Karl Larsen

Karl Larsen
Thompson Rivers University · Department of Natural Resource Science

BSc, MSc, PhD

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68
Publications
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1,569
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Publications

Publications (68)
Article
Full-text available
Populations of the British Columbia subspecies of North American badger 1 (Taxidea taxus jeffersonii) are endangered, but relatively little is known about the factors that have contributed to this status. In an effort to assess the sources of mortality within this population, we radiotagged and monitored 13 free-ranging badgers in the Thompson regi...
Article
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In this paper, we present a model for source-sink population dynamics where the locations of source and sink habitats change over time. We do this in the context of the population dynamics of the North American red squirrel, Tamiasciurus hudsonicus, within a forest environment subject to harvesting and regrowth. Harvested patches of forest are init...
Article
Unfavourable conditions within familiar environments may prompt organisms to make forays into other habitats, at least temporarily. This behaviour is in turn linked to key demographic processes such as immigration, emigration, and eventually, metapopulation dynamics. How such movements are triggered by environmental conditions (much less their inte...
Article
Full-text available
Frequent human encounters, even if benign, can influence fight-or-flight decisions in animals. Understanding how these responses are linked to human activity provides important insight into the ecology and conservation of populations, particularly those that may interact with humans. To this end, we compared the defensive behavior (rattling) of rat...
Article
Full-text available
Modelling the distribution and abundance of species at risk is extremely important for their conservation and management. We used ecological niche models (ENMs) to predict the occurrence of western rattlesnakes (Crotalus oreganus) in British Columbia (BC), Canada. We applied this to existing population estimates to support a threshold of occurrence...
Article
The Porcupine (Erethizon dorsatum) is considered ‘secure' in British Columbia, but as for many species with this status, there is a notable absence of quantitative data on population trends. In view of this issue, concerns about declining numbers of the species prompted us to conduct a preliminary survey using a questionnaire in 2005, targeting var...
Article
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Delineation of units below the species level is critical for prioritizing conservation actions for species at‐risk. Genetic studies play an important role in characterizing patterns of population connectivity and diversity to inform the designation of conservation units, especially for populations that are geographically isolated. The northernmost...
Article
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Background: The importance of thermal resources to terrestrial ectotherms has been well documented but less often considered in larger-scale analyses of habitat use and selection, such as those routinely conducted using standard habitat features such as vegetation and physical structure. Selection of habitat based on thermal attributes may be of p...
Article
The North American badger (Taxidea taxus) is a nonhibernating carnivore that occurs in areas with highly seasonal climates, such as in Canada where the animal reaches its northern limits. There, winter climate is harsh and conventional habitat is limited and patchy, possibly leading to additional energetic constraints. Using radiotelemetry and remo...
Article
Due to increasing anthropogenic pressures including land-use transformation globally, the natural process of animal migration is undergoing alterations across many taxa. Small-scale migrants provide useful systems at workable scales for investigating the influence of disturbance and landscape barriers on natural movement patterns and migrations. Th...
Article
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Peripheral populations are often characterized by small population size and low genetic diversity, with many at risk of extirpation. These characteristics may be even more pronounced in human-modified landscapes that further reduce the resiliency of populations to environmental change. Situated at the northwestern edge of the species’ range, the we...
Article
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Minimally‐invasive sampling (MIS) is widespread in wildlife studies; however, its utility for massively parallel DNA sequencing (MPS) is limited. Poor sample quality and contamination by exogenous DNA can make MIS challenging to use with modern genotyping‐by‐sequencing approaches, which have been traditionally developed for high‐quality DNA sources...
Article
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Anthropogenic disturbances often present novel habitat features to which the members of an existing population must adapt. We examined the effects of disturbance and habitat fragmentation on the movements of Northern Pacific Rattlesnakes (Crotalus o. oreganus) from 2006 through 2012 in southern British Columbia, Canada. We radio-tracked 44 adult ma...
Article
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Animal mortality resulting from collisions with vehicles has emerged as a major human-caused threat to wildlife. While direct mortality of wildlife from vehicles has been well documented, fewer studies have focused on the population-level effects of road mortality, particularly due to low-traffic volume roads. We conducted a population viability an...
Article
Full-text available
The Northern Pacific Rattlesnake (Crotalus o. oreganus) is restricted in its occurrence in Canada to British Columbia (B.C.) and is listed nationally as a Species-at-risk, yet there is a lack of demographic information, including baseline information on density, survivorship, generation time, and distribution necessary for evaluating the impacts of...
Article
Scale has been identified as a central unifying concept in ecology, yet few empirical studies examine its importance per se when quantifying species-habitat relationships. Means and associated variances of ecological variables are known to aggregate unpredictably among observational scale sizes; however, the empirical implications of these scaling...
Article
Full-text available
Mitigation of adverse effects of roads on wildlife benefits from a fundamental understanding of the number of animals killed by traffic. Road surveys are a key part in quantifying this mortality; however, without accounting for scavenging and observer detection rates, this method only reveals a minimum number of roadkilled animals. We quantified we...
Article
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We report on snake mortalities along exclusion fencing in southern British Columbia, showing Western Yellow-bellied Racer (Coluber constrictor mormon) deaths were disproportionately higher than our encounter rates with the species within the snake community. This suggests racers were susceptible to fence mortality more so than Northern Pacific Ratt...
Article
Full-text available
We report on snake mortalities along exclusion fencing in southern British Columbia, showing Western Yellow-bellied Racer (Coluber constrictor mormon) deaths were disproportionately higher than our encounter rates with the species within the snake community. This suggests racers were susceptible to fence mortality more so than Northern Pacific Ratt...
Article
Full-text available
Mammalian carnivores have adapted to successfully occupy a wide range of environments spanning tropical to polar ecosystems. Some species, however, have evolved in ways that constrain their ability to thrive in extreme environmental conditions. For example many members of the Family Mustelidae are vulnerable to extreme temperatures resulting from t...
Article
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International political boundaries challenge species conservation because they can hinder coordinated management. Peripheral transboundary species, those with a large portion of their range in one country and a small, peripheral portion in an adjacent country, may be particularly vulnerable to mismatches in management because peripheral populations...
Article
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Natural resource extraction can represent a major human modification to the landscape. Habitat reclamation is becoming an increasingly important strategy for abating the loss of biodiversity associated with these developments; however, the demographic and genetic consequences of colonizing artificial habitat remain unknown in many species. Here, we...
Article
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The spatial distributions of animals generally are affected by the availability of food, competition, predators, mates, and the need to communicate with conspecifics. An understanding of a given species’ spatial distribution is essential when considering the ecological requirements of populations as well as the impacts of anthropogenic activities a...
Article
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A critical 1st step in understanding the basic ecology of any predator is to delineate their suite of prey species. In this paper we provide data on the diet of 2 threatened snake species in British Columbia, the Western Rattlesnake (Crotalus oreganus) and the Gophersnake (Pituophis catenifer). By dissecting the gastrointestinal tracts of roadkille...
Article
The recent introduction of the Eastern Grey Squirrel (Sciurus carolinensis) into south-central British Columbia occurred within an important agricultural zone. As repercussions for the fruit-growing sector are currently unknown, we conducted trials with captive squirrels to understand the range of fruits consumed and their preferences. The squirrel...
Article
A common challenge for conservation genetic studies is finding minimally invasive sampling methods that maximize the quantity and quality of data produced. Conventional approaches rely on tissue or blood sampling, which typically require lengthy handling times, and can be hazardous for high-risk species, such as venomous snakes. Finding alternative...
Article
Contrasting movements and habitat use may occur among snakes, and these differences may reflect important local responses to habitat variation and/or signify that broad, unimodal approaches to species conservation are too coarse. Fine-scale differences in these behaviors (e.g., between neighboring conspecifics) may be underappreciated because studi...
Article
Full-text available
Species may remain present on developed landscapes over extended periods, suggesting viability, while in reality, populations may be indirectly affected in subtle and significant ways. We investigated indirect effects of human disturbance and habitat development on a population of the threatened Northern Pacific Rattlesnake Crotalus oreganus oregan...
Article
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The efficacy of surveys in detecting Canada Lynx (Lynx canadensis) can vary considerably by geographic area. we conducted surveys using digital passive infrared trail video-cameras from January to April 2013, during the breeding season of the Canada Lynx, in the John Prince Research Forest in central British Columbia. we used snow-track surveys to...
Article
Cues used by dispersing juveniles to assess habitat quality can be based on public information available to all in-dividuals or on private information obtained from experience in the natal habitat. The presence of conspecifics (public infor-mation) and natal habitat quality (private information) have been shown to influence habitat preferences in m...
Article
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If territory quality affects the fitness of its holder, then relatively unsuccessful individuals should relocate if given the opportunity to appropriate a higher quality territory. Relocation by these animals, however, may be prevented by habitat saturation, poor competitive ability, or the costs of relocating. We conducted two removal studies that...
Article
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Although garter snake populations in northern areas have been shown to undergo annual migrations, no detailed information has been available on these movements. Through biotelemetry and, to a lesser extent, mark–recapture methods, the migration of an extreme northern population of Thamnophis sirtalis was documented. Snakes emerging from a hibernacu...
Article
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Although temperate zone snakes spend a large part of each year in hibernation, we know relatively little about their behavior during this part of the annual cycle. We used radiotelemetry to monitor temperatures and movements of hibernating rattlesnakes (Crotalus viridis) in southern British Columbia and garter snakes (Thamnophis sirtalis) in northe...
Article
Gut contents of 138 northern flying squirrels (Glaucomys sabrinus) and 75 red squirrels (Tamiasciurus hudsonicus), which had been trapped from November to February in the boreal forest of northeastern Alberta, were examined to determine which fungi were consumed as food during the winter months in this habitat. Spores of epigeous Boletales, Russula...
Article
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ABSTRACT The northern goshawk (Accipiter gentilis) has been the subject of considerable interest because of the impact of logging on this species' nesting habitat. However, few studies have examined movements of fledgling birds around the nest prior to independence, and even fewer have described resource requirements of young birds during their pos...
Article
Widely distributed species often vary geographically in their ecology. Thus, results of studies done in one part of their range cannot necessarily be extrapolated readily to populations elsewhere. This problem is particularly important for threatened species whose ecology has been studied in a few disconnected locations. The Canadian toad Bufo (Ana...
Conference Paper
Background/Question/Methods Ectomycorrhizal fungi grow symbiotically on the roots of trees and provide them with nutrients and protection in exchange for carbon from photosynthesis. Many of these fungi form underground fruiting bodies; it is thought that ectomycorrhizal fungi gain long distance dispersal when small mammals eat these truffles and d...
Article
La compréhension des subtilités du processus de dispersion, telle que la manière dont les animaux en dispersion explorent ou évitent différents types d'habitat, est cruciale pour comprendre les taux de colonisation et les autres processus associés aux populations qui se produisent en milieu naturel. Au centre de la Colombie-Britannique, Canada, j'a...
Article
Full-text available
Radio-telemetry allows individual squirrels to be tracked through time and space, providing vital data on individual-and population-level parameters, and minimizing biases inherent in opportunistic observational studies. To emphasize the utility (if not necessity) of telemetry in squirrel research, we provide three case studies from our own researc...
Article
Coarse wood debris and plant communities within forested ecosystems play vital roles in the life history of many wildlife species. Descriptions of the characteristics and dynamics of these ecosystem properties therefore are crucial for guiding managers interested in maintaining biodiversity and site productivity. In North America, stands of trembli...
Article
Small mammal space use is inferred from live-capture data or various methods of tracking, with differences between these methods potentially affecting the input and subsequent inferential abilities of resulting wildlife-habitat models. Unlike tracking via radio telemetry, live trapping employs use of bait, which is known to change proximate animal...
Article
We studied the small mammal community across a mosaic of habitats created by a large wildfire in the mixed-wood boreal forest of Alberta, Canada, 5 years after the fire occurred. We focussed on four habitat types within this landscape mosaic, namely burnt stands, stands of unburnt forest within the burn, unburnt forest on the periphery of the fire,...
Article
Summary 1. It is common practice to evaluate the potential effects of management scenarios on animal populations using geographical information systems (GIS) that relate proximate landscape structure or general habitat types to indices of animal abundance. Implicit in this approach is that the animal population responds to landscape features at the...
Article
Full-text available
Multiple paternity may be a widespread phenomenon in snakes, but studies to date are inadequate for assessing the effect that phylogeny may have on paternity. Hypothetical mechanisms responsible for polyandry in snakes include intersexual conflicts and avoidance of genetic incompatibilities due to inbreeding. We analysed the offspring of six litter...
Article
Full-text available
Cameras with infra-red triggers were used to monitor the passage of wildlife through underground passages that ran under a major highway and railway. Several species of mammals were detected traveling through the passages; of particular interest was the movement of Mule Deer (Odocoileus hemionus) through a relatively small culvert that would not ha...
Article
Summary • Dispersers in heterogeneous habitat theoretically should target the habitat(s) where reproduction and survival (i.e. fitness) will be highest. However, the cues that dispersing animals respond to are not well understood: differences in habitat quality ultimately may be important, but whether animals respond to these differences may be inf...
Article
Full-text available
Because natal dispersal affects both individual fitness and population persistence, it is important to understand how dispersers are affected by habitat heterogeneity. To explore the effect of habitat on dispersal, we compared the ecology and natal dispersal of red squirrels (Tamiasciurus hudsonicus) originating from mature forest and adjacent comm...
Article
Full-text available
Predicting animal populations over time often is done using models of density-habitat relationships that assume animal density is a reflection of habitat quality. We explored whether this assumption was true for the North American red squirrel (Tamiasciurus hud- sonicus), a species present at different densities in 3 conifer habitats: white spruce...
Article
Full-text available
Wildfires play a key role in shaping the boreal forest landscape, yet the response of wildlife to the patchy mosaics they create is poorly understood. We studied songbirds 5–6 years post-fire in a large burn (9600 ha) in the boreal mixed wood forest of north-eastern Alberta. In the spring of 1995 and 1996 we estimated abundance of songbirds in four...
Article
Full-text available
Many organisms acquire and defend resources outside the breeding season and this is thought to be for immediate survival and reproductive benefits. Female red squirrels (Tamiasciurus hudsonicus) acquire traditional food cache sites up to four months prior to the presence of any physiological or behavioural cues associated with mating or offspring d...
Article
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Introduced species are a most serious threat to biodiversity, second only to habitat degradation. The eastern gray squirrel (Sciurus carolinensis) is native to eastern North America, but has been introduced to several countries outside its natural range. In Europe, it has been introduced to Britain, Ireland, and Italy, and in all 3 countries it has...
Article
Age at first reproduction influences lifetime reproductive success of individuals and growth rates of populations, and is thus of general interest to ecologists. In red squirrel (Tamiasciurus hudsonicus) populations, yearlings and older nulliparous females (age two and above) are less likely to have a litter than multiparous females (i.e. those tha...
Article
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We conducted a series of hoard manipulations on the red squirrel (Tamiasciurus hudsonicus), a solitary species that constructs central food caches, to determine if the size and content of the hoard influenced the life-history parameters and reproductive success of females. Larderhoards of jack pine (Pinus banksiana) cones were experimentally increa...
Article
Movement and settlement patterns of animal offspring, along with the costs of occupying familiar and unfamiliar habitats, have been inferred frequently, but rarely have they been documented directly. To obtain such information, we monitored the individual fates of 205 (94%) of the 219 offspring born over 3 yr in a population of the North American r...
Article
We studied geographic variation in reproductive characteristics, especially litter size and neonate size, among several populations across Canada of the wide-ranging garter snake, Thamnophis sirtalis. Gravid females differed significantly in body size among sites. However, even after we corrected for intersite differences in maternal body size, the...
Article
Full-text available
The common garter snake, Thamnophis sirtalis, ranges farther N than any other North American reptile. We examined the reproductive ecology of this species near its extreme northern limit in Wood Buffalo National Park (WBNP, 59⚬49'N, 112⚬W, Northwest Territories, Canada). Our data suggest that individual females in this population rarely gave birth...
Article
1. In dimorphic mammals, males grow faster than females, but often suffer higher mortality during periods of resource shortage. 2. We compared growth and survival of males and females in a promiscuous small mammal with a relatively small degree of dimorphism (male/female body mass ratios ranged from 1.05 to 1.11). 3. We compared two geographically...
Article
The common garter snake, Thamnophis sirtalis. has frequently been studied, but never in the far north where climatic influences on distribution and abundance might be expected to be severe. We examined the structure and dynamics of a communal den population at the northern limit of the species' range. Snakes were sampled at the hibernaculum from sp...
Article
Full-text available
Although movement patterns should reflect important aspects of a species' ecology, a survey of published information on snake movements reveals few general trends among species, populations, or individuals within populations. Snakes are sometimes difficult to study, and some of the problems associated with them (e.g., crypticity of young) will not...
Article
Full-text available
Defining 'critical' habitat for species at risk may be one of the keys to effective conservation planning, but it can be challenging for animals that maintain large home ranges and have general habitat requirements. Identifying areas that are used more intensively (core areas) within a home range could help to locate important resources and priorit...
Article
University Microfilms order no. UMI00425145. Thesis (Ph. D.)--University of Alberta, 1993. Includes bibliographical references.

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Projects (3)
Archived project
To investigate demographic parameters in a long-term mark-recapture study and estimate the population size of rattlesnakes in British Columbia, Canada, using machine learning model platforms
Project
1. Quantify rattlesnake road mortality accurately by accounting for associated sources of error (scavenging and observer detection); 2. Characterize the rattlesnake population affected by road mortality; and 3. Assess the long-term persistence of the population under the threat of roadkill and sensitivity to changes in mortality rates.