| 1. |
- Penteriani, Vincenzo, et al.
(författare)
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Female brown bears use areas with infanticide risk in a spatially confined population
- 2020
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Ingår i: Ursus (International Association for Bear Research and Management). - 1537-6176 .- 1938-5439. ; 2020:31e2, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Areas used by female brown bears (Ursus arctos) with cubs-of-the-year (hereafter, FCOY) during the first months after den exit are crucial for offspring survival, primarily because of the risk of infanticide by male bears. Therefore, FCOY may avoid areas frequented by adult males during the mating season. The main aim of this study was to identify landscape features (i.e., structure, composition, and human footprint) that may differentiate the habitat use of FCOY in the small bear population of the Cantabrian Mountains (northwestern Spain; 2001–2016) from (a) areas frequented by females with yearlings, because older cubs are at less risk of infanticide than cubs-of-the-year, and (b) bear mating areas (i.e., the riskiest areas for FCOY because of the presence of adult males). During the first months after den emergence (Apr–Jun), FCOY settled in the roughest areas of the Cantabrian Mountains at most spatial scales. This settlement pattern might represent a behavioral adaptation of FCOY to reduce the risk of encounters with males during the mating season. However, FCOY also settled in similar landscapes to those used by adult bears during the mating season, which may increase the likelihood of risky encounters. Indeed, we observed a spatial overlap between observed locations of FCOY and mating areas, which may help explain the high frequency of infanticide observed in the Cantabrian Mountains. We hypothesize that the need for both shelter and food in early spring may ‘trap’ FCOY in otherwise favorable areas that overlap with mating areas. This may occur predominately in small and confined bear populations, such as the one in the Cantabrian Mountains, where a restricted range and limited habitat availability might prevent FCOY from avoiding risky areas successfully.
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| 2. |
- Kindberg, Jonas
(författare)
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Indirect effects of bear hunting: a review from Scandinavia
- 2017
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Ingår i: Ursus. - 1537-6176. ; 28, s. 150-164
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Forskningsöversikt (refereegranskat)abstract
- Harvest by means of hunting is a commonly used tool in large carnivore management. To evaluate the effects of harvest on populations, managers usually focus on numerical or immediate direct demographic effects of harvest mortality on a population's size and growth. However, we suggest that managers should also give consideration to indirect and potential evolutionary effects of hunting (e.g., the consequences of a change in the age, sex, and social structure), and their effects on population growth rate. We define "indirect effects" as hunting-induced changes in a population, including human-induced selection, that result in an additive change to the population growth rate "lambda" beyond that due to the initial offtake from direct mortality. We considered 4 major sources of possible indirect effects from hunting of bears: (1) changes to a population's age and sex structure, (2) changes to a population's social structure, (3) changes in individual behavior, and (4) human-induced selection. We identified empirically supported, as well as expected, indirect effects of hunting based primarily on >30 years of research on the Scandinavian brown bear (Ursus arctos) population. We stress that some indirect effects have been documented (e.g., habitat use and daily activity patterns of bears change when hunting seasons start, and changes in male social structure induce sexually selected infanticide and reduce population growth). Other effects may be more difficult to document and quantify in wild bear populations (e.g., how a younger age structure in males may lead to decreased offspring survival). We suggest that managers of bear and other large carnivore populations adopt a precautionary approach and assume that indirect effects do exist, have a potential impact on population structure, and, ultimately, may have an effect on population growth that differs from that predicted by harvest models based on direct effects alone.
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| 3. |
- López-Bao, José Vicente
(författare)
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Patterns of movement of released female brown bears in the Cantabrian Mountains, northwestern Spain
- 2017
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Ingår i: Ursus. - 1537-6176. ; 28, s. 165-170
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Tidskriftsartikel (refereegranskat)abstract
- Between 2008 and 2013, 3 female brown bears (Ursus arctos; 2 cubs-of-the-year and 1 2-yr-old) were rescued, rehabilitated in captivity, radiotagged, and released back to the Cantabrian Mountains, northwestern Spain. We characterized their daily and seasonal movements post-release to gain insights into their movement strategies and the viability of bears released in human-dominated environments. The bears exhibited marked diurnal activity and were active throughout winter. Two bears demonstrated behaviors similar to those reported for wild bears, whereas one cub-of-the-year was recaptured after 21 days because she developed signs of habituation to humans.
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| 4. |
- Ordiz, Andrés, et al.
(författare)
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A practical method for measuring horizontal cover
- 2009
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Ingår i: Ursus. - 1537-6176. ; 20, s. 109-113
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new cover cylinder as a useful tool for a single observer to measure horizontal cover in the field. We compared it with 4 other methods for measuring horizontal cover at brown bear (Ursus arctos) beds, with all measurements taken 10 m from beds in the 4 cardinal directions. We also compared cylinder cover values from a fixed distance with an index of cover, namely a sighting distance, D, the minimum distance at which the cylinder could no longer be seen; we also compared measurements from a random direction and from the 4 cardinal directions. The cylinder provided measurements comparable to other devices, including a cardboard profile of a bedded bear, and was the most practical to use in the field. Measuring D was scarcely more time consuming than measuring cover from the fixed 10-m distance, and D is better for statistical analysis. We recommend the cylinder, and using the index of cover, D, taken from the 4 cardinal directions, when assessing horizontal cover for bears or other medium and large terrestrial vertebrates.
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| 5. |
- Osterman, Wilhelm H. A., et al.
(författare)
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An Andean bear population hotspot in Northern Peru
- 2021
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Ingår i: Ursus. - : Ursus. - 1537-6176. ; 32:E12
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Tidskriftsartikel (refereegranskat)abstract
- Peru is probably home to the largest population of Andean bears (Tremarctos ornatus; Peyton 1999); however, no studies have assessed the density and ecology of the species in this region in the past 20 years. Population density estimates are a cornerstone of species conservation because they help guide decision-making and monitoring of species trends. Here, we study Andean bear population density in a small area (i.e., visible area: 352 ha), Copal, in the Amazonas region in Peru between 2015 and 2017. To estimate Andean bear density, we used 3 methods: one based on capture-recapture data of bears, one based on an occupancy model, and one based on the frequency of a uniquely colored bear compared with the frequency of other black Andean bears. Our results estimated Andean bear densities between 8.85 and 17.39 bears/100 km(2); we considered our estimate of 10.38 bears/100 km(2) from capture-recapture data to be the most reliable. We also recalculated Andean bear density results from Ecuador by Molina et al. (2017), which provided a similar estimate of 11.49 bears/100 km(2). Additionally, we report a unique finding of a bear with a golden brown pelage, which we suspect to be the first case in Andean bears. During behavioral observations, Andean bears were predominantly feeding. We suggest that, although Andean bears have large home ranges, a few small areas may be of disproportionate importance to a population. Protecting small areas frequently used by a large number of bears could be an effective mean for Andean bear conservation where large reserves are not a feasible option. We also recognize the need for large-scale studies using a spatial capture-recapture framework, and to associate the results of Andean bear density with resource use in order to successfully protect high-value Andean bear habitat.
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| 6. |
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