scholarly journals Competition between apex predators? Brown bears decrease wolf kill rate on two continents

2017 ◽  
Vol 284 (1848) ◽  
pp. 20162368 ◽  
Author(s):  
Aimee Tallian ◽  
Andrés Ordiz ◽  
Matthew C. Metz ◽  
Cyril Milleret ◽  
Camilla Wikenros ◽  
...  
Keyword(s):  
Opposite Effect ◽  
Ursus Arctos ◽  
Brown Bear ◽  
Trophic Levels ◽  
Apex Predators ◽  
Brown Bears ◽  
Common Assumption ◽  
The Common ◽  
Kill Rate

Trophic interactions are a fundamental topic in ecology, but we know little about how competition between apex predators affects predation, the mechanism driving top-down forcing in ecosystems. We used long-term datasets from Scandinavia (Europe) and Yellowstone National Park (North America) to evaluate how grey wolf ( Canis lupus ) kill rate was affected by a sympatric apex predator, the brown bear ( Ursus arctos ). We used kill interval (i.e. the number of days between consecutive ungulate kills) as a proxy of kill rate. Although brown bears can monopolize wolf kills, we found no support in either study system for the common assumption that they cause wolves to kill more often. On the contrary, our results showed the opposite effect. In Scandinavia, wolf packs sympatric with brown bears killed less often than allopatric packs during both spring (after bear den emergence) and summer. Similarly, the presence of bears at wolf-killed ungulates was associated with wolves killing less often during summer in Yellowstone. The consistency in results between the two systems suggests that brown bear presence actually reduces wolf kill rate. Our results suggest that the influence of predation on lower trophic levels may depend on the composition of predator communities.

scholarly journals Brown bear communication hubs: patterns and correlates of tree rubbing and pedal marking at a long-term marking site

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10447
Author(s):  
Eloy Revilla ◽  
Damián Ramos Fernández ◽  
Alberto Fernández-Gil ◽  
Agnieszka Sergiel ◽  
Nuria Selva ◽  
...  
Keyword(s):  
Chemical Communication ◽  
Ursus Arctos ◽  
Brown Bear ◽  
Population Level ◽  
Adult Males ◽  
Communication Behaviors ◽  
Brown Bears ◽  
Low Frequencies ◽  
A Site

Chemical communication is important for many species of mammals. Male brown bears, Ursus arctos, mark trees with a secretion from glands located on their back. The recent discovery of pedal glands and pedal-marking at a site used for tree-rubbing led us to hypothesize that both types of marking form part of a more complex communication system. We describe the patterns of chemical communication used by different age and sex classes, including differences in the roles of these classes as information providers or receivers over four years at a long-term marking site. Using video recordings from a camera trap, we registered a total of 285 bear-visits and 419 behavioral events associated with chemical communication. Bears visited the site more frequently during the mating season, during which communication behaviors were more frequent. A typical visit by male bears consisted of sniffing the depressions where animals pedal mark, performing pedal-marking, sniffing the tree, and, finally, rubbing against the trunk of the tree. Adult males performed most pedal- and tree-marking (95% and 66% of the cases, respectively). Males pedal-marked and tree-rubbed in 81% and 48% of their visits and sniffed the pedal marks and the tree in 23% and 59% of visits, respectively. Adult females never pedal marked, and juveniles did so at very low frequencies. Females rubbed against the tree in just 9% of their visits; they sniffed the tree and the pedal marks in 51% and 21% of their visits, respectively. All sex and age classes performed pedal- and tree-sniffing. There were significant associations between behaviors indicating that different behaviors tended to occur during the same visit and were more likely if another individual had recently visited. These associations leading to repeated marking of the site can promote the establishment of long-term marking sites. Marking sites defined by trees and the trails leading to them seem to act as communication hubs that brown bears use to share and obtain important information at population level.

scholarly journals Long-Term Safety of Intraperitoneal Radio Transmitter Implants in Brown Bears (Ursus arctos)

2018 ◽  
Vol 5 ◽  
Author(s):  
Jon M. Arnemo ◽  
Bjørnar Ytrehus ◽  
Knut Madslien ◽  
Jonas Malmsten ◽  
Sven Brunberg ◽  
...  
Keyword(s):  
Ursus Arctos ◽  
Brown Bears ◽  
Radio Transmitter

scholarly journals The smell of success: Reproductive success related to rub behavior in brown bears

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247964
Author(s):  
Andrea T. Morehouse ◽  
Anne E. Loosen ◽  
Tabitha A. Graves ◽  
Mark S. Boyce
Keyword(s):  
Reproductive Success ◽  
Ursus Arctos ◽  
Scent Marking ◽  
Brown Bear ◽  
Parentage Analysis ◽  
Fitness Component ◽  
Brown Bears ◽  
Male And Female ◽  
Rubbing Behavior ◽  
Insight Into

Several species of bears are known to rub deliberately against trees and other objects, but little is known about why bears rub. Patterns in rubbing behavior of male and female brown bears (Ursus arctos) suggest that scent marking via rubbing functions to communicate among potential mates or competitors. Using DNA from bear hairs collected from rub objects in southwestern Alberta from 2011–2014 and existing DNA datasets from Montana and southeastern British Columbia, we determined sex and individual identity of each bear detected. Using these data, we completed a parentage analysis. From the parentage analysis and detection data, we determined the number of offspring, mates, unique rub objects where an individual was detected, and sampling occasions during which an individual was detected for each brown bear identified through our sampling methods. Using a Poisson regression, we found a positive relationship between bear rubbing behavior and reproductive success; both male and female bears with a greater number of mates and a greater number of offspring were detected at more rub objects and during more occasions. Our results suggest a fitness component to bear rubbing, indicate that rubbing is adaptive, and provide insight into a poorly understood behaviour.

scholarly journals Heart rate during hyperphagia differs between two bear species

2019 ◽  
Vol 15 (1) ◽  
pp. 20180681 ◽  
Author(s):  
Boris Fuchs ◽  
Koji Yamazaki ◽  
Alina L. Evans ◽  
Toshio Tsubota ◽  
Shinsuke Koike ◽  
...  
Keyword(s):  
Heart Rate ◽  
Ursus Arctos ◽  
Brown Bear ◽  
Black Bear ◽  
Black Bears ◽  
Brown Bears ◽  
Fat Reserves ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Increased Activity

Hyperphagia is a critical part of the yearly cycle of bears when they gain fat reserves before entering hibernation. We used heart rate as a proxy to compare the metabolic rate between the Asian black bear ( Ursus thibetanus ) in Japan and the Eurasian brown bear ( Ursus arctos ) in Sweden from summer into hibernation. In the hyperphagic period, black bears feed on fat- and carbohydrate-rich hard masts whereas brown bears feed on sugar-rich berries. Availability of hard masts has quantitative and spatial annual fluctuations, which might require increased activity and result in intraspecific stress. Using generalized additive mixed models we analysed the differences in heart rate between the two species. Black bears had decreased heart rates during summer but had doubled heart rate values throughout the hyperphagic period compared to brown bears. This letter illustrates the different physiological consequences of seasonal differences in food availability in two species of the same genus dealing with the same phenological challenge.

scholarly journals Use of salmon (Oncorhynchus spp.) by Brown Bears (Ursus arctos) in an Arctic, interior, montane environment

2019 ◽  
Vol 133 (2) ◽  
pp. 151 ◽  
Author(s):  
Mathew S. Sorum ◽  
Kyle Joly ◽  
Matthew D. Cameron
Keyword(s):  
National Park ◽  
Ursus Arctos ◽  
Brown Bear ◽  
The Arctic ◽  
Brooks Range ◽  
Brown Bears ◽  
Arctic Circle ◽  
Aerial Surveys

Salmon (Oncorhynchus spp.) is a key dietary item for temperate coastal Brown Bears (Ursus arctos) across much of their circumpolar range. Brown Bears living in Arctic, interior, and montane environments without large annual runs of salmon tend to be smaller bodied and occur at much lower densities than coastal populations. We conducted ground and aerial surveys to assess whether Brown Bears fished for salmon above the Arctic Circle, in and around Gates of the Arctic National Park and Preserve. Here, we document the use of salmon by interior Brown Bears in the Arctic mountains of the central Brooks Range of Alaska. We believe our findings could be important for understanding the breadth of the species’ diet across major biomes, as well as visitor safety in the park and Brown Bear conservation in the region.

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

Biologia ◽  
2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Witold Frąckowiak ◽  
Jörn Theuerkauf ◽  
Bartosz Pirga ◽  
Roman Gula
Keyword(s):  
Habitat Selection ◽  
Human Factors ◽  
Ursus Arctos ◽  
Brown Bear ◽  
Human Settlements ◽  
Brown Bears ◽  
Anthropogenic Structures ◽  
Selection Of

AbstractIn 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.

scholarly journals Population genetics of the main population of brown bears in southwest Asia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5660 ◽  
Author(s):  
Hüseyin Ambarlı ◽  
Deniz Mengüllüoğlu ◽  
Jörns Fickel ◽  
Daniel W. Förster
Keyword(s):  
Ursus Arctos ◽  
Brown Bear ◽  
Distribution Area ◽  
Brown Bears ◽  
Tissue Samples ◽  
Habitat Alterations ◽  
North East ◽  
The North ◽  
Conservation Actions ◽  
Lesser Caucasus

Genetic studies of the Eurasian brown bear (Ursus arctos) have so far focused on populations from Europe and North America, although the largest distribution area of brown bears is in Asia. In this study, we reveal population genetic parameters for the brown bear population inhabiting the Grand Kaçkar Mountains (GKM) in the north east of Turkey, western Lesser Caucasus. Using both hair (N = 147) and tissue samples (N = 7) collected between 2008 and 2014, we found substantial levels of genetic variation (10 microsatellite loci). Bear samples (hair) taken from rubbing trees worked better for genotyping than those from power poles, regardless of the year collected. Genotyping also revealed that bears moved between habitat patches, despite ongoing massive habitat alterations and the creation of large water reservoirs. This population has the potential to serve as a genetic reserve for future reintroductions in the Middle East. Due to the importance of the GKM population for on-going and future conservation actions, the impacts of habitat alterations in the region ought to be minimized; e.g., by establishing green bridges or corridors over reservoirs and major roads to maintain habitat connectivity and gene flow among populations in the Lesser Caucasus.

242 EFFECT OF SPERMATOZOA HEAD MORPHOMETRIC DIMENSIONS ON FREEZABILITY IN BROWN BEAR (URSUS ARCTOS)

2007 ◽  
Vol 19 (1) ◽  
pp. 237 ◽  
Author(s):  
L. Anel ◽  
V. Garcia-Macias ◽  
F. Martinez-Pastor ◽  
M. Alvarez ◽  
S. Borragan ◽  
...  
Keyword(s):  
Ursus Arctos ◽  
Present Report ◽  
Brown Bear ◽  
High Variability ◽  
Wilcoxon Test ◽  
Head Size ◽  
Brown Bears ◽  
Recovery Rates ◽  
Group A ◽  
Group B

Having recently observed that survival of red deer spermatozoa after cryopreservation seemed to reflect the size of sperm heads, we hypothesized that cryoresistance of brown bear spermatozoa might also be dependent on head size, since in a preliminary study we had also observed significant differences in sperm head sizes among male brown bears (median values for area 22.2 �m2, perimeter 18.2, length 6.1 and width 4.4 �m). In the present report, we analyzed the post-thaw survival of spermatozoa of 6 brown bears that were assigned to 2 groups (3 bears/group) based on sperm size: Group A with large-size sperm heads; Group B with small-size heads. Ejaculates were obtained by electroejaculation of adult brown bears (semi-free ranging in Cabarceno Park, Cantabria, Spain) under general anesthesia (7 mg kg-1 tiletamine + zolazepan and 2 mg kg-1 ketamine). Semen was diluted (Tes-Tris-fructose, 8% glycerol, 20% egg yolk, EDTA, and Equex paste), loaded in 0.25-mL straws, and frozen in a biofreezer at 20�C min-1 to -100�C. After storage in liquid nitrogen, samples were thawed in water at 65�C for 6 s and survival was measured. Sperm motility (TM: total, and PM: progressive; %) was assessed microscopically, and sperm viability, acrosome integrity (PI/PNA-FITC), and mitochondrial status (JC-1) were assayed for fresh and thawed sperm by flow cytometry. Recovery rates (RR: thawed/fresh � 100) were calculated for all parameters. For measurement of head size, fresh sperm samples were fixed in glutaraldehyde and slides were air-dried for 2 h. The samples were then stained with Diff-Quik� staining at 37�C. The area (Ar), perimeter (P), length (L), and width (W) of the heads of >100 spermatozoa per slide were measured (Sperm Class Analyzer�; Microptic S.L., Barcelona, Spain). Data were analyzed with the SAS ver8 system, and the Wilcoxon test was applied. The respective morphometric dimensions of the 2 groups were practically identical (Ar = 22; P = 18; L = 6; W = 4). The post-thaw recovery rates of spermatozoa from Group A were: TM: 60.1 � 29.3; PM: 54.8 � 36.0; viability: 99.4 � 8.0; acrosomes: 96.2 � 3.1; mitochondria: 70.9 � 15.5. The recovery rates for Group B were: TM: 78.7 � 13.8; PM: 69.0 � 18.8; viability: 93.8 � 5.2; acrosomes: 98.2 � 9.8; mitochondria: 72.5 � 22.5. Because of the high variability of recovery rates between males within each group, there were no statistical differences between the 2 groups. The absence of differences can be explained by the small number of males examined and the high variability between them. More studies are necessary to determine whether large sperm cells of brown bears are more susceptible to damage during cryopreservation. This work was supported in part by CANTUR S.A. and CICYT (CGL 2004-0278/BOS).

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