575 items found

Sort by: Identifier Title Type Subject

ID: Dan Kowalski
Dan Kowalski
Type: 
Subjects: 
Item 

        Dan Kowalski    

                    Description:Aquatic Research Scientist, Stream and River EcologyContact Information
Email: Dan.kowalski@state.co.us
Phone: (970) 252-6008
Education
M.S., Fishery Biology — Colorado State University, 2002
B.S., Wildlife and Fisheries Science, Forest Science Minor — The Pennsylvania State University, 1999
Current or Recent Positions
Aquatic Research Scientist — Colorado Parks and Wildlife, 2012-Present
Aquatic Biologist — Colorado Parks and Wildlife, 2003-2012
Research Associate — Colorado Cooperative Fish and Wildlife Research Unit, 2003
Aquatic Technician — Colorado Parks and Wildlife, 2002
Areas of Interest/Expertise
Stream ecology and factors influencing coldwater sport fisheries in Colorado Rivers
Current or Recent Research Projects
Habitat use, ecology and emergence dynamics of the stonefly Pteronarcys californica
Habitat use and ecology of mottled sculpin Cottus bairdi
Effects of whitewater park development on invertebrate and native fish in the Uncompahgre and Colorado Rivers
Effects of mosquito control insecticides on invertebrates in Colorado Rivers
Evaluation of an electric barrier to reduce fish entrainment in the South Canal on the Gunnison River
Effects of re-introducing the stonefly Pteronarcys californica on the invertebrate community of the Arkansas River
Publications and PresentationsKowalski, D. A., R. J. Cordes, T. B. Riepe, J. D. Drennan, and A. J. Treble. 2022. Prevalence and distribution of Renibacterium salmoninarum, causative agent of bacterial kidney disease, in wild trout fisheries in Colorado. Pages 151-157 in the Proceedings of Wild Trout Symposium XIII: Reducing the Gap between Science and Public Opinion. Kowalski, D. A., E. I. Gardunio, and C. A. Garvey. 2022. Evaluating the effects of an electric barrier on fish entrainment in an irrigation canal in Colorado. River Research and Applications 38(3): 539–547. doi:10.1002/rra.3915.Heinold, B. D., D. A. Kowalski, and R. B. Nehring. 2020. Estimating densities of larval Salmonflies (Pteronarcys californica) through multiple pass removal of post-emergent exuvia in Colorado rivers. PLOSONE 15(4). doi: 10.1371/journal.pone.0227088.Kowalski, D. A. and E. E. Richer. 2020. Quantifying the habitat preferences of the stonefly Pteronarcys californica in Colorado. River Research and Applications 36:2043-2050. doi: 10.1002/rra.3733.Walters, D. M., J. S. Wesner, R. E. Zuellig, D. A. Kowalski, and M. C. Kondratieff. 2018. Holy flux: spatial and temporal variation in massive pulses of emerging insect biomass from western U.S. rivers. Ecology 99(1): 238-240.
Walters, D.M., R.E. Zuellig, and D.A. Kowalski. 2014. Quantifying the emergence of giant stonefly (Pteronarcys californica) and its importance to terrestrial food webs in U.S. western rivers. Society for Freshwater Science. Portland, OR
Kowalski, D.A., E. Fetherman, and R.B. Nehring. 2012. Introduction of whirling disease resistant rainbow trout in the Gunnison River. 2012 Western Division American Fisheries Society Meeting, Jackson Hole, WY.
Kowalski, D.A., Schisler, G.J., and R.B. Nehring. 2009. Introduction of Myxobolus cerebralis resistant rainbow trout in the Gunnison River. Colorado-Wyoming Chapter American Fisheries Society, Fort Collins, Colorado
Kowalski, D.A. and G.J. Schisler. 2008. Introduction of Myxobolus cerebralis resistant rainbow trout in the Gunnison River. 2008 Whirling Disease Symposium, Denver, Colorado.
Kowalski D.A. and E.P. Bergersen. 2004. The toxicity of Bayluscide and TFM to Tubifex tubifex: implications for chemical control of the oligochaete host of Myxobolus cerebralis, the causative agent of whirling disease. North American Journal of Aquaculture 65(3): 171–178.​
Kowalski, D.A. and E.P. Bergersen. 2002. The toxicity of Bayluscide and TFM to Tubifex tubifex: implications for chemical control of whirling disease. 2002 Whirling Disease Symposium, Denver, Colorado​.
 [show more]                

ID: Deer Adenovirus
Deer Adenovirus
Type: Fact Sheet
Subjects: Wildlife Diseases
Pronghorn
Elk
Deer
Adenovirus
Item 

        Deer Adenovirus    
Type:Fact Sheet
Subject:Wildlife Diseases
Pronghorn
Elk
Deer
Adenovirus

                    Description:Fact sheet: “Deer adenovirus” causes death by damaging blood vessels in the lungs, intestines, and/or other organs in deer, elk, and pronghorn in Colorado.                 

ID: Demography, education, and research trends in the

interdisciplinary field of disease ecology
Demography, education, and research trends in the

interdisciplinary field of disease ecology
Type: Article
Subjects: Host-pathogen interaction
Infectious disease
Machine learning
Item 

        Demography, education, and research trends in the

interdisciplinary field of disease ecology    
Type:Article
Subject:Host-pathogen interaction
Infectious disease
Machine learning

                    Description:Micro-and macroparasites are a leading cause of mortality for humans, animals, and plants, and there is great need to understand their origins, transmission dynamics, and impacts. Disease ecology formed as an interdisciplinary field in the 1970s to fill this need and has recently rapidly grown in size and influence. Because interdisciplinary fields integrate diverse scientific expertise and training experiences, understanding their composition and research priorities is often difficult. Here, for the first time, we quantify the composition and educational experiences of a subset of disease ecology practitioners and identify topical trends in published research. We combined a large survey of self-declared disease ecologists with a literature synthesis involving machine-learning topic detection of over 18,500 disease ecology research articles. The number of graduate degrees earned by disease ecology practitioners has grown dramatically since the early 2000s. Similar to other science fields, we show that practitioners in disease ecology have diversified in the last decade in terms of gender identity and institution, with weaker diversification in race and ethnicity. Topic detection analysis revealed how the frequency of publications on certain topics has declined (e.g., HIV, serology), increased (e.g., the dilution effect, infectious disease in bats), remained relatively common (e.g., malaria ecology, influenza, vaccine research and development), or have consistently remained relatively infrequent (e.g., theoretical models, field experiments). Other topics, such as climate change, superspreading, emerging infectious diseases, and network analyses, have recently come to prominence. This study helps identify the major themes of disease ecology and demonstrates how publication frequency corresponds to emergent health and environmental threats. More broadly, our approach provides a framework to examine the composition and publication trends of other major research fields that cross traditional disciplinary boundaries. [show more]                

ID: Density and demography of snowshoe hares in central Colorado
Density and demography of snowshoe hares in central Colorado
Type: Article
Subjects: Colorado
Demography
Density
Forest management
<em>Lepus americanus</em>
Recruitment
Snowshoe hare
Survival
Telemetry
Item 

        Density and demography of snowshoe hares in central Colorado    
Type:Article
Subject:Colorado
Demography
Density
Forest management
<em>Lepus americanus</em>
Recruitment
Snowshoe hare
Survival
Telemetry

                    Description:To improve understanding of snowshoe hare ecology in the Southern Rockies and enhance the ability of agency personnel to manage subalpine landscapes for snowshoe hares (Lepus americanus) and lynx (Lynx canadensis) in the region, we estimated snowshoe hare density, survival, and recruitment in west-central Colorado, USA from July 2006–March 2009. We sampled 3 types of forest stands that purportedly provide good habitat for hares: 1) mature Engelmann spruce (Picea engelmannii)–subalpine fir (Abies lasiocarpa), 2) early seral, even-aged lodgepole pine (Pinus contorta), and 3) mid-seral, even-aged lodgepole pine that had been pre-commercially thinned. In all forest types and all seasons, snowshoe hare densities were <1.0 hares/ha. During summer, hare densities [±SE] were highest in early seral lodgepole pine (0.20 [0.01] to 0.66 [0.07] hares/ha), lowest in mid-seral lodgepole pine (0.01 [0.04] to 0.03 [0.03] hares/ha), and intermediate in mature spruce-fir (0.01 [0.002] to 0.26 [0.08] hares/ha). During winter, densities were more similar among the 3 stand types. Annual survival of hares was highest in mature spruce-fir (0.14 [0.05] to 0.20 [0.07]) and similar between the 2 lodgepole stand types (0.10 [0.03] to 0.16 [0.06]). Stand attributes indicative of dense cover were positively correlated with density estimates and explained relatively more spatial process variance in hare densities than other attributes. These same attributes were not positively correlated with hare survival. Both density and survival of hares in early seral lodgepole stands were positively correlated with the extent of similar stands in the surrounding landscape. Recruitment of juvenile hares occurred during all 3 summers in early seral lodgepole stands, 2 of 3 summers in mature spruce-fir stands, and in only 1 of 3 summers in mid-seral lodgepole. Based on estimates of density and demography specific to each forest type, we conclude that managers should maintain mature spruce-fir and early seral lodgepole stand types rather than thinned, mid-seral lodgepole stands to benefit snowshoe hares (and by association lynx) in central Colorado. Given the more persistent nature of spruce-fir compared to early seral lodgepole, and the fact that such stands cover considerably more area, mature spruce-fir may be the most valuable forest type for snowshoe hares in the region. [show more]                

ID: Density dependence in mule deer: A review of evidence
Density dependence in mule deer: A review of evidence
Type: Article
Subjects: Wildlife managers
Density dependence
<em>Odocoileus hemionus</em>
Colorado
Mule deer
Winter range habitat
Item 

        Density dependence in mule deer: A review of evidence    
Type:Article
Subject:Wildlife managers
Density dependence
<em>Odocoileus hemionus</em>
Colorado
Mule deer
Winter range habitat

                    Description:Wildlife managers often need tangible evidence of density dependence in populations to support decision making. Field experimentation to identify density dependent effects is often cost and time prohibitive. Thus, assimilation of existing knowledge into a balance of probabilities can serve as a surrogate for experimental research. A case study of such a process is found in the mule deer Odocoileus hemionus herds of Colorado. Wildlife managers and hunters expressed concern over a recent decline in western Colorado mule deer herds, yet the underlying cause of this decline is yet to be determined. In response to this management concern, we conducted a review of scientific evidence on Colorado's mule deer population dynamics. This review was done in the context of a conceptual model that portrays population growth as a function of population size, per capita growth rate and population carrying capacity. Similar declines that occurred during the 1960s and early 1990s resulted in similar reviews that identified research and management topics that would benefit mule deer. These topics included: harvest, predation, intraspecific competition, disease, interspecific competition, and habitat loss and degradation. Between the late 1990s and present time, many of these topics were addressed by research. The conventional working hypothesis in Colorado is that mule deer herds are limited by winter range habitat. We identify new gaps in knowledge and suggest potential, future research topics, as well as potential management strategies. We suggest a focus on integrated studies of multiple herbivores with density reduction experiments to address intra- and inter- specific competition. In addition, we suggest focused experiments that address the roles of mountain lion predation, black bear predation, and disease in mule deer population dynamics. [show more]                

ID: Density estimation...
Density estimation...
Type: Article
Subjects: Abundance
Density
Demographic closure
Sampling
Item 

        Density estimation...    
Type:Article
Subject:Abundance
Density
Demographic closure
Sampling

                    Description:Abundance is commonly sought after as a state variable for the study of populations. However, density (number of animals per unit area) can be a more meaningful metric because it casts the state of a population into a common currency. For example, using closed capture models from Chapter 14, we estimate 500 animals at site A and 200 animals at site B. Thus one conclusion we may reach is that habitat management at site A has positively impacted the population there compared to site B. However, if we know site A is 250 hectares and B is 100 hectares, then we realize that each has 2.0 animals/hectare. That is, on a relative scale, the different management scheme at A had no effect compared to site B. Conversely, we may estimate abundance at 2 sites to be similar and conclude management actions, or habitat types, or harvest regulations, etc. are having a similar impact, but if the sites are different sizes, then the impacts are actually quite different on a relative scale and our conclusion is erroneous. Thus, while abundance can be a useful metric, estimating density can be helpful as well. [show more]                

ID: Detection of prions from spiked and free-ranging carnivore feces
Detection of prions from spiked and free-ranging carnivore feces
Type: Text
Subjects: Diseases
Ecological epidemiology
Ecology
Infectious diseases
Prions
Item 

        Detection of prions from spiked and free-ranging carnivore feces    
Type:Text
Subject:Diseases
Ecological epidemiology
Ecology
Infectious diseases
Prions

                    Description:Abstract: Chronic wasting disease (CWD) is a highly contagious, fatal neurodegenerative disease caused by infectious prions (PrPCWD) affecting wild and captive cervids. Although experimental feeding studies have demonstrated prions in feces of crows (Corvus brachyrhynchos), coyotes (Canis latrans), and cougars (Puma concolor), the role of scavengers and predators in CWD epidemiology remains poorly understood. Here we applied the real-time quaking-induced conversion (RT-QuIC) assay to detect PrPCWD in feces from cervid consumers, to advance surveillance approaches, which could be used to improve disease research and adaptive management of CWD. We assessed recovery and detection of PrPCWD by experimental spiking of PrPCWD into carnivore feces from 9 species sourced from CWD-free populations or captive facilities. We then applied this technique to detect PrPCWD from feces of predators and scavengers in free-ranging populations. Our results demonstrate that spiked PrPCWD is detectable from feces of free-ranging mammalian and avian carnivores using RT-QuIC. Results show that PrPCWD acquired in natural settings is detectable in feces from free-ranging carnivores, and that PrPCWD rates of detection in carnivore feces reflect relative prevalence estimates observed in the corresponding cervid populations. This study adapts an important diagnostic tool for CWD, allowing investigation of the epidemiology of CWD at the community-level. [show more]                

ID: Determining the Distribution of the Three-Species in Western Colorado (Completed)
Determining the Distribution of the Three-Species in Western Colorado (Completed)

Type: 
Subjects: 
Item 

        Determining the Distribution of the Three-Species in Western Colorado (Completed)

    

                    Description:Led By
Kevin Thompson​, CPW-retired; Zachary Hooley-Underwood​, CPW
Study Area
Western Slope Waters below 8,500’
Project Status
Complete
Research Objectives
To determine the current distribution of the three-species in Colorado's Western Slope streams and rivers.
PhotosTop right: Electrofishing a randomly selected site looking for the “three-species"Bottom right: Electrofishing a site historically occupied by Bluehead Sucker and Roundtail ChubProject DescriptionThe rivers and streams of western Colorado below 8,500 feet in elevation comprise the historic native range for the three-species (Flannelmouth Sucker, Bluehead Sucker and Roundtail Chub). Evidence suggests the three-species only occupy about 50 percent of their historic native range in the upper Colorado River basin. Although extensive data have been collected on three-species distribution in Colorado's mainstem rivers, very little data exist on the presence of the three-species in smaller streams.
As a result, CPW initiated a project to rigorously determine the current distribution of the three-species within their native Colorado ranges. Researchers sampled at randomly selected locations in streams that lie within the historic native range and also at randomly selected historic sampling locations (where one or more of the three-species have been previously documented) within the Colorado River basin for three-species fish. This approach is structured to ensure that spatial balance is achieved so that the entire potential native range is included.
This research determined that occupancy of randomly selected sites was fairly low overall for all three species. Stream gradient was the variable most strongly associated with occupancy, with lower gradient sites being more frequently occupied. Each of the species have been lost from at least some of the historically identified sites. Roundtail Chub have been the most affected, occupying only 12.5% of sites where they were present before1980. The large number of surveys required to complete this study resulted in stream-specific information on a number of un-sampled and rarely sampled waters, which will aid fisheries managers in the future.

Researchers will continue to sample specific locations to follow up on this work, and answer specific questions on specific waters. The results from this study will give biologists a better idea of three-species distribution and abundance and help determine whether the present ranges of these fishes are stable. A better understanding of these dynamics will give fishery managers the information they need to make effective management decisions [show more]                

ID: Determining the Impact of Tiger Muskellunge Predation on Stocked Fish Intended to Improve Recreational Fisheries
Determining the Impact of Tiger Muskellunge Predation on Stocked Fish Intended to Improve Recreational Fisheries
Type: 
Subjects: 
Item 

        Determining the Impact of Tiger Muskellunge Predation on Stocked Fish Intended to Improve Recreational Fisheries    

                    Description:Led By
Jesse L​epak​
Study Area
Five Colorado Reservoirs (Big Creek, Clear Creek, De Weese, Parvin, and Pinewood)
Project Status
Completed
Research Objectives
To determine the effectiveness of stocking tiger muskellunge to control white sucker populations.
To determine the impact of tiger muskellunge on stocked fish, such as rainbow trout.​
Project Description
Fisheries managers often stock reservoirs and lakes in an effort to improve sport fishing for anglers and to enhance native species restoration efforts. However, white suckers have been shown to compete with salmonid species including popular sport fish like rainbow trout. 
In Colorado, fisheries managers often stock tiger muskellunge, a sterile hybrid of northern pike and muskellunge, to suppress white sucker populations, which compete with rainbow trout. However, tiger muskellunge will also prey on trout. ​
As a result, CPW initiated a research project to study tiger muskellunge predation on stocked fish, such as rainbow trout.
Researchers collected tissue samples from tiger muskellunge found in five Colorado reservoirs. Using muscle tissue chemistry, researchers could estimate the proportion of stocked fish eaten by tiger muskellunges in each reservoir.
Results from this study suggest that stocking fish in lakes and reservoirs that contain predators  may result in losses of stocked fish. Therefore, systems must be selected carefully to maximize the benefits of stocking tiger muskellunge as a biological control for undesirable species while minimizing the costs to stocked fish intended for recreational angling. This information will help fisheries managers determine the most appropriate management strategies and increase the effectiveness of fish stocking programs.​
Associated Publications​
Lepak, J.M., Cathcart, C.N., and Stacy, W.L. 2014. Tiger muskellunge predation upon stocked sport fish intended for recreational fisheries. Lake and Reservoir Management. 30:250-257.
Lepak, J.M., Fetherman, E.R., Pate, W.M., Craft, C.D. and Gardunio, E.I. 2012. An experimental approach to determine esocid prey preference in replicated pond systems.  Lake and Reservoir Management. 28:224-231. 
 [show more]                

ID: Developing Cost-Effective Strategies for Managing Moose in Colorado
Developing Cost-Effective Strategies for Managing Moose in Colorado
Type: 
Subjects: 
Item 

        Developing Cost-Effective Strategies for Managing Moose in Colorado    

                    Description:Led ByEric Bergman
Study AreaNorthwest Colorado (Rabbit Ears mountain range); Northeast Colorado (Laramie River drainage); Southwest Colorado (Upper portions of the Rio Grande River and near Lake City)
Project StatusCompleted
Research Objectives
To develop alternative cost-effective strategies for harvest and management of moose populations.
To incorporate moose life-history characteristics into management plans.
To compare moose survival rates across the state.
To collect data on moose disease and health.
Project Description
With limited budgets, wildlife managers must often prioritize management funding based on details such as:
​Species abundance​​
The a​mount of revenue generated by a species
The endangered or threatened status of a species
Moose are less abundant in Colorado than elk and deer, thus funding for moose management tends to be lower in comparison. In addition, moose populations are more difficult to estimate because most of Colorado's moose herds live in forests, making aerial observation difficult. As a result, reliable moose population data are limited. Without these data, wildlife managers cannot make fully informed licensing decisions. 
Fortunately, other factors besides population abundance can inform wildlife managers about moose population status. For example, reduced pregnancy and survival rates can indicate low food availability due to increased herd sizes. Using these other factors, researchers will develop population models that wildlife managers can use to manage moose populations in the state.Related Publications:Bergman, Eric J. 2013-2022. Evaluation and incorporation of life history traits, nutritional status, and browse characteristics in Shira's moose management in Colorado. (Annual federal aid progress reports combined into one document)
 [show more]                