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 and are another step forward towards comprehensive management of the GSL ecosystem.

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.

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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.

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07/01/2023

06/30/2024

2024

For fiscal year 2024, this project employed a comprehensive methodology to assess the energy needs of birds at the Great Salt Lake (GSL), their food acquisition strategies, and the availability of habitat to support bird populations. The methods are divided into five key objectives: I. Daily Energy Needs of Birds: Literature Review: Conduct a detailed search to identify basal metabolic rates (BMR) for shorebirds and waterfowl at GSL. Determine metabolic rates for various bird behaviors (resting, feeding, walking, swimming, flying). Behavior Analysis: Use literature to estimate the time each bird species spends in different behaviors over a 24-hour period. II. Food Acquisition by Birds: Diet Review: Perform a literature review of waterbird diets at GSL and comparable ecosystems. Energy Content of Food: Search for studies that determine the true metabolizable energy of different prey items for these bird species. III. Habitat Mapping and Seasonal Changes: Remote Sensing: Collaborate with Dr. Doug Ramsey to map GSL habitat types using Landsat and Sentinel 2 satellite imagery. Shoreline Mapping: Use spectral reflectance data to map GSL shorelines and monitor water level fluctuations. Water Depth Measurement: Track water depth changes and assess their impact on habitat types. Area Quantification: Quantify habitat areas seasonally and across different water levels using satellite imagery. IV. Bird Usage and Nesting in GSL Habitats: Aerial and Drone Surveys: Conduct bird counts using fixed-winged aircraft and drones, with GPS tracking of locations. Behavioral Observations: Count foraging vs. non-foraging birds and assess seasonal changes in foraging behavior. Nesting Surveys: Count nesting ducks and other birds, assessing nest success rates and potential limiting factors. Bird Density Calculations: Convert survey data into bird densities to determine the importance of each habitat type for foraging. V. Habitat Support for Bird Populations: Random Sampling: Use GIS to generate random points within habitat types, following established methodologies. Food Availability Assessment: Measure the biomass of food resources (plants, insects, aquatic organisms) and the physical characteristics of each habitat. Salinity and Substrate Impact: Assess how salinity and other environmental factors influence food availability and habitat quality. These methods aim to comprehensively evaluate the energy dynamics, habitat usage, and conservation needs of bird species at GSL, contributing to informed management strategies for these vital ecosystems. For fiscal year 2024, this project was initially allocated $124,396. However, the actual billing to the Utah Division of Wildlife Resources (DWR) from Utah State U. totaled $127,814. The funding sources for this project were divided as follows: 3.91% from Water Resources 72.62% from the General Fund Waterbird money 3.91% from Delta Waterfowl 19.56% from Sportsmen for Fish and Wildlife Expo Permit funds

During fiscal year 2024, Utah State University focused on developing and testing a bioenergetic model for waterbirds in various wetland areas of the Great Salt Lake (GSL). Field testing began in 2023 across several sites, including Bear River Migratory Bird Refuge, Public Shooting Grounds WMA, Ogden Bay WMA, Farmington Bay WMA, and unmanaged wetlands at Willard Spur WMA and Farmington Bay. In May and June, Utah State University analyzed the model through a foraging habitat study of American avocets and Black-necked stilts. The study involved observing foraging behaviors, collecting water and sediment samples, and recording environmental measurements such as turbidity, salinity, and water depth. A total of 110 samples were collected, with Corixidae adults and Chironomidae larvae identified as key foraging resources. In August, the research expanded to investigate the bioenergetic resources available for waterfowl during fall migration. Random transect sampling was conducted across six sites, resulting in 720 soil, water, and submerged aquatic vegetation samples to assess food availability at different water depths. In September, Utah State University began point counts to estimate waterbird density in the survey areas, completing 27 counts. Monthly counts will continue through November, and resampling of August sites will be conducted to monitor resource depletion as birds depart GSL wetlands.

This project will run through 6/30/2027, focusing on bioenergetic models for birds on the Great Salt Lake. The contract was modified to add an additional $200,000 from Water Resources, which will fund a graduate student. This student will concentrate on developing bioenergetic models for non-waterfowl species.