Brown bear habitat selection in relation to anthropogenic structures in the Bieszczady Mountains, Poland

Biologia 69/7: 926 930, 2014 Section Zoology DOI: 10.2478/s11756-014-0386-4 Brown bear habitat selection in relation to anthropogenic structures in the Bieszczady Mountains, Poland Witold Frąckowiak 1,Jörn Theuerkauf 2,BartoszPirga 3 & Roman Gula 2 * 1 Department of Ecology, Wildlife Research and Ecotourism, Pedagogical University of Cracow, Podbrzezie 3, PL-31054 Cracow, Poland; e-mail: fracko@poczta.fm 2 Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, PL-00679 Warsaw, Poland; e-mails: jtheuer@miiz.eu, rgula@miiz.eu 3 Bieszczady National Park, Lutowiska 2, PL-38713, Poland; e-mail: wrzosowe.wzgorze@gmail.com Abstract: In Europe, brown bear Ursus arctos habitats frequently overlap with human settlements and infrastructure. We tested whether anthropogenic structures played an important role in habitat selection by brown bears in the Bieszczady Mountains, Poland. We analysed 668 signs of brown bear presence recorded during 6 counts along 246 km of transects (total 1,476 km) in spring, summer and autumn of 1993 and 1994. Habitat selection of bears was more related to habitat and altitude than to human factors. Avoidance of roads, settlements and forest clearings influenced habitat selection by brown bears in spring but less in summer and autumn. Key words: Ursus arctos; habitat use; human avoidance; sign survey Introduction Humans caused the extinction of brown bears Ursus arctos L., 1758 from most of their historical range in Europe and North America (Craighead et al. 1995; Nellemann et al. 2007). Centuries of persecution are likely to have favoured bears that avoided humans (Linnell et al. 2002). Brown bears therefore tend to avoid humans at a large scale but total avoidance of people in anthropogenic landscapes is not possible (Ordiz et al. 2011). When bear range overlaps with humans, bear habitat use is likely to be affected by humans (Matson 1989; Rode & Robbins 2006; Nellemann et al. 2007). However, the way bears respond to man-made structures and human activity might be more complex than an assumed ultimate spatial avoidance (Martin et al. 2010). The Carpathian Mountains cover 160,000 km 2 and hold about 6,000 brown bears, which represent 14% of European brown bears. It is the largest continuous European population out of Russia (Salvatori et al. 2002). Due to the former communist type economies in this region, the infrastructure of the Carpathians is less developed than in comparable mountainous areas of Western Europe (Webster et al. 2001). Nonetheless, about 16 million people inhabit the region, corresponding to an average density of 76 humans per km 2 (Webster et al. 2001). Brown bears in the Carpathians inhabit mainly low human density areas (Fernández et al. 2012). The Bieszczady Mountains, part of the Carpathians and situated in the southeast of Poland, were virtually depopulated after the World War II (Augustyn 2004). Resettlements since the 1950s never attained pre-war human population densities, therefore the majority of former arable land has been naturally reforested (Augustyn 2004). This historical process created space for wildlife, especially for large carnivores. Accordingly and because of legal protection, bears, which were sporadically recorded in the Bieszczady Mts before World War II (Burzyński 1931), have expanded in space and increased in numbers after the war (Jakubiec & Buchalczyk 1997). At present, about 50 bears and large wolf Canis lupus L., 1758 and lynx Lynx lynx L., 1758 populations live in an area of roughly 2,000 km 2 in the Bieszczady Mts (Gula et al. 1998, 2002; Selva et al. 2011). Habitats of brown bears consist of forest intersected by roads and human settlements. In such conditions, patterns of habitat selection by brown bears might be mainly driven by a combination of human avoidance and foraging requirements (Bojarska & Selva 2012). In this paper, we aim at testing to which extent human activity influenced brown bear habitat use in the Bieszczady Mts in the beginning of the 1990. Using a Geographical Information System (GIS), we reanalysed data collected during this period (Gula et al. 1998) in the previously not analysed context of potential anthropogenic influence on bear habitat selection. Since the Bieszczady Mts are currently in a phase of * Corresponding author c 2014 Institute of Zoology, Slovak Academy of Sciences

Brown bear habitat selection in Poland 927 improvement of road infrastructure and of dramatic increase in traffic volumes, we think that such an analysis could serve in future as reference for changes in quality of bear habitats. Material and methods We conducted the study in the Bieszczady Mts, Poland (49 N, 22 E) in 1993 and 1994. The highest elevations in this mountain range are more than 1,300 m a.s.l., while the average elevation of valleys is about 500 m. Average temperature in July is 16 C, and 6 C in January. Average monthly precipitation is 125 mm, with an annual average of 800 1200 mm. Snow cover persists for 90 140 days, appearing in October December and disappearing by February April. The region is inhabited by numerous ungulates including red deer Cervus elaphus L., 1758, roe deer Capreolus capreolus (L., 1758), European bison Bison bonasus (L., 1758), wild boar Sus scrofa L., 1758, and large carnivores including brown bear, wolf, and lynx. The study area covers 375 km 2 and constitutes the core area of a 1,340 km 2 bear range in the Bieszczady Mts (Gula & Frackowiak 1996). Altitudes range from 400 m to 1,200 m. There are 15 villages, inhabited by 36 to 736 people, within the study area. The average human density is 6 per km 2. There are 81 km of public roads within the study area, corresponding to a road density of 0.2 km per km 2.About 70% of the area is forested, with beech Fagus silvatica, alder Alnus incana, fir Abies alba and spruce Picea abies as dominant species. During 1993 and 1994, we searched for signs of bear presence (tracks and scats) along 246 km of transects. We walked along the transects 3 times per year: in spring (15 March 15 April), summer (July) and autumn (15 October 15 November). We recorded 321 signs of bear presence in spring, 85 in summer and 262 in autumn on a total of 1,476 km of transects. We used ArcGis to calculate altitude, distance to the nearest paved public road, distance to the nearest village and distance to the nearest forest edge for the 668 locations with bear records and for randomly chosen points along the transects that were ground-proved for absence of bear signs (we kept only the 363 points for analyses where there were no signs of bear presence around the point). Based on a map of forest stands, we assigned to each of the 1,031 bear presence and bear absence points one of 5 habitat types: beech forest, coniferous stand (fir or spruce), young coniferous thicket, re-growth on former arable land (mostly alder with some birch Betula), and clearing. We then tested the influence of habitat, altitude, distance to the nearest paved public road, distance to the nearest village, and distance to the nearest forest edge on bear presence/absence. We used generalised linear models (IBM SPSS Statistics 20) with a binary logistic structure (1 = sign of bear, 0 = without sign of bear) to assess which of the 5 parameters determined most the presence by bears. Habitat was included as a nominal variable, while the other parameters were numerical. We normalised the numerical variables by square root transformation. We ranked all 31 possible models by Akaike weights (w) and assessed relative importance of variables included in the models by summing up w values (Burnham & Anderson 2002; Arnold 2010). We hypothesized that if the avoidance of humans is the main factor influencing bear habitat selection, then distance to the nearest village, road and forest edge should most determine bear presence. Additionally to the multiple regression, we presented each single factor by comparing means with those of 10,000 random points generated along the transects (to represent the real average value of habitat parameters). For each habitat, altitude, or distance class, we calculated a selection index by dividing the proportion of bear records by the proportion of random points. We used 500 m wide classes for distances and 200 m wide classes for altitudes. We calculated confidence intervals (CI) of selection indices for each class using 95% Bonferroni intervals for utilisation-availability data (Byers et al. 1984). Results In spring, the presence of bear signs was determined by habitat type (sum of w 1.00), distance to forest edge (sum of w 1.00), altitude (sum of w 1.00), distance to the road (sum of w 0.99), but little by distance to the next village (sum of w 0.28) (Table 1). Distance to the next village was the only unimportant parameter (Table 2). During this period, bears stayed on average at lower altitudes (665 ± 12 m CI), and far from villages (2.0 ± 0.1 km) and public roads (2.0 ± 0.1 km). They also avoided the area outside the forest, avoided being less than 1 km from the forest edge and avoided the vicinity of villages and roads (Fig. 1). In summer, habitat type (sum of w 1.00), altitude (sum of w 1.00), distance to road (sum of w 0.92), and distance to forest edge (sum of w 0.73) played an important role in determining habitat use (Tables 1, 2), but less distance to village (sum of w 0.45). During this period, bears were recorded on average at higher altitudes than in spring (741 ± 25 m), they preferred to stay at altitudes between 800 and 1,000 m and avoided lower altitudes between 400 and 600 m. They avoided the vicinity of public roads, and tended to stay in clearings (Fig. 1). In autumn, as in summer, only habitat type (sum of w 0.99) and altitude (sum of w 0.62) were important in determining bear habitat use (Tables 1, 2), whereas distance to forest edge (sum of w 0.44), distance to road (sum of w 0.42), and distance to village (sum of w 0.38) had low rankings. Bears avoided lower altitudes of 400 600 m, preferred to stay on average at higher altitudes (747 ± 15 m), and were frequently recorded at altitudes over 1,000 m. Discussion Factors related to humans (distance to road, village, and forest edge) played mostly in spring an important role in determining habitat use of bears. A large part of this impact could be explained by the diet choice of bears in the study area. During this period, bears feed on emerging spring geophytes, beechnuts from the previous autumn, wild mammals (predated or scavenged), and on bait (crops and carcasses of domestic animals) at hunting towers (Frąckowiak & Gula 1992; Frąckowiak 1997). This food is earlier available at lower altitudes, while higher elevations are still covered by

928 W. Frąckowiak et al. Table 1. Multiple logistic regressions of influence of type of habitat, distances to forest edge, to public roads and to villages, and altitude on brown bear presence ranked by Akaike weights (w) in the Bieszczady Mts, Poland, in 1993 1994 (models with Akaike weights of less than 0.01 are not presented but were included in the analyses). Period Rank Parameters in the model w AIC AIC Spring 1 habitat, edge, altitude, road 0.716 0.00 860.70 2 habitat, edge, altitude, road, village 0.273 1.93 862.63 3 habitat, edge, altitude, village 0.011 8.43 869.14 Summer 1 habitat, altitude, road, edge 0.378 0.00 420.55 2 habitat, altitude, road, village, edge 0.290 0.53 421.08 3 habitat, altitude, road 0.142 1.95 422.50 4 habitat, altitude, road, village 0.107 2.53 423.08 5 habitat, altitude, village, edge 0.037 4.63 425.18 6 habitat, altitude, edge 0.025 5.41 425.97 7 habitat, altitude, village 0.011 7.00 427.55 Autumn 1 habitat 0.119 0.00 842.78 2 habitat, altitude, road 0.114 0.09 842.87 3 habitat, altitude, edge, road 0.102 0.32 843.10 4 habitat, altitude, village 0.097 0.41 843.19 5 habitat, altitude, edge, village 0.088 0.60 843.38 6 habitat, edge 0.075 0.92 843.70 7 habitat, altitude 0.066 1.18 843.96 8 habitat, altitude, edge 0.055 1.54 844.32 9 habitat, road 0.049 1.77 844.55 10 habitat, village 0.046 1.89 844.68 11 habitat, altitude, road, village 0.046 1.92 844.70 12 habitat, altitude, edge, road, village 0.041 2.12 844.90 13 habitat, edge, road 0.029 2.82 845.60 14 habitat, edge, village 0.028 2.89 845.68 15 habitat, road, village 0.019 3.68 846.46 16 habitat, edge, road, village 0.011 4.71 847.49 Table 2. Averaged parameter estimates weighted by Akaike weights (β with 85% confidence interval as recommended by Arnold 2010) in logistic regressions of influence of distances to forest edge, to villages and to public roads, altitude, and type of habitat on brown bear presence in the Bieszczady Mts, Poland, in 1993 1994. A parameter is considered as unimportant if the confidence interval includes the value 0. Parameter β (spring) β (summer) β (autumn) Edge 0.028 ± 0.002 0.016 ± 0.003 0.007 ± 0.001 Village 0.002 ± 0.006 0.007 ± 0.005 0.006 ± 0.001 Road 0.033 ± 0.004 0.028 ± 0.006 0.008 ± 0.001 Altitude 0.104 ± 0.007 0.055 ± 0.004 0.017 ± 0.002 Habitat beech forest 0.641 ± 0.124 1.499 ± 0.062 0.646 ± 0.022 coniferous forest 1.047 ± 0.123 0.602 ± 0.062 0.558 ± 0.022 spruce thickets 0.608 ± 0.129 1.180 ± 0.063 0.558 ± 0.021 regrowth 1.768 ± 0.113 0.169 ± 0.068 0.165 ± 0.021 open area 0.683 ± 0.107 1.194 ± 0.055 0.279 ± 0.019 snow. Spruce thickets, frequently used by bears, provide a good place for daytime resting sites, because they are sheltered from human sight and inclement weather (Frąckowiak & Gula 1996). In summer, the diet of bears shifts towards fruits and insects, and growing vegetation at altitudes between 600 and 1,000 m attract bears, which forage in clearings for blueberries (Vaccinium spp.) and raspberries (Rubus spp.) (Frąckowiak & Gula 1992; Frąckowiak 1997). Because of the higher altitude, these areas are located farther from roads and villages, therefore bears can avoid being close to villages and main roads. In late summer and autumn, bears consume large quantities of food to gather fat reserves for the winter dormancy (Watts & Jonkel 1988). These high energetic demands during the pre-denning period oblige bears to forage intensively and use all available food sources and, therefore, can less afford to avoid humans. They also search areas suitable for denning, which in the Bieszczady Mts are frequently located over 900 m (Gula & Frąckowiak 2000), resulting in bears recorded more often at higher altitudes. Low use of areas surrounding major roads and human settlements has been shown previously (Clevenger et al. 1992; Huygens et al. 2001; Wielgus et al. 2002; Kaczensky et al. 2003; Preatoni et al. 2005; Nellemann et al. 2007) and in the Bieszczady Mts this result is supported by the observation that people rarely see brown bears (Jakubiec 2001). Bears in the study area, however, frequently foraged on anthropogenic food: crops, fruits and meat deposed as bait by hunters (Frąckowiak 1997). We therefore think that, instead of permanently avoiding the area around villages and roads, bears use

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Forest Res. 32: 1597 1606. DOI: 10.1139/X02-084 Received April 17, 2013 Accepted May 5, 2014