Peculiarities of small mammal ecology in commercial orchards, berry plantations and commensal habitats

The main objective of this study was to assess the diversity and relative abundance of small mammals in commercial orchards and berry plantations in Lithuania, as well as the population structure and ecology of small mammal species. During the research, 13 small mammal species were trapped in commercial fruit and berry farms. Therelativeabundanceofthe dominant species common vole (Microtusarvalis), yellow-neckedmouse (Apodemusflavicollis),stripedfieldmouse (A. agrarius) and bank vole(Clethrionomysglareolus) and their proportion in the investigated community varied according to year, season and habitat, with no outbreaks recorded during the study period. According to species proportions in the commercial fruit farms, M. arvalis should be the focal species for the evaluation of plant protection products.Trophic resources in commercial fruit farms are partitioned between trophic groups and between species within groups, so that more species can exploit the limited trophic space simultaneously. Clethrionomys glareolus in the apple orchards is omnivorous, its trophic niche being separated from granivores and herbivores according to δ13C, while being the closest to insectivores according to δ15N. The degree of omnivory of these voles in the orchards differed from that in surrounding meadows and forests. In our analysis of 21 elements, we found that the main sources of variability in elemental concentrations were animal species and age, crop and agricultural intensity, while location, animal gender and crop age were not important.The higher concentrations of Cu, Mn, Bi, Co, Cr, Fe, Ni, Sr and Pb in the muscle and bone of the dominant species of rodents from the crop are as in comparison to those from the control habitats supported the hypothesis that fertiliser and pesticide use in commercial gardens should account for the variation of concentrations of the elements in the muscles and bones of small mammals. Sarcocystis spp. Were detected inApodemus agrarius, A. flavicollis, Clethrionomys glareolus, Microtusarvalis and M. oeconomus in six out of 14 orchards and berry plantations. The overall prevalence of Sarcocystis spp. was 1.38%, that in voles – 2.23%, in mice – 0.79%

Ecological aspects of Red Squirrel (Sciurus vulgaris) dreys in city parks

Modified habitats often pose challenges to native fauna. Red squirrels (Sciurus vulgaris) successfully inhabits territory of the cities. However research on quite abundant red squirrel populations in urban parks of Lithuania was lacking. The investigation was carried out in two city parks (area of Giruliai park 152 ha, Pasakų park forest – 31 ha) in Vilnius, Lithuania. Both areas were mainly coniferous, dominated with pine (Pinus sylvestris). Drey (N = 415) counts were done in February and March 2014–2016. Dreys were found in eight tree species. The red squirrels’ dreys were mainly built in most widespread tree species: pine (84.8% of all dreys) and birch (8.1%). Most of the found dreys were built on the side branches at the stem (47.7%). 21.8% of the dreys were built on the branches further from the stem, 18.5% on the top branches and 12% in the stem fork-off. Most of the dreys were set in the southern exposition (33.9%). Average number of red squirrels in both parks in 2014–2016 was 0.20±0.01 squirrels/ha, the average number of dreys – 0.75±0.05 dreys/ha. The population of urban red squirrels in Vilnius city parks can be regarded as stable and having medium abundance, which is supported by supplementary feeding

Abundance and population structure of small rodents in fruit and berry farms

Fruit and berry farms are anthropogenic habitats still inhabited by small mammals, though their presence is constantly affected by agricultural activities. Based on trapping data from 2018–2022, we analyzed the abundance and population structure of the dominant rodent species to assess changes in gender and age ratios by year and habitat, the annual and seasonal dynamics of relative abundance, and the relationship between breeding parameters and abundance. The relative abundance of the dominant species, common vole, yellow-necked mouse, striped field mouse, and bank vole, and their proportion in the investigated community varied according to year, season, and habitat. No outbreaks were recorded during the study period. The abundance of the striped field mouse exhibited a downward trend independently of habitat, while the abundance and proportions of the other three species were habitat-dependent. There was no consistent pattern between litter size and relative abundance in the same or following years. Given the ongoing conflict between biodiversity conservation in Europe and agriculture, the results contribute to a better understanding of the functioning and viability of rodent populations in fruit farms and may be used in agroecology and sustainable farming

The distribution and activity of the invasive raccoon dog in Lithuania as found with country-wide camera trapping

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 & DEG;C. Below -15 & DEG;C, animals were not active, while above 25 & DEG;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

Abundance and Population Structure of Small Rodents in Fruit and Berry Farms

Fruit and berry farms are anthropogenic habitats still inhabited by small mammals, though their presence is constantly affected by agricultural activities. Based on trapping data from 2018&ndash;2022, we analyzed the abundance and population structure of the dominant rodent species to assess changes in gender and age ratios by year and habitat, the annual and seasonal dynamics of relative abundance, and the relationship between breeding parameters and abundance. The relative abundance of the dominant species, common vole, yellow-necked mouse, striped field mouse, and bank vole, and their proportion in the investigated community varied according to year, season, and habitat. No outbreaks were recorded during the study period. The abundance of the striped field mouse exhibited a downward trend independently of habitat, while the abundance and proportions of the other three species were habitat-dependent. There was no consistent pattern between litter size and relative abundance in the same or following years. Given the ongoing conflict between biodiversity conservation in Europe and agriculture, the results contribute to a better understanding of the functioning and viability of rodent populations in fruit farms and may be used in agroecology and sustainable farming

Rodent fertility in commercial orchards in relation to body mass and body condition

Although rodents are recognized as pests, they are still an important part of agricultural ecosystems. In 2018–2020, we snap-trapped small mammals in Lithuania in 18 commercial orchards (apple and plum orchards, currant and raspberry plantations) and in adjacent control habitats. We aimed to discover whether the litter size of the six most abundant rodent species depended on season, on female body mass and/or on fitness. Litter size in common and root voles was smaller in habitats with a higher intensity of agricultural practices. Compared to summer, observed litter size in autumn significantly decreased in common voles (from 5.6 to 4.8) and yellow-necked mice (from 5.8 to 4.6). In autumn, litter size and female body mass was positively correlated in all rodent species, while in summer this was characteristic to root voles (r = 0.67, p < 0.05, 45% of variation of the litter size explained) and yellow-necked mice (r = 0.53, p < 0.005, 27% respectively) only. Female body condition index and litter size correlations were weak. Potential litter size exceeded the observed rate and breeding failures were observed in all species, with the highest percentage in root, bank and common voles

Abundance and Population Structure of Small Rodents in Fruit and Berry Farms

Fruit and berry farms are anthropogenic habitats still inhabited by small mammals, though their presence is constantly affected by agricultural activities. Based on trapping data from 2018–2022, we analyzed the abundance and population structure of the dominant rodent species to assess changes in gender and age ratios by year and habitat, the annual and seasonal dynamics of relative abundance, and the relationship between breeding parameters and abundance. The relative abundance of the dominant species, common vole, yellow-necked mouse, striped field mouse, and bank vole, and their proportion in the investigated community varied according to year, season, and habitat. No outbreaks were recorded during the study period. The abundance of the striped field mouse exhibited a downward trend independently of habitat, while the abundance and proportions of the other three species were habitat-dependent. There was no consistent pattern between litter size and relative abundance in the same or following years. Given the ongoing conflict between biodiversity conservation in Europe and agriculture, the results contribute to a better understanding of the functioning and viability of rodent populations in fruit farms and may be used in agroecology and sustainable farming

Mow the grass at the mouse's peril: diversity of small mammals in commercial fruit farms

Small mammals are not only pests but also an important part of agricultural ecosystems. The common vole is a reference species for risk assessment of plant protection products in the European Union, but no data about the suitability of the species in the Baltic countries are present so far. Using the snap-trap line method, we evaluated species composition, abundance, and diversity of small mammal communities in commercial orchards and berry plantations in Lithuania, testing the predictions that (i) compared with other habitats, small mammal diversity in fruit farms is low, and (ii) the common vole is the dominant species. The diversity of small mammals was compared with control habitats and the results of investigations in other habitats. Out of ten small mammal species registered, the most dominant were common vole and striped field mouse. Small mammal diversity and abundance increased in autumn and decreased in line with the intensity of agricultural practices but were not dependent on crop type. In the most intensively cultivated fruit farms, small mammals were not found. The diversity of small mammal communities in fruit farms was significantly higher than in crop fields and exceeded the diversities found in most types of forests except those in rapid succession

Spatiotemporal variation of small mammal communities in commercial orchards across the small country

The diversity of small mammal communities is a measure of the sustainability of habitats, especially agricultural ones. Based on 2018-2020 data from 18 sites in Lithuania, we analysed factors related to diversity of such a community, specifically the relative abundances and proportions of common vole, striped field mouse, yellow-necked mouse, and bank vole. We assessed the influence of location (central, northern, eastern, southern, and western parts of the country), habitat type (orchards, berry plantations, control habitats), the year and season. The model explained 14.8-33.4% of the listed parameters with p < 0.005 or higher, with the exception of the dominance index and the proportion of the common vole. Time factor (year and season, p < 0.001) and site location (p < 0.05) had the highest influences, while that of habitat type was less significant. The results of this and the former research suggest that commercial orchards play a role in maintaining the diversity and abundance of small mammal communities in the agrolandscapes.

Common vole as a focal small mammal species in orchards of the Northern Zone

n 2018-2020, we performed a country-wide study of small mammals in commercial orchards and berry plantations with the aim of determining whether the common vole (Microtus arvalis) is a more suitable focal species than the field vole (M. agrestis) in the risk assessment of plant protection products in Lithuania (country of the Northern Zone). Common vole was present in 75% of orchards and in 80% of control habitats, accounting for 30% of all trapped individuals. The proportion of this species was stable between years and seasons. The pattern was in agreement with the intermediate disturbance hypothesis, i.e., highest in medium-aged crops, while lowest in habitats with high intensities of agricultural practices. The average relative abundance of common vole in autumn, 2.65 +/- 0.52 individuals per 100 trap days, was three times higher than that in summer, with no differences recorded between crops and control habitats. Field vole was present in 30% of locations, only accounting for 2.1% of all trapped individuals. In central and eastern European countries, common vole is more widespread and abundant than field vole. In Lithuania, common vole dominates in orchards and natural habitats and is, therefore, the most relevant small mammal species for higher tier risk assessment