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The striped field mouse (Apodemus agrarius) is expanding in several European countries, but the details of this process are not always documented due to a lack of long-term studies. We conducted an analysis of changes in relative abundances and proportions of A. agrarius in small mammal communities in nine different habitat groups in Lithuania during 1975–2023. We found an increase in the abundance and proportion of A. agrarius, increasing synanthropization of the species, and tolerance to anthropogenization of habitats. Temporal variations in the relative abundance and proportion of species were observed, with lower values in February–July and higher values in September–January. The main finding is a remarkable increase in species presence in the country after the 1990s, with a peak observed in the 2010s–2020s, confirmed by eight local studies. During these decades, it was the third most abundant species, representing 19.8–20.0% of the individuals caught. It is also important to note that A. agrarius has recently been most abundant in commensal habitats (0.029 ± 0.006 individuals/trap day), with the highest species proportion in agricultural areas (24.8 ± 1.8%). There are many indications that the expansion of A. agrarius in Lithuania is becoming invasive. [ABSTRACT FROM AUTHOR]

Habitat type and habitat change are very important factors in the body condition of small mammals that inhabit them. The response can be positive, increasing, or the opposite, decreasing body condition. We analyzed outliers of the body condition indices (BCIs) of 12 species trapped in nine different habitats during 1980–2023 in Lithuania, a mid-latitude country. Mixed and fragmented habitats, as well as commensal habitats, could be considered the least suitable for small mammals, based on the highest proportions of underfit and low proportions of best-fit individuals. On the contrary, meadows and disturbed habitats (landfills and cormorant colonies) had the highest proportions of best-fit individuals, while the proportion of under-fit individuals was much lower than expected. We found outliers in the BCI in all species, except for the under-fit harvest mice (Micromys minutus), and in all habitats, though not numerous. The presence of the highest BCI in yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) in the disturbed habitats studied and in house mice (Mus musculus) in commensal habitats may be related to the resources provided by these habitats. Our results demonstrate the feasibility of using retrospective small mammal morphometric data to analyze their relationship with habitat. [ABSTRACT FROM AUTHOR]

The Eurasian harvest mouse (Micromys minutus) is a tiny rodent of the Palearctic and Indomalayan regions, with a distinct regional species status in Europe and irregularly varying local numbers. We analysed the population of M. minutus in Lithuania (Northern Europe) based on trapping data from 1975 to 2022 and owl pellet data from 1986 to 2009. Based on both datasets, the proportion of this species in the small mammal community was similar, 1.13% and 0.62%, respectively. The proportions have remained stable across all decades. Relative abundance was 1.19 ± 0.19 individuals per 1000 trap days, stable over the long term and across the country. Irregular fluctuations in abundance were observed in some of the sites surveyed. The highest average RA was recorded in open sedge habitats, meadows and marshes. The absolute highest RA was 88 individuals per 1000 trap days in floodplain meadows after a major flood. Although the negative impact of habitat anthropogenisation has been confirmed, M. minutus does not require special conservation measures in Lithuania. [ABSTRACT FROM AUTHOR]

Cormorant colonies are often viewed negatively by fishermen and foresters due to their extremely high impact on aquatic and terrestrial ecosystems. In forests, the habitats of nesting territories are destroyed, with concomitant impacts on the animal communities. In 2011–2022, investigating three colonies of Great Cormorants (Phalacrocorax carbo), we aimed to test whether their effect on small mammals depends on colony size. In the largest colony in Lithuania, a low species richness, lower diversity and relative abundance, as well as poorer body conditions of the most abundant species was found in the nesting zone. However, once the cormorants left the nesting site, all the parameters recovered. Two small colonies had a positive impact, with higher species richness in the territory of the colony (seven and ten species), diversity (H = 1.56 and 1.49), and relative abundance (27.00 ± 2.32 and 25.29 ± 2.91 ind. per 100 trap days) compared with the control habitat (three and eight species; H = 1.65 and 0.99; 12.58 ± 1.54 and 8.29 ± 1.05 ind./100 trap-days). We conclude that up to a certain colony size, cormorant pressure is a driver of habitat succession and has similar effects on the small mammal community as other successions in disturbed habitats. [ABSTRACT FROM AUTHOR]

The house mouse (Mus musculus) is a most extensively distributed omnivorous rodent species, usually living in close association with humans. Its diet includes various vegetable matter, insects and any available human food. For the first time, we assessed the dietary niche of this species by the isotopic (δ15N and δ13C) compositions of animal hair samples in the gradient of habitats, ranging from natural to fully commensal. The main factors explaining the differences in the isotopic niche of the mice, being the proxy of their diet, were the season and the source of available food. Influence of the habitat was weak, while gender, age, body mass and body condition had no influence on the diet differences. We found that M. musculus dietary niches overlap between different habitats if mice have access to human food. Niches diverge when mice forage outdoors on natural food compared to farms where livestock feed is available. Compared to omnivorous bank vole (Clethrionomys glareolus) living synoptically, M. musculus has much wider dietary niche and consumes more foods of animal origin. Variability of the diet increases the ecological plasticity of this strongly commensal species and, together with behavioural and reproductive adaptability, allows irresistibly occupy various environments. [ABSTRACT FROM AUTHOR]

We tested small mammal (SM) community response to the influence of seasonal floods and habitat transformation in a temporal zone meadow (west Lithuania). The habitat transitioned from a natural flooded meadow in 2008–2012 to a mowed and pastured area in 2020. SM were trapped in late summer to autumn using lines of 25 traps (145 in total), the number of trapping sessions being one or several per year. We tested the hypotheses that: (1) any reaction to the multiple disturbances is species‐specific, that is, the relative abundance of SM species and their proportion in the community differs with respect to the flood magnitude and habitat transformation, and (2) at the guild level, disturbances favor habitat generalists, thereby changing the characteristics of SM community. The average relative density of SM was 20.25 individuals per 100 trap nights (range 7.56–40.67), with 4‐year‐long cyclical changes of density observed. In separate years, we recorded from 4 to 9 species; Shannon's diversity index varied from 0.46 to 2.19, with expressed change of the dominant species. Habitat generalist species were favored, while habitat specialists were disadvantaged. As the meadow transformation progressed, unfavored states in the SM community prevailed, with excessive numbers of granivore and herbivore species present. Our study suggests that multiple disturbances may lead to an increase in relative abundance, species richness, and diversity within the SM assemblages. [ABSTRACT FROM AUTHOR]

The diversity of small mammal communities (SMCs) shows the sustainability of habitats, especially agricultural ones. Gathered over three years, data from 18 sites in Lithuania were used to analyse factors related to several dependent parameters, namely, diversity (Shannon's H, dominance index and number of species trapped); the relative abundance of species in SMCs; and the abundances and proportions of the four most numerous species, specifically common vole, striped field mouse, yellow-necked mouse and bank vole. Using the General Linear Model, we assessed the influence of habitat type (commercial orchards, berry plantations, control meadows and control forests with at least two of these present at every investigation site), age of the orchard or plantation, intensity of agriculture, season and location (central, northern, eastern, southern and western parts of the country). To control temporal data variability, the year was used as a continuous predictor. The model was valid, and explained 14–31% of the listed parameters with p < 0.005 or higher, with the exception of the dominance index and the proportion of the common vole. The time factor (year and season, p < 0.001), intensity of agriculture and site location (p < 0.05) had the highest influences on the model, while those of the habitat type and its age were not significant. Univariate results suggest that old commercial orchards with low intensities of agricultural practice play a role in maintaining the diversity and abundance of SMCs. [ABSTRACT FROM AUTHOR]

By means of 845 questionnaires returned in 2009-2010, public attitudes towards the European bison were assessed in Central Lithuania. Free-ranging European bison have existed in this area for 40 years, inhabiting a suboptimal habitat characterized by intensive agriculture and fragmented forests. Despite 85.0 % of respondents reporting positive attitudes towards bison presence, 47.4 % of respondents considered the animals acceptable only if they were not closer than 10 km from their residence. Over 60 % of respondents suggested increasing the numbers of bison in the country, and 51 % suggested letting them live freely in the wild. The most negative attitude towards an increase in numbers was shown by women, respondents with lower knowledge of the species and inhabitants of biggest settlements. Public awareness relating to the European bison is lacking, as nearly 50 % of persons residing near areas inhabited by bison did not know about their presence. We conclude that, despite the high valuation placed upon the bison by the public and the ability of the bison to survive in open agrolandscapes with fragmented forests, negative public opinion may be a factor limiting the social carrying capacity for the species. Lithuanian human dimensions of this species should be taken into account when introducing the European bison elsewhere in Western Europe. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the changes in the distribution of root vole (Microtus oeconomus) in Lithuania. The study identified the stability of species distribution and abundance over a long period of time. It found that 13 localities with proportions of Microtus oeconomus are located in the south and west of Lithuania. Study authors discovered that the main habitats for Microtus oeconomus include reedbeds, meadows, shrubby areas and shores of water bodies. They also found the factors that influence the changes in Microtus oeconomus distribution, including land use, land reclamation systems, and naturalization of land reclamation systems.

The distribution of Lutra lutra in Lithuania was studied in 2007.2008 by surveying spraints and other signs of its presence (so-called standard monitoring methods). In total, 745 sites were checked in various water bodies: rivers, lakes, reclamation ditches, fish farms, and artificial reservoirs. Out of them, 584 (78.4%) were found positive. Fish farms were the most intensively used habitat . otters were found in all surveyed farms. Artificial reservoirs, medium-sized rivers, and streams were also frequently used. Within 100 m in the environs of a water body only anthropogenic landscape (towns, villages) was found to be a negative factor for otter presence. Other habitats both within 100 m in the environs and on the bank within 20 m, as well as regulation of a water body, did not influence the presence of otters. It is concluded that the situation of otters in Lithuania is good. The population is widely distributed across the country and inhabits various water bodies. [ABSTRACT FROM AUTHOR]

The stability of diversity of syntopic (inhabiting the same habitat in the same time) small mammals in commensal habitats, such as farmsteads and kitchen gardens, and, as a proxy of their diet, their isotopic niches, was investigated in Lithuania in 2019–2020. We tested whether the separation of species corresponds to the trophic guilds, whether their diets are related to possibilities of getting additional food from humans, and whether their diets are subject to seasonal trends. We analyzed diversity, dominance and distribution of hair δ13C and δ15N values. Diversity and dominance was not stable and differed according to human influence. The highest small mammal species richness occurred in commensal habitats that provided additional food. The degree of separation of species was higher in homestead habitats than in kitchen gardens, where a 1.27% to 35.97% overlap of isotopic niches was observed between pairs of species. Temporal changes in δ13C and δ15N values in the hair of the mammals were not equally expressed in different species. The isotopic overlap may depend on dietary plasticity, minimizing interspecific competition and allowing co-existence of syntopic species. Thus, small mammal trophic ecology is likely related to intensity of agricultural activities in the limited space of commensal habitats. [ABSTRACT FROM AUTHOR]

Simple Summary: Babesia microti, the causative agent of human babesiosis, is an intraerythrocytic protozoan parasite, that circulates among small rodents and ixodid ticks in many countries worldwide. Zoonotic and non-zoonotic B. microti strains have been identified in rodent populations in Europe. Analyzing eight species of small rodents collected from different habitats (meadows, forests and their ecotones) in Lithuania, we checked for the presence of B. microti and found the highest infection prevalence to be in Microtus oeconomus and Microtus agrestis rodents. Of note, this study also detected the first reported cases of Babesia parasites in Micromys minutus mice. In term of habitat, the highest prevalence of Babesia parasites was detected in rodents trapped in meadows. Our results demonstrate that rodents, especially Microtus voles, can play an important role in the circulation of the zoonotic B. microti 'Jena/Germany' strain in Lithuania. Babesia microti (Aconoidasida: Piroplasmida) (Franca, 1910) is an emerging tick-borne parasite with rodents serving as the considered reservoir host. However, the distribution of B. microti in Europe is insufficiently characterized. Based on the sample of 1180 rodents from 19 study sites in Lithuania, the objectives of this study were: (1) to investigate the presence of Babesia parasites in eight species of rodents, (2) to determine the prevalence of Babesia parasites in rodents from different habitats, and (3) to characterize the detected Babesia strains using partial sequencing of the 18S rRNR gene. Babesia DNA was detected in 2.8% rodents. The highest prevalence of Babesia was found in Microtus oeconomus (14.5%) and Microtus agrestis (7.1%) followed by Clethrionomys glareolus (2.3%), Apodemus flavicollis (2.2%) and Micromys minutus (1.3%). In M.minutus, Babesia was identified for the first time. The prevalence of Babesia-infected rodents was higher in the meadow (5.67%) than in the ecotone (1.69%) and forest (0.31%) habitats. The sequence analysis of the partial 18S rRNA gene reveals that Babesia isolates derived from rodents were 99–100% identical to human pathogenic B. microti 'Jena/Germany' strain. [ABSTRACT FROM AUTHOR]

The present work presents the development of a moose movement model to explore the value of wildlife mitigation structures and examine how hypothetical changes in land use patterns could alter wildlife habitats at landscape scales. Collisions between vehicles and animals pose a threat to humans and wildlife populations, the most dangerous collisions being with moose. Migrations of moose are generally predictable and habitat-dependent. Here, we use GIS-based simulations of moose movements to examine road-related habitat fragmentation around the main highways A1 and A2 in Lithuania. From forest data, we develop a moose habitat suitability map. Then, by running multiple simulation iterations, we generate potential moose pathways and statistically describe the most efficient potential long-range movement routes that are based on the principles of habitat utilization. Reflecting the probabilities of cross-highway moose movement, ranks are assigned to all 1 km highway segments, characterizing them in terms of their likelihood of moose movement, and thus identifying discrete migration corridors and highway crossing zones. Bottlenecks are identified through simulation, such as where sections of wildlife fencing end without highway crossing structures, thereby creating a 'spillover' effect, i.e., moose moving parallel to the highway, then crossing. The tested model has proven the prognostic capacity of the tool to foresee locations of moose-vehicle collisions with high accuracy, thus allowing it to be a valuable addition to the toolbox of highway planners. [ABSTRACT FROM AUTHOR]