The body condition index (BCI) is an indicator of both reproductive success and health in small mammals and might help to understand ecological roles of species. We analyzed BCI data from 28,567 individuals trapped in Lithuania between 1980 and 2023. We compared BCIs between species and examined differences in age groups, gender, and reproductive statuses within each species. Seven out of eighteen species had sample sizes with N < 100. In terms of species, we found that seven of the eight species with the highest average BCIs are granivores or omnivores, which can consume animal-based food at least seasonally. The two contrasting (decreasing or increasing) BCI patterns observed during ontogeny can be related to diet differences among juveniles, subadults, and adult animals. Our results demonstrate that reproductive stress has a negative impact on the BCI of adult females in all analyzed species and nearly all adult males. Although the animals with extremely low BCI consisted mostly of shrews, for the first time we found 23 common and pygmy shrews exhibiting the Chitty effect, i.e., a very high body mass resulting in a BCI > 5.0. This is the first multi-species approach of body condition at middle latitudes. The results increase our understanding of how changing environmental conditions are affecting small mammals.

Fire shapes animal communities by altering resource availability and species interactions, including between predators and prey. In Australia, there is particular concern that two highly damaging invasive predators, the feral cat (Felis catus) and European red fox (Vulpes vulpes), increase their activity in recently burnt areas and exert greater predation pressure on the native prey due to their increased exposure. We tested how prescribed fire occurrence and extent, along with fire history, vegetation, topography, and distance to anthropogenic features (towns and farms), affected the activity (detection frequency) of cats, foxes, and the native mammal community in south-eastern Australia. We used camera traps to quantify mammal activity before and after a prescribed burn and statistically tested how the fire interacted with these habitat variables to affect mammal activity. We found little evidence that the prescribed fire influenced the activity of cats and foxes and no evidence of an effect on kangaroo or small mammal (<800 g) activity. Medium-sized mammals (800-2000 g) were negatively associated with prescribed fire extent, suggesting that prescribed fire has a negative impact on these species in the short term. The lack of a clear activity increase from cats and foxes is likely a positive outcome from a fire management perspective. However, we highlight that their response is likely dependent upon factors like fire size, severity, and prey availability. Future experiments should incorporate GPS-trackers to record fine-scale movements of cats and foxes in temperate ecosystems immediately before and after prescribed fire to best inform management within protected areas.

A 3-year-old, 420 g, intact male African pygmy hedgehog (Atelerix albiventris) was presented with a sudden appearance of a mass protruding from its preputium. A detailed physical examination revealed the presence of a polyp-like mass, connected to the mucous membrane of the penis and a second, multilobular mass with a larger base. Both masses were surgically removed. While the histopathological examination of the polyp-like mass revealed only a chronic active inflammatory reaction, the histopathological examination of the multilobular mass revealed a tumorous tissue composed of spindle-shaped cells, irregularly oval or polygonal in some places. Focal tumour cells with a myxoid differentiation were observed in the greater part of this tumour. The stroma was made up of sparse fibrous tissue. The surface epithelium was hyperplastic with ulcerations and necrosis. The tumour was classified as a myxofibrosarcoma. Two weeks post-surgery, the patient did not show any clinical signs of the presented disease. According to our knowledge, this is the first published case of the surgical treatment of penile myxofibrosarcoma in an African pygmy hedgehog.

Bartonella is an intracellular parasitic zoonotic pathogen that can infect animals and cause a variety of human diseases. This study investigates Bartonella prevalence in small mammals in Yunnan Province, China, focusing on tissue tropism. A total of 333 small mammals were sampled from thirteen species, three orders, four families, and four genera in Heqing and Gongshan Counties. Conventional PCR and real-time quantitative PCR (qPCR) were utilized for detection and quantification, followed by bioinformatic analysis of obtained DNA sequences. Results show a 31.5% detection rate, varying across species. Notably, Apodemus chevrieri, Eothenomys eleusis, Niviventer fulvescens, Rattus tanezumi, Episoriculus leucops, Anourosorex squamipes, and Ochotona Thibetana exhibited infection rates of 44.4%, 27.7%, 100.0%, 6.3%, 60.0%, 23.5%, and 22.2%, respectively. Genetic analysis identified thirty, ten, and five strains based on ssrA, rpoB, and gltA genes, with nucleotide identities ranging from 92.1% to 100.0%. Bartonella strains were assigned to B. grahamii, B. rochalimae, B. sendai, B. koshimizu, B. phoceensis, B. taylorii, and a new species identified in Episoriculus leucops (GS136). Analysis of the different tissues naturally infected by Bartonella species revealed varied copy numbers across different tissues, with the highest load in spleen tissue. These findings underscore Bartonella\'s diverse species and host range in Yunnan Province, highlighting the presence of extensive tissue tropism in Bartonella species naturally infecting small mammalian tissues.

Representatives of the genus Sarcocystis are worldwide distributed apicomplexan parasites characterised by two-host prey-predator relationships. Sarcocystis spp. produce sarcocysts in the muscles and brains of intermediate hosts and develop sporocysts in the intestines of definitive hosts. Two species, Sarcocystis glareoli and Sarcocystis microti, previously assigned to the genus Frenkelia, form cysts in the brains of rodents and are transmitted through the common buzzard (Buteo buteo). In our study, brain samples of 694 small mammals caught in different regions of Lithuania were examined for Sarcocystis spp. Additionally, 10 B. buteo and two rough-legged buzzards (Buteo lagopus) were tested for sporocysts of the analysed parasites. Sarcocystis species were identified based on 28S rRNA sequence comparison. Of the eleven species of small mammals tested, Sarcocystis parasites were observed only in the bank vole (Clethrionomys glareolus). Cysts of S. glareoli were detected in 34 out of 374 C. glareolus (9.1%, 95% CI = 6.4-12.5%). Molecular investigation showed the presence of only S. glareoli in the intestines of 50% of B. buteo. Furthermore, two species, Sarcocystis sp. Rod3 and Sarcocystis sp. Rod4, were confirmed in B. lagopus. Our results demonstrate the need for further studies on Sarcocystis cycling between rodents and birds.

Activity indices are used to determine the presence and activity of small mammals, such as the hair index derived from the use of hair tubes. In contrast to trapping animals, hair tubes are non-invasive and less labor-intensive, and appear to be a suitable alternative in appropriate settings. We developed a method to calculate hair density semi-automatically. In addition, hair tube data were validated with field data using wildlife cameras for the small mammal community in grassland, wheat crops, and hedges to assess how well data from hair tubes match data from wildlife cameras. Adhesive tape with hair from hair tubes was processed and scanned. The resulting images were analyzed using a newly developed computer program that enables background and adhesive tape to be automatically distinguished from hair, providing a quantitative measure of hair density. Based on validation with wildlife cameras, hair tubes seem to be a suitable tool to estimate small mammal activity at the community level in several habitats. There was a moderate-to-strong positive correlation of the hair tube index with the sum of voles and Apodemus individuals (activity index) recorded in grasslands (Spearman\'s correlation coefficient 0.43), hedges (0.79), and wheat (0.44). The newly developed computer program allows the automatic calculation of hair density, making it easier to assess the activity of small mammals.

Bergmann\'s and Allen\'s rules are two classic ecogeographic rules concerning the physiological mechanisms employed by endotherm vertebrates for heat conservation in cold environments, which correlate with adaptive morphological changes. Thus, larger body sizes (Bergmann\'s rule) and shorter appendages and limbs (Allen\'s rule) are expected in mammals inhabiting cold environments (higher latitudes). Both rules may also apply to elevational gradients, due to the decrease in external temperature as elevation increases. In this study, we evaluated whether these patterns were true in two coexisting sigmodontine rodents across an elevational gradient in central Chile. We analyzed whether the size of the skull, body, and appendages of Abrothrix olivacea (n = 70) and Phyllotis darwini (n = 58) correlated with elevation, as predicted by these rules in a range between 154 and 2560 m. Our data revealed weak support for the Bergmann and Allen predictions. Moreover, we observed opposite patterns when expectations of Bergmann\'s rules were evaluated, whereas Allen\'s rule just fitted for ear size in both rodent species. Our results suggest that morphological changes (cranial, body, and appendage sizes) may play a minor role in the thermoregulation of these two species at high elevations, although behavioral strategies could be more critical. Other ecological and environmental variables could explain the morphological trends observed in our study. These hypotheses should be assessed in future studies to consider the relative contribution of morphology, behavior, and physiological mechanisms to the thermal adaptation of these two rodent species at high elevations.

Himalayan shrews of the genus Soriculus (Soricidae, Eulipotyphla), currently represented by four nominal species, are endemic to the Himalayas and the Gaoligong Mountains. In April 2022 and April 2023, a total of 10 specimens of Soriculus were collected from Beibeng and Damu, Medog County, Tibet, China. The morphology of the specimens was compared with the four recognised species of the genus Soriculus. Additionally, two mitochondrial (Cyt b and 12S) and three nuclear (APOB, BRCAI and RAG2) genes were sequenced to test the phylogenetic relationships of these specimens with the other species. Our results indicate that these specimens represent a distinct species, Soriculusbeibengensissp. nov., which is formally described here. The new species is distinguished from the other Soriculus species by the combination of darker pelages, smaller size, the relatively stubby nasal and the widened posterior processes of incisors. Phylogenetic analyses revealed the new species is sister to S.minor. The p-distance of Cyt b gene between S.beibengensis sp. nov. and other nominal Soriculus species ranges from 9.1-16.3%. This new species has a known distribution at an elevation of 1,500-2,125 m in Medog County, Tibet, China. The discovery of this new species from Medog County has important implications for interpreting small mammal biogeographic patterns in the eastern Himalaya and the mountain chains of south-west China.

The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary processes. Here, we studied the spatial distribution of related individuals within a population of corn mice Calomys musculinus in a seasonal cycle to infer dispersal patterns. The sampling was carried out from spring 2005 to winter 2006 in field borders of intensively managed agroecosystems. Genotyping data from 346 individuals with 9 microsatellites showed spatial genetic structure was weak for males, but not for females. The results indicate a complex spatial kinship dynamic of related females across all seasons. Which, contrary to our expectations, dispersal distances decrease with the increase of the population abundance. Meanwhile, male dispersal distances were greater when population abundance increased and thus the availability of active females. Males disperse greater distances to mate and sire offspring with distant females as a possible inbreeding avoidance mechanism. This study shows that C. musculinus is capable of much greater scattering distances than previously reported and that dispersal occurs fluidly and without barriers across the agroecosystem. The indirect benefit of dispersal on individual fitness could be related to relaxing the competition in the natal area and increasing the mating rate. Our study highlights the value of combining genetic relatedness, fieldwork observations, and behavioral data to estimate dispersal at a fine geographical scale.

Companion animal ownership has evolved to new exotic animals, including small mammals, posing a new public health challenge, especially due to the ability of some of these new species to harbour zoonotic bacteria, such as Salmonella, and spread their antimicrobial resistances (AMR) to other bacteria through the environment they share. Therefore, the objective of the present pilot study was to evaluate the current epidemiological AMR situation in commensal Escherichia coli and Salmonella spp., in non-traditional companion animal small mammals in the Valencia region. For this purpose, 72 rectal swabs of nine different species of small mammals were taken to assess the antimicrobial susceptibility against 28 antibiotics. A total of one Salmonella enterica serovar Telelkebir 13,23:d:e,n,z15 and twenty commensal E. coli strains were isolated. For E. coli strains, a high prevalence of AMR (85%) and MDR (82.6%) was observed, although neither of them had access outside the household. The highest AMR were observed in quinolones, one of the highest priority critically important antimicrobials (HPCIAs) in human medicine. However, no AMR were found for Salmonella. In conclusion, the results showed that small mammals\' commensal E. coli poses a public health risk due to the high AMR found, and the ability of this bacterium to transmit its resistance genes to other bacteria. For this reason, this pilot study highlighted the need to establish programmes to control AMR trends in the growing population of new companion animals, as they could disseminate AMR to humans and animals through their shared environment.