Bogdan Cristescu

Temporal autocorrelation functions for movement rates from global positioning system radiotelemetry data

Autocorrelation has been viewed as a problem in telemetry studies because sequential observations are not independent in time or space, therefore violating assumptions for statistical inference. Yet nearly all ecological and behavioural data are autocorrelated in both space and time. We argue that there is much to learn about the structure of ecological and behavioural data from patterns of autocorrelation. Such patterns include periodicity in movement and patchiness in spatial data, which can be characterized by an autocorrelogram, semivariogram or spectrum. We illustrate the utility of temporal autocorrelation functions (ACFs) for analysing step-length data from GPS telemetry of wolves (Canis lupus), cougars (Puma concolor), grizzly bears (Ursus arctos) and elk (Cervus elaphus) in western Alberta. ACFs often differ by season, reflecting differences in foraging behaviour. In wilderness landscapes, step-length ACFs for predators decay slowly to apparently random patterns, but sometimes display strong daily rhythms in areas of human disturbance. In contrast, step lengths of elk are consistently periodic, reflecting crepuscular activity.

Diet and Environment Shape Fecal Bacterial Microbiota Composition and Enteric Pathogen Load of Grizzly Bears

Background Diet and environment impact the composition of mammalian intestinal microbiota; dietary or health disturbances trigger alterations in intestinal microbiota composition and render the host susceptible to enteric pathogens. To date no long term monitoring data exist on the fecal microbiota and pathogen load of carnivores either in natural environments or in captivity. This study investigates fecal microbiota composition and the presence of pathogenic Escherichia coli and toxigenic clostridia in wild and captive grizzly bears (Ursus arctos) and relates these to food resources consumed by bears. Methodology/Principal Findings Feces were obtained from animals of two wild populations and from two captive animals during an active bear season. Wild animals consumed a diverse diet composed of plant material, animal prey and insects. Captive animals were fed a regular granulated diet with a supplement of fruits and vegetables. Bacterial populations were analyzed using quantitative PCR. Fecal microbiota composition fluctuated in wild and in captive animals. The abundance of Clostridium clusters I and XI, and of C. perfringens correlated to regular diet protein intake. Enteroaggregative E. coli were consistently present in all populations. The C. sordellii phospholipase C was identified in three samples of wild animals and for the first time in Ursids. Conclusion This is the first longitudinal study monitoring the fecal microbiota of wild carnivores and comparing it to that of captive individuals of the same species. Location and diet affected fecal bacterial populations as well as the presence of enteric pathogens.

Bacterial populations and metabolites in the feces of free roaming and captive grizzly bears

Gut physiology, host phylogeny, and diet determine the composition of the intestinal microbiota. Grizzly bears (Ursus arctos horribilis) belong to the Order Carnivora, yet feed on an omnivorous diet. The role of intestinal microflora in grizzly bear digestion has not been investigated. Microbiota and microbial activity were analysed from the feces of wild and captive grizzly bears. Bacterial composition was determined using culture-dependent and culture-independent methods. The feces of wild and captive grizzly bears contained log 9.1 +/- 0.5 and log 9.2 +/- 0.3 gene copies x g(-1), respectively. Facultative anaerobes Enterobacteriaceae and enterococci were dominant in wild bear feces. Among the strict anaerobes, the Bacteroides-Prevotella-Porphyromonas group was most prominent. Enterobacteriaceae were predominant in the feces of captive grizzly bears, at log 8.9 +/- 0.5 gene copies x g(-1). Strict anaerobes of the Bacteroides-Prevotella-Porphyromonas group and the Clostridium coccoides cluster were present at log 6.7 +/- 0.9 and log 6.8 +/- 0.8 gene copies x g(-1), respectively. The presence of lactate and short-chain fatty acids (SCFAs) verified microbial activity. Total SCFA content and composition was affected by diet. SCFA composition in the feces of captive grizzly bears resembled the SCFA composition of prey-consuming wild animals. A consistent data set was obtained that associated fecal microbiota and metabolites with the distinctive gut physiology and diet of grizzly bears.

Perception of human-derived risk influences choice at top of the food chain.

On human-used landscapes, animal behavior is a trade-off between maximizing fitness and minimizing human-derived risk. Understanding risk perception in wildlife can allow mitigation of anthropogenic risk, with benefits to long-term animal fitness. Areas where animals choose to rest should minimize risk from predators, which for large carnivores typically equate to humans. We hypothesize that high human activity leads to selection for habitat security, whereas low activity enables trading security for forage. We investigated selection of resting (bedding) sites by GPS radiocollared adult grizzly bears (n = 10) in a low density population on a multiple-use landscape in Canada. We compared security and foods at resting and random locations while accounting for land use, season, and time of day. On reclaimed mines with low human access, bears selected high horizontal cover far from trails, but did not avoid open (herbaceous) areas, resting primarily at night. In protected areas bears also bedded at night, in areas with berry shrubs and Hedysarum spp., with horizontal cover selected in the summer, during high human access. On public lands with substantial human recreation, bears bedded at day, selected resting sites with high horizontal cover in the summer and habitat edges, with bedding associated with herbaceous foods. These spatial and temporal patterns of selection suggest that bears perceive human-related risk differentially in relation to human activity level, season and time of day, and employ a security-food trade-off strategy. Although grizzly bears are presently not hunted in Alberta, their perceived risks associated with humans influence resting-site selection.

Does sex matter? Temporal and spatial patterns of cougar-human conflict in British Columbia.

Wildlife-human conflicts occur wherever large carnivores overlap human inhabited areas. Conflict mitigation can be facilitated by understanding long-term dynamics and examining sex-structured conflict patterns. Predicting areas with high probability of conflict helps focus management strategies in order to proactively decrease carnivore mortality. We investigated the importance of cougar (Puma concolor) habitat, human landscape characteristics and the combination of habitat and human features on the temporal and spatial patterns of cougar-human conflicts in British Columbia. Conflicts (n = 1,727; 1978–2007) involved similar numbers of male and female cougars with conflict rate decreasing over the past decade. Conflicts were concentrated within the southern part of the province with the most conflicts per unit area occurring on Vancouver Island. For both sexes, the most supported spatial models for the most recent (1998–2007) conflicts contained both human and habitat variables. Conflicts were more likely to occur close to roads, at intermediate elevations and far from the northern edge of the cougar distribution range in British Columbia. Male cougar conflicts were more likely to occur in areas of intermediate human density. Unlike cougar conflicts in other regions, cattle density was not a significant predictor of conflict location. With human populations expanding, conflicts are expected to increase. Conservation tools, such as the maps predicting conflict hotspots from this study, can help focus management efforts to decrease carnivore-human conflict.

Large Omnivore Movements in Response to Surface Mining and Mine Reclamation

Increasing global demands have resulted in widespread proliferation of resource extraction. Scientists are challenged to develop environmental mitigation strategies that meet societal expectations of resource supply, while achieving minimal disruption to sensitive “wilderness” species. We used GPS collar data from a 9-year study on grizzly bears (Ursus arctos) (n = 18) in Alberta, Canada to assess movements and associated space use during versus after mining. Grizzly bear home range overlap with mined areas was lower during active mining except for females with cubs, that also had shortest movements on active mines. However, both females with cubs and males made shorter steps when on/close to mines following mine closure and reclamation. Our results show differences in bear movement and space-use strategies, with individuals from a key population segment (females with cubs) appearing most adaptable to mining disturbance. Preserving patches of original habitat, reclaiming the landscape and minimizing the risk of direct human-induced mortality during and after development can help conserve bears and other wildlife on industrially modified landscapes.

Focusing ecological research for conservation.

Ecologists are increasingly actively involved in conservation. We identify five key topics from a broad sweep of ecology that merit research attention to meet conservation needs. We examine questions from landscape ecology, behavioral ecology, ecosystem dynamics, community ecology, and nutrient cycling related to key topics. Based on literature review and publication trend assessment, consultation with colleagues, and roundtable discussions at the 24th International Congress for Conservation Biology, focused research on the following topics could benefit conservation while advancing ecological understanding: 1. Carbon sequestration, requiring increased linkages to biodiversity conservation; 2. Ecological invasiveness, challenging our ability to find solutions to ecological aliens; 3. Individual variation, having applications in the conservation of rare species; 4. Movement of organisms, integrating ecological processes across landscapes and scales and addressing habitat fragmentation; and 5. Trophic-level interactions, driving ecological dynamics at the ecosystem-level. Addressing these will require cross-disciplinary research under the overarching framework of conservation ecology.

Competition and coexistence in a small carnivore guild

The potential for strong competition among small sympatric carnivores results in a need for coexistence strategies whereby competitors partition along spatial, temporal and dietary axes as a means to reduce ecological overlaps. We determined spatial and temporal partitioning patterns of a guild of small African carnivores: the African wildcat Felis silvestris lybica, grey mongoose Galerella pulverulenta, small-spotted genet Genetta genetta, striped polecat Ictonyx striatus, and the yellow mongoose Cynictis penicillata. We quantified the degree of spatial and temporal co-occurrence of the small carnivores using camera trap data over a year-long period. Carnivores separated into two temporal groups: nocturnal species (wildcat, polecat and genet) and diurnal species (mongooses). In addition, carnivores within the same temporal group had strong patterns of reduced spatial co-occurrence. The smaller bodied carnivores showed lower co-occurrence with the larger bodied African wildcat than expected by chance, supporting the idea of dominant competitor avoidance. Thus, small carnivores likely minimise competitive interactions through spatio-temporal habitat partitioning.

Wildlife Habitat Selection on Landscapes with Industrial Disturbance

Technological advancements in remote sensing and telemetry provide opportunities for assessing the effects of expanding extractive industries on animal populations. Here, we illustrate the applicability of resource selection functions (RSFs) for modelling wildlife habitat selection on industrially-disturbed landscapes. We used grizzly bears ( Ursus arctos ) from a threatened population in Canada and surface mining as a case study. RSF predictions based on GPS radiocollared bears (n during mining = 7; n post mining = 9) showed that males and solitary females selected areas primarily outside mineral surface leases (MSLs) during active mining, and conversely inside MSLs after mine closure. However, females with cubs selected areas within compared to outside MSLs irrespective of mining activity. Individual variability was pronounced, although some environmental- and human-related variables were consistent across reproductive classes. For males and solitary females, regional-scale RSFs yielded comparable results to site-specific models, whereas for females with cubs, modelling the two scales produced divergent results. While mine reclamation may afford opportunities for bear persistence, managing public access will likely decrease the risk of human-caused bear mortality. RSFs are powerful tools that merit widespread use in quantitative and visual investigations of wildlife habitat selection on industrially-modified landscapes, using Geographic Information System layers that precisely characterize site-specific conditions.

Ecological effects of mine reclamation on grizzly bears

The grizzly bear (Ursus arctos) is a threatened species in Alberta and although we have studied grizzly bear response to forest seral stage change, little is known about the response to coal mine reclamation by bears. We addressed basic ecological questions to describe landscape change effects on grizzly bears, focusing on Luscar and Gregg River reclaimed coal mines in west-central Alberta as case studies. We summarize bear use of mine mineral disturbance limits in relation to season, habitat, diet, and designated human access trails. Eight adult bears were monitored intensively during 2008-2010 using GPS radiocollars that allowed tracking of their movement and distribution on the landscape and facilitated collection of scats for diet analysis. Bears were present on reclaimed mines mostly during summer and fed primarily on vegetative matter. Although habitats were similar on the two mines under study, on Luscar mine bears had higher use of undisturbed forested areas and were closer to forest edge than on Gregg River mine. We attribute these differences primarily to higher presence of humans on Luscar mine, but bears responded differently to motorized and non-motorized trails. While reclaimed mines can provide habitat and forage for grizzly bears during summer, maintaining undisturbed forest patches and access management are necessary to ensure persistence of grizzly bears on reclaimed mining areas.