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Waterbird Bioenergetics Models for Great Salt Lake
Region: Northern
ID: 7638
Project Status: Proposed
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Project Details
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Need for Project
The western U.S. drought, rising temperatures, and an increase in human population growth have led to a higher demand of water in Utah and as a result, the elevation of Great Salt Lake is at an all-time low (Wurtsbaugh 2016, USGS 2021). The surface area of GSL can fluctuate dramatically because it is shallow, with an average depth of about 16 feet (See Figure 1). Currently, there are vast areas of lakebed exposed. This situation has created large disconnections among GSL bays and wetlands and has resulted in less bird use. The GSL ecosystem hosts upwards of 10 million birds every year, making it a critical habitat for migratory birds along both the Pacific and Central flyways. Hundreds of thousands of waterfowl and shorebirds nest and stage at GSL every year, including phalaropes, stilts, snowy plovers, willets, avocets, cinnamon teal, gadwall, and mallards (Sorensen et al. 2020). Great Salt Lake's abundant and diverse food and habitat resources are a crucial part of sustaining waterbird populations in the Western Hemisphere. The importance of Great Salt Lake on a flyway scale has almost certainly increased due to the near depletion of other saline lakes in the western U.S. The evidence of this is the significant increase in the number of eared grebes visiting GSL every year. At peak counts, almost 5 million or over 90% of their entire population eat brine shrimp at GSL at one given time. When the other western saline lakes were healthier and available for grebes to rest and forage at along their migrations, GSLEP biologists observed about one million grebes at GSL at a time. Typically, an increase in bird use is a good thing, but it may also mean entire populations of birds are becoming increasingly dependent on the GSL ecosystem for survival. Currently, the large bays of GSL are a sliver of what they have been in the past (See Figure 1 comparison). The GSL bays are massive areas that offer significant food resources for waterbirds, and their existence is one of the main reasons GSL is so important to migratory birds (Miller et al. 2009, Winter and Wurtsbaugh 2015, Frank 2016, Downard et al. 2017, Frank and Conover 2019). These bays do not contain water control structures, naturally ebb and flow, and are generally more susceptible to drought and upstream consumption of water in comparison to the impounded wetlands along GSL. Presently, the Utah Division of Wildlife Resources (UDWR) oversees nine Waterfowl Management Areas (WMAs) around GSL and has authority to manage this habitat and the water that flows into them to support avian species. The UDWR wetland managers have the ability to move water into and out of different impoundments within their respective areas and can intentionally manipulate habitat for birds. Excluding invasive weed management, the UDWR WMAs currently manage for waterfowl productivity on an anecdotal and observational basis. While this has seemingly worked in the past, the new challenges GSL and its wetlands face warrant future management decisions based on data. Given the current shrinking of western saline lakes, including GSL, these impoundment areas have become ever more important in sustaining waterbird populations in the West. In order for the management of UDWR's WMAs around GSL to be in accordance with the goals of the Wildlife Action Plan and Utah's Wetland Program Plan, we need to develop a scientifically valid approach to evaluating the carrying capacity of Great Salt Lake (GSL) and its associated wetlands. Fortunately, the Great Salt Lake Ecosystem Program (GSLEP), along with contracted researchers, have been monitoring waterbird and brine shrimp populations at GSL and its wetlands for over 20 years and has one of the most extensive datasets in the West. At present, GSLEP is developing a GSL Model. It will forecast the potential impacts of specific abiotic and biotic conditions on the South Arm of GSL and the brine shrimp population. The GSLEP aims to have a more holistic dataset that will allow for the creation of a bioenergetics model for waterbirds at GSL. The bioenergetics model will help wetland managers across GSL (e.g., state, federal, non-profit groups, and duck clubs) to make informed decisions regarding water management for birds. Similar to the GSL model, the GSLEP aims to forecast the food requirements of shorebirds and waterfowl so that managers can make more informed decisions regarding water control, habitat manipulation, and project schedules. These data are invaluable a
Provide evidence about the nature of the problem and the need to address it. Identify the significance of the problem using a variety of data sources. For example, if a habitat restoration project is being proposed to benefit greater sage-grouse, describe the existing plant community characteristics that limit habitat value for greater sage-grouse and identify the changes needed for habitat improvement.
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Objectives
1. Understand seasonal macroinvertebrate densities and propagation rates in both impounded wetlands and Bear River, Ogden and Farmington bays Despite intensive study and research regarding brine shrimp in the pelagic portions of GSL, there is relatively little understanding of the available food resources in the associated bays and extensive wetlands of GSL. While there have been some studies conducted on macroinvertebrates in GSL wetlands, there is still a lack of understanding of the potential effects that management has on macroinvertebrate abundance and distribution. 2. Understand the seasonal forage needs of shorebirds, waterfowl, and other waterbirds in GSL impounded wetlands and Bear River, Ogden and Farmington bays Most (57%) GSL wetlands are managed with the purpose of providing waterbird habitat. The managed wetlands contain an array of dikes, canals, and water control structures that help to create vast impoundments of water. There are many benefits of impounded wetlands, such as higher assurance wetlands will contain water during summer months (i.e. beneficial use), ability to somewhat control what food grows (i.e. depth of water), ability to control timing of flooding/draining, ability to manage invasive weeds and carp, and many more. However, it is possible that depending on the timing of water delivery and the depth at which these impoundments are being managed for, that certain avian species will be limited. 3. Understand the relationship between GSL elevation and the amount of available habitat for shorebirds, waterfowl and other waterbirds. Water availability is a main concern for wetland managers across the GSL ecosystem (Kijowski et al. 2020). While many GSL wetlands have senior water rights, it is still not a guarantee that GSL wetlands will always have enough water to manage for all species of birds. Furthermore, the vast extensive bays of GSL are the last to receive water, and there is no guarantee of water reaching those areas, especially in the hot summer months. The Wasatch Front is continuing to grow and develop, and this has the potential to change the timing and amount of water delivered to GSL wetlands and bays. If we are able to quantify forage based on the available habitat (e.g. available water), we can determine carrying capacity for shorebirds, waterfowl, and other waterbirds based on the level of GSL. Overall, developing a JV-style bioenergetic model for GSL shorebirds and the same style model for GSL waterfowl are the two overarching goals of this proposal.
Provide an overall goal for the project and then provide clear, specific and measurable objectives (outcomes) to be accomplished by the proposed actions. If possible, tie to one or more of the public benefits UWRI is providing.
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Project Location/Timing Justification (Why Here? Why Now?)
This project is being designed, implemented, and carried out by Utah State University. The project locations are focused on important bird areas in and around the Great Salt Lake. A full project proposal is available on demand.
LOCATION: Justify the proposed location of this project over other areas, include publicly scrutinized planning/recovery documents that list this area as a priority, remote sensing modeling that show this area is a good candidate for restoration, wildlife migration information and other data that help justify this project's location.
TIMING: Justify why this project should be implemented at this time. For example, Is the project area at risk of crossing an ecological or other threshold wherein future restoration would become more difficult, cost prohibitive, or even impossible.
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Relation to Management Plans
This relates to goals and objectives in our management plan to maintain healthy habitat for waterfowl and other wetland species. Understanding waterfowl and shorebird bioenergetics is a key component in understanding what habitats and forage to manage for.
List management plans where this project will address an objective or strategy in the plan. Describe how the project area overlaps the objective or strategy in the plan and the relevance of the project to the successful implementation of those plans. It is best to provide this information in a list format with the description immediately following the plan objective or strategy.
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Fire/Fuels
Not applicable
If applicable, detail how the proposed project will significantly reduce the risk of fuel loading and/or continuity of hazardous fuels including the use of fire-wise species in re-seeding operations. Describe the value of any features being protected by reducing the risk of fire. Values may include; communities at risk, permanent infrastructure, municipal watersheds, campgrounds, critical wildlife habitat, etc. Include the size of the area where fuels are being reduced and the distance from the feature(s) at risk.
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Water Quality/Quantity
Not applicable
Describe how the project has the potential to improve water quality and/or increase water quantity, both over the short and long term. Address run-off, erosion, soil infiltration, and flooding, if applicable.
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Compliance
Not applicable
Description of efforts, both completed and planned, to bring the proposed action into compliance with any and all cultural resource, NEPA, ESA, etc. requirements. If compliance is not required enter "not applicable" and explain why not it is not required.
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Methods
I. How much energy does an individual bird need daily to meet its needs? A bird's DEE is a function of the species' basal metabolic rate (BMR). DEE changes based on the bird's behavior, condition, and weather. 1. Complete a literature search to aid in determining BMR for shorebirds and waterfowl at GSL. Utilizing accepted BMRs, determine metabolic rates of shorebirds and waterfowl for five behaviors: resting, feeding, walking, swimming, and flying. 2. Complete a literature review to determine the proportion of time during a 24-hour day that each bird species spends doing each behavior. II. How does a bird acquire enough energy (i.e., food) to meet its daily energy needs? Information on the diet of shorebirds, waterfowl, and other waterbirds of GSL has been summarized by Barber and Cavitt (2012) for Willard Spur and by Roberts (2013) for GSL pelagic bays. Some published papers on avian diets are available for California gulls (Greenhalgh 1952, Conover et al. 2009), eared grebes (Cullen et al. 1999, Roberts and Conover 2014), avocets (Osmundson 1990), phalaropes (Frank and Conover 2021), common goldeneye, northern shoveler, and green-winged teal (Vest and Conover 2011, Roberts and Conover 2014). Studies from other areas, such as the Prairie Potholes and Central Valley JVs, can also be used to determine the diets of shorebirds and waterfowl on GSL. 1. Complete a literature search on the diets of waterbirds. 2. Complete a literature search to determine the true metabolizable energy of different prey items (Miller and Eadie 2006, Brasher et al. 2007). III. How large is each habitat type in GSL marshes, and how does the extent of these areas change seasonally and across water levels? I have asked Dr. Doug Ramsey, an expert in remote sensing and Geographic Information Systems (GIS), to help with this endeavor, because using satellite imagery to map habitat types is outside of my area of expertise. 1. Use satellite imagery collected by Landsat and the European Space Agency's Sentinel 2 satellite to map different habitat types at GSL (e.g., bare ground, deep wetland, shallow wetland). 2. Use an established water body "index" derived from spectral reflectance as measured by Landsat and Sentinel to map out the shoreline of lakes, including very shallow areas. Dr. Ramsey worked with one student to produce the attached image of frequency of inundation for the GSL (see Figure 3). 3. Measure the relative depth of water or the absolute depth with ground data. We will follow the methods of Elhag and Bahrawi (2019); they used satellite images to track depth changes of shallow shores to monitor sediment deposits. 4. Measure the water depths of shores and impoundments at GSL across time. 5. Quantify the area in each habitat type using satellite image maps, and how these areas vary in size by season and water levels. We can follow the methods of Long et al. (2017); they used aerial imagery to map the GSL distribution of open water, playas, and different plant species, including Phragmites, cattails, and saltgrass, with 1-m resolution. IV. How many bird use days does each GSL habitat type support, including the number of ducks that nest there? The Utah Division of Wildlife Resources' Great Salt Lake Ecosystem Program developed an ecosystem-based survey of waterbirds in GSL wetlands based on counts made from April 26 to September 22 in 1997-2001 and estimated bird use days (Paul and Manning 2002). These and other data (Cavitt 2006) are useful for estimating the total number of birds of different species or species groups in GSL wetlands during each season and bird use days. Unfortunately, these data are not precise enough to determine bird use of the different habitat types we identify in our satellite imagery. For this study, I will complete the following. 1. Conduct counts of bird species and their GPS locations using fixed-winged aircraft and drones. 2. Count the number of birds that are "foraging" or "not foraging" based on their behavior using scan sampling (Frank and Conover 2021). 3. Quantify the proportion of time each species or species group spends foraging in each habitat type and how this changes seasonally. 4. Count the number of nesting ducks and other nesting birds, determine their nest success rate, and why they are not higher. 5. Convert these data into bird densities (#birds/ km2 of habitat) to determine the importance of different habitat types as foraging areas. V. How many bird use days can each GSL habitat type support? Ultimately, habitat types will be defined based on how they are used by birds, which in turn, relies on the abundance of prey items available in each habitat type. Important habitat variables include salinity, substrate type, turbidity, vegetation, water depth, and when the habitat is covered with water. As GSL shrinks in volume, its salinity will increase. This, in turn, will impact the quality and quantity of food available for birds. To estimate food availability in different habitats, I will repeatedly do the following. 1. Use GIS to generate 50 random points within each habitat type. This is the number that Ringelman et al. (2015) demonstrated was necessary to produce reliable bioenergetic models within each habitat type. 2. Measure food availability directly at the random points to determine the biomass of palatable plant parts (e.g., seeds and tubers), insects, and aquatic and benthic organisms. 3. Measure salinity, substrate type, turbidity, vegetation, water depth, and when the random points are flooded. 4. Collect a core sample at each random point. Each core sample will include a soil sample and sample of the water column at flooded sites, following the methods of Frank and Conover (2021). Sampling will be repeated monthly to assess temporal variation in prey abundance and to determine if foraging by birds is intense enough to deplete food supplies. Measure food availability within each core sample. 5. Determine the impact of salinity of water and soil on the plant and invertebrate communities.
Describe the actions, activities, tasks to be implemented as part of the proposed project; how these activities will be carried out, equipment to be used, when, and by whom.
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Monitoring
Utah State University if completing this study. We will monitor progress by requiring progress reports, completed documents, necessary presentations.
Describe plans to monitor for project success and achievement of stated objectives. Include details on type of monitoring (vegetation, wildlife, etc.), schedule, assignments and how the results of these monitoring efforts will be reported and/or uploaded to this project page. If needed, upload detailed plans in the "attachments" section.
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Partners
Utah State U., Utah Division of Water Resources, Sportsman for Fish and Wildlife, Delta Waterfowl.
List any and all partners (agencies, organizations, NGO's, private landowners) that support the proposal and/or have been contacted and included in the planning and design of the proposed project. Describe efforts to gather input and include these agencies, landowners, permitees, sportsman groups, researchers, etc. that may be interested/affected by the proposed project. Partners do not have to provide funding or in-kind services to a project to be listed.
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Future Management
A detailed bioenergetics model for avian species in and around Great Salt Lake helps infer how managers will focus conservation and restoration efforts in the future.
Detail future methods or techniques (including administrative actions) that will be implemented to help in accomplishing the stated objectives and to insure the long term success/stability of the proposed project. This may include: post-treatment grazing rest and/or management plans/changes, wildlife herd/species management plan changes, ranch plans, conservation easements or other permanent protection plans, resource management plans, forest plans, etc.
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Sustainable Uses of Natural Resources
Not applicable
Potential for the proposed action to improve quality or quantity of sustainable uses such as grazing, timber harvest, biomass utilization, recreation, etc. Grazing improvements may include actions to improve forage availability and/or distribution of livestock.
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