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Fort St. John, Canada

Johnson C.J.,University of Northern British Columbia | Hodder D.P.,John Prince Research Forest | Crowley S.,John Prince Research Forest
Ecological Research | Year: 2013

Monitoring the distribution and abundance of populations is an important component of efforts to meet management or conservation goals. Although the objectives for such studies are easy to define, cost-effective, precise, and accurate estimates are often elusive. We tested the efficacy and compared the cost-effectiveness of methods for estimating the number and recording the distribution of river otter (Lontra canadensis). We genotyped otter hair sampled using two noninvasive instruments and compared those results with a hypothetical study design based on DNA extracted from fecal matter. Patterns of distribution generated from DNA collected at latrine sites were then compared to observations of otter collected using VHF radiotelemetry. We achieved a high probability of genotyping river otter with a small number of hairs (i.e., 59.0 % probability of producing a genotype with 1 guard hair and >5 under hair samples) collected using wire body snares and knaplock hair snags. Body snares were more effective at collecting otter hair, but there was relatively little additional cost to using both sampling instruments. Genotyped hair resulted in a high multi-year recapture rate (61.9 %). Hair collection and genotyping was the most cost-effective method for monitoring populations of river otter ($168.50 US/datum) followed by radiotelemetry ($264.50 US/datum), and the extraction of DNA from fecal matter ($266.00 US/datum). However, the noninvasive techniques did not represent the full distribution and fine-scale movements of otter, as observed using radiotelemetry. There has been much recent reporting of the efficacy of fecal matter as a source of DNA for conducting mark-recapture population estimates for mesocarnivores. Our data suggested that collecting DNA in hair may be a more cost-effective and efficient approach. © 2013 The Ecological Society of Japan. Source

Rea R.V.,University of Northern British Columbia | Hodder D.P.,John Prince Research Forest | Hjeljord O.,Norwegian University of Life Sciences | Langen A.,BC Northern Lights
Scandinavian Journal of Forest Research | Year: 2010

In order to maximize food intake per harvesting effort and minimize energy expenditures required to move between feeding patches in nature, herbivores such as moose (Alces alces L.) generally select large plant shoots when browsing in winter. To determine moose preferences for shoots of different morphologies, an experiment was conducted in northern British Columbia in which shoots from birches cut at different times of the growing season were fed in 2 consecutive years to eight human-habituated moose in cafeteria-style feeding trials. The results indicate that moose preferred smaller winter shoots of birches regardless of when the parent plant was cut and also appeared to reject larger shoots containing sylleptic branches. It is argued that the preferences for smaller shoots by moose detected in these trials should be observable under natural conditions, but are generally only supported by literature from some parts of Scandinavia. The findings underscore the importance that factors such as mouth filling per harvesting effort, snow depth and consistency, predators and browse patch distribution must have on foraging decisions made by moose while browsing in the wild. Implications of the findings include the significance of cutting time on the size of shoots produced by birch after cutting, how this affects moose browsing birch and, subsequently, how managers can theoretically use cutting time as a tool in forest cleaning operations to direct the foraging efforts of moose towards or away from forest plantations. © 2010 Taylor & Francis. Source

Crowley S.,University of Northern British Columbia | Johnson C.J.,University of Northern British Columbia | Hodder D.,John Prince Research Forest
Journal of Mammalogy | Year: 2012

Animals interact with their environment at multiple spatial, temporal, and behavioral scales. Few studies of selection for latrine sites by river otters (Lontra canadensis) have considered spatial scale, and no studies have integrated scales of behavior. We used an information theoretic model comparison approach to identify elements of otter habitat that influence the presence, consistency, and intensity of latrine-site activity at 2 spatial scales. We identified and monitored 73 latrine sites in central British Columbia, Canada, during the open-water season in 2007 and 2008. We inventoried latrines and randomly selected sites along the adjacent shoreline, and used those data in the form of a binary resource selection function to model fine-scale selection of latrine sites. At the scale of the landscape, we used a resource selection function and data from geographic information systems to model coarse-scale selection of latrine sites. Drawing on those same data, we used binary and count models to quantify factors that contributed to the consistency (high versus low use) and intensity (number of scats) of otter activity at latrine sites. Fine-scale habitat characteristics were better at predicting the presence of latrine sites when compared to coarse-scale geographic information system data. In general, the presence, consistency, and intensity of latrine activity at the fine scale were influenced by visual obscurity, larger trees, and characteristics of conifer trees. The presence of latrine sites at the coarse scale could not be accurately described by any of the models. The consistency and intensity of activity of otters at latrine sites at the coarse scale, however, was best predicted by habitat characteristics beneficial to fish. These results provide insight into the spatial and behavioral scales of latrine-site activity by river otters that can be incorporated into management, monitoring, and conservation strategies. © 2012 American Society of Mammalogists. Source

Crowley S.,University of Northern British Columbia | Johnson C.J.,University of Northern British Columbia | Hodder D.,John Prince Research Forest
Wildlife Biology | Year: 2012

Unknown causes of heterogeneity in the presence or detection of wildlife tracks and other signs could bias interpretations of population indices derived from surveys. These surveys can be the basis of management decisions for populations of wildlife. However, we know very little about potential biases affecting the presence of tracks in the landscape. We used an Information Theoretic Model Comparison approach to investigate the role of environmental, demographic and behavioural influences on the presence of river otter Lontra canadensis snow tracks in central British Columbia, Canada, from January to March 2008. We repeatedly located five radio-collared otters and recorded the presence of tracks within an estimated 100-m radius of the otter's location. We used combinations of five variables to develop logistic regression models that predicted the presence or absence of snow tracks when the location of otters was known. The presence of snow tracks was best described by a model containing covariates for gender and movement distance per day. The probability of detecting snow tracks was higher for male compared to female otters and was positively related to the daily movement distance of the individual animal. Track-sign heterogeneity among individuals could bias surveys that assess and monitor river otter populations, and should be incorporated into the design and interpretation of track surveys. © 2012 Wildlife Biology, NKV. Source

Crowley S.,University of Northern British Columbia | Johnson C.J.,University of Northern British Columbia | Hodder D.P.,John Prince Research Forest
Ecoscience | Year: 2013

Fluctuations in the distribution and abundance of prey resources are an important influence on the foraging ecology of carnivores. Spatio-temporal variation in the diet of river otters (Lontra canadensis), however, is not well understood. In addition, we have limited knowledge about seasonal changes in otter activity at latrine sites and how these changes may relate to changes in otter diet. We used a combination of scat content and stable-isotope analyses to assess the contributions of different prey items to otter diet. We investigated the spatio-temporal variation in the availability of prey groups as it influenced the composition of otter diet and the number of scat deposited at latrine sites. A combination of fish spawning period, water-body type, and lake best described the presence of salmonidae, minnows, and insects in otter scats. The number of scats was best described by a two-week calendar time measurement and geographic location. Scat deposition was positively influenced by a time period when no fish were spawning (early July) and the kokanee (Oncorhynchus nerka) spawning period (early September). In general, the stable-isotope analysis agreed with the results of the scat content analysis: fish dominated the diet, with lesser contributions from other prey items. The stable-isotope analysis, however, suggested that sockeye salmon, larger species of fish (burbot, lake trout), and birds contributed more than was revealed by scat content analysis. Management strategies require accurate and unbiased information on wildlife distribution and abundance that is often measured from surveys of sign; this study provides some of the critical information needed to interpret surveys for river otters. We also suggest implications for other wildlife species. Source

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