570 items found

Sort by: Identifier Title Type Subject

ID: Plant and mule deer responses to pinyon-juniper removal by three mechanical methods.
Plant and mule deer responses to pinyon-juniper removal by three mechanical methods.
Type: Article
Subjects: Mule deer
Pinyon pine
Juniper
Item 

        Plant and mule deer responses to pinyon-juniper removal by three mechanical methods.    
Type:Article
Subject:Mule deer
Pinyon pine
Juniper

                    Description:Land managers in western North America often reverse succession by removing pinyon (Pinus spp.) and juniper (Juniperus spp.) trees to reduce fire risk and increase forage for wildlife and livestock. Because prescribed fire carries inherent risks, mechanical methods such as chaining, roller-chopping, and mastication are often used. Mechanical methods differ in cost and the size of woody debris produced, and may differentially impact plant and animal responses. We implemented a randomized, complete-block, split-plot experiment in December 2011 in the Piceance Basin, northwestern Colorado, USA, to compare mechanical methods and to explore seeding (subplot) interactions. We assessed vegetation 1-, 2-, 5-, and 6-years post-treatment, and mule deer (Odocoileus hemionus) response via GPS locations 3–8 years post-treatment. By 2016, treated plots had 3–5 times higher perennial grass cover and ~10 times higher cheatgrass (Bromus tectorum) cover than untreated control plots. Roller-chopped plots had both the highest non-native annual forb cover, and when seeded, the highest density of bitterbrush (Purshia tridentata), a nutritious shrub used by mule deer. Masticated plots had higher bitterbrush use during summer and fall, leaving less forage available for winter. Days of winter mule deer use from GPS point locations in chained and roller-chopped plots was ~70% higher than in control plots, while winter use in masticated plots was similar to control plots. Mule deer use appears related to a combination of hiding cover, resulting from residual woody debris, and winter forage availability. Roller-chopped plots provide the best combination of hiding cover and winter forage, but mastication or chaining, applied leaving dispersed security cover, may be better options at large scales or when invasive species concerns exist. [show more]                

ID: Population Assessment of Pelagic Fishes Using Hydroacoustics
Population Assessment of Pelagic Fishes Using Hydroacoustics
Type: 
Subjects: 
Item 

        Population Assessment of Pelagic Fishes Using Hydroacoustics    

                    Description:Led By
Bill Pate at Colorado State University, Andrew Treble, and Lake and Reservoir Researchers
Study Area
Select coldwater reservoirs
Project Status
Ongoing
Research Objectives
Monitor the depth-distribution, density, size structure, and abundance of pelagic fish species in key coldwater reservoirs.
Monitor zooplankton species assemblage and density.
Monitor invasive Mysis shrimp densities where present.
Project Description
​Hydroacoustic surveys enable rapid estimation of the abundance, density, size structure, and depth-distribution of pelagic (or offshore/open water) fish species such as kokanee and lake trout. Mobile hydroacoustics is a quantitative method for sampling the water column of a large lake or reservoir with sound that allows for greater spatial coverage than gill netting or midwater trawling. Survey transects are completed overnight during the dark of the moon to allow for greater spatial distribution of the fish.
Hydroacoustic surveys are generally most effective when few pelagic species are present, and Colorado has many coldwater reservoirs containing relatively simple pelagic fish assemblages. Kokanee waters, such as Lake Granby and Blue Mesa Reservoir, provide upwards of $30 million in economic benefit to the state annually and are vital broodstocks that supply eggs to support statewide stocking efforts. Hydroacoustic surveys conducted on these and other waters are necessary for monitoring the health of these valuable fisheries and identifying when additional management interventions or research might be required to ensure stable populations.
In addition, monitoring zooplankton species assemblages and Mysis shrimp densities are an important aspect of this assessment project. Kokanee are an obligate planktivorous species that feed on zooplankton like Daphnia, and lake trout rely upon Mysis shrimp when young before turning to kokanee or other fishes as a forage base. In addition, detrimental invasive species of zooplankton such as Daphnia lumholtzi can be detected as early as possible through this monitoring program. Better monitoring practices allow for more informed management decisions for a given water body.
Associated Publications
Lepak, J.M., W.M. Pate, P. Cadmus, A.G. Hansen, K.D. Gallaher, and D. Silver. 2024. Response of an invasive aquatic crustacean to the fish toxicant rotenone. Lake and Reservoir Management 40:330-337.
 [show more]                

ID: Post-conference report
Post-conference report
Type: Text
Subjects: Partners in the Outdoors conference
Item 

        Post-conference report    
Type:Text
Subject:Partners in the Outdoors conference

                    Description:Post-conference report for the Partners in the Outdoors conference                

ID: Post-Flood Recovery Assessment and Stream Restoration Guidelines for the Colorado Front Range
Post-Flood Recovery Assessment and Stream Restoration Guidelines for the Colorado Front Range
Type: 
Subjects: 
Item 

        Post-Flood Recovery Assessment and Stream Restoration Guidelines for the Colorado Front Range    

                    Description:Report by Eric E. Richer, Matt C. Kondratieff, and Benjamin D. Swigle (November 19, 2014)Abstract:Severe flooding impacted rivers and streams in the Colorado Front Range during September 2013. The flooding had devastating effects on communities and infrastructure, but had many beneficial effects on river ecosystems and stream functions. Flooding is a natural component of river systems that is vital for many ecological and physical processes. Following the flood, rebuilding infrastructure was given top priority and permitting processes were suspended or expedited to facilitate reconstruction activities. In many cases, emergency reconstruction activities led to degradation of stream functions and aquatic habitat. Degradation was often associated with the creation of trapezoidal and armored channels. Initial monitoring following the flood showed variable impacts to fish populations, with changes in trout abundance ranging from -58% to +69% at sites that were severely impacted by the flood but not further altered during emergency reconstruction. Monitoring sites that underwent substantial channel alterations during emergency reconstruction had an average change in trout abundance of -95%. Floods may provide an opportunity to improve a variety of stream functions related to channel stability, flood conveyance, geomorphology, water quality, and habitat connectivity. However, programmatic constraints at both the state and federal level limit opportunities to improve rivers beyond their preflood condition. Addressing permitting and funding constraints prior to the next major flood could greatly improve the efficiency and effectiveness of emergency flood response while reducing long-term maintenance and stream restoration costs. [show more]                

ID: Post-Stocking Performance of Triploid Walleye
Post-Stocking Performance of Triploid Walleye
Type: 
Subjects: 
Item 

        Post-Stocking Performance of Triploid Walleye    

                    Description:Post-Stocking Performance of Triploid Walleye
​​​​​​​​Led By
Lake and Reservoir Researchers and Colorado State University (CSU)
Study Area
Select reservoirs
Project Status
Ongoing
Research Objectives
Measure the post-stocking feeding, growth and survival of sterile walleye relative to their non-sterile counterparts.
Determine the most appropriate stocking procedures for sterile walleye.
Evaluate the potential for sterile walleye to interfere with unwanted natural reproduction.
Project Description
​Every spring CPW collects eggs from wild populations of walleye to raise in the hatchery and stock back out into reservoirs to supplement fisheries. Some of these eggs are specially treated to produce “triploids”. Triploidy is induced by placing fertilized eggs into a hydrostatic pressure chamber. As a result, the fry that hatch retain an extra set of chromosomes (unlike their normal “diploid” counterparts), rendering them incapable of naturally-reproducing over their lifespan. Because triploid walleye are sterile, they can be stocked to support sport fisheries in strategic locations where natural walleye reproduction is not wanted.
Interest in triploid walleye as a management tool is increasing. However, little is known about their post-stocking performance. Understanding post-stocking performance helps identify best stocking practices and calibrate expectations on potential fishery quality. CPW researchers along with collaborators from CSU have been examining numerous aspects of triploid walleye ecology, including how well they grow and survive after being stocked, the types of prey they eat, their uptake of contaminants like mercury, and potential to interfere with unwanted natural reproduction.
General findings to date indicate that triploids eat and grow similarly to diploids, but do not survive as well early in life, which could potentially be overcome by stocking larger fingerlings rather than fry. Both triploid males and females of mature age exhibited negligible development of reproductive tissues. This was expected for females, but not males, suggesting that the ability of triploid males to interfere with unwanted natural reproduction may be relatively low. However, limited development of reproductive tissues contributed to lower mercury levels in triploid fish compared to diploids, making them safer to eat. Research on triploid walleye is ongoing, but they represent a promising management tool for providing desirable sport fisheries in sensitive locations where natural reproduction is not wanted for purposes of native fish protection or other management objectives. 
Associated Publications
Farrell, C.J., A.G. Hansen, M.M. Brandt, C.M. Myrick, B.M. Johnson. 2024. An evaluation of the relative size, condition, and apparent survival of triploid walleye in the wild. North American Journal of Fisheries Management 44:172-188.
Farrell, C.J., B.M. Johnson, A.G. Hansen, and C.M. Myrick. 2022. Induced triploidy reduces mercury bioaccumulation in a piscivorous fish. Canadian Journal of Fisheries and Aquatic Sciences 79:202-212 (Received Editor’s Choice Award).
Farrell, C.J., B.M. Johnson, A.G. Hansen, C.A. Myrick, E.C. Anderson, T.A. Delomas, A.D. Schreier, and J.P. Van Enennaam. 2022. Cytological and molecular approaches for ploidy determination: results from a wild walleye population. North American Journal of Fisheries Management 42:849-856.
Farrell, C.J., B.M. Johnson, A.G. Hansen, B. Avila, and C.M. Myrick. In revision. Does reproduction cause growth deceleration? Induced sterility illuminates the effects of reproduction of growth. Canadian Journal of Fisheries and Aquatic Sciences.
Hansen, A.G., C.J. Farrell, and B.M. Johnson. 2023. Simulated effects of imperfect sterile sport fish stocking on persistence of fertile fish in new exploited populations. North American Journal of Fisheries Management 43:908-934.
 [show more]                

ID: Practical guidance on characterizing availability in resource selection functions under a use–availability design
Practical guidance on characterizing availability in resource selection functions under a use–availability design
Type: Article
Subjects: Autocorrelation
GPS radio telemetry
Resource selection function (RSF)
Spatial point process
Species distribution model
Use–availability data
Wildlife
Item 

        Practical guidance on characterizing availability in resource selection functions under a use–availability design    
Type:Article
Subject:Autocorrelation
GPS radio telemetry
Resource selection function (RSF)
Spatial point process
Species distribution model
Use–availability data
Wildlife

                    Description:Habitat selection is a fundamental aspect of animal ecology, the understanding of which is critical to management and conservation. Global positioning system data from animals allow fine-scale assessments of habitat selection and typically are analyzed in a use–availability framework, whereby animal locations are contrasted with random locations (the availability sample). Although most use–availability methods are in fact spatial point process models, they often are fit using logistic regression. This framework offers numerous methodological challenges, for which the literature provides little guidance. Specifically, the size and spatial extent of the availability sample influences coefficient estimates potentially causing interpretational bias. We examined the influence of availability on statistical inference through simulations and analysis of serially correlated mule deer GPS data. Bias in estimates arose from incorrectly assessing and sampling the spatial extent of availability. Spatial autocorrelation in covariates, which is common for landscape characteristics, exacerbated the error in availability sampling leading to increased bias. These results have strong implications for habitat selection analyses using GPS data, which are increasingly prevalent in the literature. We recommend that researchers assess the sensitivity of their results to their availability sample and, where bias is likely, take care with interpretations and use cross validation to assess robustness. [show more]                

ID: Prairie Dog Burrow Timelapse
Prairie Dog Burrow Timelapse
Type: 
Subjects: 
Item 

        Prairie Dog Burrow Timelapse    

                    Description:How many species can you count in this video? Bonus points for naming them all!

This is the story of how our Avian Research and Wildlife Health Programs teamed up with partners to study and test a new plague vaccine and improve habitat for endangered black-footed ferrets and other wildlife. Avian Researchers have documented the benefits of maintaining active prairie dog colonies for many species such as ferruginous hawks, golden eagles, various grassland songbirds, coyotes, and badgers.

https://cpw.state.co.us/learn/Pages/WildlifeHealth.aspx
https://cpw.state.co.us/learn/Pages/RAV-Plague-Management.aspx [show more]                

ID: Predation On Stocked Fish Fact Sheet
Predation On Stocked Fish Fact Sheet

Type: 
Subjects: 
Item 

        Predation On Stocked Fish Fact Sheet

ID: Predation risk across a dynamic landscape: effects of anthropogenic land use, natural landscape features, and prey distribution
Predation risk across a dynamic landscape: effects of anthropogenic land use, natural landscape features, and prey distribution
Type: Article
Subjects: Carnivores
Disturbance ecology
Energy development
Habitat fragmentation
Mule deer
Predation risk
Resource selection
Item 

        Predation risk across a dynamic landscape: effects of anthropogenic land use, natural landscape features, and prey distribution    
Type:Article
Subject:Carnivores
Disturbance ecology
Energy development
Habitat fragmentation
Mule deer
Predation risk
Resource selection

                    Description:PurposeHuman-mediated landscape changes alter habitat configuration, which strongly structures animal distributions and interspecific interactions. The effects of anthropogenic disturbance on predator–prey relationships are fundamental to ecology, yet less well understood. We determined where predation events occurred for fawn and adult female mule deer from 2008 to 2014 in critical winter range with extensive energy development. We investigated the relationship between predation sites, energy infrastructure, and natural landscape features across contiguous areas experiencing different degrees of energy extraction during periods of high and low intensity development.
MethodsWe contrast spatial correlates of 286 mortality locations with random landscape locations and mule deer distribution estimated from 350,000 GPS locations. We estimated predation risk with resource selection functions and latent selection difference functions.
ResultsRelative to the distribution of mule deer, predation risk was lower closer to pipelines and well pads, but higher closer to roads. Predation sites occurred more than expected relative to availability and deer distribution in deeper snow and non-forested habitats. Anthropogenic features had a greater influence on predation sites during the period of low activity than high activity, and natural landscape characteristics had weaker effects relative to anthropogenic features throughout the study. Though canids accounted for the majority of predation events, felids exhibited stronger landscape associations, driving the observed spatial patterns in predation risk to mule deer.
ConclusionsThe emergence of varied interactions between predation and landscape features across contexts and years highlights the complexity of interspecific interactions in highly modified landscapes.
 [show more]                

ID: Predicting persistence of Rio Grande Cutthroat Trout populations in an uncertain future
Predicting persistence of Rio Grande Cutthroat Trout populations in an uncertain future
Type: Article
Subjects: Rio Grande Cutthroat Trout
<em>Oncorhynchus clarkii virginalis</em>
Bayesian network model
Item 

        Predicting persistence of Rio Grande Cutthroat Trout populations in an uncertain future    
Type:Article
Subject:Rio Grande Cutthroat Trout
<em>Oncorhynchus clarkii virginalis</em>
Bayesian network model

                    Description:The Rio Grande Cutthroat Trout Oncorhynchus clarkii virginalis (RGCT) occupies just 12% of its ancestral range. As the southernmost subspecies of Cutthroat Trout, we expect a warming climate to bring additional stressors to RGCT populations, such as increased stream temperatures, reduced streamflows, and increased incidence of wildfire. We developed a Bayesian network (BN) model using site-specific data, empirical research, and expert knowledge to estimate the probability of persistence for each of the 121 remaining RGCT conservation populations and to rank the severity of the threats they face. These inputs quantified the genetic risks (e.g., inbreeding risk and hybridization risk), population demographics (disease risk, habitat suitability, and survival), and probability of stochastic disturbances (stream drying risk and wildfire risk) in an uncertain future. We also created stream temperature and base flow discharge models coupled with regionally downscaled climate projections to predict future abiotic conditions at short-term (2040s) and long-term (2080s) time horizons. In the absence of active management, we predicted a decrease in the average probability of population persistence from 0.53 (current) to 0.31 (2040s) and 0.26 (2080s). Only 11% of these populations were predicted to have a greater than 75% chance of persisting to the 2080s. Threat of invasion by nonnative trout had the strongest effect on population persistence. Of the 78 populations that are already invaded or lacking complete barriers, 60% were estimated to be extirpated by 2080 and the remainder averaged only a 10% chance of persistence. In contrast, the effects of increased stream temperatures were predicted to affect the future persistence of only 9% of the 121 RGCT populations remaining, as most have been restricted to high-elevation habitats that are cold enough to buffer against some stream warming. Our BN model provides a framework for evaluating threats and will be useful to guide management actions that are likely to provide the most benefit for long-term conservation. [show more]                