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Browsing by Author "Kendall, William, committee member"

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    Assessing bird-mediated ecosystem services and disservices in Colorado apple orchards
    (Colorado State University. Libraries, 2016) Mangan, Anna Mattern, author; Pejchar, Liba, advisor; Werner, Scott J., committee member; Kendall, William, committee member; Ode, Paul, committee member
    Agriculture provides food, fuel and fiber to our growing human population and as the largest terrestrial biomes, crop and pastureland are major drivers of land use change. Small organic farms have the potential to provide habitat for biodiversity while also contributing to food security. My research examined the characteristics of organic apple orchards associated with habitat use of human-adapted and human-sensitive birds as well as how birds influence fruit production positively through insect pest control and negatively through fruit damage. I used a stratified study design to survey birds, observe bird frugivory, capture birds to collect and analyze avian fecal samples, and assess bird and insect damage with an exclosure experiment in small organic farms in western Colorado. I calculated species richness and community similarity among apple blocks and adjacent habitat and evaluated bird habitat use as a function of orchard characteristics (i.e., location in orchard, size of apple block or edge-to-area ratio). I calculated the proportion of bird observations associated with apple frugivory and the proportion of fecal samples that were positive for codling moth DNA to identify bird species that could affect production. I compared bird damage to apples as a function of orchard characteristics and investigated factors that influenced codling moth damage, including access to fruit and moths by birds. I found that organic apple orchards in this region provided habitat for 42 human-adapted and 27 human-sensitive bird species and the bird community in orchards was relatively similar to shrub/tree habitat adjacent to apple blocks. There was sufficient data to model habitat use by seven species; however, use did not vary as a function of the orchard characteristics I measured. Similarly, apple damage by birds and codling moths was consistent within and across apple blocks that varied in size and variety. However, codling moth damage was negatively associated with the exclusion of birds. The molecular technique used to detect codling moth DNA in fecal samples was successful and one species (brown-headed cowbird) had fecal samples positive for codling moth DNA. Five species of birds (Bullock's oriole, common raven, house finch, Lewis's woodpecker, and western scrub-jay) were observed foraging on apples. However, the effect of birds as either agents of fruit damage or pest control in this agroecosystem appeared rather minor. These results demonstrate that organic apple orchards have the potential to provide habitat for diverse bird communities, including species typically sensitive to human activities. Further, because rates of bird-induced fruit damage were low and attributed to a small subset of the avian community, these agroecosystems may provide bird habitat without compromising production.
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    Effects of a non-lethal chemical repellent on airport bird communities
    (Colorado State University. Libraries, 2024) Urchek, Kathleen, author; Pejchar, Liba, advisor; Werner, Scott, committee member; Kendall, William, committee member; Bright, Alan, committee member
    Human-wildlife conflicts are likely to occur wherever the interests and activities of humans and wildlife overlap. Airport environments are a prime example of where such conflict is pervasive because wildlife can view airports as habitat, yet the presence of wildlife increases the risk of collision. As humans increase our reliance on air travel and development encroaches on natural areas, conflicts between humans and wildlife will continue to be prevalent in airport settings, thus creating the need for effective management tools. To assess the effectiveness of one such tool, we evaluated the effect of a non-lethal chemical repellent on bird abundance, species richness, movement, and behavior in airport settings. Following a Before After Control Impact Paired study design we compared the changes among each variable from a period of pre-treatment to a period of active treatment, in both treated and control sites. Using Poisson and zero-inflated mixed effects models we found that the repellent is likely effective in shifting birds from treated to untreated areas within airports, and that the abundance of two common species, Bobolinks and European Starlings, declined following treatment. We also found that the repellent does not change the frequency in which birds move out of treated plots and intersect with runways, but may be altering the within-plot behavior of Eastern Meadowlarks, Red-winged Blackbirds, and Sandhill Cranes. Our mixed findings highlight the need for continued study of the mechanisms behind avian response to chemical repellents in airport settings. Although a diverse set of approaches will always be needed to alleviate the many human-wildlife conflicts associated with airports, here we show that, to promote co-existence with wildlife, this chemical repellent can be a part of that toolset.
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    Gunnison sage-grouse demography and conservation
    (Colorado State University. Libraries, 2012) Davis, Amy Jane, author; Doherty, Paul F., advisor; Phillips, Michael L., committee member; Kendall, William, committee member; Pejchar, Liba, committee member; Webb, Colleen, committee member
    To view the abstract, please see the full text of the document.
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    Management strategies for multi-use recreational fisheries: coexistence of kokanee and trophy lake trout in western waters
    (Colorado State University. Libraries, 2013) Pate, William M., author; Johnson, Brett, advisor; Kendall, William, committee member; Lepak, Jesse, committee member; Teel, Tara, committee member
    Kokanee Oncorhynchus nerka are stocked in coldwater reservoirs throughout the western United States for sport fishing and they are a popular fish for both managers and anglers alike. Lake trout Salvelinus namaycush have also been introduced to many western reservoirs, partly because they can attain relatively large sizes (> 30 kg). These piscivores require a large, high quality forage base to sustain high growth rates, and kokanee can fulfill this requirement. However, where lake trout and kokanee co-occur, lake trout often grow in size and numbers and their consumptive demand increases beyond the capacity of the kokanee population to support. Consequently, kokanee abundance declines followed by precipitous declines in lake trout growth and body condition. My work focused on finding a management strategy that could produce sustainable fisheries for both in Blue Mesa Reservoir, Colorado, where lake trout appear to have diminished kokanee abundance. In 2009, managers began a lake trout removal program in an attempt to achieve the primary management goal of a sustainable, hatchery-dependent kokanee population and the secondary goal to provide a trophy lake trout fishery. I developed an age-structured kokanee population model using estimates of natural mortality, harvest, and predation from lake trout with a fixed annual stocking quota of kokanee fry. Age-specific estimates of natural and fishing mortality were estimated using an allometric model and creel survey, respectively. I then determined lake trout consumptive demand on the kokanee population with a bioenergetics model by estimating lake trout abundance, growth rates, diet, and energy densities of predator and prey species. Then alternative management scenarios to reduce lake trout consumptive demand were evaluated using the Fishery Analysis and Modeling Simulator parameterized for the Blue Mesa Reservoir lake trout population. After estimating the current level of lake trout removal (μ = 0.231 for age-4 through age-9), it was incrementally increased to determine the level that allowed for a stable kokanee population (μ = 0.381). The simulations suggested that removal of lake trout must be intensified if kokanee and fast-growing lake trout are to persist in Blue Mesa Reservoir, Colorado.
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    Stonecat ecology in St. Vrain Creek, CO
    (Colorado State University. Libraries, 2018) D'Amico, Timothy W., author; Winkelman, Dana, advisor; Kendall, William, committee member; Hess, Ann, committee member
    Stonecat Noturus flavus are a small-bodied native catfish found from southern Canada to the southern United States, and from the Appalachian Mountains to the Rocky Mountains. In Colorado, there are two remaining populations of Stonecat, including one geographically isolated population in St. Vrain Creek, which runs through the Front Range in Longmont, CO. There are five major drainages running through Colorado's Front Range, which is where most of the state's population is concentrated. As such, these streams are highly urbanized. When compared to the other four major Front Range streams, St. Vrain Creek contains a disproportionately high number of native fish species, including Colorado Species of Special Concern such as Stonecats. There has not yet been a quantitative analysis of population demographic parameters or individual habitat selection preferences of Stonecats. I sought to estimate both of these through a mark-recapture study using passive integrated transponder (PIT) tags. There are a number of assumptions associated with mark-recapture studies which I addressed through individual experiments, including tag loss, physical closure and detection probability of known tags. I evaluated tag loss under laboratory conditions. PIT tags were surgically implanted into the peritoneal cavity of Stonecats (n = 157) ranging from 71 mm to 213 mm through an incision closed with a single Braunamid suture and the fish were monitored for 120 weeks. After 120 weeks, there were fifteen lost tags (9.6%) and eight mortalities (5.0%). I evaluated our dataset of individual encounter histories and covariates including time since tagging, fish length and tag type in a multistate model framework using Program MARK. Time since tagging has an inverse effect on tag loss; if fish are going to lose tags, it will be relatively soon post-tagging. Additionally, fish length has a negative effect, with tag loss decreasing with fish length. These results support our assumption that using PIT tags to individually mark Stonecats is an appropriate method, and we now have a better understanding of tag loss rates over a long-term study period. I evaluated population demographic parameters and individual habitat selection preferences of Stonecats in a field experiment. PIT tags were surgically implanted in Stonecats (n = 679) ranging from 70 mm to 230 mm. I monitored tagged Stonecats with both static and mobile PIT antennae. Our results from the static antennae show that the proportion of Stonecat encounters are higher at night and during the summertime. From the mobile PIT antenna results, I determined Stonecats prefer coarse substrate at an intermediate velocity (0.29 m/s) and intermediate depth (0.3 m). Conclusions from this study will be used to inform future urban stream management in conjunction with managing for sensitive fishes such as Stonecats.