570 items found
Space use
Spatial statistics
Utilization distribution
Space use
Spatial statistics
Utilization distribution
Summary
- Analyses based on utilization distributions (UDs) have been ubiquitous in animal space use studies, largely because they are computationally straightforward and relatively easy to employ. Conventional applications of resource utilization functions (RUFs) suggest that estimates of UDs can be used as response variables in a regression involving spatial covariates of interest.
- It has been claimed that contemporary implementations of RUFs can yield inference about resource selection, although to our knowledge, an explicit connection has not been described.
- We explore the relationships between RUFs and resource selection functions from a hueristic and simulation perspective. We investigate several sources of potential bias in the estimation of resource selection coefficients using RUFs (e.g. the spatial covariance modelling that is often used in RUF analyses).
- Our findings illustrate that RUFs can, in fact, serve as approximations to RSFs and are capable of providing inference about resource selection, but only with some modification and under specific circumstances.
- Using real telemetry data as an example, we provide guidance on which methods for estimating resource selection may be more appropriate and in which situations. In general, if telemetry data are assumed to arise as a point process, then RSF methods may be preferable to RUFs; however, modified RUFs may provide less biased parameter estimates when the data are subject to location error.
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Ecology
Ecology
<em>Odocoileus hemionus</em>
Survival
<em>Odocoileus hemionus</em>
Survival
Rainbow Trout
Rainbow Trout
Led By
Lake and Reservoir Researchers
Study Area
Select reservoirs
Project Status
Ongoing
Research Objectives
- Characterize and quantify interactions among key fish predators and prey in select reservoirs when required for addressing existing or emerging management uncertainties.
Project Description
Understanding how different species interact is central to sport fisheries management. For example, if predation on stocked fish intended for anglers (e.g., rainbow trout) limits development of a recreational fishery, modifying stocking practices (e.g., size of fish or timing) or other actions may be needed to improve the survival of stocked fish.
Alternatively, the recruitment success, growth and survival of sport fish sustained through natural reproduction rather than stocking can depend on numerous factors such as fluctuations in water levels or primary forage fish populations. Understanding relationships among factors helps identify potential management actions for improving sport fish growth and survival when necessary.
Lake and Reservoir Researchers use a suite of sampling methods and analytical tools to characterize reservoir food webs and predator-prey interactions when detailed assessments are needed to address management uncertainties. Sampling methods include various types of nets to catch different life-stages of fish occupying near- and offshore habitats to characterize spatial-temporal interactions among species. Analytical tools such as stable isotopes (chemical composition of fish), bioenergetics models, and population dynamics models are used to map food webs and quantify the influence of different species on others.
Current research involves investigating interactions between rainbow smelt and walleye in Horsetooth Reservoir (northeast Colorado). Rainbow smelt, a small-bodied forage fish, were introduced in 1983 to provide a prey base for walleye and smallmouth bass. The population of smelt can fluctuate dramatically. When highly abundant in the reservoir, growth of sport fish greatly improves, but they also limit natural reproduction by walleye through competition with and/or predation on larval/juvenile walleye. This research aims to identify management strategies for balancing the advantages of smelt with their disadvantages as the primary forage fish in the Horsetooth Reservoir food web.
Associated Publications
Hansen, A.G., J.S. Thompson, L.N. Hargis, D. Brauch, and B.M. Johnson. 2019. Predatory threat of introduced yellow perch in a salmonid dominated reservoir food web. North American Journal of Fisheries Management 39:172-190.
Johnson, B.M., W.M. Pate, and A.G. Hansen. 2017. Energy density and dry matter content in fish: new observations and an evaluation of some empirical models. Transactions of the American Fisheries Society 146:1262-1278.
Johnson, B.M., J.M. Lepak, and B.A. Wolff. 2015. Effects of prey assemblage on mercury bioaccumulation in a piscivorous sport fish. Science of the Total Environment 506-507:330-337.
Lepak, J.M., C.N. Cathcart, and W.L. Stacy. 2014. Tiger muskellunge predation upon stocked sport fish intended for recreational fisheries. Lake and Reservoir Management 30:250-257.
Lepak, J.M., A.G. Hansen, E.T. Cristan, and D. Williams. 2023. Rainbow smelt (Osmerus mordax) influence on walleye (Sander vitreus) recruitment failure: mitochondrial DNA evidence supporting the predation hypothesis. Journal of Fish Biology 103:1543-1548.
Lepak, J.M., A.G. Hansen, B.M. Johnson, K. Battige, E.T. Cristan, C.J. Farrell, W.M. Pate, K.B. Rogers, A.J. Treble, and T.W. Walsworth. In press. Cyclical multi-trophic-level responses to a volatile, introduced forage fish: learning from four decades of food web observation to inform management. Fisheries.
Pate, W.M., B.M. Johnson, J.M. Lepak, and D. Brauch. 2014. Managing for coexistence of kokanee and trophy lake trout in a montane reservoir. North American Journal of Fisheries Management 34:908-922.
Wolff, B.A., B.M. Johnson, and J.M. Lepak. 2017. Changes in sport fish mercury concentrations from food web shifts suggest partial decoupling from mercury loading in two Colorado reservoirs. Archives of Environmental Contamination and Toxicology 72:167-177.Predation on Stocked Fish fact sheetFish Bioenergetics Research fact sheet
[show more]
Led ByEric Bergman, Nathaniel Rayl
Study Areas
- Avalanche Creek elk herd (DAU E-15)
- Bear’s Ears elk herd (DAU E-2)
Project StatusOngoing
Research Objectives
- To assess how elk respond to human recreation
- To evaluate the influence of human recreation on elk distribution
- To estimate calf and adult female survival and cause-specific mortality rates
- To quantify pregnancy rates and nutritional condition
- To evaluate factors influencing survival, pregnancy rates, and nutritional condition
Project DescriptionIn Colorado, outdoor recreation contributes 511,000 jobs, $62.5 billion in economic output, and $9.4 billion in local, state, and federal tax revenue. Thus, the economies of Colorado, its counties, and its communities, rely on managing the landscape for a multitude of outdoor recreational opportunities.
The sensitivity of elk to human presence and human activity has been a topic of interest for many decades. In Colorado, increasing public concerns over human recreational use have coincided with declines in elk productivity, but a direct relationship to this activity in Colorado remains unaddressed. This research aims to better understand the influence of human recreation on elk behavior and distribution.
PublicationsCrews, S., N.D. Rayl, M.W. Alldredge, E.J. Bergman, C.R. Anderson Jr., E.H. VanNatta, J.D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097.
Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., and G. Bastille-Rousseau. 2025. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports 15:7807Bastille-Rousseau, G., S. A. Crews, E. B. Donovan, M. E. Egan, N. T. Gorman, J. B. Pitman, A. M. Weber, E. M. Audia, M. R. Larreur, H. Manninen, S. Blake, M. W. Eihholz, E. Bergman, and N. D. Rayl. 2024. A multi‐property assessment of intensity of use provides a functional understanding of animal movement. Methods in Ecology and Evolution 15:345-357. Egan, M. E., N. T. Gorman, S. Crews, M. W. Eichholz, D. Skinner, P. E. Schlichting, N. D. Rayl, E. J. Bergman, E. H. Ellington, and G. Bastille-Rousseau. 2024. Estimating encounter-habitat relationships with scale-integrated resource selection functions. Journal of Animal Ecology 93:1036-1048.
[show more]