Tamias Sibiricus Research Articles

Stylostome of the trombiculid mite larvae Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) feeding on two host species in the Russian Far East

Stylostome and skin inflammatory reaction during feeding of Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) larvae on the naturally infected host animals – voles Myodes rufocanus Sundevall, 1846 and Asian chipmunk Tamias sibiricus (Laxmann, 1769) were studied by histological methods. In addition, larvae were studied in scanning electron microscope (SEM). The apical hypostomal portions form a temporal sucker, which applies to the host skin during feeding. Larval feeding on both naturally infected voles and chipmunks causes an epidermal hyperkeratosis and a permanent delayed inflammation with predominance of neutrophil leukocytes, dilation of dermal capillaries and local hemorrhages. Larvae tend to feed in tight groups and may attach themselves to both ‘living’ epidermis and hypertrophic stratum corneum. The stylostome is organized nearly identically in the two host species, which points to the species-specific character of the feeding tube in trombiculid larvae. The stylostome does not penetrate the epidermis through, so it may be classified as belonging to the epidermal type. The stylostome is produced by a solidifying larval secretion and composed of the proximal eosinophil cone and the main stylostome tube, both pale-pink in azure-II-eosin with a greyish peripheral portion more pronounced in voles. No longitudinal and transverse stratification is found in the stylostome composition. In contrast with other trombiculid larvae studied so far, larvae of N. talmiensis also ingest, besides liquefied nutrients, a pure blood that reveals a possibility for trombiculid larvae to be natural bloodsuckers.

Where do Chip and Dale come from? Origins of invasive populations of the Siberian chipmunk in Europe

Where do Chip and Dale come from? Origins of invasive populations of the Siberian chipmunk in Europe

Alien and invasive terrestrial vertebrate species on Corfu, Ionian Islands, Greece

The Ionian Island of Corfu is rich in both species and habitats, but is also under pressure from heavy tourism, substantial water abstraction, and increased development, all of which have caused both loss and fragmentation of habitats. In addition, invasive alien species (IAS) constitute a global problem and may cause substantial problems for indigenous wildlife, especially on islands. To be able to successfully control IAS it is important to identify them, report their status, and raise awareness as early as possible. Here we present the status of ten alien species reported from Corfu, four of which are considered as invasive, the coypu (Myocastor coypus), the raccoon (Procyon lotor), the Siberian chipmunk (Tamias sibiricus), and the American pond slider (Trachemys scripta). Measures required as outlined by the EU Working Group on Invasive Alien Species are briefly discussed.

Inter-trophic Interaction of Gut Microbiota in a Tripartite System.

Gut microbiota can be transmitted either environmentally or socially and vertically at intraspecific level; however, whether gut microbiota interact along trophic levels has been largely overlooked. Here, we characterized the gut bacterial communities of weevil larvae of Curculio arakawai that infest acorns of Mongolian oak (Quercus mongolica) as well as acorn-eating mammals, Siberian chipmunk (Tamias sibiricus), to test whether consumption of seed-borne larvae remodels the gut bacterial communities of T. sibiricus. Ingestion of weevil larvae of C. arakawai significantly altered the gut bacterial communities of T. sibiricus. Consequently, T. sibiricus fed larvae of C. arakawai showed higher capability to counter the negative effects of tannins, in terms of body weight maintenance, acorn consumption, N content in feces, urine pH, and blood ALT activity. Our results may first show that seed-borne insects as hidden players have a potential to alter the gut microbiota of seed predators in the tripartite system.

Squirrel-Seed Interactions: The Evolutionary Strategies and Impact of Squirrels as Both Seed Predators and Seed Dispersers

For many squirrel species, their intense—arguably coevolutionary— interactions with seed and nut producing trees have significantly shaped their biology and diversity. Here we provide an overview of this relationship in a range of forest types worldwide. We first review the evidence for how forest composition (conifer, hardwood, mixed hardwood and overall diversity of tree species) influences interactions between squirrels and seed trees and, ultimately, the role of squirrels as either seed predators or seed dispersers. We review, for example, the intense selective pressure squirrels exert on conifer trees as seed predators and the diversity of morphological traits and behavioral strategies that allow them to efficiently exploit this critical resource. In contrast, we show how the squirrel's role shifts to one of seed disperser in hardwood forests and how the specifics of this interaction varies further with forest structure, forest composition and climactic conditions. We then review the growing evidence for the tight ecological and evolutionary dance between the squirrels and the oaks that has shaped the biology of both across the globe. We show how a suite of seed (acorn) characteristics (e.g., chemical gradients, germination schedules, seedling morphology and tolerance-resistance strategies) are all intimately tied to the scatter-hoarding decisions of several squirrel species. And, based on studies in oak forests in Central America, Mexico, North America, and Eurasia–many by the authors–we also highlight the behavioral strategy of embryo excision now reported for six species across at least four genera of squirrels. This behavior, glaringly absent in other scatter-hoarding rodents worldwide, is now known be an innate trait in at least two species, one in Asia and another in North America. We review extensive recent research on one species of squirrel, the Siberian chipmunk (Tamias sibiricus), which exhibits a suite of behavioral strategies unique to that of other squirrels that independently contributes to seed dispersal and establishment. Finally, we outline numerous remaining questions concerning plants and other taxa of squirrels still open to investigation.

Exclusion of interspecific competition reduces scatter-hoarding of Siberian chipmunk Tamias sibiricus: A field study.

Although food availability and the abundance of seed predators have been postulated to affect seed dispersal, it is not clear how seed-eating animals modify their scatter-hoarding strategies in response to different levels of interspecific competition. We placed paired germinated and ungerminated acorns of Quercus mongolica on 30-cm high platforms to exclude potential interspecific competition of the predominant larder hoarders Apodemus peninsulae and Myodes rufocanus, to investigate seed dispersal by a predominant scatter-hoarder, Tamias sibiricus, in the field in north-eastern China. Our results showed that T. sibiricus ate more acorns in situ in the absence of interspecific competition. In the presence of interspecific competition of A. peninsulae and C. rufocanus, however, more acorns were scatter-hoarded by T. sibiricus. Regardless of interspecific competition, germination of acorns showed no significant effects on seed dispersal patterns, inconsistent with the "seed perishability hypothesis" that animals avoid hoarding seeds with high perishability. Exclusion of interspecific competition, though relatively increasing the per capita seed abundance, appears to reduce seed dispersal, scatter-hoarding and seedling establishment. Therefore, we propose that moderate interspecific competition rather than competition exclusion may benefit seed scatter-hoarding and seedling establishment.

Первые сведения о фауне и населении грызунов (Rodentia) и насекомоядных (Eulipotyphla) Хингано-Архаринского заказника

This is the first data on the fauna and biotopical distribution of rodents and insectivores of the Khingano-Arkharinskyi zakaznik. The preliminary results are based on field research led in 2011, 2012, 2015 and 2017. Five species of shrews (Sorex caecutiens, S. daphaenodon, S. tundrensis, S. isodon, S. roboratus) and nine species of rodents (Sciurus vulgaris, Tamias sibiricus, Craseomys rufocanus, Myodes rutilus, Alexandromys maximowiczii, Micromys minutus, Apodemus peninsulae, A. agrarius, Sicista caudata) were reliably detected, including the first find of S. caudata in Amurskaya Oblast (this is the most northwestern point of the range, 190 km to west-northwest from the previously known place). A track on snow has been found that was possibly left by Neomys fodiens. The possibility of residence of other species is discussed according to their ranges analysis and presence in Khinganskyi Nature Reserve situated 40 km to the south. The whole Middle Amur region is a territory with a complex landscape structure with intermixture of boreal, nemoral and steppe biotic components and the corresponding «transitional» character of the fauna. Many species have range borders here. Two steppe species (Cricetulus barabensis, Urocitellus undulatus) living in Khinganskyi Reserve or on adjacent territories cannot be found in the zakaznik. Two nemoral species (Erinaceus amurensis and Сrocidura lasiura, rare in Khinganskyi Reserve) have their northern range borders near the southern border of the zakaznik, they are likely to be absent here due to lack of needed habitats. The zakaznik is situated on the northern periphery of Alexandromys fortis range and the western periphery of Sorex gracillimus range, further field research is needed to clarify their status here. Two more species (Sorex minutissimus, Pteromys volans) have not been found yet but they obviously live on this territory.

Managing invasive Siberian chipmunks Eutamias sibiricus in Italy: a matter of attitudes and risk of dispersal

Eradication of invasive alien species is a form of pest control linked to biodiversity conservation, which usually involves animal killing. Squirrels are prominent among invasive alien species in Italy, with four species introduced. Three of them are included within the list of alien species of European concern, and their eradication and control is recommended. However, their local control is not an easy task, being often hindered by the general public. We propose a socio-ecological approach to evaluate the feasibility of eradicating Siberian chipmunks Eutamias sibiricus populations in Italy. We performed a structured questionnaire to assess the social perception of invasive Siberian chipmunks in urban parks, and to identify groups of visitors who might oppose eradication. We also carried out geographic profiling to test for the spatial expansion of chipmunk populations. Overall, park visitors regarded chipmunks positively and appreciated to see them, but human-chipmunk interactions were still rare. We did not identify any group of visitors with a strong attachment to chipmunks, who might oppose future control programs. Geographic profiling showed that chipmunks in Valeggio sul Mincio are starting to expand outside of their introduction site. Data from questionnaires show that chipmunks eradication, coupled with adequate communication initiatives, might be feasible. Moreover, geographic profiling indicates that time for a rapid removal is running out. Socio-ecological approaches, combining the analysis of structured questionnaires administered to stakeholders and statistical modeling of pest observations, could be a valuable tool to decide the feasibility and the urgency of invasive alien species control.

Differently sized cuckoos pose different threats to hosts.

Hole-nesting tits Parus spp. have been classified as “unsuitable” hosts for cuckoo parasitism because cuckoos cannot enter a cavity if the entrance is too small. However, Chinese tits could reject alien eggs and egg ejection rate increased with the local diversity of parasitic cuckoo species. Antiparasitic behavior among Chinese tits may have evolved due to greater size variation among sympatric cuckoo species. This raises the question of whether differently sized parasitic cuckoos pose different threats to Chinese tits. A green-backed tit Parus monticolus population that is sympatric with Asian emerald cuckoo Chrysococcyx maculatus (eme-cuckoo, small-sized parasite) and common cuckoo Cuculus canorus (com-cuckoo, large-sized parasite), and a cinereous tit P. cinereus population that is only sympatric with com-cuckoo were chosen as study organisms. We observed behavioral response and recorded alarm calls of the 2 tit species to eme-cuckoo, com-cuckoo, chipmunk Tamias sibiricus (a nest predator) and dove Streptopelia orientalis (a harmless control), and subsequently played back alarm calls to conspecific incubating females. In dummy experiments, both tit species performed intense response behavior to chipmunk, but rarely responded strongly to the 3 avian species. In playback experiments, both tit species responded strongly to conspecific chipmunk alarm calls, but rarely responded to dove alarm calls. The intensity of response of incubating female green-backed tits to eme-cuckoo and com-cuckoo alarm calls were similar to that of chipmunk alarm calls, while the intensity to eme-cuckoo alarm calls was higher than the intensity to dove alarm calls which was similar to that of com-cuckoo alarm calls. In contrast, few female cinereous tits responded to eme-cuckoo and com-cuckoo alarm calls. These findings indicated that the threat level of eme-cuckoo was slightly greater than that of com-cuckoo for sympatric green-backed tits, but not for allopatric cinereous tits.

Cache placement near nests by a multiple-prey loader, the Siberian chipmunk

The rapid sequestering hypothesis predicts that scatter-hoarding animals quickly sequester food items by storing seeds in caches near seed sources to reduce competition. However, tests of this hypothesis usually use food-hoarding animals with a single load or a small load size. How multiple-load animals place their caches between food sources and nests remains largely unknown. Here, we hypothesized that multiple-load animals, compared to single-load animals, may not necessarily sequester food items but adopt alternative hoarding strategies due to their multiple-load ability. In this study, we presented seeds at different distances from the nests of the multiple-loading Siberian chipmunk, Tamias sibiricus, and mapped the spatial distribution of their caches in multiple-compartment enclosures to test our hypothesis that a multiple-prey loader will consistently establish caches near nests rather than rapidly sequester near the seed source. By using multiple-compartment enclosures with different distances between the seed source and nests, and given potential intra- and interspecific competition, we found chipmunks consistently placed their caches near nests but away from the seed source. Cache placement near nests may serve as an alternative strategy that not only guarantees a maximum harvest rate at the seed source but also ensures effective cache defence near nests. Moreover, scatter-hoarding seeds near nests may alternatively guarantee a food supply if larder-hoarded seeds are depleted or lost. Unlike seeds sequestered near food sources, caches near nests imply long dispersal distances for seeds in our study. Therefore, scatter hoarding by multiple-prey loaders is expected to be ecologically important for the structure and function of tree communities, especially in ecosystems in which seeds depend on food-hoarding animals for dispersal and germination.

Visual and auditory cues facilitate cache pilferage of Siberian chipmunks (Tamias sibiricus) under indoor conditions.

In the struggle for survival, scatter-hoarding rodents are known to cache food and pilfer the caches of others. The extent to which rodents utilize auditory/visual cues from conspecifics to improve cache-pilfering is unknown. Here, Siberian chipmunks (Tamias sibiricus) were allowed to search for caches of Corylus heterophylla seeds (man-made caches and animal-made caches) after experiencing cues from a conspecific's cache-searching events. For each type of cache, 3 experimental scenarios were presented: (1) alone (control); (2) auditory/visual (hearing and seeing conspecific's cache-searching events); and (3) auditory only (hearing conspecific's cache-searching events only) with random orders. The subjects located man-made caches faster, harvested more caches, and hoarded more seeds both in the auditory/visual and the auditory only treatments compared to the control, while scatter-hoarding more seeds in the auditory/visual treatment but larder-hoarding more seeds in the auditory only treatment. Compared to the control, the animals spent less time locating animal-made caches, harvested more caches, ate fewer seeds, larder-hoarded more seeds and hoarded more seeds in total both in the auditory/visual and the auditory only treatments, while eating more seeds and hoarded fewer seeds in total in the auditory only treatment than in the auditory/visual treatment. The results also show that females spent less time locating the animal-made caches, but they scatter-hoarded fewer seeds than males in the auditory/visual treatment. To the best of our knowledge, this is the first report that visual and/or auditory cues of conspecifics improve cache-pilfering and hoarding in rodents.

Scatter‐hoarding and cache pilfering of rodents in response to seed abundance

AbstractSeed caching and reciprocal cache pilferage play an important role in the coexistence of food‐hoarding animals. Understanding what affects seed caching and how cache pilferage occurs is an important question in seed dispersal ecology. However, tracking seed fate and cache pilferage presents substantial practical difficulties. Siberian chipmunks Tamias sibiricus always remove the entire pericarp when scatter‐hoarding acorns of Mongolian oak Quercus mongolica, whereas wood mice Apodemus peninsulae often store whole acorns in their caches. These differences in behavior provide an opportunity to investigate unilateral cache pilferage of T. sibiricus from A. peninsulae in response to seed abundance. In this study, tagged acorns were released at the peak and end periods of seed rain from Q. mongolica. This allowed us to investigate seed caching and unilateral cache pilferage at different seed abundances. We found that a higher proportion of acorns were cached at lower level of seed abundance (toward the end of seed rain), mainly because T. sibiricus rather than A. peninsulae scatter‐hoarded significantly more acorns at this time. Cache distances decreased with increasing seed abundance, indicating that acorns were cached further away and into smaller caches at lower seed abundance. Unexpectedly, unilateral cache pilferage by T. sibiricus was not significantly influenced by seed abundance—remaining at around 28% during both periods of high and low seed abundance.

British Red Squirrels Remain the Only Known Wild Rodent Host for Leprosy Bacilli.

Eurasian red squirrels (Sciurus vulgaris) in the British Isles are the most recently discovered animal reservoir for the leprosy bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Initial data suggest that prevalence of leprosy infection is variable and often low in different squirrel populations. Nothing is known about the presence of leprosy bacilli in other wild squirrel species despite two others (Siberian chipmunk [Tamias sibiricus], and Thirteen-lined ground squirrel [Ictidomys tridecemlineatus]) having been reported to be susceptible to experimental infection with M. leprae. Rats, a food-source in some countries where human leprosy occurs, have been suggested as potential reservoirs for leprosy bacilli, but no evidence supporting this hypothesis is currently available. We screened 301 squirrel samples covering four species [96 Eurasian red squirrels, 67 Eastern gray squirrels (Sciurus carolinensis), 35 Siberian chipmunks, and 103 Pallas's squirrels (Callosciurus erythraeus)] from Europe and 72 Mexican white-throated woodrats (Neotoma albigula) for the presence of M. leprae and M. lepromatosis using validated PCR protocols. No DNA from leprosy bacilli was detected in any of the samples tested. Given our sample-size, the pathogen should have been detected if the prevalence and/or bacillary load in the populations investigated were similar to those found for British red squirrels.

Integrating climate and land‐use change scenarios in modelling the future spread of invasive squirrels in Italy

AbstractAimThe establishment and spread of invasive alien species may be influenced by several mutually interacting factors, whose understanding is paramount to develop effective biosecurity policies. However, studies focused on modelling spatially explicit patterns of future invasion risk have so far focused on species response to climate change impacts, while land‐use change has been neglected. We investigated how the interplay between climate and land‐use change could affect the future potential distribution and dispersal corridors of four alien squirrels introduced to Europe (Sciurus carolinensis, Callosciurus finlaysonii, Callosciurus erythraeus and Eutamias sibiricus).Location and MethodsOur study was conducted in Italy. We used Species Distribution Models and circuit theory methods to test whether future scenarios based only on climate change predict a different effect on range and connectivity of alien squirrel populations, compared to scenarios that include both climate and land‐use changes.ResultsScenarios based only on climate change predicted a range increase and a high geographic stability (>50%) for most species, with different, yet limited, effects on connectivity corridors. Conversely, scenarios based on both climate and land‐use change showed a loss in range extent and a low geographic stability (<50%) of both range and dispersal corridors for most species.Main conclusionsScenarios considering both climate and land‐use change provide predictions on invasion risk that overturn those including only climate change. The effect of global warming alone would lead to a considerable range expansion of all species. Conversely, when land‐use change is added, a potential loss in suitable habitat and dispersal corridors is predicted for alien squirrels, hence limiting their range expansion. We recommend using multiple drivers in models to obtain reliable predictions for implementing biosecurity policies related to invasive alien species.

Endozoochory by granivorous rodents in seed dispersal of green fruits

Although the role of frugivores in seed dispersal has attracted scientific attention, it remains unclear whether granivorous rodents can act as frugivores to interact mutualistically with fruit-producing plants, especially those bearing green fruits inconspicuous to avian frugivores. In this study, we tracked fruit removal of the tara vine (Actinidia arguta (Siebold & Zucc.) Planch. Ex Miq.) and variegated kiwi vine (Actinidia kolomikta (Rupr. & Maxim.) Maxim.) in a temperate forest and presented fruits to the granivorous rodents Siberian chipmunk (Tamias sibiricus (Laxmann, 1769)), Korean field mouse (Apodemus peninsulae (Thomas, 1907)), and gray red-backed vole (Clethrionomys rufocanus (Sundevall, 1846) = Myodes rufocanus (Sundevall, 1846)) in the laboratory to answer this question. Seeds were collected from rodent feces to see the effects of gut passage on seed germination to determine the role of granivorous rodents in endozoochory of A. arguta and A. kolomikta. We presented clear evidence of endozoochory by granivorous rodents in seed dispersal of the two Actinidia species. Rodents appeared to play an alternative role in dispersing plants bearing green fruits. Moreover, we observed increased germination rates after gut ingestion by the granivorous rodents. Our study evidenced endozoochory of granivorous rodents and provided new insight into the mutualist interactions between rodents and plant species bearing fleshy fruits containing tiny seeds. We suggest future studies pay more attention to endozoochory of rodents and establish their mutualistic relationship with fruit-bearing plants in temperate forests.

The importance of taxonomy in species distribution models at a global scale: the case of an overlooked alien squirrel facing taxonomic revision

AbstractThe Siberian chipmunk is native to north‐eastern Asia, but alien populations of this squirrel, introduced through the pet trade, occur in many European countries. This rodent has been listed as an invasive species of European concern, being a potential vector of ticks spreading Lyme disease. We aimed to assess its current distribution range and to identify areas of potential invasion. Two sets of species distribution models were conducted, one considering the locations of the species (n = 625 occurrences) and the other with only the occurrences of the Korean subspecies (the invasive one in Europe; n = 255 occurrences), which might be a separate species from the Siberian one. We included 19 uncorrelated predictors (two topographic, nine land cover, five bioclimatic and three anthropogenic variables), which may represent the habitat characteristics of the target species. Most of the northern hemisphere supports the establishment of the Siberian chipmunk, particularly for the invasive Korean subspecies (especially in Europe, where it is already established), mostly in urban areas. Anthropogenic food supply was found to be an important factor promoting the growth of alien populations of chipmunks, whereas the presence of the native red squirrel at the time of introduction may limit it.

Within- and between-year variations of reproductive strategy and cost in a population of Siberian chipmunks.

Reproduction costs depend on the general life-history strategies employed by organisms for resource acquisition, the decision rules on resource allocation, and the resource availability. Although the predictability of resource availability is expected to influence the breeding strategy, the relationship between predictability and strategy has rarely been investigated at the population level. One reason is that, while the resource availability is commonly variable in space and time, their predictability is generally assumed constant. Here, we addressed the temporal variation of the breeding strategy and its associated survival cost in a hibernating population of Tamias sibiricus, in which food resources vary in their availability between years and in their predictability within years. Based on 11years of mark-recapture data, we used multi-event modelling to investigate seasonal variations in reproduction costs of female chipmunks that breed twice a year (spring and summer). In summer, during which a large variety and quantity of resources is available (income breeding strategy), the proportion of breeding females was consistent across years and reproduction yielded no mortality cost. In contrast, in spring, the proportion of breeding females was positively correlated with the amount of resources available for hibernation (partial capital breeding strategy). Spring reproduction yielded no immediate cost, but induced a delayed mortality cost over the next winter if future unknown conditions were unfavorable. Our findings highlight complex temporal reproductive patterns in a short-lived species: not only does the modality of resource acquisition vary among seasons, but also the decision rule to breed and its associated cost.

Scatterhoarders move pilfered seeds into their burrows

Although cache pilferage by food-hoarding animals has been well investigated, whether cache pilfering contributes to seed redistribution remains to be explored. In this study, we presented seeds exposed on the ground (including clumped and scattered seeds) and buried in artificial caches to Siberian chipmunks Tamias sibiricus and Korean wood mice Apodemus peninsulae exhibiting different food-hoarding behaviors, to investigate how seed distribution patterns affected seed fates and where pilfered seeds have gone in rodent-proof enclosures. Our results showed that both T. sibiricus and A. peninsulae handled more seeds exposed on the ground than buried in the caches. Scattered seeds were less likely to be eaten by rodents compared to clumped seeds and those buried in artificial caches. Exposed seeds in the enclosures were more likely to be scatterhoarded by T. sibiricus, while pilfered seeds from artificial caches were more likely to be larderhoarded than those easily accessible on the ground. Although buried seeds in artificial caches were less likely to be pilfered by rodents, both scatterhoarder (T. sibiricus) and larderhoarder (A. peninsulae) concealed pilfered seeds in their burrows. We also found that primary scatterhoarder T. sibiricus appeared to be effective pilferer, whereas A. peninsulae that primarily larderhoard seeds seemed to be poor pilferer, providing further evidence that the ability of food-hoarding animals to pilfer is correlated with how extensively they scatterhoard seeds. Our study highlights the importance of seed distribution patterns in affecting the hoarding behavior of scatterhoarding rodents, but not for larderhoarding rodents. Although cache pilferage by food-hoarding animals has been well investigated, whether cache pilfering contributes to seed redistribution remains to be well explored. Our study first showed that both scatterhoarders and larderhoarders concealed pilfered seeds in their burrows, challenging the previous assumption that cache pilferage will result in redistribution of dispersed seeds.

Improved spatial memory promotes scatter hoarding by Siberian chipmunks

Spatial memory can improve cache recovery in scatter-hoarding mammals; however, we lack knowledge about how spatial memory affects scatter-hoarding behavior. Captive-reared Siberian chipmunks (Tamias sibiricus) were orally dosed with docosahexaenoic acid (DHA) and uridine-5-monophosphate (UMP) for 6 weeks to test if improved spatial memory affects scatter hoarding. Oral administration of DHA and UMP significantly increased the relative size of hippocampi of the chipmunks and increased concentration of hippocampal DHA and eicosapentaenoic acid (EPA). Consequently, spatial ability of chipmunks in a Y-maze was significantly improved after administration of DHA and UMP. More importantly, chipmunks that received DHA and UMP scatter hoarded more seeds than control animals. This study shows that scatter hoarding in a mammal is associated with improvement in spatial memory, suggesting the potential role of spatial memory in determining food-hoarding behavior.

Arthropods and associated pathogens from native and introduced rodents in Northeastern Italy.

Introduced Siberian chipmunks Eutamias sibiricus have been reported to be important reservoirs for human Lyme disease, as they may host high numbers of hard ticks carrying Borrelia spp. and other pathogens. In the present study, we assessed the prevalence of Borrelia spp. and other pathogenic bacteria in ectoparasite arthropod species infesting Siberian chipmunks and coexisting native small rodents. Small rodents were trapped with Sherman traps in Veneto (NE Italy), where the largest Italian populations of chipmunks occur. A total of 14 individual ticks were found on 223 rodents, with 6 more ticks obtained from stored dead chipmunks from the same study area. Ectoparasites were screened for pathogens by molecular analyses including species-specific PCR amplifications. Rickettsia monacensis, Borrelia lusitaniae, and Anaplasma platys were present in the parasites of both native rodents and introduced chipmunks. The present findings suggest a role for the invasive species E. sibiricus in the maintenance of the Ixodes ricinus life cycle, which may result in the modification of the transmission dynamics of tick-borne pathogens. Moreover, the presence of Rickettsia in urban populations of chipmunks may represent a serious risk for human health and should be investigated further.