Data on the historical distribution of the golden jackal in Europe and its primary habitats are scarce. There are many new data on the population explosion and the rapid spread of the in Europe. However, the main factors for this expansion, the core population and its routes of dispersal, remain controversial or insufficiently studied. This study provides a profound analysis of the history of the jackal’s (Canisaureusmoreoticus Geoffroy, 1835) occurrence in Europe, the factors limiting or those triggering its expansion on the continent. The analysis shows that the timing of the species appearance in Europe still remains unclear. Historical data show that the species is a typical inhabitant of South-Eastern Europe, with some pulsations within its core area, as well as extensions to the north and west of it in favourable periods. Nowadays, the increase of the species range in Europe is the largest documented population explosion on the continent. We argue that this expansion originates from only three core populations, the Peri-Strandja area and the Dalmatian coast in the Balkans and the east parts of Western Transcaucasia in the Caucasus. This population explosion is largely due to a unique combination of factors of an anthropogenic nature.

Urbanisation presents both challenges and opportunities for bat populations. Understanding the composition and distribution of urban bat species is the first step toward their effective conservation. However, comprehensive studies on urban bat diversity remain scarce in Bulgaria. To address this gap, we conducted a year-long acoustic survey on five different habitats in the urbanised territory of Veliko Tarnovo. Our study identified the presence of eight bat species and other distinct acoustic groups within the urban environment. Bats were found to utilise various habitats across the urban landscape. Although the activity was highest during May and September, bats remained active all year round, including the winter. Our study provides insights into synanthropic bats’ seasonal and microhabitat-dependent use of urban areas. These findings will establish a baseline for future research focusing on habitat preferences, population dynamics, and interactions with urbanisation. Such research is essential for the effective management and conservation of bat populations in urban environments.

A resident Golden jackal family behaviour was studied over eight years (2017-2024) and especially over two successive post-birth seasons (May-September) in 2023 and 2024, utilising stationary bait-site camera-trap recordings on the Bulgarian bank of the Danube River. Earlier research on the cooperative breeding in golden jackals suggests that the cubs are typically cared for by the breeding pair and possibly by young helpers (1+/ 2+ years old). However, here we show that the presence of an adult, non-breeding helper (‘uncle’) can be systematic, helping the breeding female for several years, thus replacing the father, who, in our case, did not seem to contribute in the care for the young. Our observations also suggest repeated instances of food sharing by the non-breeding senior male adult, directed towards junior adults (last year’s jackals). Furthermore, food sharing behaviour amongst junior adults and towards the cubs was also recorded. Our data help revealing a more extended presence of ’helpers’ than is traditionally described in literature, with more than one or two junior adults remaining with the group to assist the breeding female during the denning period. This extended helping behaviour may contribute to the resilience of jackal family groups, particularly in contexts of pronounced hunting pressure, as is the case within our study area. We conclude that this specific behaviour, amongst other factors, may help to explain the demographic success in the European Golden jackal and with this, its significant recent expansion beyond its traditional habitats.

Elevation is a strong proxy for the thermal environment because it causes a predictable drop in temperature and food availability. This restricts cave-dwelling bats to species with specific metabolic traits, such as torpor or migration to avoid cold stress. In this context, we aimed to reveal how thermal niche differentiation structures 25 cave-dwelling bat assemblages along elevation gradients in two of the largest Bulgarian mountains—Stara Planina and Rhodopi. Multivariate PERMANOVA showed significant differences in bat assemblages among elevation groups (F = 1.616, p = 0.046), with altitude and temperature explaining 32.4% of the variance (p = 0.001). A high degree of species turnover (91.12% dissimilarity), driven by temperature niches, was observed: mesophilic Rhinolophus species dominated warm, low-elevation caves, while cold-adapted Myotis species were more common at high elevations. SIMPER analysis identified R. euryale as an indicator in low-elevation caves (p = 0.012) and the M. myotis/blythii complex at high elevations (p = 0.003). Alpha diversity showed no variation across elevation groups (p = 0.293), indicating that species turnover occurs without overall changes to local diversity. Mid-elevation assemblages lacked specific indicator species and resembled high-elevation communities, forming an ecotone. Thermal niche partitioning, as a physiological filter, shapes cave-dwelling bat assemblages and affects climate change range-shift predictions.