Djuro Huber

Recovery of large carnivores in Europe’s modern human-dominated landscapes

The conservation of large carnivores is a formidable challenge for biodiversity conservation. Using a data set on the past and current status of brown bears (Ursus arctos), Eurasian lynx (Lynx lynx), gray wolves (Canis lupus), and wolverines (Gulo gulo) in European countries, we show that roughly one-third of mainland Europe hosts at least one large carnivore species, with stable or increasing abundance in most cases in 21st-century records. The reasons for this overall conservation success include protective legislation, supportive public opinion, and a variety of practices making coexistence between large carnivores and people possible. The European situation reveals that large carnivores and people can share the same landscape. Many populations of brown bears, lynx, grey wolves, and wolverines persist successfully outside protected areas in Europe. Success for Europes large carnivores? Despite pessimistic forecasts, Europes large carnivores are making a comeback. Chapron et al. report that sustainable populations of brown bear, Eurasian lynx, gray wolf, and wolverine persist in one-third of mainland Europe. Moreover, many individuals and populations are surviving and increasing outside protected areas set aside for wildlife conservation. Coexistence alongside humans has become possible, argue the authors, because of improved public opinion and protective legislation. Science, this issue p. 1517

A multidimensional approach to managing the European brown bear in Croatia

Abstract Because of its biological characteristics, its important place in the minds of humans, and the considerable international interest for its conservation, management of the brown bear (Ursus arctos) in Europe is challenging. The Brown Bear Management Plan for Croatia (BMPC) was approved in 2004 and addressed interests such as ecology, aesthetics, and economics, as well as concern for the safety of people and property. It attempts to ensure conditions for the long-term survival of the brown bear, a species listed as endangered by some international regulations but as a game species (subject to regulated hunting) in others, including Croatia. Careful evaluation of actions affecting population size represents the most critical part of this plan. Those actions should sustain long-term viability of the bear population while maintaining densities at a level that minimize human–bear conflict. To achieve this goal, a series of actions and measures have to be regulated that are related to (1) bear habitat, (2) human activities in the habitat (e.g., highway construction, feeding of bears by humans), (3) prevention of problematic bear occurrences, and (4) the scientific monitoring of population changes. Although the plans development and implementation is the responsibility of bear management experts, various interests groups were considered. In large carnivore management, and especially in bear management, there are no final and universal solutions. Changes in the number of bears, areas of their presence, or behavior require new decisions. This plan offers guidelines for the decision-making process, and, because it includes a revision process, can be adapted to address new circumstances that arise. Citizens interested in conservation, not only in Croatia but also in neighboring countries, expect Croatia to work toward maintaining the long-term existence of as many bears as possible in appropriate habitats, with as few negative effects as possible. This plan is an important step in fulfilling those expectations.

Distance-based Criteria to Identify Minimum Number of Brown Bear Females with Cubs in Europe

Abstract Counts of females with cubs-of-the-year (FWC) have been used as an index for monitoring brown bear (Ursus arctos) populations or estimating a minimum number of adult females in several small and medium-sized populations. Because discriminating among family groups is crucial to this procedure, we sought to improve criteria used to differentiate among FWC using spatial and temporal distances between sightings. We used telemetry data from 11 FWC from southern and central Europe and 15 FWC from Sweden to determine the likelihood that observations were of the same FWC based on the distance moved and elapsed time period. Euclidean distances traveled by each FWC were estimated daily. We then calculated straight-line distances traveled by each FWC using intervals of 1–180 days, or the maximum available. We obtained the maximum values (highest percentiles) of distances over time for each FWC. We considered 2 periods of bear activity: early spring, from first observations after denning until 30 June, and the remaining active season from 1 July until the onset of denning. Native FWC living in the boreal forest of Scandinavia moved farther than those living in the temperate forests of southern and central Europe. Differences among FWC in southern and central Europe may be related to habitat characteristics and to the origin (native or released) of the bears we studied. For example, based on the upper 95% prediction interval of the curve fitted of the 80 percentile in the early spring–June period, 2 observations 30 days apart are unlikely to be of the same individual if >13 km apart for FWC in the boreal forest, >15 km and >7 km, respectively, for released and native FWC in southern and central Europe. Our findings may be useful for biologists and managers to help differentiate FWC and thereby estimate the minimum number of family groups present, particularly in areas with low densities of FWC.

EFFECTS OF SEX, AGE, CAPTURING METHOD, AND SEASON ON SERUM CHEMISTRY VALUES OF BROWN BEARS IN CROATIA

Sixty seven serum samples collected from 43 European brown bears (Ursus arctos) from Croatia were tested for ≤31 serum chemistry parameters. Results were grouped and compared by bears origin (method of capture), sex, age, mass, and season sampled. Greatest differences were found between captive and free-living bears, and minor differences were found when sex, age, mass, or season of sampling were compared. Creatine kinase was significantly different among three categories of bears with the highest mean value of 924 IU/l in snare captured free-living bears compared to 67.8 IU/l in captive ones. Results of these tests provide reference values for European brown bears.

Serologic survey for selected viral and rickettsial agents of brown bears (Ursus arctos) in Croatia

Sera from 22 (13 wild and nine captive) European brown bears (Ursus arctos) from Croatia were tested to 18 viral and rickettsial agents. Serologic evidence of exposure was found to the following agents (number positive/number examined): Bhanja virus (3/15), Tahyna virus (3/15), West Nile virus (4/15), Naples sandfly fever virus (1/15), human adenovirus (1/22), influenza A (1/22) and B (1/22) virus, cytomegalovirus (1/22), parainfluenza virus 1 (2/22), Chlamydia psittaci (1/22), Coxiella burnetii (2/22), and canine parvovirus 2 (CPV-2) (7/22). Evidence of exposure to arboviruses was found exclusively among free-living bears. Evidence of exposure to agents usually transmitted directly was predominant among captive bears. Canine parvovirus 2 antibodies were the most frequently found antibodies and the only antibody common to both groups of bears. This may be the first report of antibodies to CPV-2 in bears.

Border Security Fencing and Wildlife: The End of the Transboundary Paradigm in Eurasia?

The ongoing refugee crisis in Europe has seen many countries rush to construct border security fencing to divert or control the flow of people. This follows a trend of border fence construction across Eurasia during the post-9/11 era. This development has gone largely unnoticed by conservation biologists during an era in which, ironically, transboundary cooperation has emerged as a conservation paradigm. These fences represent a major threat to wildlife because they can cause mortality, obstruct access to seasonally important resources, and reduce effective population size. We summarise the extent of the issue and propose concrete mitigation measures.

Effects of Sex, Age, Body Mass, and Capturing Method on Hematologic Values of Brown Bears in Croatia

Effects of various intrinsic and extrinsic factors on 17 hematologic values from 56 brown bears (Ursus arctos) sampled in Croatia from 1981 to 2005 were evaluated. Differences between female and male bears were detected for number of erythrocytes, sedimentation rate after 30 min, and number of leukocytes and segmented neutrophils. Significant differences between free-living vs. captive and snared vs. not snared bears were detected for the same three parameters: leukocytes, segmented neutrophils, and eosinophils. It was concluded that the physical exertion of bears snared by leg, rather than their free-living status, influenced differences of results among these groups. The obtained mean values are useful reference values for the species.

Denning of Brown Bears in Croatia

Twenty-eight dens of 15 different European brown bears (Ursus arctos) were located, monitored and measured during 1981-92. Ten of them were used by females with cubs, 9 by single females, 5 by males, and 4 by bears of unknown category. Occasionally bears used >1 den in the same winter (4 bears used 2-5 dens, mean = 3). Only 2 of these den changes were attributed to human disturbance. The local abundance of natural caves is probably the reason most dens (22) were built in rock cavities; 3 were ground nests under the canopy of conifers; 2 were excavated cavities under the roots of large standing trees, and 1 was in a horizontal hollow tree. Int. Conf. Bear Res. and Manage. 9(2):79-83

Serologic survey for leptospirae in European brown bears (Ursus arctos) in Croatia.

From 1981 to 1991, sera of 42 European brown bears (Ursus arctos) from three areas in Croatia were tested for antibodies against 12 Leptospira interrogans serovars: grippotyphosa, sejroe, australis, pomona, canicola, icterohaemorrhagiae, tarassovi, saxkoebing, ballum, bataviae, poi, and hardjo. Diagnostic levels of antibody were found in 17 (40%) of 42 sera. Evidence of exposure to at least one of the serovars was found in seven of 14 free-ranging bears from the Lika region, four of 12 free-ranging bears from the Gorski Kotar region, zero of six orphaned cubs from the Gorski Kotar region, and six of 10 captive bears from the Zagreb Zoo. Based on the antibody titers, we implicated the following serovars: australis in five bears, sejroe in two bears, canicola in one bear, and icterohaemorrhagiae in one bear. There was a strong correlation between serovars implicated by this survey and serovars previously isolated from small mammals in Croatia.

Diet of Eurasian lynx Lynx lynx in the northern Dinaric Mountains (Slovenia and Croatia) Importance of edible dormouse Glis glis as alternative prey

The Eurasian lynx Lynx lynx (Linnaeus 1758) is an opportunistic predator that usually selects the smallest ungulate available. Its diet varies considerably among different regions; therefore it is important to study lynx diet in different parts of the species’ range. We studied the diet of lynx from the endangered Dinaric population in Slovenia and Croatia by analyzing lynx scats, prey remains, and stomach contents. Dinaric lynx mainly killed European roe deer Capreolus capreolus (0.64 frequency of occurrence, 79% of all consumed biomass), which were used more frequently during winter and spring. Ungulates were killed more often by adult males than by lynx of other age and sex groups. In contrast to studies from other regions, lynx in the northern Dinaric Mountains also frequently fed on the edible dormice Glis glis (0.18 frequency of occurrence, 7% of all consumed biomass). This large rodent appears to be an important alternative prey, especially for females and young lynx, and was the reason for the highest use of rodents reported so far for the Eurasian lynx. Edible dormice in Dinaric forests have highly variable numbers of active animals. Seasonal and possibly annual variation in dormouse availability obviously affects lynx diet. This is a rare example where variability in the availability of the alternative prey and not the preferred prey leads to the dietary shift. This study confirms the opportunistic nature of Eurasian lynx and the regional variability of its diet.