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Giant pandas (Ailuropoda melanoleuca) use chemical cues to determine identity, gender, and sexual receptivity of conspecifics. We hypothesized that volatile chemical profiles of free-ranging giant pandas are detectable in air. Therefore, we aimed to identify volatile compounds produced by free-ranging giant pandas residing in the Wolong Nature Reserve (Sichuan, China) through field air analysis/solid phase microextraction/gas chromatography–mass spectrometry (FAA/SPME/GCMS). From 28 June to 12 July 2017, 3 SPME fibers were secured to trees that appeared to have previous marking activity. Trail cameras confirmed that a single giant panda performed scent-marking behavior at one sampling location. The abundance of 7 compounds were elevated in samples collected from the tree visited by the giant panda compared with controls. Three of these compounds (Ethane, 1,1-dinitro-; Octane, 4-ethyl-; 2(1H)-Pyridinethione, 3-ethoxy-6-methyl-) were unique to the giant panda visit. Novel methods to detect giant pandas would benefit conservation efforts. We suggest our method also may be used to study chemical communication in other bear species.
Management of large carnivore populations represents an important challenge in conservation, requiring balancing their cultural, economic, and ecological value with potential risks of human–wildlife conflicts. Harvest can provide an effective tool for managing populations, but it can be difficult to define appropriate harvest quotas or assess the consequences of other conservation measures. We introduce the web-application ‘demetR’ (“Dynamic Environment for Modeling and Estimating Trajectories in R,” available at https://pop-eco.shinyapps.io/demetR/) to evaluate the effects of harvest scenarios and other conservation policies on brown bear (Ursus arctos) and American black bear (U. americanus) populations. We developed a Bayesian population trajectory model to simulate brown bear and black bear populations in response to user-defined demographic parameters and harvest. Model simulations are performed using fixed or stochastic demographic parameters, allowing for informative and non-informative priors. We provide an overview of the general layout, along with descriptions of model inputs and outputs. We then provide examples of bear populations simulated using deterministic and stochastic approaches with varying levels of harvest. Performing computer simulations of different management scenarios offers an economical and efficient way to test practices before their application, and can be valuable for decision-making. This model can also be applied to other species with similar life-history traits. Future developments will provide users with greater input flexibility and adaptations to specific population structures of other large carnivores. Management decisions can be costly, with long-lasting ecological and economic consequences. Models such as the one we present here, in the context of structured decision-making and adaptive management, can improve the quality and quantity of information needed to make these decisions.
We characterized a brown bear (Ursus arctos) feeding aggregation that occurred in an oak (Quercus spp.) forest in the Cantabrian Mountains (NW Spain), during the hyperphagia period 2017 (Sep to Dec), which was an atypical year in terms of low fructification success due to late frost events and drought. We described (1) number, sex, and age class of aggregated bears; (2) temporal use of the area; and (3) bear interactions. We identified a minimum of 31 individuals, representing 10% of the estimated Cantabrian bear population. The number of adults increased during the study period, whereas the number of subadults decreased, which could be related to a displacement of subadults by dominant adults. The proximity of the aggregation site to a public road attracted numerous people to observe the bears. To minimize adverse bear–human interactions, we recommend providing educational material on best bear-viewing practices as well as on-site staffing.
Prolonged reproductive behavior of American black bears (Ursus americanus) has been reported in the southeastern United States compared with other regions, but functional spermatogenesis or potential fertility has not previously been described for these bears. Additionally, methods for gamete collection are only in early stages of development for ursids. Testicles were collected from 29 post-pubertal legally hunter-killed black bears in eastern North Carolina, USA, in November 2016. Active spermatogenesis was identified in 48.3% (14/29) of bears via histology. Epididymal sperm collection was attempted via mincing (n = 29), vas deferens flush (n = 24), and percutaneous aspiration (n = 5). Epididymal mincing identified sperm in 78.6%, and vas flush in 53.8%, of bears with spermatogenesis on histology. Percutaneous aspiration was unsuccessful. These findings provide evidence that male bears may maintain reproductive capabilities into the late autumn in this region, and that under the conditions of this study, sperm can be collected via epididymal mincing or vas deferens flush, but not percutaneous aspiration.
Recruitment of brown bear (Ursus arctos) offspring into a population is the product of initial cub production and subsequent survival and is a critical component of overall population status and trend. We investigated the relationship between maternal body size, body condition, and age (as a surrogate for gained experience) and recruitment of dependent offspring (≥1 yr old) in 4 Alaska, USA (2014–2017), brown bear populations using logistic regression. Body size alone was our top predictor of the presence of offspring and appeared in all top models. Our data suggest that bear size is the primary driver of productivity across all 4 study populations, with larger bears having a greater chance of being observed with offspring. The effect of body condition was likely confounded by the increased energetic costs of supporting cubs through time and had a negative relationship with recruitment. Age (experience) was positively related to recruitment. Understanding the relative importance of body size, body condition, and age on the recruitment of offspring provides insights into life-history trade-offs female bears must manage as they strive to meet the nutritional costs of cub production and rearing, while minimizing risks to themselves and their offspring. Further assessment of long-term longitudinal studies of brown bears that assess the lifetime reproductive output of individuals would be highly informative to further assess the effect of experience on recruitment and to support the management of brown bear populations for recovery, conservation, sustained yield, and ecosystem function.
Habitat loss and overexploitation extirpated American black bears (Ursus americanus) from most of the Central Appalachians, USA, by the early 20th Century. To attempt to restore bears to the southwestern portion of this region, 2 reintroductions that used small founder groups (n = 27 and 55 bears), but different release methods (hard vs. soft), were conducted during the 1990s. We collected hair samples from black bears during 2004–2016 in the reintroduced Big South Fork (BSF) and Kentucky–Virginia populations (KVP), their respective Great Smoky Mountains (GSM) and Shenandoah National Park (SNP) source populations, and a neighboring population in southern West Virginia (SWV) to investigate the early genetic outcomes of bear reintroduction. Despite having undergone genetic bottlenecks, genetic diversity remained similar between reintroduced populations and their sources approximately 15 years after the founder events (ranges: AR = 4.86–5.61; HO = 0.67–0.75; HE = 0.65–0.71). Effective population sizes of the reintroduced KVP and BSF (NE = 31 and 36, respectively) were substantially smaller than their respective SNP and GSM sources (NE = 119 and 156, respectively), supporting founder effects. Genetic structure analysis indicated that the hard-released (i.e., no acclimation period) KVP founder group likely declined considerably, whereas the soft-released BSF founder group remained mostly intact, suggesting superior effectiveness of soft releases. Asymmetrical gene flow via immigration from the SWV has resulted in the KVP recovering from the initial founder group reduction. Sustained isolation, small NE, and small population size of the BSF may warrant continued genetic monitoring to determine if gene flow from neighboring populations is established or NE declines. For future bear reintroductions, we suggest managers consider sourcing founders from populations with high genetic diversity and soft-releasing bears to locales that are, if possible, within the dispersal capability of extant populations to mitigate the potential consequences of founder effects and isolation.
There are 3 American black bear (Ursus americanus) populations in the state of Georgia, USA. We used multi-locus microsatellite genotypes derived from bear hair and tissue samples collected across these populations to assess levels of genetic diversity within and between populations. We used population assignment clustering to evaluate whether there has been recent immigration into the smallest of the 3 populations, the Central Georgia Bear Population. Compared with other bear populations in the United States, the North Georgia and South Georgia Bear Populations have relatively high rates of genetic diversity (Ho = 0.72 ± 0.02, A = 6.68 ± 0.32, and Ho = 0.72 ± 0.02, A = 6.82 ± 0.35, respectively). In contrast, the Central Georgia Bear Population has relatively low rates (Ho = 0.46 ± 0.03, and A = 3.96 ± 0.20). Fixation indices for pairings between Georgia bear populations indicated that the North Georgia Bear Population was more similar to the South Georgia Bear Population than either was to the Central Georgia Bear Population. Our findings suggest that the Central Georgia Bear population has experienced long-term genetic isolation and genetic drift. Of a sample of 365 bears from Central Georgia, we only detected 1 immigrant and no evidence of gene flow into the population. We recommend development and implementation of plans to encourage gene flow toward the Central Georgia Bear Population.
Harvest can affect the size and composition of wildlife populations. American black bear (Ursus americanus) populations in the Central Interior Highlands, Arkansas, USA, were nearly extirpated as a result of harvest and habitat change, but have expanded geographically and demographically since reintroduction in the late 1950s and early 1960s. Harvest levels have increased since baiting was permitted on private land in 2001; therefore, we initiated demographic analyses of 2 black bear populations to evaluate the effect of this policy change. We evaluated composition of harvest in response to baiting and used noninvasive genetic sampling in conjunction with capture–recapture methods to estimate density, survival, and population growth rate (λ) of black bear populations at locations within the Ouachita (2006–2008) and Ozark (2009–2011) national forests, Arkansas. More males were harvested than females with the use of bait. Capture probability varied annually; thus, multi-year data were valuable for capturing accurate population parameters. Density was approximately 14 bears/100 km2 in the Ouachitas and approximately 26/100 km2 for the Ozarks, which was greater than estimates from historical data (1989–1990). Thus, these populations maintained or exceeded previous density estimates while the use of bait was allowed on private land. However, as with any harvested population, it will be important to continue to monitor the population to be able make decisions about appropriate harvest policies going forward.
Wild populations of giant pandas (Ailuropoda melanoleuca) have steadily increased in the past 2 decades, but the species' distribution remains highly fragmented. Since 2009, an introduction program has worked to rescue the giant panda population of Liziping National Nature Reserve in southwestern Sichuan Province, China. Using Global Positioning System and activity collar data collected between May 2011 and March 2016, we investigated the post-release behavior of the first 5 pandas introduced to Liziping, 4 of which were bred in captivity. Using a change-point analysis, we tested several models of post-release adjustment to the habitat. We found that it took 3–4 months for captive-bred individuals to exhibit movement patterns characteristic of their long-term behavior. Furthermore, we found that, for these individuals, post-adjustment behavior varied by season, with activity levels peaking between May and July, a period of high resource availability. This also corresponded with a decrease in large movement events, where individuals were less likely to travel long distances quickly during these months. Unlike wild giant pandas in more northerly reserves, the 5 pandas released in Liziping (both captive-bred and translocated) did not exhibit any seasonal migration between elevations. Finally, we found that our study individuals had 2 daily periods of activity, which was comparable to those reported in the literature for wild individuals. Our results suggest that captive-bred giant pandas are able to successfully adjust to the wild and, after a period of adjustment, settle into long-term behavior patterns.