Tal Avgar

Tal Avgar
Utah State University | USU · Department of Wildland Resources

PhD

About

67
Publications
33,670
Reads
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2,733
Citations
Additional affiliations
April 2017 - April 2018
University of Guelph
Position
  • Fellow
April 2015 - present
University of Alberta
Position
  • Banting postdoctoral fellow
January 2013 - April 2015
University of Alberta
Position
  • Killam postdoctoral fellow

Publications

Publications (67)
Article
Full-text available
Wildlife translocations alter animal movement behavior, so identifying common movement patterns post-translocation will help set expectations about animal behavior in subsequent efforts. American and Eurasian beavers (Castor canadensis; Castor fiber) are frequently translocated for reintroductions, to mitigate human-wildlife conflict, and as an eco...
Article
Full-text available
Seasonal migration is a behavioral response to predictable variation in environmental resources, risks, and conditions. In behaviorally plastic migrants, migration is a conditional strategy that depends, in part, on an individual’s informational state. The cognitive processes that underlie how facultative migrants understand and respond to their en...
Article
Full-text available
Adaptive cognitive biases, such as “optimism,” may have evolved as heuristic rules for computationally efficient decision-making, or as error-management tools when error payoff is asymmetrical. Ecologists typically use the term “optimism” to describe unrealistically positive expectations from the future that are driven by positively biased initial...
Article
Optimizing energy acquisition and expenditure is a fundamental trade‐off for consumers, strikingly reflected in how mobile organisms use space. Several studies have established that. home range size decreases as resource density increases, but the balance of costs and benefits associated with exploiting a given resource density is unclear. We evalu...
Article
Full-text available
Cognition, defined as the processes concerned with the acquisition, retention and use of information, underlies animals’ abilities to navigate their local surroundings, embark on long-distance seasonal migrations, and socially learn information relevant to movement. Hence, in order to fully understand and predict animal movement, researchers must k...
Preprint
Anomalous diffusion or, more generally, anomalous transport, with nonlinear dependence of the mean-squared displacement on the measurement time, is ubiquitous in nature. It has been observed in processes ranging from microscopic movement of molecules to macroscopic, large-scale paths of migrating birds. Using data from multiple empirical systems, s...
Article
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Habitat‐selection analyses allow researchers to link animals to their environment via habitat‐selection or step‐selection functions, and are commonly used to address questions related to wildlife management and conservation efforts. Habitat‐selection analyses that incorporate movement characteristics, referred to as integrated step‐selection analys...
Preprint
Full-text available
Resource-selection and step-selection analyses allow researchers to link animals to their environment and are commonly used to address questions related to wildlife management and conservation efforts. Step-selection analyses that incorporate movement characteristics, referred to as integrated step-selection analyses , are particularly appealing be...
Article
Full-text available
Despite being widely used, habitat selection models are rarely reliable and informative when applied across different ecosystems or over time. One possible explanation is that habitat selection is context-dependent due to variation in consumer density and/or resource availability. The goal of this paper is to provide a general theoretical perspecti...
Article
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Ecology and management programs designed to track population trends over time increasingly are using passive monitoring methods to estimate terrestrial mammal densities. Researchers use motion‐sensing cameras in mammal studies because they are cost‐effective and advances in statistical methods incorporate motion‐sensing camera data to estimate mamm...
Article
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One of the most challenging tasks in wildlife conservation and management is to clarify how spatial variation in land cover due to anthropogenic disturbance influences wildlife demography and long‐term viability. To evaluate this, we compared rates of survival and population growth by woodland caribou (Rangifer tarandus caribou) from 2 study sites...
Article
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Reduced body size and accelerated life cycle due to warming are considered major ecological responses to climate change with fitness costs at the individual level. Surprisingly, we know little about how relevant ecological factors can alter these life history trade‐offs and their consequences for individual fitness. Here, we show that food modulate...
Article
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Camera traps (CTs) are an increasingly popular tool for wildlife survey and monitoring. Estimating relative abundance in unmarked species is often done using detection rate as an index of relative abundance, which assumes that detection rate has a positive linear relationship with true abundance. This assumption may be violated if movement behavior...
Article
Full-text available
1.Space‐use behaviour reflects trade‐offs in meeting ecological needs and can have consequences for individual survival and population demographics. The mechanisms underlying space‐use can be understood by simultaneously evaluating habitat selection and movement patterns, and fine‐resolution locational data are increasing our ability to do so. 2.We...
Article
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Although temperature is recognized as a major determinant of many ecological processes, it is still not clear whether temperature increase caused by climate change will strengthen or weaken species interactions. One hypothesis is that interactions will respond non‐monotonically to temperature because thermal performance curves, which determine the...
Article
Full-text available
Advances in tracking technology have led to an exponential increase in animal location data, greatly enhancing our ability to address interesting questions in movement ecology, but also presenting new challenges related to data management and analysis. Step-selection functions (SSFs) are commonly used to link environmental covariates to animal loca...
Article
Outdoor recreation on trail networks is a growing form of disturbance for wildlife. However, few studies have examined behavioural responses by large carnivores to motorised and non‐motorised recreational activity — a knowledge gap that has implications for the success of human access management aimed at improving habitat quality for wildlife. We u...
Preprint
Full-text available
1. Advances in tracking technology have led to an exponential increase in animal location data, greatly enhancing our ability to address interesting questions in movement ecology, but also presenting new challenges related to data manage- ment and analysis. 2. Step-Selection Functions (SSFs) are commonly used to link environmental covariates to ani...
Article
Full-text available
The ideal free distribution assumes that animals select habitats that are beneficial to their fitness. When the needs of dependent offspring differ from those of the parent, ideal habitat selection patterns could vary with the presence or absence of offspring. We test whether habitat selection depends on reproductive state due to top‐down or bottom...
Article
The fine-scale behavior of wildlife when crossing roads and interacting with traffic is likely to mirror natural responses to predation risk including not responding, pausing, avoiding, or increasing speed during crossing. We generated coarse-scale behavioral predictions based on these expectations that could be assessed with GPS radiotelemetry. We...
Article
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1. Net displacement is an integral component of numerous ecological processes and is critically dependent on the tortuosity of a movement trajectory and hence on the temporal scale of observation. Numerous attempts have been made to quantitatively describe net displacement while accommodating tortuosity, typically evoking a power law, but scale-dep...
Article
Full-text available
Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint wer...
Article
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Occupancy models are increasingly applied to data from wildlife camera-trap (CT) surveys to estimate distribution, habitat use, or relative abundance of unmarked animals. Fundamental to the occupancy modeling framework is the temporal pattern of detections at camera stations, which is influenced by animal population density and the speed and scale...
Article
Full-text available
Habitat-selection analysis lacks an appropriate measure of the ecological significance of the statistical estimates—a practical interpretation of the magnitude of the selection coefficients. There is a need for a standard approach that allows relating the strength of selection to a change in habitat conditions across space, a quantification of the...
Article
We evaluated alternative hypotheses that anthropogenic disturbance can attract versus displace wolver-ines (Gulo gulo luscus). Our research took place in boreal forests of northwestern Alberta where we employed radiotelemetry to track wolverine habitat use over three years. We used resource selection functions (used/available design) to analyze wol...
Article
Full-text available
Roads are a prevalent, ever-increasing form of human disturbance on the landscape. In many places in western North America, energy development has brought human and road disturbance into seasonal winter range areas for migratory elk. 2.We sought to evaluate predictions from the risk-disturbance hypothesis when studying elk response to roads during...
Article
Full-text available
Habitat-selection analyses are often used to link environmental covariates, measured within some spatial domain of assumed availability, to animal location data that are assumed to be independent. Step-selection functions (SSFs) relax this independence assumption, by using a conditional model that explicitly acknowledges the spatiotemporal dynamics...
Article
Full-text available
Predator space use influences ecosystem dynamics, and a fundamental goal assumed for a foraging predator is to maximize encounter rate with prey. This can be achieved by disproportionately utilizing areas of high prey density or, where prey are mobile and therefore spatially unpredictable, utilizing patches of their prey's preferred resources. A th...
Article
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1. Ecological patterns and processes often take place within linear-feature networks, and this has implications when analysing the spatial configuration of such patterns or processes across a landscape. 2. One such pattern is the use of landscapes by human recreationists: an important variable in animal habitat selection and behaviour. Due to the d...
Article
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Context In southwestern Alberta, human development, including roads, is encroaching on the landscape and into the range of a partially migratory population of elk (Cervus elaphus). Objectives To quantify factors influencing among- and within-home-range selection of winter range in this population. Methods We studied individual habitat selection a...
Article
Full-text available
Spatial self-organization can occur in many ecosystems with important effects on food web dynamics and the maintenance of biodiversity. The consumer-resource interaction is known to generate spatial patterning, but only a few empirical studies have investigated the effect of the consumer on resource distribution. Here we report results from a large...
Article
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The use of multiple working hypotheses to gain strong inference is widely promoted as a means to enhance the effectiveness of scientific investigation. Only 21 of 100 randomly selected studies from the ecological and evolutionary literature tested more than one hypothesis and only eight tested more than two hypotheses. The surprising rarity of appl...
Article
Full-text available
Habitat-based prediction of population density relies on relationships between landscape configuration (i.e., abundance of land-cover types) and equilibrium density. This may be accomplished by estimating resource selection probability functions (RSPFs) based on presence–absence data, or by relating carrying capacity to landscape covariates. We use...
Article
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The relationship between selection at coarse and fine spatiotemporal spatial scales is still poorly understood. Some authors claim that, to accommodate different needs at different scales, individuals should have contrasting selection patterns at different scales of selection, while others claim that coarse scale selection patterns should reflect f...
Article
Full-text available
A resource selection function is a model of the likelihood that an available spatial unit will be used by an animal, given its resource value. But how do we appropriately define availability? Step-selection analysis deals with this problem at the scale of the observed positional data, by matching each used step (connecting two consecutive observed...
Article
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Site-specific variation in relative habitat abundance and disturbance regimes may produce differences in habitat preferences of associated populations. An evaluation of the predictive power of habitat selection models across space would benefit our understanding of the reliability of models of selection and space use in predicting animal occurrence...
Article
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Population-level demographic characteristics as estimated by standard logistic growth models (i.e., carrying capacity and intrinsic growth rate) should vary with changes in habitat quality and availability of resources. However, few published studies have tested this hypothesis by comparing population growth rates across broad bioclimatic gradients...
Article
Full-text available
1.Although local variation in territorial predator density is often correlated with habitat quality, the causal mechanism underlying this frequently observed association is poorly understood and could stem from facultative adjustment in either group size or territory size. 2.To test between these alternative hypotheses we used a novel statistical f...
Article
Full-text available
Movement patterns offer a rich source of information on animal behavior and the ecological significance of landscape attributes. This is especially useful for species occupying remote landscapes where direct behavioral observations are limited. In this study we fit a mechanistic model of animal cognition and movement to GPS positional data of woodl...
Article
Full-text available
Migration is well developed among mammals, but there has been little attempt to date to review common ecological constraints that may guide the evolution of migration among mammals, nor to consider its prevalence across different taxa. Here we review several alternate hypotheses for the evolution of migration in mammals based on improvements in ene...
Conference Paper
Full-text available
Background/Question/Methods Woodland caribou populations in the boreal forest are declining across North America as well as exhibiting dramatic range contraction. Multiple causal factors may be implicated, including climate change, declining food resources, enhanced predation risk due to apparent competition, and avoidance of areas of heavy human...
Article
Energetic balance is a central driver of individual survival and population change, yet estimating energetic costs in free and wide ranging animals presents a significant challenge. Animal-borne activity monitors (using accelerometer technology) present a promising method of meeting this challenge and opens new avenues for exploring energetics in n...
Article
Memory is critical to understanding animal movement but has proven challenging to study. Advances in animal tracking technology, theoretical movement models and cognitive sciences have facilitated research in each of these fields, but also created a need for synthetic examination of the linkages between memory and animal movement. Here, we draw tog...
Conference Paper
Background/Question/Methods Collecting detailed information on animals that are difficult to track in largely inaccessible environments poses a barrier to ecological research. We deployed tracking collars for 18-36 weeks on 46 individual female woodland caribou (Rangifer tarandus caribou) in northern Ontario, Canada. Each collar incorporates a Gl...
Article
Theory predicts that consumers can increase their energy intake by spending more time within resource-rich areas and/or by avoiding areas where local competitor densities are high. A consumer whose movements are described by a simple random walk can achieve these objectives by adjusting its turn frequency and/or speed. We recorded movements, as ser...
Article
Full-text available
Observations of the migration patterns of Norwegian red deer show that some animals ride waves of greener vegetation as spring spreads across the landscape, whereas others jump ahead in anticipation of this higher-quality food.
Article
Within the rapidly developing field of movement ecology, much attention has been given to studying the movement of individuals within a subset of their population's occupied range. Our understanding of the effects of landscape heterogeneity on animal movement is still fairly limited as it requires studying the movement of multiple individuals acros...
Article
Full-text available
According to optimal foraging theory, foraging decisions are based on the forager's current estimate of the quality of its environment. However, in a novel environment, a forager does not possess information regarding the quality of the environment, and may make a decision based on a biased estimate. We show, using a simple simulation model, that w...
Data
Full-text available
Matlab code for the foraging simulation without memory. (PDF)
Data
Full-text available
Matlab code for the foraging simulation with memory. (PDF)
Data
Full-text available
A description of the different parameters used in the model. (PDF)
Article
1. Despite the popular use of diffusion models to predict the spatial spread of populations over time, we currently know little about how diffusion rates change with the state of the environment or the internal condition of individuals. To address this gap in our understanding, we measured rates of spread for many populations of the rotifer Brachio...
Article
Full-text available
The functional response is a fundamental model of the relationship between consumer intake rate and resource abundance. The random walk is a fundamental model of animal movement and is well approximated by simple diffusion. Both models are central to our understanding of numerous ecological processes but are rarely linked in ecological theory. To d...
Conference Paper
Background/Question/Methods Numerous contributions to ecological research have steamed from the incorporation of classical models from physics (e.g., diffusion, random-walk and ideal gas models) as null hypotheses in the interpretation of individual and population movement patterns. Ideal gas-based models (e.g., Holling’s disk equation) focus on p...
Article
Full-text available
: Using an individual‐based model, Scharf and coworkers showed that ambush predators may encounter prey more frequently than active predators. We show that this surprising result emerges because active predators were oblivious to prey during movement, an assumption that refutes the common conception about active foraging and lessens the key differe...
Article
Full-text available
Plant recruitment in nature exhibits several distinctive patterns ranging from hump shaped to monotonically decreasing with distance from the seed source. We investigate the role of postdispersal seed predation in shaping these patterns, introducing a new mechanistic model that explicitly accounts for the movement strategy used by seed eaters. The...
Article
Foraging traits of seed predators are expected to impact the spatial structure of plant populations, community dynamics and diversity. Yet, many of the key mechanisms governing distance- or density-dependent seed predation are poorly understood. We designed an extensive set of field experiments to test how seed predation by two harvester ant specie...