Figure - available from: Ecosphere
This content is subject to copyright. Terms and conditions apply.
Black bear (Ursus americanus) population and individual variation in den location and spring space use in relation to reproductive class for Michigan, Missouri, and Mississippi, 2008–2017. FC, female with cubs; FY, female with yearlings; FA, female alone; M, males. Population values show overall inter‐individual variation, individual values compare the same female with themselves at different reproductive states. Top: den distance to nearest road (population n = 161, individual n = 48), middle: road index (population n = 161, individual n = 47), and bottom: spring home range size (population n = 117, individual n = 27). Road index = values above zero indicate road avoidance in relation to the den emergence home range (see Materials and Methods for details).
Source publication
Den sites are important for many species’ ecology, and individuals should choose den sites that minimize risk and maximize energy gain. We examined den site selection and spring space use for black bears (Ursus americanus) at the individual level, and analyzed support for the anthropogenic risk avoidance and infanticide avoidance hypotheses. We obt...
Similar publications
Valentin' s rock lizard (Darevskia valentini) is suggested to be the parent for several parthenogenetic species (e.g., D. armeniaca, D. bendimahiensis, D. sapphirina, and D. unisexualis) that evolved through hybridization. Complex evolutionary processes (including reticulate evolution) are occurring within the areas where Valentin' s rock lizard co...
Citations
... Throughout their range, black bears typically select for forested areas with abundant herbaceous vegetation (Herrero 1972, Bastille-Rousseau et al. 2011, Fortin et al. 2013, Costello et al. 2016, Bowersock et al. 2021. To assess this for our study area, we classified vegetation communities as being forested or non- The presence of roads also can influence the spatial and temporal distribution of black bears (Kasworm and Manley 1990, Berger 2007, Gunther et al. 2018, Gantchoff et al. 2019, Zeller et al. 2019). Therefore, we used a geospatial layer of paved roads (Spatial Analysis Center 2010) and the st_distance function in the sf package in program R (R Development Core Team 2013, Pebesma 2018) to compute proximity to the nearest paved road. ...
The quality and availability of resources are known to influence spatial patterns of animal density. In Yellowstone National Park, relationships between the availability of resources and the distribution of grizzly bears ( Ursus arctos ) have been explored but have yet to be examined in American black bears ( Ursus americanus ). We conducted non‐invasive genetic sampling during 2017–2018 (mid‐May to mid‐July) and applied spatially explicit capture‐recapture models to estimate density of black bears and examine associations with landscape features. In both years, density estimates were higher in forested vegetation communities, which provide food resources and thermal and security cover preferred by black bears, compared with non‐forested areas. In 2017, density also varied by sex, with female densities being higher than males. Based on our estimates, the northern range of Yellowstone National Park supports one of the highest densities of black bears (20 black bears/100 km ² ) in the northern Rocky Mountains (6–12 black bears/100 km ² in other regions). Given these high densities, black bears could influence other wildlife populations more than previously thought, such as through displacement of sympatric predators from kills. Our study provides the first spatially explicit estimates of density for black bears within an ecosystem that contains the majority of North America's large mammal species. Our density estimates provide a baseline that can be used for future research and management decisions of black bears, including efforts to reduce human–bear conflicts.
... Fine-scale monitoring of complete family groups can reveal more information about group structure, interactions between parents and their young, neonate care in social species, and changes in parental care as neonates age (Laurenson 1994, Mills et al. 2008, Moriarty et al. 2012, O'Malley et al. 2018. Use of rVHF technology in other carnivores may allow for a more thorough analysis of natal and subsequent den site use, maternal spatial use relative to neonate location, and the identification of initial exploration or dispersal events away from the mother, all of which may be overlooked with less frequent monitoring (Fernández and Palomares 2000, Mills et al. 2008, Gantchoff et al. 2019. ...
Fine‐scale monitoring of neonate mammals can provide important data about survival rates and cause‐specific mortality. However, the VHF transmitters and collars frequently used to monitor neonate mammals necessitate logistically intensive field efforts, often requiring personnel to check on collared animals several times a day. We adapted technology that creates a proximity link between GPS collars fitted on adult animals to expandable VHF collars fitted for use on neonate cougar kittens (Puma concolor). We describe and evaluate the use of this system, which resulted in an 87% success rate of tracking kittens from ~5 weeks to 6 months of age. Our experience with these collars suggests that this technology can be used to enhance understanding of neonate survival and to gain information about maternal behavior and time allocation with offspring, providing a new source of data that was previously unobservable.
... Bears may be forced to use suboptimal dens that have diminished security protection that exposes individuals to predation Harestad 1996, Garrison et al. 2007) or cause mortalities due to flooding (Alt 1984). The sustainability of bear populations may be reduced if suitable dens are not well-distributed across the landscape; pregnant female black bears have been found to den closer to roads than other sex and age classes, possibly to reduce the risk of infanticide (Gantchoff et al. 2019). The net effect of the reduction in supply is that suitable den sites may become a factor that limits black bear populations in this landscape (Alt 1984, Oli et al. 1997, Hersey et al. 2005. ...
American black bears (Ursus americanus) require suitable den
sites that provide security and cover to successfully survive the
winter denning period. On Vancouver Island, British Columbia,
Canada, black bears prefer to use cavities associated with
large‐diameter hollow trees or structures derived from trees
(i.e., cavities in or under logs, root boles and stumps) as den
sites. Extensive harvesting of coastal forests has reduced the
availability of natural den structures such that their supply may
affect population sustainability. I attempted to develop new
methods to address the declining supply of denning opportunities
by creating and testing new den structures constructed
in trees, stumps and from plastic. Between 2014–2021,
I created or deployed and monitored 17 potential den
structures in 2 study areas that were believed to have low
den supply. I documented up to 51 visits by bears at each
structure; every one of the video‐monitored structures was
investigated at least 5 times. None of the plastic artificial den
structures were used by bears, but an enhanced natural
structure was used as a den over 4 consecutive winters. My
work indicates that bears will find and investigate all natural or
artificial denning structures in their environment, but artificial
structures do not appear to be a viable method to mitigate
losses of dens caused by forest harvesting.
... Road networks can: (a) affect surrounding ecosystems by increasing pollutants due to vehicle traffic (Forman et al., 2003); (b) facilitate the arrival and spread of non-native species (Schowalter, 1988;Watkins et al., 2003); (c) allow human access to previously pristine areas Steyaert et al., 2016); (d) modify ecological communities (Trombulak & Frissel, 2000); (e) fragment and/or destroy habitats (Coffin, 2007;Forman et al., 2003;Riitters et al., 2004); (f) increase wildlife mortality (Morales- Penteriani et al., 2018); and (g) represent barriers to movement that may reduce population viability and gene exchange (Epps & Keyghobadi, 2015;Holderegger & Di Giulio, 2010;Shepard et al., 2008). Moreover, these effects vary depending on road type and consequent traffic loads (Chen & Koprowski, 2019;Kore n et al., 2011;Northrup et al., 2012), which may modify animal behaviour (Barber et al., 2010;Morales-Gonz alez et al., 2020), habitat selection and parental investment (Frid & Dill, 2002), as well as increase energetic costs and physiological stress of animals (Houston et al., 2012;Jacobson et al., 2016;Wasser et al., 2011). However, not all the effects of roads are deleterious per se, and it has been reported how roads can function as attractants, providing advantages for communication, foraging, movement, refuge or thermoregulation (Hill et al., 2021). ...
... Similarly, roads have also been described as occasional attractants to brown bears as they facilitate communication (Gonz alez-Bernardo et al., 2021;Sato et al., 2014) or movement (Hill et al., 2021;Roever et al., 2010). Along the same line, some age classes such as females with cubs and subadults may use roads to avoid risky encounters with adult males (Graham et al., 2010;Penteriani et al., 2018), as also occurs in other ursids (Gantchoff et al., 2019). Moreover, traffic volume associated with the type of road has also been shown to determine the severity of road impacts on bears (Elfstr€ om et al., 2008;Northrup et al., 2012). ...
Roads are human infrastructure that heavily affect wildlife, often with marked impacts on carnivores, including brown bears Ursus arctos. Here, we assessed the potential impact of road networks on the distribution of brown bears in the small, isolated and endangered Cantabrian population of north‐western Spain. To ascertain whether local road networks affect brown bear spatial distribution, we first assessed potential influences on the distance of bear locations to roads using candidate models which included topographic variables, landcover types, bear age and reproductive status, traffic volume and road visibility. Then, we built two sets of habitat suitability models, both with and without roads, to discern the possible loss of habitat suitability caused by roads. The mean distance of bear locations to the nearest road was 968 ± 804 m and the closest road was a low traffic road in 72.5% of cases. Candidate models showed little influence of our variables on bear distance to the nearest road, with the exception of elevation. Habitat suitability models revealed that road networks in our study area seem to have almost no effect on brown bear habitat suitability, except for females with yearlings during the denning season. However, this result may also be a consequence of the fact that only a small proportion (16.5%) of the cells classified as suitable bear habitats were crossed by roads, that is, most of the roads are primarily located in unsuitable bear habitats in the Cantabrian Mountains. Compared to previous studies conducted in other populations, mainly North American ones, our findings might suggest a different response of Eurasian brown bears to roads due to a longer bear‐human coexistence in Europe versus North America. However, the indirect approach used in our study does not exclude other detrimental effects, for example, road mortality, increased stress and movement pattern disruption, only detectable by more direct approaches such as telemetry.
... Water is one of the indispensable conditions for animal survival. Our results show that when selecting habitat, ABBs tend to avoid the main road, which is consistent with other studies and supports the anthropogenic risk avoidance hypothesis (Gantchoff et al., 2019). ...
Large carnivores maintain the balance of ecosystems. Understanding distribution and population changes are necessary prerequisites for scientific conservation strategy. The east of Jilin Province is the habitat of endangered Amur tiger (Panthera tigris altaica). The Chinese government has focused the monitoring on protecting the Amur tiger. However, little is known about Asiatic black bear (ABB, Ursus thibetanus) distribution, population dynamics in the wild, and protection awareness of local residents in Jilin Province, China. We conducted a integrative survey in mountain areas of eastern Jilin to determine ABB distribution. We explored the drivers of the distribution of ABB in Jilin using logstic regression, we further predicted the habitat suitability and potential suitable habitat of the ABB. Totally, we surveyed 112 grids (15 km × 15 km) from November 2015 to January 2019. Logistic regression analysis revealed that the main factors driving ABB distribution in Jilin are forest coverage, distance from protected areas, distance from main roads (railways and highways), and distance from water bodies. The results of questionnaire survey showed that the local residents’ understanding of ABB distribution is congruent with our field research. They believed that the number of ABBs has gradually increased in the past ten years. Nevertheless, the local residents have a negative attitude toward the ABBs, which may adversely affect efforts to protect them, possibly leading to more conflicts between humans and bears. Therefore, there is a need to consider ways to change the attitude of the locals through the strengthening of the protection propaganda and advocating management as being critical for the protection of ABBs. Our research provides a scientific basis for future conservation planning. We recommend taking local people’s attitude into consideration during conservation management strategy making to reduce human-bear conflicts and promote the coexistence of humans and bears.
... Our findings provide new insights about the influence of forage quality on resource selection by black bears, but we acknowledge that our inferences are based on a relatively small sample size, dominated by females (5 of 7 bears). Although female and male bears select different food resources to meet their varying metabolic needs during the year (Gunther et al. 2002, Apps et al. 2006, Gantchoff et al. 2019, early snowpack limits spring resources to lower elevation areas of the Northern Range (Notaro et al. 2019). Therefore, male and female bears likely were restricted to the same areas and resources during spring Berger 2003, Johnson et al. 2015). ...
In temperate regions of the world, food resources are seasonally limited, which causes some wildlife species to seek out nutrient‐rich resources to better meet their caloric needs. Animals that utilize high‐quality resources may reap fitness benefits as they prepare for mating, migration, or hibernation. American black bears (Ursus americanus) are omnivores that consume both plant and animal food resources to meet macronutrient needs. Black bears capitalize on high‐quality food resources, such as soft mast in summer and hard mast during autumn, but we know less about the importance of resource quality during spring. Therefore, we sought to understand the relationship between the spatiotemporal variation in the availability of food and resource selection of black bears during spring. We also aimed to infer potential changes in foraging tactics, from opportunistic foraging to more active selection. Although black bears are described as opportunistic omnivores, we hypothesized they select areas with high‐quality forage when available. We instrumented 7 black bears with GPS collars in 2017 and 2018 and estimated fine‐scale resource selection with integrated step‐selection functions. We found evidence that black bear movements were influenced by forage quality of vegetative food resources. However, we failed to find evidence that black bears actively alter their movements to take advantage of seasonal neonate elk. Although black bears represent a substantial cause of mortality for neonate elk, we found that black bears likely feed on neonates encountered opportunistically while traveling between patches of high‐quality forage. Few studies have shown evidence of an omnivorous species capitalizing on spatiotemporal variation in forage quality, yet our data suggest this may be an important strategy for species with diverse diets, particularly where resources are seasonally limited.
... First, this may be an artefact of small sample sizes, driven by the apparent difference in slope to structures among natal den sites and potential den sites. Alternatively, this may reflect selection of den sites by female Andean bears to reduce the risk of infanticide by adult males; female American black bears have been seen to select den sites at greater risk of human disturbance, apparently to reduce the risk of infanticide by males (Gantchoff et al. 2019). ...
... Adult male Andean bears are suspected to kill smaller conspecifics (Castellanos et al. 2016), as has been suspected or reported in several other bear species (Alt and Gruttadauria 1984, Swenson et al. 1997, Derocher and Wiig 1999, Joshi et al. 1999, McLellan 2005, Stirling and Ross 2011, Gardner et al. 2014, Karamanlidis et al. 2015, Gantchoff et al. 2019). Thus, female Andean bears at Cerro Venado might have selected natal dens with small entrances in defense against adult male bears and puma. ...
... Association with roads may also serve a role in intraspecific avoidance. Female black bears with cubs den closer to roads, whereas males and females without cubs den further from roads compared to the habitat available to them (Gantchoff et al. 2019). This difference in selection is likely to result from females avoiding males in order to reduce the risk of infanticide, and has also been documented for brown bears (Graham et al. 2010). ...
... Males with larger home ranges and greater risk-taking behaviour might consume more resources from roads than females (Lee et al. 2004), while juveniles are sometimes more likely to associate with roads as a mechanism to avoid aggressive adults (McLellan & Shackleton 1988). Within the same sex and age class, road use may be influenced by reproductive status (Gantchoff et al. 2019). At an even finer scale, there can be variability at the individual level driven by behavioural differences or variation in familiarity with the landscape (Ascensão et al. 2014). ...
1. Roads have numerous negative impacts for mammals, but may also serve as attractants due to altered vegetation or provisioning of resources.
2. We reviewed the use of roads and their associated features by mammals, in order to understand the ecological factors contributing to road use.
3. We documented 129 studies that recorded road use by 116 mammalian species, spanning 15 orders and 35 families, in six continents. Carnivora was the most common order (40 species, 34% of all 116 species), followed by Artiodactyla (24 species, 20%) and Rodentia (21 species, 18%). The species were placed in the IUCN categories Least Concern (88 species, 76% of all 116 species), Vulnerable (11 species, 9%), Near Threatened (9 species, 8%), Endangered (6 species, 5%), and Critically Endangered (2 species, 2%).
4. We assigned road use to five ecological categories, reflecting the reason for it, with subcategories where appropriate: (1) communication; (2) foraging (subcategories: anthropogenic food, herbivory, predation, salt, scavenging, water); (3) movement (subcategories: bridges, environmental alterations, habitat connectivity); (4) refuge (subcategories: avoidance, burrowing and denning, cover, roosting); and (5) thermoregulation. Foraging, movement, and refuge were the most common uses.
5. Roads provide a variety of resources to mammals, but road use is highly dynamic in time and space. We suggest that the use of roads by mammals is extensive, both geographically and taxonomically. Road use is likely to influence mammalian ecology while contributing to the risk of collisions with vehicles.
... Bears may be forced to use suboptimal dens that have diminished security protection that exposes individuals to predation Harestad 1996, Garrison et al. 2007) or cause mortalities due to flooding (Alt 1984). The sustainability of bear populations may be reduced if suitable dens are not well-distributed across the landscape; pregnant female black bears have been found to den closer to roads than other sex and age classes, possibly to reduce the risk of infanticide (Gantchoff et al. 2019). The net effect of the reduction in supply is that suitable den sites may become a factor that limits black bear populations in this landscape (Alt 1984, Oli et al. 1997, Hersey et al. 2005. ...
Starting in 2014, a project aimed at increasing the supply of black bear dens on Vancouver Island using a new and innovative approach was undertaken in the Jordan River and Campbell River watersheds. The project attempted to create black bear dens using existing forest structures (e.g., hollow trees and stumps) and artificial structures in areas where past forest harvesting has reduced the number of the large trees needed by bears for denning.
Coastal black bears typically only use cavities in and under large trees because these are the only spots that keep them warm and dry during the cool and wet winter weather. Black bears use these dens for 3-6 months during which time females give birth to cubs. Generations of bears often reuse the same den.
The team, led by Helen Davis of Artemis Wildlife Consultants, worked to create potential bear dens in large hollow cedar stumps by covering the top and creating an entry for bears. In addition to enhancing natural structures, the team installed 13 artificial black bear dens made of plastic that simulate naturally-occurring den structures. Davis included placing a bit of vegetation and bear hair in all the cavities to make it seem “more like home” to bears when they investigated the structures.
Davis has been monitoring the “new” dens with motion-sensitive video cameras (see various videos at: https://www.youtube.com/channel/UCJY3ayUnQCLMkqGGUiBcoHQ) and was excited to document the use of one of the structures by a bear over the 3 winters (2017-18, 2018-19, 2019-2020). Davis and her technician (Ahousaht First Nation member Michael “Bear” Charlie, working for the Pacheedaht First Nation) created the den in 2015 by finding a large, hollow western redcedar stump, cutting an entrance into the cavity and capping the stump with plywood. The bear that used the den can be seen moving and digging inside the den and pulling piles of vegetation into the den to create its “nest” (see video: https://www.youtube.com/watch?v=AKGcz7CC-fA). No artificial structures have been used by bears despite extensive investigation of the structures by bears.
Black bear dens are not protected by regulation on Vancouver Island or the south coast of British Columbia. Some natural dens may occur in “legacy” trees that provincial government requires protection of, but many bear dens occur in trees that are smaller than this, so there are likely few dens protected through such legislation. Davis started a campaign to get these structures protected through legislation (see Petition: http://chng.it/y9dw8wY4K4).
With efforts to restore large mammal populations following extirpations, it is vital to quantify how they are impacted by human activities and gain insights into population dynamics in relation to conservation goals. Our objective was to characterize cause-specific mortality of black bears (Ursus americanus) throughout their range. We first quantified cause-specific mortality for 247 black bears in one harvested and two non-harvested populations. We then simulated a small recolonizing population with and without anthropogenic mortality. Lastly, we conducted a meta-analysis of all published black bear mortality studies throughout North America (31 studies of 2630 bears). We found anthropogenic mortality was greater than natural mortality, non-harvest anthropogenic mortality (e.g. poaching, defense of property, etc.) was greater in non-harvested populations, and harvesting was one of the major causes of mortality for bears throughout their range. Our simulation indicated that removing anthropogenic mortality increased population size by an average of 23% in 15 years. We demonstrated that bears are exposed to high levels of anthropogenic mortality, and the potential for human activities to slow population growth in expanding populations. Management and conservation of wide-ranging mammals will depend on holistic strategies that integrate ecological factors with socio-economic issues to achieve successful conservation and coexistence.
