Jolanta Stankevičiūtė

Understanding the trophic ecology of the European brown hare (Lepus europaeus) is essential for its conservation in intensifying agricultural landscapes. To explore dietary niches across habitats, sexes, and age groups, we applied stable isotope analysis of carbon (δ¹³C) and nitrogen (δ¹⁵N) in hair samples from 151 hares collected in Lithuania and Poland from 2023 to 2025. δ¹³C and δ¹⁵N values varied significantly by country and habitat, but not by sex or age. Lithuanian hares exhibited lower δ¹³C values and a wider isotopic niche, reflecting more diverse foraging in heterogeneous habitats. In contrast, Polish hares from uniform orchard landscapes showed higher δ¹³C enrichment and narrower isotopic ranges, indicating greater dietary specialization on cultivated plants. Temporal variation was minimal, and isotopic overlap among months and years was high. These results suggest that habitat heterogeneity, rather than demographic factors, drives dietary flexibility in L. europaeus. Thus, stable isotope analysis provides a powerful tool for linking agricultural land use with trophic niche breadth in farmland mammals. Promoting mixed cropping systems, permanent vegetation, and structurally diverse habitats could improve food quality and support the recovery of declining hare populations.

Apicomplexan parasites of the genus Sarcocystis utilize a wide range of vertebrate hosts, including reptiles, birds, and mammals, and follow a complex two-host prey–predator life cycle. Sarcocysts develop within the muscle tissue of intermediate hosts, while oocyst sporulation occurs in the intestines of definitive hosts. Despite their broad host range, the role of Mustelidae predators in the transmission and maintenance of Sarcocystis species remains poorly understood, highlighting the need for targeted studies in this area. In 2023, 20 intestinal samples were collected from European pine martens (Martes martes) in Latvia. Light microscopy revealed sporocysts of Sarcocystis spp. in 70.0% of the samples. Sarcocystis species were identified by using the analysis of obtained cox1 and ITS1 sequences. Using molecular methods, Sarcocystis spp. were confirmed in 85.0% of the samples examined, and co-infections with two or more different parasite species were established in 30.0% samples. We detected eight Sarcocystis species (S. arieticanis, S. bertrami, S. capracanis, S. cruzi, S. entzerothi, S. hjorti, S. morae, and S. truncata) associated with intermediate hosts such as cervids, cattle, sheep, goats, and horses. Additionally, a genetically novel species, Sarcocystis sp. 25MmLV, was detected in a single European pine marten. These findings suggest that European pine martens serve as definitive hosts for multiple Sarcocystis species, particularly those infecting cervids.

Apicomplexan Sarcocystis and Trichinella nematodes are food-borne parasites whose life cycle is carried-out in various wildlife and domestic animals. The gray wolf (Canis lupus) is an apex predator acting as an ecosystem engineer. This study aimed to identify the species of Sarcocystis and Trichinella found in the muscles of gray wolves in Lithuania. During the 2017–2022 period, diaphragm, heart, and hind leg samples of 15 animals were examined. Microscopical analysis showed the presence of two types of Sarcocystis parasites in 26.7% of the analyzed muscle samples. Based on the sequencing of five loci, nuclear 18S rDNA, 28S rDNA, ITS1, mitochondrial cox1, and apicoplast rpoB, S. arctica, and S. svanai were identified. The current work presents the first report of S. svanai in gray wolf. Phylogenetically, S. svanai clustered together with S. lutrae, infecting various carnivorans, and S. arctica was most closely related to S. felis from domestic cats. Trichinella spp. were found in 12 gray wolves (80%). For the first time, Trichinella species were molecularly identified in gray wolves from Lithuania. Trichinella britovi was confirmed in all of the isolated Trichinella larvae using a multiplex PCR. Gray wolves in Lithuania may serve as a major source of zoonotic pathogens due to the presence of these parasites.

The increasing migrating goose populations seasonally feed in the agricultural fields and grasslands. Annually, farmers encounter and abide the challenges of intense winter wheat and permanent grasslands grazing pressures. In Lithuania, migrating geese caused damages initiate conflicts between farmers, conservationists and hunters. Thus, we aimed to determine the winter wheat and permanent grasslands yield reduction by observing migrating geese grazing intensity and characteristics. In three Lithuanian south-western and central regions we established 15 study areas. During the spring migration geese droppings were counted every 10-15 days. Harvested winter wheat and hay were dried and weighted, wheat ears were counted, grains extracted and weighted. Results proved that migrating geese obvously damage and reduce yield of both winter wheats and permanent grasslands. Grazing reduced winter wheat ear development and grain weight. The high grazing pressure of 7.45 droppings/m2 reduced yield by 10.8%. In the permanent grasslands high grazing pressure was 10,49±0,43SE droppings/m2. High intensity grazing in the grasslands reduced yield by 15.2%.

Wildfowl meat infected with S. rileyi macrocysts is not suitable for human consumption. Ducks are among the main game birds in Europe, and S. rileyi infections cause significant economic losses. In 2011–2022, a total of 2649 anseriforms collected in Lithuania and 619 Mallards (Anas platyrhynchos) hunted in the Kaliningrad region of Russia, Belarus, and Latvia were tested for macrocysts. In Lithuania, macrocysts were detected in 206 of 2362 Mallards (8.7%) and in two of 88 (2.3%) Eurasian Teals (Anas crecca). The prevalence of macrocysts in the other three countries, Belarus (5.9%), Russia (5.0%), and Latvia (3.1%), was similar. For species identification, macrocysts isolated from 37 Mallards (21 from Lithuania, 8 from Russia, 6 from Belarus, and 2 from Latvia) were subjected to sequencing of the ITS1 region. Based on DNA analysis, S. rileyi was confirmed in all tested birds. By comparing the infection rates of macrocysts in Mallards in Lithuania, significant differences were observed in different years (p = 0.036), and a significantly higher prevalence of infection was established in November–December than in September–October (p = 0.028). Given the amount of data per decade on the prevalence of S. rileyi, awareness of infection needs to be increased.