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Beginning in the 1960s, restoration of the European bison (Bison bonasus) in Ukraine has resulted in seven herds with approximately 350 total individuals currently. For the first time, we describe characteristics of habitats used by these seven European bison herds located in forest, forest-steppe, and mountain zones of Ukraine. During the growing season across all ecological zones and herds, we observed variation in bison use of woodland and open habitats associated with temporal variation in landscape scale habitat characteristics. During winter across all ecological zones and herds, variation in habitat use declined dramatically with supplementary feeding that incentivized sedentary association with woodlands. Our descriptive field observations are intended to improve understanding of European bison landscape ecology and serve as a basis for additional quantitative investigations. [ABSTRACT FROM AUTHOR]

We assessed habitat selection patterns of the European bison ( Bison bonasus) reintroduced to the Bieszczady Mountains (the Eastern Carpathians, Poland) using presence data and Ecological Niche Factor Analysis. During the growing season, bison selected habitats at higher elevations close to natural grasslands, coniferous forest, and stands with broken canopy, while in winter - lower elevations, close to agricultural areas and alder or pine stands. In both seasons, bison avoided busy roads. The use of low-elevation valleys in winter can be a trade-off between the access to good habitats with milder climate, and the risk associated with close proximity to people. Relative tolerance to proximity to infrastructure indicates that good quality habitats in its vicinity can be considered suitable for further expansion of the species' range. Optimal sites for bison introductions in the Carpathians should include areas at lower elevations, providing winter refuges, and allow unrestricted access to summer habitats at higher elevations. [ABSTRACT FROM AUTHOR]

Reintroductions are an important tool for re-establishing or reinforcing populations of threatened species, and thus to restore ecosystems. However, predicting how reintroduced populations will spread is difficult, and past reintroductions often lacked a thorough assessment of habitat availability and connectivity. Using the case of reintroduced European bison ( Bison bonasus L.) in the northern Carpathians, we show how habitat suitability models in combination with connectivity assessments based on circuit theory can remedy such shortcomings, and identify potential habitat patches and corridors between these. European bison were reintroduced in our study area in the 1960s, and against prior expectation, have not spread along the Carpathian ridge, but instead expanded their range towards human settlements. Our analyses provide an explanation for this pattern. Although we identified a network of suitable habitat patches along the Carpathian ridge, the functional connections between them were limited due to a number of major barriers to movement. To avoid future conflicts between European bison and people, and to achieve the long-term goal of a viable bison metapopulation in this region, conservation action should focus on establishing connectivity between habitat patches through the creation and legal protection of corridors and wildlife passages, which would benefit Carpathian wildlife in general. Our study emphasizes the importance of landscape-scale connectivity analyses to guide restoration efforts, and of adaptive management to ensure the success of reintroduction projects. [ABSTRACT FROM AUTHOR]

Abstract: Habitat connectivity is important for the survival of species that occupy habitat patches too small to sustain an isolated population. A prominent example of such a species is the European bison (Bison bonasus), occurring only in small, isolated herds, and whose survival will depend on establishing larger, well-connected populations. Our goal here was to assess habitat connectivity of European bison in the Carpathians. We used an existing bison habitat suitability map and data on dispersal barriers to derive cost surfaces, representing the ability of bison to move across the landscape, and to delineate potential connections (as least-cost paths) between currently occupied and potential habitat patches. Graph theory tools were then employed to evaluate the connectivity of all potential habitat patches and their relative importance in the network. Our analysis showed that existing bison herds in Ukraine are isolated. However, we identified several groups of well-connected habitat patches in the Carpathians which could host a large population of European bison. Our analysis also located important dispersal corridors connecting existing herds, and several promising locations for future reintroductions (especially in the Eastern Carpathians) that should have a high priority for conservation efforts. In general, our approach indicates the most important elements within a landscape mosaic for providing and maintaining the overall connectivity of different habitat networks and thus offers a robust and powerful tool for conservation planning. [Copyright &y& Elsevier]

Where populations are confined to fragmented, human-dominated landscapes, preventing declines and extirpations will often rely on metapopulation management. Spatially-explicit population viability analyses provide tools to evaluate how well the local management efforts can be combined to conserve metapopulations across large areas. Yet, metapopulation models have rarely been combined with tools to assess the cost-effectiveness of different conservation strategies. European bison Bison bonasus only occur in small, fragmented populations, making their long-term survival dependent on establishing a metapopulation across eastern Europe. We parameterized a European bison metapopulation model based on time-series of bison demography and a habitat suitability map to assess the viability of bison populations in the Carpathians and the relative cost-effectiveness of (i) reintroductions, (ii) wildlife overpasses and (iii) anti-poaching measures in establishing a viable bison metapopulation. Our results suggest that the Carpathians could support a viable metapopulation of European bison provided that active efforts are taken to safeguard bison and connect isolated herds. With such steps, our model forecasts that bison numbers could increase substantially over the next 100 years as local populations increase and bison recolonize parts of the Carpathians. Reintroductions appear to be the most cost-effective approach for establishing a viable bison metapopulation among our scenarios, especially when coupled with wildlife overpasses to improve connectivity among herds. The most promising region for a bison metapopulation in the Carpathians was south-eastern Poland, Ukraine and northern Romania. We identified several candidate regions for reintroductions and wildlife overpasses, especially in the border region of Romania and Ukraine. Site-specific assessments of both habitat suitability, and the costs and benefits of a large bison population, should target those regions. . Synthesis and applications. Our results highlight how careful conservation planning can identify solutions to preserve large mammals in human-dominated landscapes. Choosing the most effective option from a range of management strategies is a central challenge for wildlife managers. We have shown that incorporating cost-effectiveness analyses into metapopulation models can elucidate the relative value (gain per unit cost) of different conservation management options, allowing decision makers to choose cost-effective options to preserve large mammals. Our model projections also provide hope for establishing a viable free-ranging European bison population in the Carpathians, one of the last relatively wild areas in Europe. [ABSTRACT FROM AUTHOR]

Abstract: European Bison (Bison bonasus) barely escaped extinction in the early 20th century and now only occur in small isolated herds scattered across Central and Eastern Europe. The species’ survival in the wild depends on identifying suitable habitat for establishing bison metapopulations via reintroductions of new herds. We assessed European Bison habitat across the Carpathian Mountains, a stronghold of European Bison and one of the only places where a viable bison metapopulation may be possible. We used maximum entropy models to analyze herd range maps and habitat use data from radio-collared bison to identify key habitat variables and map European Bison habitat across the entire Carpathian ecoregion (210,000km2). Forest cover (primarily core and perforated forests) and variables linked to human disturbance best predict bison habitat suitability. Bison show no clear preference for particular forest types but prefer managed grasslands over fallow and abandoned fields. Several large, suitable, but currently unoccupied habitat patches exist, particularly in the eastern Carpathians. This available suitable habitat suggests that European Bison have an opportunity to establish a viable Carpathian metapopulation, especially if recent trends of declining human pressure and reforestation of abandoned farmland continue. Our results also confirm the suitability of a proposed Romanian reintroduction site. Establishing the first European Bison metapopulation would be a milestone in efforts to conserve this species in the wild and demonstrate a significant and hopeful step towards conserving large grazers and their ecological roles in human-dominated landscapes across the globe. [Copyright &y& Elsevier]