Diana Zlatanova’s research while affiliated with Sofia University "St. Kliment Ohridski" and other places

The recovery of wolves (Canis lupus) across Europe is a notable conservation success in a region with extensive human alteration of landscapes and high human population densities. We provide a comprehensive update on wolf populations in Europe, estimated at over 21,500 individuals by 2022, representing a 58% increase over the past decade. Despite the challenges of high human densities and significant land use for agriculture, industry, and urbanization, wolves have demonstrated remarkable adaptability and increasing population trends in most European countries. Improved monitoring techniques, although varying in quality and scope, have played a crucial role in tracking this recovery. Annually, wolves kill approximately 56,000 domestic animals in the EU, a risk unevenly distributed and differently handled across regions. Damage compensation costs 17 million EUR every year to European countries. Positive economic impacts from wolf presence, such as those related to reducing traffic accidents with wild ungulates or supporting wildlife tourism, remain under studied. Wolf recovery in Europe is supported by diverse policy and legal instruments such as LIFE programs, stakeholder platforms, as well as the EU Habitats Directive and the Bern Convention. Coexisting with newly established wolf populations in Europe entails managing impacts on human activities, including livestock depredation, competition for game, and fear of attacks on humans, amidst varying social and political views on wolf recovery. Sustainable coexistence continues to operate in evolving and complex social, economic, and political landscapes, often characterized by intense debates regarding wolf policies.

Three‐quarters of the planet's land surface has been altered by humans, with consequences for animal ecology, movements and related ecosystem functioning. Species often occupy wide geographical ranges with contrasting human disturbance and environmental conditions, yet, limited data availability across species' ranges has constrained our understanding of how human pressure and resource availability jointly shape intraspecific variation of animal space use. Leveraging a unique dataset of 758 annual GPS movement trajectories from 375 brown bears ( Ursus arctos ) across the species' range in Europe, we investigated the effects of human pressure (i.e., human footprint index), resource availability and predictability, forest cover and disturbance, and area‐based conservation measures on brown bear space use. We quantified space use at different spatiotemporal scales during the growing season (May–September): home range size; representing general space requirements, 10‐day long‐distance displacement distances, and routine 1‐day displacement distances. We found large intraspecific variation in brown bear space use across all scales, which was profoundly affected by human footprint index, vegetation productivity, and recent forest disturbances creating opportunity for resource pulses. Bears occupied smaller home ranges and moved less in more anthropized landscapes and in areas with higher resource availability and predictability. Forest disturbances reduced space use while contiguous forest cover promoted longer daily movements. The amount of strictly protected and roadless areas within bear home ranges was too small to affect space use. Anthropized landscapes may hinder the expansion of small and isolated populations, such as the Apennine and Pyrenean, and obstruct population connectivity, for example between the Dinaric Pindos population and the Alpine or Carpathian population. Our findings call for actions to maintain bear movements across landscapes with high human footprint, for example by maintaining forest integrity, to support viable bear populations and their ecosystem functions.

Three-quarters of the planets land surface has been altered by humans, with consequences for animal ecology, movements and related ecosystem functioning. Species often occupy wide geographical ranges with contrasting human disturbance and environmental conditions, yet, limited data availability across species ranges has constrained our understanding of how human impact and resource availability jointly shape intraspecific variation of animal space use. Leveraging a unique dataset of 752 annual GPS movement trajectories from 370 brown bears (Ursus arctos) across the species range in Europe, we investigated the effects of human impact (i.e., human footprint index), resource availability, forest cover and disturbance, and area-based conservation measures on brown bear space use. We quantified space use at different spatio-temporal scales during the growing season (May - September): home range size; representing general space requirements, 10-day long-distance displacement distances, and routine 1-day displacement distances. We found large intraspecific variation in brown bear space use across all scales, which was profoundly affected by human footprint index, vegetation productivity, and recent forest disturbances creating opportunity for resource pulses. Bears occupied smaller home ranges and moved less in more anthropized landscapes and in areas of higher resource availability. Forest disturbances reduced space use while contiguous forest cover promoted longer daily movements. The amount of strictly protected and roadless areas within bear home ranges were too small to affect space use. Anthropized landscapes may hinder the expansion of small and isolated populations, such as the Apennine and Pyrenean, and obstruct population connectivity, for example between the Alpine or Carpathian with the Dinaric Pindos populations. Our findings call for actions to maintain bear movements across landscapes with high human footprint, for example by maintaining forest integrity, to support viable bear populations and their ecosystem functions.

The circadian activity of selected mammal species and the temporal overlap with human presence or between species were analysed in 2013-2014 on the territory of the Sinite Kamani Nature Park, Eastern Stara Planina. The purpose of this study was to determine how the human presence affected the circadian activity of mammal species in this protected area. The wild boar (n = 68) showed 22% overlap with the humans (n = 54) in its circadian activity (Δ = 0.22, CI 0.02-0.21) while the roe deer (n = 144) activity overlapped in 49% with the human activity (Δ = 0.49, CI 0.29-0.51). The European brown hare (n=26) activity had a 23% overlap (Δ = 0.23, CI 0.07-0.26), the golden jackal (n = 42)-36% (Δ = 0.36, CI 0.22-0.49) and the red fox (n = 131)-24% (Δ = 0.24, CI 0.06-0.25). The overlap between the red fox and European brown hare activity was 81% (Δ = 0.81, CI 0.71-0.93), between red fox and golden jackal-71% (Δ = 0.71, CI0.49-0.77) and between red fox and Martes sp.-81% (Δ = 0.81, CI 0.72-0.93). The target species avoided the range of time when humans were active. This forced the species to use a narrower temporal niche when sharing the same space. These results provided insights for the better management of the species in the protected areas.

The report Large carnivore distribution maps and population updates 2017 – 2022/23 is based on the latest information and provides the best available overview of brown bear (Ursus arctos), Eurasian lynx (Lynx lynx), wolf (Canis lupus), golden jackal (Canis aureus), and wolverine (Gulo gulo) distributions and population sizes at a European continental scale (covering 34 countries). This document has been prepared with the assistance of Istituto di Ecologia Applicata and with the contributions of the IUCN/SSC Large Carnivore Initiative for Europe (chair: Luigi Boitani) under contract N° 09.0201/2023/907799/SER/ENV.D.3 “Support for Coexistence with Large Carnivores”, “B.4 Update of the distribution maps” for the European Commission.

Rehabilitation of injured or immature individuals has become an increasingly used conservation and management tool. However, scientific evaluation of rehabilitations is rare, raising concern about post-release welfare as well as the cost-effectiveness of spending scarce financial resources. Over the past 20 years, events of juvenile Eurasian lynx presumably orphaned have been observed in many European lynx populations. To guide the management of orphaned lynx, we documented survival, rehabilitation and fate after the release and evaluated the potential relevance of lynx orphan rehabilitation for population management and conservation implications. Data on 320 orphaned lynx was collected from 1975 to 2022 from 13 countries and nine populations. The majority of orphaned lynx (55%) were taken to rehabilitation centres or other enclosures. A total of 66 orphans were released back to nature. The portion of rehabilitated lynx who survived at least one year after release was 0.66. Release location was the best predictor for their survival. Of the 66 released lynx, ten have reproduced at least once (8 females and 2 males). Conservation implications of rehabilitation programmes include managing genetic diversity in small, isolated populations and reintroducing species to historical habitats. The lynx is a perfect model species as most reintroduced populations in Central Europe show significantly lower observed heterozygosity than most of the autochthonous populations, indicating that reintroduction bottlenecks, isolation and post-release management have long-term consequences on the genetic composition of populations. The release of translocated orphans could be a valuable contribution to Eurasian lynx conservation in Europe. It is recommended to release orphans at the distribution edge or in the frame of reintroduction projects instead of a release in the core area of a population where it is not necessary from a demographic and genetic point of view. Rehabilitation programmes can have conservation implications that extend far beyond individual welfare benefits.

In 2021 in northwestern Bulgaria, on the territory of State Forestry "Midzhur", West Stara Planina Mtn, we analysed the temporal and spatial activity of the roe deer (Capreolus capreolus) in an area with scarce other large ungulates. In the locations where both wolf and roe deer were recorded a significant (75%) temporal overlap between the two species was found (Δ = 0 75, range 0.62-0.96 at CI 95). Although the overlap between the activity of the roe deer in locations with and without wolf registrations was high (Δ = 0.72, range 0.58-0.92 at CI 95), the activity had two clearly different main peaks-around 18:00 in locations without wolves and around 05:00 h in locations with wolves. The results of the time-spacing analysis showed that the average time for a roe deer to appear after the presence of a wolf (min = 8:17 h) was greater than the time needed for the wolf to appear after a roe deer (min = 1:35 h). The difference in the spatial distribution of roe deer in areas with and without wolf presence was not statistically significant; yet the highest detection rate of roe deer was recorded in locations with wolf registrations. This allowed us to conclude that the roe deer as a potential main prey species of the wolf in the region was not avoiding the predator spatially but temporarily while the wolf the strategy of the wolf was to synchronize its circadian activity with that of the roe deer.

The European pine marten Martes martes, an endangered and protected species in Bulgaria, was registered with a camera trap outside its currently known distribution, in Lyulin Mtn., Western Bulgaria. The two new detections were at a relatively low altitude (902 m a.s.l.), within a beech (Fagus sylvatica L.) and common oak (Quercus robur L.) forest. The pine martens in Lyulin Mtn. might face poaching due to the external similarities to the sympatric stone marten (Martes foina Erxl.). Thus, a much more detailed study of the distribution of the species in Lyulin Mtn. is needed, which would aid in planning suitable and effective conservation measures.

Изучаването на времевата и пространствената активност на бозайниците е особено важен аспект от цялостното разбиране на екологията на изследваните видове. Чрез метода на фотокапаните през 2021 г. в Държавно Ловно стопанство „Витошко Студена“ бяха проучени избора на местообитания и денонощната активност на благородния елен (Cervus elaphus L.), сърната (Capreolus capreolus L.) и дивата свиня (Sus scrofa L.). И за трите вида предпочитаното местообитание беше поляна с единични храсти, като най-отчетливо то бе изразено при сърната с 68 % от всички независими регистрации на вида. Резултатите от анализа на денонощната активност показаха, че сърната има бимодална активност с два пика – около 7:00 и 21:00 ч., докато при благородният елен и дивата свиня активността е предимно нощна с пик около 22:00 ч.

The Balkan chamois Rupicapra rupicapra balcanica Bolkay, 1925 has a highly fragmented distribution in the mountainous regions of the Balkan Range, including Bulgaria. In 2022, we recorded chamois using camera traps in two locations outside its known distribution range, i.e. in the municipality of Chuprene on the territory of State Forestry Enterprise Midzhur. This is the first well-documented evidence of the presence of the species in the Western Stara Planina Mtn., Bulgaria. The origin of the animals is, most probably, associated with a poorly documented attempt to reintroduce 12 individuals in the region in 2016, with no proper follow-up monitoring or official progress report.