Water Shrew Research Articles

Environmental factors affecting capture rate of the Japanese Water Shrew, Chimarrogale platycephala

Environmental factors affecting capture rate of the Japanese Water Shrew, <i>Chimarrogale platycephala</i>

New Neomys fossils (Soricidae, Insectivora) from the Middle Pleistocene of China

Three fossil Neomys specimens from the middle Pleistocene Shanyangzhai cave sediments of Qinhuangdao city, Hebei Province, China were assigned to the fossil species of Water Shrew, Neomys bohlini. The specimens show some characteristics, such as large size, condylar joint separation, and ascending ramus tilt, which are obviously different from Crocidura and Sorex. Remains of fossil Neomys are very rare. This is the first report of the species from the Zhoukoudian since 1936.

A northern refugium of the Mediterranean water shrew Neomys anomalus in Słowiński National Park (N Poland)

Abstract The influence of recent anthropogenic and climatic changes on the distribution or population size of individual species should be especially pronounced at the boundaries of their geographical ranges. Therefore, in summers 2008-2010, we live-trapped small mammals and analysed habitat features on 14 study plots comprising various wet habitats of Słowiński National Park (at the Baltic coast in northern Poland) in order to recognize the current distribution and population size of Neomys anomalus Cabrera, 1907 in its northernmost population in Europe. N. anomalus was, however, captured only on one plot - a wet, unmown meadow crossed by unkempt drainage ditches, situated on the Gać Peninsula (Półwysep Gacki). This result, compared to historical data, suggests that neither the abundance of N. anomalus has increased nor its range has been extended. We give a detailed description of the habitat in this study plot. The information can be useful in the protection of this rare shrew species with very specific habitat requirements.

Beobachtungen zum Paarungs- und Aufzuchtverhalten der Wasserspitzmaus Neomys fodiens (Soricidae)

Five European Water Shrews (Neomys fodiens) were kept in an indoor enclosure of 2.7 m2 where one couple mated regularly. Multiple copulations appeared over a period of about 12hours. Ten litters with 56 offspring were born and 33 survived. The female gave birth to her latest litter at an age of about 20 month, 2 month later as the end of the reported lifespan in nature. The period of fertility lasted 336 days and is comparable to those of Crocidura. At the end of this period three times signs of pseudopregnancy were detected: After copulating the female started building her nest and intensified this behaviour after about three weeks, at the end of the expected “gestation” swollen nipples could also be noticed, but no offspring inside the nest. The female died at an age of about 38 month.After successful copulations a copulatory lock was achieved and the female could track her mate. The mating behaviour can be classified as follows: a) male entering female's territory, b) precopulatory chasing, c) approaching of the mates, d) mounting and repeated copulations attempts, e) successful copulation, male slipping down from female's back, f) copulatory lock and resting, g) cleaning sexual organs, h) continuing chasing and further copulations or i) displacing the male and finishing sexual behaviour. Driving off the male from female's territory could last some time. No special calls were uttered in the close context of copulatory behaviour, only the known ones while chasing, some low contact calls inside the nest and aggressive calls while driving off the male.

Cytochrome-bSequence Variation in Water Shrews (Sorex palustris) from Eastern and Western North America

Mitochondrial DNA sequence data for the cytochrome-b gene was used to assess genetic divergence among samples of Sorex palustris (Water Shrew) from eastern and western North America. Phylogenetic analysis revealed the presence of three previously observed clades—Cordilleran (S. p. navigator and S. p. brooksi), Coastal (S. bendirii), Boreal (S. p. palustris)—along with a novel Eastern clade (S. p. gloveralleni and/or S. p. albibarbis). Intraspecific divergence between the Boreal and Eastern clades was 3.42%, exceeding interspecific divergence between the Cordilleran and Coastal clades (3.35%). Application of the genetic species concept to the results of this study suggests that the Boreal and Eastern clades of Water Shrews warrant further investigation for recognition as two distinct sister species (i.e., S. palustris and S. albibarbis, respectively). Additional samples and analysis of nuclear markers will be required to substantiate this proposed taxonomic revision.

Chemoarchitecture of Layer 4 Isocortex in the American Water Shrew (Sorex palustris)

We examined the chemoarchitecture of layer 4 isocortex and the number of myelinated nerve fibers of selected cranial nerves in the American water shrew (Sorex palustris). This study took advantage of the opportunity to examine juvenile brain tissue, which often reveals the most distinctive cortical modules related to different sensory representations. Flattened cortical sections were processed for the metabolic enzyme cytochrome oxidase, revealing a number of modules and septa. Subdivisions related to sensory representations were tentatively identified by performing microelectrode recordings in a single adult shrew in this study, combined with microelectrode recordings and anatomical findings from a previous investigation. Taken together, these results suggest that characteristic chemoarchitectonic borders in the shrew neocortex can be used to delineate and quantify cortical areas. The most obvious subdivisions in the water shrew include a relatively small primary visual cortex which responded to visual stimuli, a larger representation of vibrissae in the primary somatosensory cortex, and a prominent representation of oral structures apparent in the more rostral-lateral cortex. A presumptive auditory area was located in the far caudal cortex. These findings for the cortex are consistent with counts from optic, auditory and trigeminal nerves, suggesting that somatosensory inputs dominate the shrew’s senses whereas visual and auditory inputs play a small role in navigation and in finding prey. More generally, we find that shrews share unusual features of cortical organization with moles, supporting their close taxonomic relationship.

The Eurasian water shrew: an unsuitable candidate species for a vertebrate bio‐indicator of aquatic pollution

AbstractThe Eurasian water shrew Neomys fodiens is a semi‐aquatic predator of freshwater invertebrates. As water quality affects the diversity and abundance of aquatic invertebrates, water shrews could potentially be used as a vertebrate bio‐indicator of water quality. To date, no detailed studies have empirically examined the impacts of water quality on Eurasian water shrew occurrence. Bait‐tube surveys were undertaken in winter and summer over 3 years at 26 different wetland locations across Sussex, UK, which varied in water quality. Bait tubes were used to confirm water shrew presence at specific sites and derive an index of activity using frequency of occurrence of faeces within tubes. Water quality was measured using six direct physical and chemical indicators (dissolved oxygen, pH, water temperature, ammonia, nitrate and phosphate) and two derived indices of biological indicators based on aquatic invertebrate composition. We found no linear relationship between any physical, chemical or biological water quality indicators and water shrew occurrence. Generalized linear models indicate that water shrew presence and frequency of occurrence are more affected by site and season than water quality. Thus, water shrews may be more tolerant of poor water quality than previously envisaged. Overall, our study indicates that water shrews are not suitable vertebrate bio‐indicators of water quality.

Influence of montane isolation and refugia on population structure ofSorex palustrisin western North America

The contemporary geographic distribution and interrelation of populations result from landscape structure, habitat specificity, and historical climate fluctuations. We examined the impact of Pleistocene environmental history on mitochondrial genealogies of the water shrew (Sorex palustris) in montane systems of western North America to test hypotheses concerning historical recolonization. Our main focus lies on the regional scale of the Pacific Northwest and the extent to which disjunct populations are associated with discrete, isolated mountains. We analyzed 87 specimens from the entire western portion of the species range to assess broadscale genealogical relationships. We then examined 61 individuals selected from 21 specific high-elevation sites in the Pacific Northwest to test whether these populations are structured in accord with distinct montane regions. Across western North America in general the relationship among S. palustris lineages is unresolved, suggesting a recent and rapid radiation from a common ancestral population. In the Pacific Northwest we found evidence of clades that are uniquely associated with individually isolated montane regions, clades that are distributed across several montane regions, and distinct clades that co-occur within the same montane region. We conclude that populations of S. palustris in western North America are derived from a single, southern, late-Pleistocene refugium. We also suggest that lineages shifted geographically by following the most northerly postglacial expansion of the boreal forest system. DOI: 10.1644/09-MAMM-A-378.1.

Radiotelemetry Applied to Field Studies of Shrews

Abstract: Radiotelemetry is a widely used method to study ecology, behavior, and physiology of different animals but has rarely been used on shrews. Small body size, wide neck and narrow skull, high mobility, and fragility of shrews cause problems for both transmitter attachment and the safety of the animals. We developed a method for nonpermanent attachment of transmitters, which allowed us to track such small mammals as the Eurasian water shrews (Neomys fodiens; n = 39, mean body mass 14.9 g), Mediterranean water shrews (Neomys anomalus; n = 32, 10.9 g), and common shrews (Sorex araneus; n = 51, 8.1 g). We used microtransmitters weighing 0.47 g, but those we applied to the larger Neomys species were heavier (0.67 g) because we fortified them with a layer of hard material to prevent damage from biting. We glued a transmitter directly to the skin on a shrew's back, with the anterior edges particularly well sealed. We tracked shrews in the wild and in outdoor enclosures. Transmitters usually dropped off together with peeled skin (on average, after 56.0 hr, n = 92 observations), but if not dropped and if the signal was not lost, mean duration of monitoring was 96.7 hours (n = 37) and in 2 cases exceeded 194 hours. Other advantages of our attachment method were 1) it was less invasive and easier to apply than implantation of transmitters into the body cavity, and 2) we could find dropped transmitters and reuse them. We give suggestions on how to minimize the risk of injury to animals by correct handling, manipulation, and gluing. In conclusion, we recommend radiotelemetry as a useful technique for studying shrew behavior in both free‐living populations and experimental enclosures.

Radiotelemetry Applied to Field Studies of Shrews

Radiotelemetry is a widely used method to study ecology, behavior, and physiology of different animals but has rarely been used on shrews. Small body size, wide neck and narrow skull, high mobility, and fragility of shrews cause problems for both transmitter attachment and the safety of the animals. We developed a method for nonpermanent attachment of transmitters, which allowed us to track such small mammals as the Eurasian water shrews (Neomys fodiens; n = 39, mean body mass 14.9 g), Mediterranean water shrews (Neomys anomalus; n = 32, 10.9 g), and common shrews (Sorex araneus; n = 51, 8.1 g). We used microtransmitters weighing 0.47 g, but those we applied to the larger Neomys species were heavier (0.67 g) because we fortified them with a layer of hard material to prevent damage from biting. We glued a transmitter directly to the skin on a shrew's back, with the anterior edges particularly well sealed. We tracked shrews in the wild and in outdoor enclosures. Transmitters usually dropped off together with peeled skin (on average, after 56.0 hr, n = 92 observations), but if not dropped and if the signal was not lost, mean duration of monitoring was 96.7 hours (n = 37) and in 2 cases exceeded 194 hours. Other advantages of our attachment method were 1) it was less invasive and easier to apply than implantation of transmitters into the body cavity, and 2) we could find dropped transmitters and reuse them. We give suggestions on how to minimize the risk of injury to animals by correct handling, manipulation, and gluing. In conclusion, we recommend radiotelemetry as a useful technique for studying shrew behavior in both free-living populations and experimental enclosures.

Effects of non-native spruce plantations on small mammal communities in subarctic birch forests

Voles and shrews are key species in northern forest ecosystems. Thus, it is important to quantify to what extent new forestry practices such as planting of non-native tree species impact these small mammals. In northern Norway stands of coastal subarctic birch forests have increasingly been converted to non-native spruce stands during the last century. This leads to changes in the forest floor vegetation and soil conditions that can be expected to negatively impact the community of ground-dwelling small mammals. In this 10-year trapping study we contrasted seasonal small mammal population abundances in spruce plantations with four birch forest varieties. Six different small mammal species were trapped (in descending order of abundance; common shrew Sorex araneus, red vole Myodes rutilus, field vole Microtus agrestis, grey-sided vole M. rufocanus, pygmy shrew S. minutus and water shrew Neomys fodiens). None of the voles appeared to exhibit temporal dynamics resembling population cycles. The three most numerous species were clearly less abundant in the spruce plantations compared to the other forest types. Autumn abundances were most impacted by spruce plantations, indicating that growth rates in the reproductive season were more influenced than winter declines. Species associated with productive forest habitats (i.e. field vole and common shrew) were most impacted by tree species conversion. Still young spruce plantations inter-mixed with birch trees and the ecotone habitat, sustained small mammal abundances comparable to the native birch forests. This implies that managing spruce plantations to maintain a mix of different tree species and high spatial heterogeneity (i.e. more ecotones), will reduce the negative impacts on the small mammal community. On the contrary, if young spruce plantations, as they age become spruce monocultures covering larger parts of the landscapes than they do presently, the negative effects on small mammal communities may be larger than observed in the present study.

Muscle aging and oxidative stress in wild-caught shrews

Red-toothed shrews (Soricidae, subfamily Soricinae) are an intriguing model system to examine the free-radical theory of aging in wild mammals, given their short (<18months) lifespan and high mass-specific metabolic rates. As muscle performance underlies both foraging ability and predator avoidance, any age-related decline should be detrimental to fitness and survival. Muscle samples of water shrews (Sorex palustris) and sympatrically distributed short-tailed shrews (Blarina brevicauda) were therefore assessed for oxidative stress markers, protective antioxidant enzymes and apoptosis. Activity levels of catalase and glutathione peroxidase increased with age in both species. Similarly, Cu,Zn-superoxide dismutase isoform content was elevated significantly in older animals of both species (increases of 60% in the water shrew, 25% in the short-tailed shrew). Only one oxidative stress marker (lipid peroxidation) was age-elevated; the others were stable or declined (4-hydroxynonenal adducts and dihydroethidium oxidation). Glutathione peroxidase activity was significantly higher in the short-tailed shrew, while catalase activity was 2x higher in water shrews. Oxidative stress indicators were on average higher in short-tailed shrews. Apoptosis occurred in <1% of myocytes examined, and did not increase with age. Within the constraints of the sample size we found evidence of protection against elevated oxidative stress in wild-caught shrews.

The chromosomes of the European water shrew (Neomys fodiens).

HereditasVolume 62, Issue 3 p. 348-356 Open Access THE CHROMOSOMES OF THE EUROPEAN WATER SHREW (NEOMYS FODIENS ) KARL FREDGA, KARL FREDGA INSTITUTE OF GENETICS, UNIVERSITY OF LUND, SWEDENSearch for more papers by this authorALBERT LEVAN, ALBERT LEVAN INSTITUTE OF GENETICS, UNIVERSITY OF LUND, SWEDENSearch for more papers by this author KARL FREDGA, KARL FREDGA INSTITUTE OF GENETICS, UNIVERSITY OF LUND, SWEDENSearch for more papers by this authorALBERT LEVAN, ALBERT LEVAN INSTITUTE OF GENETICS, UNIVERSITY OF LUND, SWEDENSearch for more papers by this author First published: August 1969 https://doi.org/10.1111/j.1601-5223.1969.tb02244.xCitations: 2AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume62, Issue3August 1969Pages 348-356 ReferencesRelatedInformation

Cornea, retina, and lens morphology in five Soricidae species (Soricomorpha: Mammalia)

We analyzed the cornea, retina, and lens of five species of Soricidae (pygmy shrew, Sorex minutus; common shrew, Sorex araneus; Millet's shrew, Sorex coronatus; water shrew, Neomys fodiens; greater white-toothed shrew, Crocidura russula) by light and electron microscopy. In all of these species, the corneal epithelium showed a dead cell layer, which may increase the refractive power of the cornea, thereby reducing the hypermetropy that would be expected in a small eye. Moreover, the anterior surface of the lens was more curved than the posterior, thus minimizing spherical aberrations. The thicker lens and its smaller radii of curvature indicated that Sorex species and N. fodiens have a higher refractive lens power than the most nocturnal species, C. russula. In addition, only in the retina cone inner segments of the most diurnal species (genus Sorex) did we find megamitochondria that might act as microlenses to enhance the efficiency of cones. In C. russula, the scarcity of cones and the relatively small yet abundant rod nuclei were found to be consistent with its habits. The flat lens and its more anterior arrangement, together with the lack of megamitochondria in the retina of C. russula, indicated that this species has less visual acuity than the other shrews studied here.

Muscle senescence in short‐lived wild mammals, the soricine shrews Blarina brevicauda and Sorex palustris

Red-toothed (soricine) shrews are consummate predators exhibiting the highest energy turnovers and shortest life spans (ca. 18 months) of any mammal, yet virtually nothing is known regarding their physiological aging. We assessed the emerging pattern of skeletal muscle senescence (contractile/connective tissue components) in sympatric species, the semi-aquatic water shrew (WS), Sorex palustris, and the terrestrial short-tailed shrew (STS), Blarina brevicauda, to determine if muscle aging occurs in wild, short-lived mammals (H(0): shrews do not survive to an age where senescence occurs), and if so, whether these alterations are species-specific. Gracilis muscles were collected from first-year (n=17) and second-year (n=17) field-caught shrews. Consistent with typical mammalian aging, collagen content (% area) increased with age in both species (S. palustris: approximately 50%; B. brevicauda: approximately 60%). Muscle was dominated by stiffer Type I collagen, and the ratio of collagen Type I:Type III more than doubled with age. The area ratio of muscle:collagen decreased with age in both species, but was considerably lower in adult STS, suggesting species-specificity of senescence. Extracellular space was age-elevated in B. brevicauda, but was preserved in S. palustris ( approximately 50 vs. 10% elevation). Though juvenile interspecific comparisons revealed no significance, adult WS myocytes had 68% larger cross-sectional area and occurred at 28% lower fibers/area than those of adult STS. We demonstrate that age-related muscle senescence does occur in wild-caught, short-lived mammals, and we therefore reject this classic aging theory tenet. Our findings moreover illustrate that differential age adjustments in contractile/connective tissue components of muscle occur in the two species of wild-caught shrews.

A Peculiar Cusp on the Fourth Upper Premolar of the Japanese Water ShrewChimarrogale platycephala

The Japanese water shrew, Chimarrogale platycephala is distributed over Honshu and Kyushu, Japan. Occasionally this shrew species displays a small cusp at the anterolingual portion to hypocone of the fourth upper premolar (P 4 ) (Fig. 1). To date, this cusp has not been recorded from Chimarrogale or the related mammals (Repenning 1967; Kawamura 1992; Dannelid 1998). In the present paper, I have investigated the variation of this cusp in C. platycephala from Japan and in C. himalayica from Nepal and Taiwan.

Non‐invasive genetic identification of small mammal species using real‐time polymerase chain reaction

DNA identification of non-invasive samples is a potentially useful tool for monitoring small mammal species. Here we describe a novel method for identifying five small mammal species: wood mouse, bank vole, common shrew, pygmy shrew and water shrew. Species-specific real-time polymerase chain reaction primers were designed to amplify fragments of the mitochondrial cytochrome b gene from hair and scat samples. We also amplified nuclear DNA from scats, demonstrating their potential as a source of DNA for population genetic studies.

Differences in swimming and diving abilities between two sympatric species of water shrews: Neomys anomalus and Neomys fodiens (Soricidae)

Swimming and diving abilities of two syntopic species of water shrews, Neomys anomalus and Neomys fodiens, were tested in aquaria using video recordings taken from three views (lateral distant, lateral close and dorsal). The frequency and total duration of diving, as well as the mean duration of diving and floating bouts, were significantly higher in N. fodiens than in N. anomalus. Frequency of paddling during surface swimming was lower in N. fodiens than in N. anomalus. N. fodiens dived mainly for long distances at the bottom of the aquarium and performed a wider range of dive profiles than N. anomalus, which preferred rather short and shallow dives. The two species differed also significantly in their fineness ratios (describing how streamlined their bodies are) when diving. When swimming, N. fodiens had a relatively wider body and performed narrower movements with its tail than N. anomalus. These results show quantitatively and qualitatively for the first time that N. fodiens is more proficient at swimming and diving than N. anomalus. The results also help to explain the inter-specific differences in efficiency of underwater foraging, and support the idea of segregation of ecological niches of these species based on their different foraging modes (diving vs. wading).

増補版食虫類の自然史7．カワネズミの生態と保全 最近の知見

増補版食虫類の自然史7．カワネズミの生態と保全 最近の知見

Effects of latitude and allopatry on body size variation in European water shrews

We studied the intra- and interspecific size variability of 271 water shrewsNeomys fodiens (Pennant, 1771) andN. anomalus Cabrera, 1907 from seven sample sites along a latitudinal transect from Bosnia and Herzegovina to Poland.Neomys anomalus was the only water shrew in three Dinaride karst fields, while it was sympatric with N.fodiens in remaining sites. The first principal component scores (PC1; 72.2% of variance explained), derived from principal components analysis of 13 cranial, mandibular and dental measurements, were used as the size factor. One-way ANOVA detected significant interpopulation variation in both species; intraspecific variation, however, was much more pronounced inN. anomalus. No latitudinal size pattern was found in N. fodiens (r = −0.42, p = 0.58), while mean PC1 scores correlated significantly and negatively with latitude inN. anomalus (r = −0.92, p = 0.004). Therefore, along a north to south transect,N. anomalus converged in size towards N. fodiens, which suggests that the former species occupies increasingly more aquatic habitats in the same direction. Individuals from allopatric populations ofN. anomalus from Slovenia and Bosnia and Herzegovina were, on average, larger than sympatric conspecific populations from the same latitudinal zone, which is consistent with the hypothesis of character displacement.