Small Mammal Taxa Research Articles

Vector competence of Ixodes ricinus instars for the transmission of Borrelia burgdorferi sensu lato in different small mammalian hosts

BackgroundMany pathogens and parasites can infect multiple host species, and the competence of different hosts as pathogen reservoirs is key to understanding their epidemiology. Small mammals are important hosts for the instar stages of Ixodes ricinus ticks, the principal vector of Lyme disease in Europe. Small mammals also act as reservoirs of Borrelia afzelii, the most common genospecies of the Borrelia burgdorferi sensu lato (s.l.) spirochetes causing Lyme disease in Europe. However, we lack quantitative estimates on whether different small mammal species are equally suitable hosts for feeding I. ricinus and whether they show differences in pathogen transmission from host to tick.MethodsHere, we analysed the feeding success and prevalence of B. burgdorferi s.l. infections in 12,987 instar I. ricinus found on captured small mammals with known infection status in Norway (2018–2022).ResultsWe found that larvae were more likely to acquire a blood meal from common shrews (Sorex araneus, 46%) compared to bank voles (Myodes glareolus, 31%) and wood mice (Apodemus sylvaticus, 36%). Nymphs tended to be more likely to acquire a blood meal from wood mice (66%) compared to bank voles (54%). Common shrews harboured few nymphs (n=19). Furthermore, we found that larvae feeding on infected bank voles (11%) were more likely to be infected with B. burgdorferi s.l. than larvae on infected common shrews (7%) or wood mice (4%).ConclusionsOur study provides quantitative evidence of differences in suitability for the instar stages of I. ricinus across taxa of small mammals and highlights how even known small mammal host species can differ in their ability to feed ticks and infect larval ticks with the pathogen causing Lyme disease.Graphical

Dispersal and early evolution of the first modern cricetid rodents in Western Europe: new data from the Vallès-Penedès Basin (Catalonia)

Modern cricetids originated in Asia and dispersed into Western Europe by the end of the early Miocene, where they quickly became major components of the rodent faunas. Here we review the early Miocene rodent record of the genera Democricetodon Fahlbusch, 1964 and Megacricetodon Fahlbusch, 1964 in the Vallès-Penedès Basin (Catalonia, Spain). Democricetodon is represented by four species in the studied sites (D. hispanicus Freudenthal, 1967, D. cf. decipiens (Freudenthal & Daams, 1988), D. gracilis Fahlbusch, 1964 and a large-sized undetermined species) and Megacricetodon by one (M. primitivus (Freudenthal, 1963)). The cricetid succession bears several similarities with that of the nearby Calatayud-Montalbán Basin (East-Central Spain) to the point that the same detailed local biostratigraphy could be extended to the Catalan basin. The rare presence of certain Democricetodon species (D. gracilis) and other small mammal taxa also reveal affinities with regions beyond the Iberian Peninsula and indicate that the Vallès-Penedès Basin was more humid and forested than inland Iberian basins during the early Miocene.

Small mammals killed in discarded bottles along roadsides in central Nebraska

Littered debris along roadways traps and kills small vertebrates. In Nebraska, at least 20 species of small mammals are small enough to enter openings of discarded bottles and cans. We surveyed roadsides for littered bottles and cans containing vertebrate remains in central parts of the state. We observed 459 bottles and 278 aluminum cans along 17.6 km of roadsides in Nebraska. Littered bottles contained 41 vertebrate remains representing nine taxa of small mammals. Glass bottles contained the majority of individuals, plastic bottles had a few individuals, and no vertebrate remains were detected in aluminum cans. Harvest mice (Reithrodontomys spp.) were the most frequently observed taxa trapped in bottles, followed by short-tailed shrews (Blarina spp.). Remains of a juvenile Hispid Cotton Rat (Sigmodon hispidus) in a glass bottle suggest that more species are at risk when individuals are young. Bottles with openings higher than their base contained more vertebrates (21.1%) than those lying flat (3.8%) or those with openings facing downward (1.2%). Overall, about 5.7% of bottles had vertebrate remains in Nebraska, which is slightly greater than studies in the eastern United States. Densities of littered bottles were much lower along roads in Nebraska than roadways in the eastern United States, resulting in fewer mortalities per km. Human population density appears associated with littered debris, thus numbers of vertebrates killed in these roadside hazards likely is greater in eastern Nebraska and near population centers where most of the state’s population reside. In Nebraska, six species of small mammals are species of conservation need, and thus, at risk from littered debris. Reduction and removal of litter along roadsides not only is aesthetically pleasing, but it can also reduce mortality of small mammals and other animals, such as small insects.

Pequeños vertebrados del relleno kárstico del Pleistoceno Superior de Avetrana (Apulia, Sur de Italia)

El depósito (cavidad kárstica) de La Grave, localidad cercana a la pequeña ciudad de Avetrana (Tarento, Italia meridional), ha dado lugar a numerosos fósiles de vertebrados. Los restos de grandes mamíferos han sido objeto de varios estudios. En este trabajo se examinan los restos de pequeños vertebrados y se identifican cuatro taxones de anfibios (Bufo bufo, Bufotes gr. B. viridis, Hyla gr. H. Arborea and Rana (s.l.) sp.), cuatro de reptiles (Testudo hermanni, Podarcis sp., Zamenis gr. Z. longissimus, Natrix natrix), y nueve de pequeños mamíferos (Erinaceus europaeus, Crocidura suaveolens, Arvicola italicus, Microtus (Terricola) savii, Microtus (Microtus) arva­lis, Apodemus gr. A. sylvaticus - A. flavicollis, Hystrix (Acanthion) vinogradovi, Oryctolagus cuniculus and Lepus corsicanus). Desde un punto de vista biocronológico, los datos sobre los vertebrados pequeños y grandes indican una edad entre el comienzo del Pleistoceno tardío (MIS 5e) y la parte central del MIS 3. Es probable que el estrato fosilífero más reciente (nivel 8) se haya depositado durante un período más frío en comparación con las capas anteriores. Los datos de pequeños vertebrados fósiles combinados con los que proceden de los grandes mamífe­ros y aves evidencian la presencia, cerca de la cavidad kárstica, de espacios abiertos (praderas) con charcos de agua, bordeados por zonas boscosas y, no muy lejos, la presencia de una costa rocosa.

New records of bats and terrestrial small mammals from the Seli River in Sierra Leone before the construction of a hydroelectric dam.

Sierra Leone is situated at the western edge of the Upper Guinean Forests in West Africa, a recognised biodiversity hotspot which is increasingly threatened by habitat degradation and loss through anthropogenic impacts. The small mammal fauna of Sierra Leone is poorly documented, although bats and rodents account for the majority of mammalian diversity. Based on morphological, genetic and echolocation data, we recorded 30 bat (Chiroptera), three shrew (Soricomorpha) and eleven rodent (Rodentia) species at the Seli River in the north of the country in 2014 and 2016, during a baseline study for the Bumbuna Phase II hydroelectric project. In 2016, 15 bat species were additionally documented at the western fringe of the Loma Mountains, a recently established national park and biodiversity offset for the Bumbuna Phase I dam. Three bat species were recorded for the first time in Sierra Leone, raising the total number for the country to 61. Further, two bat species are threatened and endemic to the Upper Guinean Forest and several taxa of small mammals are poorly known or represent undescribed species. Overall, the habitats of the project area supported a species-rich small mammal fauna including species of global conservation concern. Suitable mitigation measures and/or offsets are necessary to maintain biodiversity and ecosystems in a region that is under high human pressure.

Factors affecting the permeability of road mitigation measures to the movement of small mammals

Mitigation measures, such as wildlife-exclusion fencing and crossing structures (overpasses, underpasses, culverts), have been widely demonstrated to reduce the negative effects of roads on medium-sized and large animals. It is unclear how these mitigation measures influence the movement of small mammals (<5 kg). Our study has three objectives: (1) to test whether culverts improve highway permeability; (2) to determine factors associated with culvert use, such as culvert obstruction by snow; (3) to evaluate factors contributing towards fence permeability, such as the presence of a culvert, snow depth, and fence mesh size. We used snow tracking to assess the movement for four small-mammal taxa along the Trans-Canada Highway corridor in Banff National Park, Alberta, Canada. We found that the presence of a culvert within 100 m of transects significantly improved fence and highway permeability. Obstruction of the culvert entrance by snow was negatively correlated with the probability of use, and therefore, of highway permeability. Furthermore, the mesh size of the fencing did not affect fence or highway permeability. We recommend that culvert entrances be located on the outside of fenced right-of-ways to reduce obstruction by highway maintenance activities such as snowplowing.

FossilMustela nigripesfrom Snake Creek Burial Cave, Nevada, and Implications for Black-Footed Ferret Paleoecology

Morphometric measurements were used to classify 11 mustelid dentaries from Snake Creek Burial Cave (SCBC), a late Pleistocene to early Holocene—aged paleontological locality in eastern Nevada, that were undifferentiated between Mustela nigripes (black-footed ferret) and Neovison vison (American mink) due to their similar size and morphology. We, therefore, classified the SCBC fossils using 10 linear measurements of the dentary using extant M. nigripes and N. vison as proxy. Discriminant function and principal component analyses grouped the 11 unknown SCBC specimens within extant M. nigripes exclusively. Confirmation of M. nigripes at SCBC is significant because Cynomys spp. (their primary prey source today) have not been found at this site or other nearby Great Basin localities. Occurrence of this now-endangered taxon among the SCBC paleofauna and review of additional localities lacking Cynomys suggest that several geographically and temporally discrete prehistoric M. nigripes populations were sustained by other small mammal taxa. If this inference is true, facilitating dietary diversity in reintroduced M. nigripes populations could improve the species' resilience to future adversities, including anthropogenic climate change.

Eagles, owls, and coyotes (oh my!): Taphonomic analysis of rabbits and guinea pigs fed to captive raptors and coyotes

There is the potential for multiple accumulating agents of small mammals (<4.5kg body weight) at fossil sites, however, the lack of diverse predator and prey experimental and actualistic studies often makes it difficult to attribute the accumulator(s) of small mammals. I report the results of experimentally created assemblages of rabbits (Oryctolagus cuniculus) and guinea pigs (Cavia porcellus) fed to a bald eagle (Haliaeetus leucocephalus), great horned owl (Bubo virginianus), and coyote (Canis latrans). The analysis provides a taphonomic assessment of two small mammal taxa that differ in size and build and are broadly representative of small mammals recovered from archaeological sites. The ingested and non-ingested portions of the prey remains were analyzed for skeletal-, digested-, deleted-, and fractured-part representation, bone breakage, and bone surface modifications. The rabbit and guinea pig samples are compared and taphonomic differences between predators and prey taxa are observed. The predators produced variable and distinctive intra- and interspecific skeletal-, digested-, deleted-, and fractured part profiles. Bone surface modification frequency differences between the samples show a mixture of significant and non-significant intra- and interspecific comparisons. This study expands the range of small mammal experimental and actualistic studies to include prey of underrepresented size and build (guinea pigs) and characterizes the signatures of predator accumulations of small mammals. Often archaeological assemblages feature a mixture of accumulators, this analysis of raptor and mammalian carnivore predation on rabbits and guinea pigs will aid in the differentiation of predation between raptors, mammalian carnivores, and humans in the archaeological record.

How Far into Europe Did Pikas (Lagomorpha: Ochotonidae) Go during the Pleistocene? New Evidence from Central Iberia.

This paper reports the first find of pika remains in the Iberian Peninsula, at a site in central Spain. A fragmented mandible of Ochotona cf. pusilla was unearthed from Layer 3 (deposited some 63.4±5.5 ka ago as determined by thermoluminescence) of the Buena Pinta Cave. This record establishes new limits for the genus geographic distribution during the Pleistocene, shifting the previous edge of its known range southwest by some 500 km. It also supports the idea that, even though Europe’s alpine mountain ranges represented a barrier that prevented the dispersal into the south to this and other taxa of small mammals from central and eastern Europe, they were crossed or circumvented at the coldest time intervals of the end of the Middle Pleistocene and of the Late Pleistocene. During those periods both the reduction of the forest cover and the emersion of large areas of the continental shelf due to the drop of the sea level probably provided these species a way to surpass this barrier. The pika mandible was found accompanying the remains of other small mammals adapted to cold climates, indicating the presence of steppe environments in central Iberia during the Late Pleistocene.

Small mammals and stratigraphic position of the “Großberg-Bank” (lower Oberrad Formation, MN1, early Miocene) at Laubenheim Quarry in the Mainz Basin, SW Germany, and their implications for early Miocene biostratigraphy

The Grosberg-Bank from the limestone quarry Mainz-Laubenheim (Heidelberger Zementwerke AG) southeast of Mainz, which is part of the Oberrad Formation of the Mainz Basin, yielded a relatively rich earliest Miocene vertebrate association. Within the Hydrobia marl of the Grosberg-Bank, a large number of disarticulated bones, about 480 teeth, and several mandible fragments of mainly medium-sized terrestrial mammals have been recovered in addition to other vertebrate faunas. Twenty taxa could be identified, thereof 13 small mammal taxa. Based on the coexistence of a progressive form of the eomyid Rhodanomys schlosseri and the moschids Pomelomeryx cf. boulangeri and Amphitragulus sp. the locality is placed within the uppermost MN1 zone, a similar level to that of the locality Lautern 2 (Lower Freshwater Molasse, southern Germany). Comparisons with the mammalian assemblages of various Central European MN1 and MN2 localities confirm this correlation. The terrestrial vertebrates of the Grosberg-Bank have been washed in by streams with accompanying gallery forests pervading the apparently savannah-like hinterland of the Mainz Basin lagoon.

Diversity and richness of small mammals at a well-conserved site of The Yungas in Jujuy Province, Argentina

AbstractWe present the results obtained from 12 small-mammal surveys conducted between 1996 and 2013 in “Finca Las Capillas”, province of Jujuy, Argentina. This region has been formally recognized as an “Area of Importance for the Conservation of Bats” (AICOM) based on the diversity of species detected in our previous studies. This site in the Yungas forests of northwestern Argentina still maintains an excellent conservation status due to restrictions to human activities involving deforestation and limitations to cattle-raising imposed 50 years ago. A total of 39 species belonging to three orders, namely, Didelphimorphia, Chiroptera and Rodentia, were recorded. The species accumulation curve revealed that our records represent 83–95% of the community, and with high diversity indexes. Several of the genera and species that we recorded from our collection trips have been included in the fauna of Argentina. Our previous studies and the present findings provide new records for the province or significant extensions to previously known distributions of several taxa of small mammals. These results show that the site represents an icon for conservation in such a fragmented and exploited area as the Yungas in Argentina today.

Evolutionary and ecological response of pocket gophers (Thomomys talpoides) to late-Holocene climatic change

Late-Holocene evolutionary and ecological response of pocket gophers (Thomomys talpoides) and other species to climatic change is documented by mammalian fossils from Lamar Cave, a palaeontological site in northern Yellowstone National Park. Pocket gophers illustrate ecological sensitivity to a series of mesic to xeric climatic excursions in the sagebrush-grassland ecotone during the last 3200 years, increasing in abundance during mesic intervals, and declining in abundance during xeric intervals. Four other small mammal taxa (Microtussp.,Peromyscus maniculatus, Neotoma cinereaandSpermophilus armatus) also show response to climatic change, increasing or decreasing in abundance in accordance with their preferred habitat requirements. To determine evolutionary response to climate, two craniodental characters for the northern pocket gopher (Thomomys talpoides) are investigated in modern representatives within a 400 km radius of Lamar Cave and then tracked through the time spanned by the fossils. One morphologic character shows that variation in body size, primarily a plastic response to the environment, demonstrates few taxonomically consistent patterns of geographic variation across 39 modern localities. In contrast, the other character indicates genetic relatedness within subspecies. Stasis in the genetically controlled character indicates that the same subspecies of pocket gopher (T. talpoides tenellus) has occupied northern Yellowstone for at least 3200 years. However,T. t. tenellusdoes show plastic response to climatic change because pocket gophers during the Medieval Warm Period were smaller than at any other time spanned by the deposit.

Evolutionary and ecological response of pocket gophers (Thomomys talpoides) to late-Holocene climatic change

Late-Holocene evolutionary and ecological response of pocket gophers (Thomomys talpoides) and other species to climatic change is documented by mammalian fossils from Lamar Cave, a palaeontological site in northern Yellowstone National Park. Pocket gophers illustrate ecological sensitivity to a series of mesic to xeric climatic excursions in the sagebrush-grassland ecotone during the last 3200 years, increasing in abundance during mesic intervals, and declining in abundance during xeric intervals. Four other small mammal taxa (Microtus sp., Peromyscus maniculatus, Neotoma cinerea and Spermophilus armatus) also show response to climatic change, increasing or decreasing in abundance in accordance with their preferred habitat requirements. To determine evolutionary response to climate, two craniodental characters for the northern pocket gopher (Thomomys talpoides) are investigated in modern representatives within a 400 km radius of Lamar Cave and then tracked through the time spanned by the fossils. One morphologic character shows that variation in body size, primarily a plastic response to the environment, demonstrates few taxonomically consistent patterns of geographic variation across 39 modern localities. In contrast, the other character indicates genetic relatedness within subspecies. Stasis in the genetically controlled character indicates that the same subspecies of pocket gopher (T. talpoides tenellus) has occupied northern Yellowstone for at least 3200 years. However, T. t. tenellus does show plastic response to climatic change because pocket gophers during the Medieval Warm Period were smaller than at any other time spanned by the deposit.

Effects of phylogenesis, morphology and habitat preferences on predatory exposure in a Mediterranean small mammal community

Data obtained in three‐year field study on a Mediterranean prey‐predators community in central Italy are discussed. In particular, the aim of this paper was to test whether some parameters linked to the morphology, phylogenesis and habitat preferences of a given potential prey could affect its predatory exposure. Eight predator species belonging to two different guilds (snakes and owls) were found at the study area, while ten preyed small mammal taxa were recognized in predator diets. One of the main factors emerging from this study was the great importance of body mass similarity in assessing the degree of overlap of predatory exposure between two small mammal taxa. On the contrary, the phylogenetic relationship between prey was of very little importance, probably because each phylogenetic group is composed by different potential prey species living in different habitats. In conclusion, due to the apparent lack of importance in the overlap of habitat preferences between the various prey in the overlapping of their predatory exposure, it could be stressed that the body mass similarity can be said to play the most relevant role in determining the overlap of predator community, exerciting a selective pressure on two different preyed taxa, and their effective predation risk.

Small mammals (Insectivora, Lagomorpha, and Rodentia) from the early Pleistocene (Irvingtonian) Leisey Shell Pit Local Fauna, Hillsborough County, Florida

Twelve species of small mammals, including one species of Insectivora, two species of Lagomorpha, and nine species of Rodentia, are reported from the early Pleistocene (early Irvingtonian) Leisey Shell Pit Local Fauna, Hillsborough County, Florida. Most taxa of small mammals are rare in the Leisey fauna. The most common species is the sigmodontine rodent Sigmodon libitinus, followed in abundance by the hydrochaerid Neochoerus sp., the arvicoline Pedomys sp., the soricid Blarina cf. B. carolinensis, the geomyid Geomys pinetis, the giant castorid Castoroides leiseyorum, the erethizontid Erethizon dorsatum, and the leporid Sylvilagus floridanus. Four undescribed species of rodents occur at Leisey, three of which, the arvicolines Pedomys and Synaptomys sp. and the large peromyscine Podomys sp., are represented by insufficient material for formal description. Castoroides leiseyorum is described as a new species that differs from the Rancholabrean C. ohioensis in the absence of a mesopterygoid fossa, but is similar to lhe latter in size and most other morphological characters. Biochronological analysis of the rodents and lagomorphs from Leisey indicates a late early Irvingtonian age, probably between 1.3 and 1.0 Ma. C. leiseyorum, S. libitinus, and the undescribed species of Pedomys, Synaptomys, and Podomys are known only from Florida late early Irvingtonian faunas. The records of S. floridanus, G. pinetis, and E. dorsatum from Leisey are among the oldest occurrences of these extant species. Other Florida small mammal faunas similar in age to Laisey are Haile 16A, Haile 21A, and Payne Creek Mine. Correlative early Irvingtonian faunas from western North America include: Gilliland, Texas; Holloman, Oklahoma; Kentuck and Wathena, Kansas; Sappa, Nebraska; and Java, South Dakota.

Small Mammals from a Holocene Sequence in Central Texas and Their Paleoenvironmental Implications

An abundant and diverse vertebrate fauna including 15 taxa of small mammals has been recovered from the Wilson-Leonard archaeological site (41 WM 235), Williamson Co., Texas. Faunal remains are from a 4.5-m continuous stratigraphic section dating from over 9,000 YBP to <2,000 YBP. The presence of Microtus pinetorum-ochrogaster (pine vole-prairie vole), Oryzomys palustris (northern rice rat), and Blarina sp. (short-tailed shrew) in the sequence suggest moister conditions in central Texas during that time interval. The Wilson-Leonard archaeological site contains a fossiliferous stratigraphic sequence preserved in an open-air deposit. This is unusual in central Texas where most Holocene fossils have been recovered from caves and represent deposition during short periods of time (Lundelius, 1967). Several taxa from the site no longer live in the study area, including Microtus, Oryzomys, Blarina, and Onychomys. Of these, most prefer habitats with more available moisture than there is at present in Williamson Co. Onychomys is generally found in somewhat more arid environments than currently present in this area. Paleoenvironmental reconstruction from the Wilson-Leonard small mammals supports the work of others (Lundelius, 1967; Bryant and Holloway, 1985; Graham, 1987) suggesting that along with an overall warming trend, more moist conditions were prevalent in central Texas for much of the Holocene. MATERIALS AND METHODS-The Wilson-Leonard archaeological site was situated along the northeastern edge of the Edwards Plateau near the city of Leander, Williamson Co., Texas (Fig. 1). Austin, the nearest major city, was about 32 km to the southeast. The site was located along Spanish Oak Creek near its confluence with Brushy Creek. The area was in the Balconian biotic province which was characterized, in this part of the province, by Mexican cedar (Juniperus mexicana), Texas oak (Quercus texana), and stunted live oak (Quercus virginia) (Blair, 1950). Average annual rainfall for the last 10 years was 86.08 cm (United States Department of Commerce, 1977-1986). The Balconan biotic pr vince included a mixture of vertebrate taxa from several different biotic provinces (Blair, 1950). Fossiliferous concentrate (420 kg) were recovered from a column 4.5 m deep in the northwest quadrant of Unit E28/S78. Excavation of the Wilson-Leonard site was by the Texas Department of Highways and Public Transportation, Austin, Texas, under the supervision of F. Weir, who also provided all radiocarbon dates (pers. comm.). Specimens described in this report were recovered by washing sediment from 45 levels through '/16 inch screens. Levels 1 (top) to 45 (bottom) were collected at 10-cm intervals. Concentrate remaining after screening was sorted under a dissecting microscope for vertebrate bones, invertebrates, and plants. Approximately 41,600 identifiable and unidentifiable bones and teeth were recovered. Of these, 3,178 were assigned to small mammal taxa. Vertebrate remains were identified using modern osteological collections at the Shuler Museum of Paleontology, Southern Methodist University, Dallas, Texas. The specimens will be cataloged into the Shuler Museum of Paleontology collections. RESULTS AND DISCUSSION-The majority of identified small mammalian remains are referred to Sylvilagus (cottontail rabbit) and Geomys (pocket gopher). Most of the specimens are poorly preserved and fragmentary. Preservation quality decreases down section, and the paucity of material from the lowest levels is a function of preservation bias rather than original content. Identified specimens (primarily isolated teeth) are easily assigned to genus but are often difficult to identify to species. This content downloaded from 157.55.39.159 on Sun, 18 Sep 2016 05:47:06 UTC All use subject to http://about.jstor.org/terms 200 The Southwestern Naturalist vol. 35, no. 2

Small-Mammal Distributions Across the Prairie-Forest Transition of Minnesota and North Dakota

Thirteen taxa of small mammals were collected in the continuous forest, aspen groves, riparian woodland and prairie areas of the prairie-forest transition. Mammals captured were placed in three groups on the basis of habitat selection. Of the forest species, Peromyscus maniculatus gracilis was the most restricted and occurred only in or near conifer forest. P. leucopus noveboracensis was found in coniferous, deciduous and river-bottom forests and in large aspen groves. Clethrionomys gap peri had a similar distribution, but was also found in some small aspen groves with grassy ground cover. Tamias striatus was collected in the continuous forest and nearby large groves. Eutamias minimus and Synaptomys cooperi were collected only in the continuous forest. The prairie species, P. m. bairdii, Onychomys leucogaster and Microtus pennsylvanicus, were found essentially in grassland situations. P. m. bairdii also occurs in aspen groves and river-bottom forests where P. 1. noveboracensis is absent. M. pennsylvanicus appears to be a permanent resident in young groves with a grassy undercover. The nonselective species, Sorex cinereus, Blarina brevicauda and Zapus hudsonius, were found throughout the area in all habitats trapped. Sorex arcticus may also be present in moister habitats throughout the transition. The small-mammal fauna of the prairie-forest ecotone includes fragments of both prairie and forest faunas and reflects the state of flux in the plant associations.