Search

The body condition index (BCI) values in small mammals are important in understanding their survival and reproduction. The upper values could be related to the Chitty effect (presence of very heavy individuals), while the minimum ones are little known. In this study, we analyzed extremes of BCI in 12 small mammal species, snap-trapped in Lithuania between 1980 and 2023, with respect to species, animal age, sex, and participation in reproduction. The proportion of small mammals with extreme body condition indices was negligible (1.33% with a BCI < 2 and 0.52% with a BCI > 5) when considering the total number of individuals processed (n = 27,073). When compared to the expected proportions, insectivores and herbivores were overrepresented, while granivores and omnivores were underrepresented among underfit animals. The proportions of granivores and insectivores were higher, while those of omnivores and herbivores were lower than expected in overfit animals. In several species, the proportions of age groups in underfit and overfit individuals differed from that expected. The male–female ratio was not expressed, with the exception of Sorex araneus. The highest proportion of overfit and absence of underfit individuals was found in Micromys minutus. The observation that individuals with the highest body mass are not among those with the highest BCI contributes to the interpretation of the Chitty effect. For the first time in mid-latitudes, we report individuals of very high body mass in three shrew species. [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 relationship between the body condition of different small mammal species and the habitat they occupy is poorly analyzed. We analyzed the body condition index, BCI, of 18 small mammal species trapped in forest, shrub, wetland, meadow, riparian, mixed and fragmented, disturbed, agricultural, and commensal habitats of Lithuania during the span of 1980–2023. The composition of small mammal communities was habitat-dependent, being richest in meadows, with eighteen species, and poorest in riparian habitats, with nine species. A significant variation in the BCI with respect to habitat was observed in eight small mammal species (Sorex araneus, S. minutus, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Alexandromys oeconomus, Microtus agrestis, and M. arvalis). The highest average BCI for most of these species was found in disturbed habitats, with S. minutus and M. arvalis showing the highest BCI in agricultural habitats. The lowest average BCI for most species was found in mixed habitats, while C. glareolus and M. arvalis exhibited the lowest BCI in shrub habitats. In general, species dominating certain habitats did not have the highest BCI. This is the first multi-species, multi-habitat study of body condition in small mammals at mid-latitudes. [ABSTRACT FROM AUTHOR]

A review of 113 scientific and other publications on the smallest and most abundant deer in Lithuania, the roe deer (Capreolus capreolus), is presented, along with an analysis based on compound annual population growth rates of population numbers, hunting bags, and roadkill. This review covers the species' history in the country from the last glaciation onwards, the changes in numbers from 1934 to 2023, hunting bag changes from 1965 to 2022, roadkill numbers from 2002 to 2022, data on roe deer reproduction, habitat selection, genetic diversity, pathogens, and damage to forest stands. It also provides an overview of species management and selection for trophies. Despite the exponential increase in roe deer numbers since 1990 and the dominance of this species in roadkill, even on urban roads, the number and density of animals and the damage they cause to forest stands are relatively low compared to other European countries. Within the observed period, drops in numbers were related to harsh winters in 1969/1970 and 1995/1996. Poaching, especially coinciding with weakened enforcement during the period of political–economic transition in the early 1990s, has also had a negative impact on population numbers, as have recent increases in the number of large predators. Population growth over the recent period does not correlate with hunting mortality, which has remained stable at an average of 16.9% since 2002. [ABSTRACT FROM AUTHOR]

This editorial discusses the abundance and dynamics of small mammals and their predators. Small mammals, such as rodents and insectivores, play important roles in ecosystems, including seed dispersal and serving as prey for larger carnivores. However, they are often considered pests in human-dominated environments. The editorial introduces a special issue that includes 10 papers on this topic, with studies conducted in European countries, New Zealand, and Chile. The papers cover a range of topics, including the effects of alien species, pest control in agroecosystems, historical trends in small mammal populations, and the activity of small mammals in response to predation risk. The editorial highlights the unintended consequences of human actions, such as the introduction of predators to control small mammal populations, and the need for new management strategies for conservation. [Extracted from the article]

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]

The raccoon dog (Nyctereutes procyonoides Gray, 1834) is an invasive mammal widespread in northern, eastern, and central Europe, where it damages biodiversity and carries a wide range of pathogens. Surveys of this species in Lithuania ceased before 2000, so there is a lack of scientific information on its distribution and relative abundance. In 2019–2022, we carried out a nationwide recording of raccoon dogs using camera traps (101 sites, sampling effort of 15,563 trapping days). The species was found at 64 sites (63.4% of the sites surveyed), with an average relative shooting frequency of 4.30 photographs per 100 days. The frequency of raccoon dogs was higher at camera sites where lynx (Lynx lynx Linnaeus, 1758) or wolves (Canis lupus Linnaeus, 1758) were recorded compared to sites where predators were absent (7.95 vs. 3.21 photos/100 days, p < 0.05). The highest raccoon dog activity (69.5% of records) was observed at night and at temperatures between −3 and +5 °C. Below −15 °C, animals were not active, while above 25 °C, there was very little activity. Diurnal activity (36.1% of daytime records in April–June) increased during estrus, gestation, and rearing of pups. We conclude that wide-scale camera trapping is a suitable method for raccoon dog surveys. [ABSTRACT FROM AUTHOR]

Cervid roadkill, including moose, red deer and roe deer, can pose a risk to drivers and are frequently registered. However, the roadkill influence on overall cervid populations is not fully known, especially by roadkill that are not officially registered. The aim of this study was to assess the impact of cervid roadkill on population abundance, evaluating (i) the proportion of ungulate–vehicle collisions not registered by official bodies, (ii) the number of roadkill in relation to hunted animals and (iii) the proportion of roadkill that occurs in forest habitat. The number of unreported roadkill was calculated based on a roadkill index assessed during 3815 registration sessions on main and national roads in Lithuania from 2002–2022. During this period, 373 moose, 712 red deer and 9179 roe deer roadkill were unreported, correlating to 13.8%, 95.8% and 31.1% of those registered by the Traffic Supervision Service. In conclusion, 39.5%, 17.5% and 20.1% of roadkill were registered on roads through forests. Moose roadkill amounted to a figure corresponding to 10% of those hunted, with the same figure for red deer being 1.8%, neither adding much mortality. At 16.5%–16.6%, the figure for roe deer might be important. [ABSTRACT FROM AUTHOR]

Roadkill and other impacts of roads on wildlife create pressures on society and the environment, requiring the implementation of mitigation measures in response. Due to various natural and anthropogenic causes, the locations of wildlife–vehicle collisions are not stable in time and space. The identification of urban and wildlife corridor intersections can help anchor collision locations along high-risk road sections. Urban and wildlife corridors and their intersections were identified in a case study of Lithuania using a landscape connectivity identification method based on circuit theory. A strong relationship was found between the numbers of urban–wildlife corridor intersections and the numbers of wildlife–vehicle collisions. Short road sections were characterised by the number of urban–wildlife corridor intersections, mammal–vehicle collisions, and the presence of fencing. Multi-criteria analyses identified the road sections where wildlife fencing is, simultaneously, the longest, and the number of mammal–vehicle collisions and the number of urban–wildlife corridor intersections are highest. The results show that identifying wildlife and urban corridor intersections can reinforce locations for permanent roadkill mitigation measures. The identification of crossing structure type and location within shortlisted road sections and evaluation of their efficiencies remain the challenges for field research. [ABSTRACT FROM AUTHOR]