-2014 were followed by a year with a peak in the wood mouse population. For many of the remaining instances, there rather was a minor peak 2 or 3 years after the mast. In multiple logistic regression models, the probability of a wood mouse population peak after a mast year of sessile oak was positively related to a snow-corrected temperature index of the previous winter and negatively to a small rodent population index of the previous autumn. The present study thus supports the hypothesis that longer periods with snow-free ground and subzero temperatures negatively affect wood mouse winter survival. Because it may be difficult for wood mice to survive on a diet consisting of acorns alone, the negative relationship with the rodent population index of the previous year is most likely caused by an over-exploitation of necessary alternative food resources, such as other plant seeds and arthropods. Stored acorns not utilized during one winter are assumed to benefit wood mice in a succeeding winter, giving a delayed population peak relative to the mast year. [ABSTRACT FROM AUTHOR]

Urbanisation and agriculture dramatically modify the landscapes available for use by wildlife, affecting key aspects of their ecology such as survival, foraging, predation, competition and reproductive success. Relatively little is known about the effects of urbanisation and agriculture on the genetic structure, gene flow and genetic diversity of wild species. Here, landscape genetic techniques were applied to compare local genetic diversity and gene flow between wood mouse populations in urban and arable landscapes. Using nine microsatellite markers, individuals were genotyped from six arable and seven urban sample sites. Inter-population genetic differentiation was significantly greater in urban than arable habitat, while allele richness, private allele richness and heterozygosity were higher for arable sample sites, with varying degrees of significance. These suggest that urban habitat was sufficiently fragmented to limit gene flow. To test the effect of landscape features on gene flow, several cost-distance measures were generated. Overland distance and Euclidean distance correlated best with inter-population genetic differentiation in arable habitat, whereas distances that accommodated differences in habitat quality better explained differentiation in urban habitat. There was no evidence that margins adjacent to roads, rivers or railways facilitated gene flow. Together, the results indicate that urban landscapes expose wood mice to greater fragmentation in habitat quality than arable areas, leading to greater population isolation that is not mitigated by the presence of dispersal corridors. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a case study demonstrating the application of 3 individual-based, spatially explicit population models (IBMs, also known as agent-based models) in ecological risk assessments to predict long-term effects of a pesticide to populations of small mammals. The 3 IBMs each used a hypothetical fungicide (FungicideX) in different scenarios: spraying in cereals (common vole, Microtus arvalis), spraying in orchards (field vole, Microtus agrestis), and cereal seed treatment (wood mouse, Apodemus sylvaticus). Each scenario used existing model landscapes, which differed greatly in size and structural complexity. The toxicological profile of FungicideX was defined so that the deterministic long-term first tier risk assessment would result in high risk to small mammals, thus providing the opportunity to use the IBMs for risk assessment refinement (i.e., higher tier risk assessment). Despite differing internal model design and scenarios, results indicated in all 3 cases low population sensitivity unless FungicideX was applied at very high (×10) rates. Recovery from local population impacts was generally fast. Only when patch extinctions occured in simulations of intentionally high acute toxic effects, recovery periods, then determined by recolonization, were of any concern. Conclusions include recommendations for the most important input considerations, including the selection of exposure levels, duration of simulations, statistically robust number of replicates, and endpoints to report. However, further investigation and agreement are needed to develop recommendations for landscape attributes such as size, structure, and crop rotation to define appropriate regulatory risk assessment scenarios. Overall, the application of IBMs provides multiple advantages to higher tier ecological risk assessments for small mammals, including consistent and transparent direct links to specific protection goals, and the consideration of more realistic scenarios. Integr Environ Assess Manag 2016;12:46-57. © 2015 SETAC [ABSTRACT FROM AUTHOR]

Vertebrate scavengers can modify surface deposited human remains which can hinder forensic investigations. The effects of such scavenging vary between species and regions. Published research into the effects of the scavenging of human remains is dominated by work from North America with few studies covering Northwestern Europe. Forensic scientists, investigators, and police search officers in Northwestern Europe are often left questioning on a basic level as to which scavengers are active and how they might affect human remains. This paper presents the results of a field study utilizing deer ( Cervus nippon; Capreolus capreolus) as surface deposits observed by motion detection cameras in a British woodland. The most common avian and rodent scavenger species recorded included the buzzard ( Buteo buteo), carrion crow ( Corvus corone), wood mouse ( Apodemus sylvaticus), and gray squirrel ( Sciurus carolinensis). The scavenging behaviors observed were affected by seasonality, rates of decomposition, and insect activity. Scavenging by buzzards, unlike carrion crows, was most frequent during fall to winter and prior to insect activity. Overall, avian scavengers modified and scavenged soft tissue. Rodents scavenged both fresh and skeletonized remains with gray squirrels only scavenging skeletal remains. Wood mice were most active in winter and scavenged both soft tissue and bone. [ABSTRACT FROM AUTHOR]

Post-dispersal seed predation is a crucial phenomenon for plant recruitment, and its incidence can be hypothesized to increase in ecologically and geographically marginal populations of threatened species, such as yew ( Taxus baccata). Here we examine the among- and within-population patterns of seed consumption by rodents and evaluate to what extent they are linked to marginality in Mediterranean low-density yew stands. Among populations we tested: (i) whether the rates of seed predation found in our marginal sites were consistently higher than in populations from core regions; (ii) within populations we evaluated whether rodents preferred microhabitats with greater seed availability (beneath female yew trees) or with lower predation risk (shrubs) in two seeding seasons (fall-winter 2005 and 2006). Predation rates were extremely high (92.5%) and they were well above values reported for core populations (65.4%), to the extent that rodents almost completely depleted the experimental seeds in all populations and years. Our expectation of lower predation rates with decreasing vegetation cover was also confirmed for all years and populations, suggesting that rodent foraging was risk-sensitive. This microhabitat effect outweighed the effect of seed availability under female yew trees, implying also that rodents selectively consumed the most valuable seeds in terms of their recruitment prospects. Overall, our results suggest that the mechanisms underlying seed depletion and its demographic consequences are linked to the effects of reduced yew performance in ecologically marginal habitats. [ABSTRACT FROM AUTHOR]

This study tested the relationships between both individual-level and predation-risk factors and the size of two home-range regions ( HRR), defined as areas of different intensities of use., We have expanded on previous home-range studies by testing the effects of two previously ignored individual-level factors: androgenization and energy reserves (body fat)., Location data were collected for wild individuals of Apodemus sylvaticus using the novel method of implanted PIT tags and mobile recording stations. A total of 68 home ranges were estimated using kernel density estimation. Home ranges were split into two regions ( HRR): the 'core', representing the most intensively used areas, and 'periphery' regions. Body mass, body fat, sex, anogenital distance ( AGD) (a proxy for androgenization) and the proportion of HRR, covered by antipredatory features (shrubs and fallen trees), were tested for their relationship with the size of core and periphery HRRs. Models were constructed for each HRR for three seasons: nonbreeding season (NBS), early and late breeding seasons (LBSs), to account for seasonal variation in behaviour associated with changes in food abundance and reproductive cycles., Body fat had a negative relationship with periphery size and an interaction with sex on core size in the early breeding season (EBS). Body mass also had a significant interaction with sex on core size in the EBS. Androgenization has a strong effect on home range size in both sexes: AGD had a positive relationship with both HRRs for males in the LBS and females in the NBS. Males had larger peripheries than females in both early and LBSs. Habitat features that reduce predation risk explain HRR size throughout the breeding period., This study emphasizes the importance of embracing natural complexity to gain insight into the drivers of space use behaviour; the consideration of individual and ecological factors, the recognition of the species-specific selective pressures that seasonal change presents for each sex and the identification of biologically meaningful home range areas will help advance the field. [ABSTRACT FROM AUTHOR]

Chemical signals left by predators are a potential source of information about the risk of predation, and small mammals are known to take them into account when making decisions. We investigated whether wood mice ( Apodemus sylvaticus) are more likely to avoid the faeces of resident predators (red fox Vulpes vulpes and common genet Genetta genetta) vs. a novel predator (European pine marten Martes martes). Odour recognition would increase perceived predation risk and reduce food intake by individual mice. Wood mice response to predators was analysed by live-trapping using two untreated controls (baited/non-baited) and traps experimentally manipulated with three predator treatments (faeces of red fox, common genet or pine marten). Traps were baited with 4 g of toasted corn, and food intake by wood mice was determined as the amount of bait remaining in each trap. We found that traps treated with faeces of resident predators were the most avoided, and the number of captures in traps treated with pine marten faeces was similar to the control-baited traps. The variation found in food intake was explained by the interaction between the types of treatment and breeding condition. Food intake was similar in control-baited traps and in traps with faeces of pine marten, but when predation risk by resident predators (red fox and common genet) was simulated, breeders reduced food intake significantly as compared to non-breeders. These results indicate that predator recognition and feeding behaviour under predation risk depend on individual factors and the balance of costs-benefits in each particular predation risk situation at a given place and time. [ABSTRACT FROM AUTHOR]

Seed-caching rodents play a key role in the ecology of seed dispersal by not only consuming but also dispersing seeds. Rodent foraging behaviour is usually framed within optimal models, which predict that their decisions should maximize food intake and minimize foraging costs. Although predation risk and seed pilferage by conspecifics have been envisaged as two potential costs, their relevance for seed-caching behaviour and seed dispersal has barely been addressed., To test the effect of predation and pilferage risk on the patterns of seed predation/dispersal by rodents, we performed a field experiment using a tri-trophic-level model (plant-mice-carnivore ; Quercus spp- Apodemus sylvaticus- Genetta genetta) and the scents of the predator and conspecifics as direct cues. The behaviour of mice was analysed with video cameras set for continuous recording on consecutive nights, and we used tagged acorns to assess the patterns of acorn predation and dispersal., Our results revealed that rodents were able to discriminate between the scents of genet and conspecifics and modified their seed dispersal behaviour accordingly. Mice spent more time 'sniffing' in rodent cages than in genet cages, where they displayed more 'vigilance and freezing' behaviours. In sites with mice scents, acorns were dispersed at shorter distances and were less predated. Conversely, in sites with genet scents acorn removal was delayed., These results show that chemosensory information on predators and conspecifics influences the foraging decisions of seed-caching rodents over short spatial and temporal scales. This might entail cascading effects on the regeneration of plants. In sites where rodents perceive the risk of predation, inefficient foraging behaviour may result in less successful seed dispersal. Conversely, the detection of conspecific scents may increase dispersal efficiency and seedling recruitment., Ultimately, the relationships between two distant levels in trophic webs (plants-carnivores) appear intricate, since carnivores may affect seed dispersal by changing the foraging behaviour of their prey (the seed disperser). This indirect relationship should be considered as a new dimension of the ecology of seed dispersal by small rodents. [ABSTRACT FROM AUTHOR]

Seed dispersal, a critical phase in the life history of many plants, is poorly understood due to the difficulty of tracking and monitoring dispersing seeds until they reach their ultimate fate. Scatter-hoarding rodents play a substantial part in the seed dispersal process of many plant species, however, existing tracking methods do not allow seed monitoring without risk of influencing the hoarding process and seed fate., Here, we describe and test the use of Passive Integrated Transponders ( PIT) tags inserted into seeds for the tracking and monitoring of large seeds dispersed by rodents. Unlike other tagging methods, PIT tagging combines the advantages of leaving no external cues and being readable without disturbance of caches. Rodents cannot remove these tags., We evaluated the performance of PIT tagging through a series of trials with Quercus acorns dispersed by rodents, both in North America and in Europe, with equipment from different manufacturers. We quantified effects of tagging on seed removal and caching, cache pilferage and seed germination, by comparison between PIT-tagged and untagged acorns. We evaluated the detectability of buried tags to researchers., Minimal effects of PIT tagging on seed removal, caching, pilferage and germination were found. Buried PIT tags were retrieved with high reliability by naïve researchers, even at burial depths up to 30 cm. Identification codes could be read even when multiple tags were buried at a single location, as in larder hoarding., The method was successfully applied in two field studies of dispersal of Quercus palustris and Q. rubra acorns by Eastern grey squirrels Sciurus carolinensis in North America, and Q. robur acorns by Wood mice Apodemus sylvaticus in the Netherlands. The proportion of seeds recovered was comparable to that in studies using traditional thread tags., We conclude that PIT tagging is a particularly suitable method for tracking and monitoring of seeds dispersed by scatter-hoarding rodents. PIT tagging solves most of the main problems generally encountered when following the fate of rodent-dispersed seeds over time. [ABSTRACT FROM AUTHOR]

Immune defences and the maintenance of immunological homeostasis in the face of pathogenic and commensal microbial exposures are channelled by innate antimicrobial pattern recognition receptors ( PRRs) such as toll-like receptors ( TLRs). Whilst PRR-mediated response programmes are the result of long-term host-pathogen or host-commensal co-evolutionary dynamics involving microbes, an additional possibility is that macroparasitic co-infections may be a significant modifier of such interactions. We demonstrate experimentally that macroparasites (the model gastrointestinal nematode, Heligmosomoides) at peripheral sites of infection cause substantial alteration of the expression and function of TLRs at a systemic level (in cultured splenocytes), predominantly up-regulating TLR2, TLR4 and TLR9-mediated cytokine responses at times of high standing worm burdens. We consistently observed such effects in BALB/c and C57 BL/6 mice under single-pulse and trickle exposures to Heligmosomoides larvae and in SWR and CBA mice under single-pulse exposures. A complementary long-term survey of TLR2-mediated tumour necrosis factor-alpha responses in wild wood mice ( Apodemus sylvaticus) was consistent with substantial effects of macroparasites under some environmental conditions. A general pattern, though, was for the associations of macroparasites with TLR function to be temporally dynamic and context-dependent: varying with different conditions of infection exposure in the field and laboratory and with host genetic strain in the laboratory. These results are compelling evidence that macroparasites are a major and dynamic modifier of systemic innate antimicrobial responsiveness in naturally occurring mammals and thus likely to be an important influence on the interaction between microbial exposures and the immune system. [ABSTRACT FROM AUTHOR]

The Cova dels Xaragalls is a small open karst system, located in the municipality of Vimbodí-Poblet ( Tarragona, Catalonia, NE Spain). It is an important Holocene archaeological site that was inspected in the 1970s but from which little has been published. New excavations starting in 2008 have exposed a deep Late Pleistocene stratigraphical sequence. In this paper, we present for the first time palaeoenvironmental and palaeoclimatic reconstructions of this Late Pleistocene succession on the basis of both the small-vertebrate assemblages and the charcoals. Results from the small-vertebrate associations along the sequence indicate that the landscape had open-woodland habitats in the vicinity of the Cova del Xaragalls, with wet points in the surrounding area. Woodland habitats were dominant throughout the sequence, as evidenced by the abundance of the species Apodemus sylvaticus, but were better developed during warm periods (layers C5 and C8), whereas during cold periods (layers C4 and C3) the environment was slightly more humid in response to higher mean annual precipitation and the opening of the landscape. The charcoal analysis indicates that the woodland surrounding the cave was composed mainly of Pinus (more than 90% was identified as Pinus), but that during the cold period ( C3- C4) it incorporated some Quercus ilex/ coccifera and Angiosperm indet., probably linked with greater precipitation. Comparisons are made with other long palaeoenvironmental sequences from the northeastern Iberian Peninsula and with global marine isotopic curves, providing a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the Late Pleistocene in the woodland areas surrounding the Cova dels Xaragalls. [ABSTRACT FROM AUTHOR]

Populations of the common vole Microtus arvalis in mid-western France show cyclic dynamics with a three-year period. Studies of cyclic vole populations in Fennoscandia have often found inter-specific synchrony between the voles and other small mammals which share the voles' predators. Although predators are central to the favoured mechanism to explain Fennoscandian vole cycles and the spatial variation of small mammal populations, their role in vole cycles elsewhere, including France, is less clear. Establishing whether alternative prey species in France cycle in parallel with voles as they do in Fennoscandia is thus an important step towards understanding the generality of predators' influence on cyclic vole populations. We applied spatial and temporal autocorrelation and cross-correlation methods to French populations of M. arvalis and two sympatric non-cyclic small mammal species, Apodemus sylvaticus and Crocidura russula. Patterns of time-lagged cross-correlation between the abundance of M. arvalis and the other two species suggested synchrony in their dynamics beyond that expected of stochastic environmental variation, and indicated a weak three-year cycle in A. sylvaticus and C. russula that was in phase with that of M. arvalis. We interpret the synchrony between these species as the effect of shared predators and environmental stochasticity. Abundance within species showed weak spatial autocorrelation in June at scales consistent with dispersal being the mechanism responsible, but a more general lack of spatial structure within and between species was consistent with the strong spatial synchrony at regional scales often found in fluctuations of small mammal abundance. [ABSTRACT FROM AUTHOR]

One of the most important structures for an individual's survival is a refuge, especially for species subject to significant predatory pressure or living in environments affected by severe climatic conditions. We studied how wood mice ( Apodemus sylvaticus), inhabiting a Mediterranean environment, use nests and the factors that could be determining this use. Radio-tracking of 16 mice allowed us to detect 24 diurnal nests, which were used with a high fidelity rate (1.75 nests/animal). Nest sites that had been identified using radio-tracking were matched with 24 randomly selected non-nest sites (located within an area defined by the sum of all individual home ranges), and all sites were characterized according to their macro- and micro-habitat parameters. Using a generalized linear model, we tested three hypotheses: (1) a nest's use is influenced by its proximity to food patches; (2) the degree of sheltering provided by each site influences its use; and (3) nest use is constrained by a combination of food- and shelter-related features. Females had higher nest fidelity than males, and the degree of sheltering provided by each site had a positive significant influence on its use. Nests offering higher protection (e.g., under thick vegetation), good drainage (e.g., sleep slopes), and lower human and predatory disturbance (far from orchards) were most often used. The proximity to food patches seemed to negatively influence nest use. Results indicate the need to preserve patches of natural dense vegetation near riparian habitats, which is in agreement with the focus of mammalian protection plans in Mediterranean agricultural landscapes. These patches are important areas for Apodemus sylvaticus, an acorn disperser species, which is preyed on by raptors and mammalian carnivores. [ABSTRACT FROM AUTHOR]

Successful seed dispersal by animals is assumed to occur when undamaged seeds arrive at a favourable microsite. Most seed removal and dispersal studies consider only two possible seed fates, predation or escape intact. Whether partial consumption of seeds has ecological implications for natural regeneration is unclear. We studied partial consumption of seeds in a rodent-dispersed oak species. Fifteen percent of dispersed acorns were found partially eaten in a field experiment. Most damage affected only the basal portion of the seeds, resulting in no embryo damage. Partially eaten acorns had no differences in dispersal distance compared to intact acorns but were recovered at farther distances than completely consumed acorns. Partially eaten acorns were found under shrub cover unlike intact acorns that were mostly dispersed to open microhabitats. Partially eaten acorns were not found buried proportionally more often than intact acorns, leading to desiccation and exposure to biotic agents (predators, bacteria and fungi). However, partial consumption caused more rapid germination, which enables the acorns to tolerate the negative effects of exposure. Re-caching and shrub cover as microhabitat of destination promote partial seed consumption. Larger acorns escaped predation more often and had higher uneaten cotyledon mass. Satiation at seed level is the most plausible explanation for partial consumption. Partial consumption caused no differences in root biomass when acorns experienced only small cotyledon loss. However, root biomass was lower when acorns experienced heavy loss of tissue but, surprisingly, they produced longer roots, which allow the seeds to gain access sooner to deeper resources. Synthesis. Partial consumption of acorns is an important event in the oak regeneration process, both quantitatively and qualitatively. Most acorns were damaged non-lethally, without decreasing both dispersal distances and the probability of successful establishment. Faster germination and production of longer roots allow partially eaten seeds to tolerate better the exposure disadvantages caused by the removal of the pericarp and the non-buried deposition. Consequently, partially consumed seeds can contribute significantly to natural regeneration and must be considered in future seed dispersal studies. [ABSTRACT FROM AUTHOR]

Male sex-biased parasitism (SBP) occurs across a range of mammalian taxa and two contrasting sets of hypotheses have been suggested for its establishment. The first invokes body size per se and suggests that larger individuals are either a larger target for parasites, trade off growth at the expense of immunity or cope better with parasitism than smaller individuals. The second suggests a sex-specific handicap whereby males have reduced immunocompetence compared to females due to the immunodepressive effects of testosterone. The current study investigated whether sex-biased parasitism is driven by host ‘body size’ or ‘sex’ using a rodent–tick ( Apodemus sylvaticus– Ixodes ricinus) system. Moreover, the presence or absence of large mammals at study sites were used to control the presence of immature ticks infesting wood mice, allowing the impacts of parasitism on host body mass and female reproduction to be assessed. As expected, male mice had greater tick loads than females and analyses suggested this sex-bias was driven by body mass as opposed to sex. It is therefore likely that larger individuals are a larger target for parasites, trade off growth at the expense of immunity or adapt behavioural responses to parasitism based on their body size. Parasite load had no effect on host body mass or female reproductive output suggesting individuals may alter behaviour or life history strategies to compensate for costs incurred through parasitism. Overall, this study lends support to the ‘body size’ hypothesis for the formation of sex-biased parasitism. [ABSTRACT FROM AUTHOR]

We examined the genetic structure of natural populations of the European wood mouse Apodemus sylvaticus at the microgeographic (<3 km) and macrogeographic (>30 km) scales. Ecological and behavioural studies indicate that this species exhibits considerable dispersal relative to its home-range size. Thus, there is potential for high gene flow over larger geographic areas. As levels of population genetic structure are related to gene flow, we hypothesized that population genetic structuring at the microgeographic level should be negligible, increasing only with geographic distance. To test this, four sites were sampled within a microgeographic scale with two additional samples at the macrogeographic level. Individuals ( n=415) were screened and analysed for seven polymorphic microsatellite loci. Contrary to our hypothesis, significant levels of population structuring were detected at both scales. Comparing genetic differentiation with geographic distance suggests increasing genetic isolation with distance. However, this distance effect was non-significant being confounded by surprisingly high levels of differentiation among microgeographic samples. We attribute this pattern of genetic differentiation to the effect of habitat fragmentation, splitting large populations into components with small effective population sizes resulting in enhanced genetic drift. Our results indicate that it is incorrect to assume genetic homogeneity among populations even where there is no evidence of physical barriers and dispersal can occur freely. In the case of A. sylvaticus, it is not clear whether dispersal does not occur across habitat barriers or behavioural dispersal occurs without consequent gene flow. [ABSTRACT FROM AUTHOR]

The relative importance of density-dependent and -independent processes in determining population density has been predicted to vary according to whether the population concerned is located near the centre or the periphery of the species' range. Thus, density-independent processes should be more pronounced near the periphery. The long-tailed wood mouse Apodemus sylvaticus in Iceland is at the northern and western edge of its geographical range. We estimated the autumn population density in an open habitat in south-western Iceland in 9 years out of 10 during 1996–2005 in order to monitor the annual maximum population size. Furthermore, we estimated population density and survival at c. 5-week intervals from September 2001 to October 2003 and from September 2004 to November 2005 in order to reveal the causes of variation in maximum population size. The estimated autumn population density was low, ranging from 2.7 to 8.9 mice ha−1 while spring densities ranged from 0.4 to 0.8 mice ha−1. Apparent monthly survival probabilities ranged from 0.4 to 0.7 per month in autumn and 0.7 to 0.9 in winter. Our results suggest that low temperature in early winter (October–December) is the major determinant of population density in the following autumn, explaining 74% of the variation in autumn population density. No significant correlation was found between either the NAO index or the NAO winter index and variation in wood mouse population density in autumn. Differential mortality in early winter results in variation in spring population size. This study shows clear evidence of density-independent control of a mammal population at the edge of its geographical range as opposed to the mostly density-dependent control previously recorded near its centre of distribution. [ABSTRACT FROM AUTHOR]

We analysed the effects of Quercus crispula acorn abundance on the density dependence of the large Japanese wood mouse Apodemus speciosus using time series data (1992–2007). The data were obtained in a forest in northern Hokkaido, Japan, by live-trapping rodents and directly counting acorns on the ground. Acorn abundance in one year clearly influenced the abundance of wood mice in the following year in all models examined based on the Gompertz and Ricker model; in addition, the abundance of wood mice had effects on the population. Acorn abundance influenced the strength of density dependence (intraspecific competition) of the wood mouse population. When the abundance of acorns was high, density dependence was relaxed, and as a result the equilibrium density at which the population growth rate decreased to zero became higher. Those effects of acorn abundance were regarded as a nonlinear perturbation effect (sensu Royama ). The nonlinearity of density dependence was also detected; higher densities had stronger effects on population growth rates. [ABSTRACT FROM AUTHOR]

Multiple paternity was investigated for the first time in natural populations of the wood mouse Apodemus sylvaticus. Thirteen females and their respective litters sampled within distinct habitats, seasons and years were screened for eight microsatellite loci. Allelic variation was compared with a dataset comprising 307 adult mice collected from the same source populations as pregnant females. Multiple paternity was unambiguously identified in seven litters (53.8%). In each case, a minimum of two or three male parents were involved. Populations of A. sylvaticus inhabiting the northern latitudes of the species range are characterized by annual cycles of abundance during which numbers can fluctuate by several orders of magnitude. Hence, the discovery of multiple paternity within litters sampled between May and July (high and low densities, respectively) in all years suggests that polyandry maximizes genetic diversity of the litter and, hence, survival of some of the offspring through such cycles. The results indicate that polyandry is a common mode of reproduction within wild populations of A. sylvaticus. [ABSTRACT FROM AUTHOR]

The study of ecological differences among coexisting microparasites has been largely neglected, but it addresses important and unusual issues because there is no clear distinction in such cases between conventional (resource) and apparent competition. Here patterns in the population dynamics are examined for four species of Bartonella (bacterial parasites) coexisting in two wild rodent hosts, bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus). Using generalized linear modeling and mixed effects models, we examine, for these four species, seasonal patterns and dependencies on host density (both direct and delayed) and, having accounted for these, any differences in prevalence between the two hosts. Whereas previous studies had failed to uncover species differences, here all four were different. Two, B. doshiae and B. taylorii, were more prevalent in wood mice, and one, B. birtlesii, was more prevalent in bank voles. B. birtlesii, B. grahamii, and B. taylorü peaked in prevalence in the fall, whereas B. doshiae peaked in spring. For B. birtlesii in bank voles, density' dependence was direct, but for B. taylorii in wood mice density dependence was delayed. B. birtlesii prevalence in wood mice was related to bank vole density. The implications of these differences for species coexistence are discussed. [ABSTRACT FROM AUTHOR]

Quercus suber, Quercus ilex and Quercus coccifera (Cork, Holm and Kermes oaks, respectively) are common evergreen oak species that coexist in the landscapes of the western part of the Mediterranean basin. Rodents are the main acorn predators and thus one of the main factors for understanding recruitment patterns in oaks. In this paper we analyse to what extent mice prefer acorns from one oak species over another in three oak species studied using acorn removal experiments and video tape recordings. Twenty labelled acorns from each of the three Quercus species (60 acorns) were placed in 40 cm×40 cm quadrats on each plot. Because selection might vary as a result of the vegetation context, we performed the trials in the five main vegetation types within the study area (four replicates in each vegetation type) in order to control for habitat influences on rodent acorn preferences (a total of 20 plots). The removal of 1,200 acorns occurred within 68 days. Mice removed 98.7% of the acorns. Q. ilex acorns were preferred over Q. suber and Q. coccifera in all vegetation types except in pine forest, where no acorn preferences were detected. Acorn removal rates differed with vegetation type, correlating positively with shrub cover. The distance at which acorns were displaced by rodents (mean =4.6 m±5.1 SD) did not differ between acorn species, but varied among vegetation types. Bigger acorns of Q. coccifera were selected only after Q. ilex and Q. suber acorns were depleted, while no size selection was detected for the latter two species. Thus, we conclude that rodents show preference for some oak acorns and that landscape context contributes significantly to rodent activities and decisions. [ABSTRACT FROM AUTHOR]

We investigated the binding of Cd, Cu, and Zn to metallothionein (MT) and other metal-binding proteins in free-living wood mice (Apodemus sylvaticus L.) captured in four areas along a metal pollution gradient. We measured total and cytosolic Cd, Cu, and Zn concentrations in mouse liver and kidney by means of inductively coupled plasma-mass spectrometry (ICP-MS). Total (Cu, Cd, Zn)-MT levels were determined in the same tissues by means of the cadmium thiomolybdate saturation assay. Metal speciation of metalloproteins was studied by means of size-exclusion high-performance liquid chromatography-ICP-MS. Liver and kidney of wood mice from the site adjacent to the pollution source showed the highest Cd and Zn concentrations (total and cytosolic) and (Cu, Cd, Zn)-MT levels compared to the other sites farther away from the pollution source. No or only small site differences in tissue Cu concentrations were observed. Almost all the variation (85-95%) in hepatic and renal (Cu, Cd, Zn)-MT levels was explained by the total or cytosolic hepatic Zn and Cd concentration or the renal Cd concentration, respectively. An analysis of the cytosolic metal speciation showed that the Cd-MT, Cu-MT, and Zn-MT fractions in liver and kidney increased significantly with increasing cytosolic metal concentrations. Metals associated with the other cytosolic protein fractions did not increase with increasing exposure. These results illustrate the important role of MT in metal homeostasis and detoxification processes. We conclude that MT is a useful biomarker for environmental metal contamination in free-living wood mice. [ABSTRACT FROM AUTHOR]

Aim The distinct nature of island populations has traditionally been attributed either to adaptation to particular insular conditions or to random genetic effects. In order to assess the relative importance of these two disparate processes, insular effects were addressed in the European wood mouse, Apodemus sylvaticus (Linnaeus, 1758). Location Wood mice from 33 localities on both mainland and various Atlantic and western Mediterranean islands were considered. This sampling covers only part of the latitudinal range of A. sylvaticus but included the two main genetic clades identified by previous studies. Islands encompass a range of geographical conditions (e.g. small islands fringing the continent through large and isolated ones). Methods The insular syndrome primarily invokes variations in body size, but ecological factors such as release from competition, niche widening and food availability should also influence other characters related to diet. In the present study, the morphology of the wood mice was quantified based on two characters involved in feeding: the size and shape of the mandibles and first upper molars. The size of the mandible is also a proxy for the body size of the animal. Patterns of morphological differentiation of both features were estimated using two-dimensional outline analysis based on Fourier methods. Results Significant differences between mainland and island populations were observed in most cases for both the mandibles and molars. However, molars and mandibles displayed divergent patterns. Mandible shape diverged mostly on islands of intermediate remoteness and competition levels, whereas molars exhibited the greatest shape differentiation on small islands, such as Port-Cros and Porquerolles. A mosaic pattern was also displayed for size. Body and mandible size increased on Ibiza, but molar size remained similar to mainland populations. Mosaic patterns were, however, not apparent in the mainland populations. Congruent latitudinal variations were evident for the size and shape of both mandibles and molars. Main conclusions Mosaic evolution appears to characterize insular divergence. The molar seems to be more prone to change with reduced population size on small islands, whereas the mandible could be more sensitive to peculiar environmental conditions on large and remote islands. [ABSTRACT FROM AUTHOR]

1. Plant defensive compounds and predation risk are main determinants of herbivore foraging, though empirical studies have seldom measured the combined effects of these two factors. By considering the interaction between the herb Helleborus foetidus and its main fruit and seed predator, the Wood Mouse Apodemus sylvaticus, we evaluated whether the defensive role against seed predators of compounds present in H. foetidus unripe fruits holds across a micro-landscape that differs in foraging costs (i.e. predation risk). 2. First, we used standardized food patches that simulated fruiting H. foetidus plants to ascertain fruit preferences of captive mice. Then, by means of field experiments, we assessed the combined effects of fruit ripening and predation risk on foraging by free-ranging mice. 3. Captive mice avoided plants with unripe fruit and avoided consuming unripe fruits within a particular plant. Free-ranging mice also avoided unripe fruits in safe microhabitats (rocky substrate), but not in risky microhabitats (bare ground) where few fruits were consumed. This unexpected result may be driven by predation risk experienced by mice foraging on H. foetidus fruits, and/or plant defensive compounds acting in a dose-dependent manner. 4. Frugivorous mice responded to both chemical defences present in unripe H. foetidus fruits as well as to predation cost though such response was sequential. Plant defence compounds appeared to play a part in mouse foraging only after mice selected low predation risk microhabitats. 5. Our study indicates that both digestive and ecological factors influence foraging decisions, which in turn affects pressures exerted by herbivores on plant populations. [ABSTRACT FROM AUTHOR]

We investigated the effects of environmental pollution on genetic damage in wood mice (Apodemus sylvaticus) by means of the comet assay, with special attention to the role of age and gender as potential confounding variables. The present study was carried out at four sites along a pollution gradient in the vicinity of Antwerp (Belgium), with a nonferrous smelter as the main pollution source. We measured the concentration of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) in mouse liver and kidney and the concentration of organochlorine compounds (polychlorinated biphenyls and 1,1-dichloro-2,2-bis( p-chlorophenyl)ethylene) in mouse muscle tissue to assess individual exposure. Cadmium exposure was very high at the sites closest to the smelter, and exposure to this metal decreased with increasing distance from the smelter. Exposure to the other pollutants was low to moderate at the different sites. Genetic damage was higher in mice from populations in the vicinity of the nonferrous smelter compared with that in the control populations. A significant increase in genetic damage with age was observed at the most polluted sites, but not at the control sites. Genetic damage was higher in male mice than in female mice at the most polluted site, but not at the other areas. Yet, no obvious relationship was found between individual pollutant levels and individual genetic damage levels. We conclude that the comet assay can be used to compare genotoxicity at the population level if the confounding variables of gender and age are taken into account. However, its use for individual health risk assessment remains questionable. [ABSTRACT FROM AUTHOR]

1. Two published data sets of helminths of the wood mouse Apodemus sylvaticus (L.) were analysed to test the hypothesis that the structure of these component communities is influenced by interactions between species. A range of tests, with differing null models, was applied to tease out the importance of controlling for subgroupings (e.g. sex, age, site, year, season) within the data when searching for significant associations based on prevalence (co-occurrence, presence/absence) or abundance (quantitative associations) data. 2. Significant differences from null models were detected for associations based on prevalence, but when subgroup constraints were taken into consideration, most lost significance. Among three and 15 pair-wise associations possible in data sets 1 and 2, respectively, only that between Trichuris muris and Heligmosomoides polygyrus was not dependent on context, and that between H. polygyrus and Catenotaenia pusilla, while always positive, varied in magnitude among sites of capture. 3. Pair-wise comparisons of abundance revealed three significant associations, only one of which ( H. polygyrus with C. pusilla) still remained significant after controlling for quantified extrinsic and intrinsic factors . With increasing burdens of H. polygyrus, mice carried more of other helminth species and this relationship remained significant after controlling for confounding factors. 4. Overall, positive co-occurrences of pairs of helminths of A. sylvaticus were highly context dependent and quantitative associations were weak and not convincing. Therefore, interactions between parasites are unlikely to play a dominant role among the processes that structure the component community of helminths in wood mice, in selected study sites in the south of England. [ABSTRACT FROM AUTHOR]

1. As companion animals, domestic cats Felis catus can attain very high densities, and have the potential to exert detrimental effects on prey species. Yet, there is a paucity of information on the impact of cat predation in urban areas, where most cats are likely to be present. 2. We quantified the minimum number of animals killed annually by cats in a 4.2-km2 area of Bristol, UK, by asking owners to record prey animals returned home by their pets. The potential impact of cat predation on prey species was estimated by comparing the number of animals killed with published estimates of prey density and annual productivity. 3. Predator density was 229 cats/km2. 4. Five mammal, 10 bird and one amphibian prey species were recorded. Mean predation rate was 21 prey/cat/annum. The most commonly recorded prey species was the wood mouse Apodemus sylvaticus. 5. Predation on birds was greatest in spring and summer, and probably reflected the killing of juvenile individuals. For three prey species (house sparrow Passer domesticus, dunnock Prunella modularis, robin Erithacus rubecula), estimated predation rates were high relative to annual productivity, such that predation by cats may have created a dispersal sink for juveniles from more productive neighbouring areas. The impact of cats on these species therefore warrants further investigation. [ABSTRACT FROM AUTHOR]

1. The creation of grassy field margins, as part of the UK Government's Environmental Stewardship (ES) scheme, is one of a number of measures proposed to mitigate the adverse effects of arable intensification on wildlife. Widespread development of these margins will potentially increase the amount of habitat available to small mammals in arable landscapes, as many species do not inhabit the cropped area. 2. The aim of this study was to determine what impact ES-type margins might have on small mammals. We compared small mammal abundance and biomass in spring and autumn on 3-m-wide and 6-m-wide grassy margins with that on conventionally managed field edges that have no margin (0 m wide) and are intensively cultivated to the field edge. 3. Bank voles Clethrionomys glareolus, wood mice Apodemus sylvaticus and common shrews Sorex araneus were the most abundant species; few field voles Microtus agrestis were captured on any margin. In autumn, bank vole and common shrew numbers were higher on the grassy margins than on conventional field edges, and margin width per se was positively associated with bank vole abundance. The number of wood mice captured did not differ among the different margin types. 4. Total small mammal biomass increased between spring and autumn on the 3-m- and 6-m-wide grassy margins, but decreased on the 0-m-wide margins. Total biomass in autumn was three times higher on 6-m-wide margins compared with the conventional arable field edges. [ABSTRACT FROM AUTHOR]

Polymorphism at neutral markers and at MHC loci in rodent populations living on islands is generally low. The main genetic factors that may contribute to a reduced level of genetic variability are genetic drift, reduced gene flow and founder events. We investigated the pattern of polymorphism at the second exon of the Mhc-DQA gene in island populations ofApodemus sylvaticusand in their mainland counterparts to investigate the pattern of MHC polymorphism in a phylogeographical context and to assess the impact of insularity on diversity at this locus.Eight north Mediterranean populations ofApodemus sylvaticuswere studied, including five island populations (Majorca, Minorca, Porquerolles, Port-Cros and Sicily) and three mainland populations.cDNA sequencing and nucleotide sequences analyses. Synonymous and non-synonymous substitutions were examined at the PBR and non-PBR sites. The DQA allelic distribution in populations was compared with the woodmouse phylogeography.This study presents novel DQA alleles. High polymorphism of the DQA locus is recorded in natural populations ofA. sylvaticuswith 13 alleles being widely distributed irrespective of the geographical origin and palaeoclimatic history of populations. The DQA locus does not show the expected pattern for non-synonymous substitutions at the PBR sites. However, island populations show a weak loss of polymorphism in comparison with their mainland counterparts.The DQA locus in the woodmouse seems to be subject to weak selection and does not allow resolution of phylogeographical relationships among European woodmouse populations. The presence of at least three alleles in island populations and the maintenance of five alleles between the two European lineages over 1.5 Myr suggest that balancing selection may act within populations, and more precisely within island populations, to maintain genetic variability. This study shows that phylogeographical studies are a prerequisite for any genetic investigation of selected genes in natural populations. [ABSTRACT FROM AUTHOR]

1. While the effect on animals of handling them and fitting them with radio tags has been investigated, little work has been reported testing the effect of the presence of a human observer tracking an animal.2. The activity of wood mice fitted with radio collars and confined to a semifield pen was measured in the presence and the absence of a human observer. Free-ranging wood mice were radio tracked by using two protocols:‘fixes’ taken periodically, and periods of continuous tracking.3. There was no significant difference in any quantified aspect of the animals’ behaviour. This suggests that the presence of a human tracker has a negligible effect on the behaviour of wood mice. [ABSTRACT FROM AUTHOR]

To test two models of how wood mouse Apodemus sylvaticus populations in different patches might interact, we estimated parameters from capture-mark-recapture data in four habitats (set-aside, crop, boundary and woodlot) at two sites in arable farmland. In the source–sink model, populations in ‘source’ patches have fitness>1, while in ‘sink’ patches fitness is<1; dispersal is constrained so there is a net flow of individuals from sources to sinks. In the balanced dispersal model, patches may vary in quality and carrying capacity, but there are no sinks and no constraints on dispersal; fitness is equal across patches. Our results broadly support balanced dispersal. Patches close together were more likely to exchange individuals than those far apart, there was no evidence of density-dependent dispersal and little evidence for directionality of movement. Overall population growth rates were similar in all patches (range: 0.99–1.05). Times when no animals were known to be alive occurred in some patches and could be attributed to stochastic events. On one crop patch, however, extinction followed high abundance, and coincided with poor recruitment, suggesting sink dynamics. Recruitment rates were highest in boundary and crop, but surprisingly, the proportion of individuals in reproductive condition, timing of breeding and pregnancy rates did not vary between habitats. Apparent survival rates were lowest in crop, although recapture rates were high. While female body size in December did not vary between habitats, males on set-aside were smaller than elsewhere. In general, the balanced dispersal model best described arable wood mouse populations, but dynamics on one patch suggested an ‘attractive’ sink. Our results demonstrate that more than one model for dispersal dynamics between populations may apply within the same landscape, for the same species. [ABSTRACT FROM AUTHOR]

Pre- and post-dispersal Helleborus foetidus (Ranunculaceae) seed predation by mice Apodemus sylvaticus as well as post-dispersal seed removal by ants was studied, during two years, in six plant populations within three geographical regions (Caurel, Cazorla and Mágina) of the Iberian Peninsula. An observational approach revealed strong interregional differences in seed predation by mice during the pre-dispersal phase, with high and similar rates of predation in Cazorla and Mágina and much lower rates in Caurel. There were also significant inter-annual variations on pre-dispersal seed predation by mice, while the existing habitat-related differences (of lower magnitude) were not consistent across regions. Field experiments based on seed-offering exclosures, showed that, despite some interregional variation, post-dispersal seed removal by ants was consistently high through all spatial and temporal scales considered, with most seeds being removed within 48 h. Conversely, post-dispersal seed predation by mice was highly variable among regions, being very high in Cazorla and minimal or absent in Caurel and Mágina. Interestingly, in Cazorla, in presence of mice, the number of seeds removed was rather independent of the presence/absence of ants, while under mice exclusion, it was determined by the presence/absence of ants. Conversely, in Caurel, the number of seeds removed by each remover agent (ants or mice) was independent of the presence/absence of the other agent. Thus, though uniquely in Cazorla, mice limited the number of seeds available to ants and, therefore, in this region could potentially have interfered on the development of seed traits that enable ants to efficiently harvest them. Our results support the notion that geographical variation over the Iberian Peninsula of mice seed predation may have promoted a mosaic of well-matching and mismatching situations between H. foetidus diaspore traits and the characteristics of ant communities, which is consistent with some recent theories on the geographical structure of interactions. [ABSTRACT FROM AUTHOR]

We determined the individual and population responses to food availability of wood mice Apodemus sylvaticus wintering in small forest woodlots by means of a food addition experiment. The allocation of the extra provided energy to the maintenance of body condition and reproduction was expected to vary between sexes due to their different energy investment in reproduction and to the different indirect costs of reproduction associated with different hormone-mediated susceptibilities to parasite infections. There were no effects of food supplementation on the density of adult males or on the overall density of mice. However, adult females were marginally more abundant and the sex ratio was more balanced in supplemented woodlots. Body condition (as estimated by body mass, body mass relative to body size, and amount of fat reserves), did not differ among treatments for either adult males or females. The prevalence and intensity of endoparasites of short life cycle (oxyurid nematodes) were lower in food-supplemented woodlots than in controls and lower in females than in males. No differences were found for endoparasites with long life cycles (telacid nematodes and cestodes). Males with intermediate parasite loads were in better body condition than either nonparasitized or highly parasitized individuals, and the body condition of each group of males was better in food-supplemented woodlots than in controls. This nonlinear relationship between parasite loads and body condition was apparently due to indirect costs of reproduction in control woodlots, where there was a direct relationship between male reproductive effort (relative testis size) and parasite loads. This relationship was not found in supplemented. woodlots. Most individuals were breeding actively at the end of winter. Males had larger testicles, and females showed an advanced breeding, and probably enhanced survival and larger litter sizes, in supplemented woodlots. Individual mice wintering in Mediterranean fragmented forests are thus food limited, and directed most of the extra provided food resources to reproduction without losing body condition or antiparasite abilities. This enhanced reproduction, rather than improved body condition, may translate into larger population densities and recruitment. [ABSTRACT FROM AUTHOR]