The worldwide population of Wilson's Phalaropes ( Phalaropus tricolor) has declined by 70% since the 1980s, causing the U.S. Fish and Wildlife Service to be petitioned to list Wilson's Phalaropes as a threatened species. The petition noted that Great Salt Lake (GSL) has been shrinking and becoming more saline, and hypothesized that this is causing the population decline. An alternate hypothesis to the one listed in the petition argued that high concentrations of mercury (Hg) and selenium (Se) in GSL are responsible. We tested this sec-ond hypothesis by collecting 32 Wilson's and 49 Red-necked ( Phalaropus lobatus) Phalaropes from GSL and deter-mining Hg and Se levels. Concentrations of Hg in livers were higher in Red-necked Phalaropes (x = 1.04 mu g/g of tissue, wet weight) than in Wilson's Phalaropes (x = 0.65 mu g/g of tissue, wet weight), while Se concentrations in Red-necked Phalaropes (x = 3.47 mu g/g mu g/g of tissue, wet weight) were lower than Wilson's Phalaropes (x = 4.31 mu g/g of tissue, wet weight). Concentrations of Hg and Se were not correlated with body mass in either species. Most sampled phalaropes were below the recognized standard for moderate risk of health effects for both Hg and Se. Our study found little evidence to support the hypothesis that high levels of Hg or Se are having an adverse impact on the health of Wilson's Phalaropes. Received 23 June 2024, accepted 24 Feb 2025.

The number of ground-nesting ducks in the marshes of Great Salt Lake (GSL), Utah has drastically decreased in the past few decades. One potential cause for this decline is the increase in climate extremes caused by global warming. From 2019 through 2023, GSL marshes experienced 1 year of historic spring rainfall (2019), 2 years of historic droughts (2021 and 2022), and 1 year of record snowfall (2023). We used this time period to test the hypothesis that climate extremes impact both the number of duck nests and their fate (i.e., successful, depredated, or abandoned). We counted 563 nests of cinnamon teal (Spatula cyanoptera), 168 mallards (Anas platyrhynchos), and 220 gadwalls (Mareca strepera). Nest numbers varied among years and were positively correlated with the amount of spring rainfall (April and May). Clutch sizes differed among years and were lowest during the drought years. Raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) were the major predators of nests. The percentage of all duck nests that were depredated varied among years and increased from 40% and 46% during the 2 wet years to 75% and 90% during the 2 drought years. The percentage of nests that were successful varied among years and were highest during the wet years. The yearly percentage of successful nests was negatively correlated with the abundance of all predators and positively correlated with snowfall because few skunks and raccoons survived the winter of 2023 with its heavy snowfall. Daily survival rates (x$$ \overline{x} $$ = 0.93), were similar among duck species, but varied among years; DSRs were lowest during the drought years (0.86 and 0.92) and highest during the wet years (0.96 for both years). Our results suggest that climate extremes will have an adverse impact on both the number of duck nests and the percentage of them that are successful.

We estimated the abundance of Eared Grebes ( Podiceps nigricollis) ) on Great Salt Lake (GSL) during 2009-2021 to determine how many Eared Grebes are on GSL throughout the year. Eared Grebes numbers averaged similar to 250,000 daily during the spring migration (April and May). During summer and winter, few Eared Grebes were on GSL, but they reappeared during the fall staging period when Eared Grebe numbers averaged 968,000 in September, 320,000 in October, and 524,000 in November. Our aerial counts underestimated the total number of Eared Grebes on GSL but still provided an accurate index for how their numbers vary throughout the year. From 2012 through 2021, 582 Eared Grebes were collected from GSL for another study, but the carcasses were analyzed for this study to determine morphological changes related to migration. Males outnumbered females, and adults were 4 times more common than juveniles. Males weighed 7% more than females, while adults and juveniles did not differ in mass. When Eared Grebes first arrived on GSL during August, they weighed 330-350 g, but mean body mass increased to 525 g by 16 October. In December, mean body mass declined to 474 g, liver mass by 72%, stomach mass by 56%, and stomach contents by 87% to reduce wing loading during migration. The morphological changes that we observed on GSL were similar to those observed among Eared Grebes on Mono Lake, California.

AbstractGround‐nesting ducks can reduce nest depredation by selecting nest sites where local physical structures or vegetation provide olfactory or visual concealment. We evaluated nest‐site selection by comparing duck nests to random sites during 2019 and 2020 in the impounded wetlands of Great Salt Lake (GSL), Utah, USA. During wet springs, most of the wetlands are underwater, leaving only the dams available as nesting substrate. We located the nests of 399 cinnamon teal (Spatula cyanoptera), 137 mallards (Anas platyrhynchos), and 162 gadwalls (Mareca strepera) on the dams. At nest and random sites, we measured overhead concealment, lateral concealment, average height of vegetation in the nest patch, standard deviation of vegetation height in the nest patch, tallest vegetation within 1 m of nest, dam width, and distance from the nest to the road along the center of the dam. We found that mallards and gadwalls did not select for any of these characteristics. Cinnamon teal selected for nest sites that had more overhead concealment. We also found mixed evidence that cinnamon teal selected nest sites where dams were wider. All species also favored heterogeneous patches of vegetation for nesting over homogenous ones. Duck nests had a clumped distribution in wetlands that contained colonies of American avocets (Recurvirostra americana), black‐necked stilts (Himantopus mexicanus), and common terns (Sterna hirundo), with nests located inside the colonies, but showed a random distribution in other wetlands. Prior to 1980, approximately half of the world's population of cinnamon teal nested in GSL wetlands, but since that time the nesting population has declined greatly. Given this decline, management actions should be conducted that will improve overhead cover and widen dikes within the species' nesting habitat.

Nest depredation is one of the greatest threats posed to ground-nesting ducks. We employed cameras to monitor 164 duck nests (71 cinnamon teal, Spatula cyanoptera, 44 gadwall, Mareca strepera, 38 mallard, Anas platyrhynchos, and 11 nests of unknown species) in the wetlands surrounding Great Salt Lake, from 2015–2021. Of the 164 nests, 21% were successful, 73% were depredated and 7% were abandoned. We observed predators at 99 of the 119 depredated nests; predators at 20 nests went undetected. Raccoons (Procyon lotor, depredated nests) and striped skunks (Mephitis mephitis, ) were the most common of the 99 nest predators recorded. Other predators that depredated nests included long-tailed weasels (Mustela frenata), northern harriers (Circus hudsonius), California gulls (Larus californicus), Sandhill cranes (Antigone canadensis), common ravens (Corvus corax), coyotes (Canis latrans) and red foxes (Vulpes vulpes). Neither the number of eggs removed per depredation event nor the number of eggs remaining varied by predator species. Depredated nests were easier for predators to find than undisturbed, incubated nests, resulting in 68% of depredated nests being visited by multiple predators. All hens detected the approach of a predator and flushed before the predator reached the nest; no hens attempted to defend their nest or attack the predator. Only 21% of hens returned to their depredated nest, and those that did remained off their nest an average of 33 h and 23 h after their nest was depredated by a raccoon or skunk, respectively. Seventeen percent of hens resumed incubation of their depredated nest, but only 1 nest to which a hen returned successfully hatched an egg. Depredation events of raccoons and skunks were not distributed randomly during the 24-hour day, but rather occurred most often during the night and nautical twilight, and rarely during the day. Depredation events of avian predators occurred during the day, rarely during twilight, and none during the night. Depredation events during the night were more likely when the wind was calm but temperature, humidity, and actual moon illumination had no impact. Depredation events by skunks and raccoons occurred more often during the 1st and 4th phases of the moon (new moon) than in the 2nd or 3rd phase.

Brine shrimp Artemia franciscana provide food for many migrating and staging birds that spend summer and fall on Great Salt Lake, Utah, USA. Artemia produce live young and cysts (hard-walled eggs); these cysts are commercially harvested on Great Salt Lake and support a large industry in Utah. It is unclear the impact that millions of hungry birds have on the Artemia population in the lake. To help assess that, this study evaluated cyst viability (percentage of cysts that contain an embryo) and hatchability (percent of cysts that hatch) from cysts that had passed through the digestive tract of eared grebes Podiceps nigricollis and cysts obtained directly from Great Salt Lake at the same site where each grebe was collected. Hatchability was significantly higher for cysts collected from the water column (19%) than from the stomach (0.3%) or intestines (3%) of eared grebes. Viability also was significantly different for cysts collected from the water column (29%), stomach (0.7%), and intestines (5%). These results indicate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall after the adult population of Artemia dies off due to the water becoming too cold. Also, enough cysts survive their passage through the digestive system that grebes can vector hatchable cysts to other waterbodies.

The number of ground-nesting ducks in the wetlands of Great Salt Lake, Utah has drastically decreased in the past few decades. A potential cause for this decline is the increase of predator species and their abundances, which has caused most nests to fail from depredation. Ground-nesting ducks may be able to reduce the risk of nest depredation by selecting nest sites where local physical structures or vegetation provides olfactory or visual concealment. To test this, we used logistic exposure models to look at the effect of nest-site characteristics on daily survival rates (DSRs) of nests during 2019, 2020, and 2021 in the wetlands of Great Salt Lake, Utah. We found 825 duck nests including 458 cinnamon teal (Spatula cyanoptera), 166 mallards ( Anas platyrhynchos), and 201 gadwalls (Mareca strepera). DSRs were 0.9714 +/- 0.0019 in 2019, 0.9282 +/- 0.0049 in 2020, and 0.8274 +/- 0.0185 in 2021. Survival rates varied among years but not among duck species. Striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) were responsible for 85% of depredated nests. Nests located near other duck nests had higher DSRs than more dispersed nests. Neither visual nor olfactory characteristics correlated with increased DSRs based on AICc analysis. Nests located inside a mixed nesting colony of American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and common terns (Sterna hirundo) had higher DSRs than duck nests outside the colony. Increased nesting densities of ducks and other colonial waterbirds had the greatest impact on nesting success. Increased nest density may be encouraged through early spring green-up.

Great Salt Lake (GSL), Utah, is home to some of the world's largest concentrations of Wilson's Phalaropes (Phalaropus tricolor), Red-necked Phalaropes (Phalaropus lobatus), American Avocets (Recurvirostra ameri-cana), and Black-necked Stilts (Himantopus mexicanus). These birds spend several weeks on GSL feeding on larvae, pupae, and adult brine flies (Ephydra spp.) before migrating to their wintering grounds in Central and South America. Unfortunately, GSL is shrinking in size and becoming more saline due to water diversions and climate change. Assessing how a smaller and more saline GSL will affect adult brine flies is difficult without knowing their temporal and spatial dis-tribution on GSL. During 2014 and 2015, we measured adult brine fly abundance across different GSL bays during July through September, when phalaropes are staging on the lake. Abundance of adult brine flies showed a bimodal pattern, peaking during weeks 27-29 and then again during week 33. Wilson's Phalaropes were abundant during the first peak in fly numbers but not during the second peak; Red-necked Phalaropes exhibited the opposite pattern. Time of day and weather had little impact on adult fly numbers, with the exception that abundance was positively correlated with air tem-perature. During this study, a deep brine layer (which is toxic to brine fly larva) existed at water depths >6 m, and adult brine fly abundance was low over these areas. Adult brine fly abundance did not differ with distance from shore or time of day but was positively correlated with salinity. Substrate impacted their abundance, with adult brine flies being 5 times more abundant over microbialites-which are rocky, reef-like structures-than over sand or mud. Phalarope numbers were also highest over microbialites. Thus, most brine fly eggs are laid over microbialites, which is the preferred habitat for brine fly larvae and pupae. Information about the temporal and spatial distribution of adult brine flies is critical for wildlife managers who are tasked with ensuring that GSL will continue to support the large avian populations that depend on GSL's adult brine flies for their existence.

Birds often nest in the same area where they were raised (natal philopatry). The level of natal philopatry among non-migratory Canada Geese Branta canadensis in New Haven County, Connecticut, USA, was studied by banding 731 fledglings, then following them over their lives. The proportion of fledglings that returned to New Haven County to nest as adults (i.e. natal return rates) was 0.22 overall: 0.31 for females and 0.12 for males. These rates increased to 0.60 for females and 0.29 for males after correcting for mortality prior to first breeding (i.e. natal homing rates). For 29 fledglings (2 males and 27 females) that hatched in the Maltby Lakes and returned as adults to breed in New Haven County, I knew the location of their natal site, first nesting site, final nesting site, and the identity of their parents and mate. These 29 birds are referred to as "subjects". During their first nesting year, 28 of 29 subjects (96%) raised their young at their natal brood-rearing site: 17 (59%) nested on their natal lake, 6 (21%) nested on their natal area (often an island within the lake), and 2 (7%) on their natal territory. These percentages were higher than expected if geese were selecting nest sites at random for brood-rearing sites and natal lakes, but not for natal areas or natal territories. Natal philopatry rates were similar during the subjects' first and last nesting year, and there was also no difference between subjects raised in creche broods and those raised in two-parent families. Natal philopatry could be mistaken for parental philopatry (i.e. offspring nesting close to their parents). To test this, the location of nesting territories was examined for those subjects that had parents nesting concurrently on a new nesting territory rather than at the subject's natal territory. Results showed that both natal and parental philopatry occurred; distances to the natal territory and parents' current territory were similar. Geese that exhibit natal philopatry will complicate efforts to manage geese at large scales, such as states or flyways.

Human-wildlife interactions increase exponentially as more and more humans and wildlife crowd into the same limited space. Such interactions often become conflicts when wildlife threaten human health and safety, well-being, or the food supply. This second edition of Human-Wildlife Interactions: From Conflict to Coexistence provides a comprehensive review of the severity of these problems and the methods used to resolve clashes between humans and wildlife. During his forty-year career as a wildlife professor and scientist, Dr. Michael Conover, founder of journal Human-Wildlife Interactions, has become a recognized leader of the scientific field of human-wildlife interactions. In this book, he presents the range of methods for wildlife damage management, including employing lethal methods; distributing supplemental food; changing the behavior of either humans or wildlife; and excluding or repelling wildlife. Backed by numerous case studies and informative side bars, the book documents resolutions to specific human-wildlife conflicts throughout the literature. Containing full color illustrations throughout, the second edition of Human-Wildlife Interactions: From Conflict to Coexistence provides authoritative coverage and depth of both theoretical and practical information. It serves as an invaluable resource for students, researchers, and professional wildlife managers.

ABSTRACT Great Salt Lake, Utah, USA, is a critical staging area for Wilson's ( Phalaropus tricolor ) and red‐necked ( Phalaropus lobatus ) phalaropes. Both phalarope species depend upon abundant invertebrate prey in Great Salt Lake to fuel fall migrations, but the lake currently faces the threat of becoming increasingly saline due to water diversions and climate change. The lake changes may decrease the ability of Great Salt Lake to support the large populations of phalaropes that currently depend upon it. Assessing how a smaller and more saline Great Salt Lake will affect phalaropes is difficult without knowing what phalaropes are consuming during staging. We collected phalaropes from 4 different Great Salt Lake bays from 2012 through 2015 and identified prey items in their upper digestive tracts. We measured wet weights of different food items and examined total mass of food consumed by weighing gizzard contents. Phalarope diets differed across time and bays, and between phalarope species. Red‐necked phalaropes primarily consumed corixids (Corixidae) and brine fly ( Ephydra hians, Ephydra cinerea ) larva, pupa, and adults, whereas Wilson's phalaropes consumed brine flies, chironomids (Chironomidae) and Daphnia ( Daphnia magna ). Despite the abundance of brine shrimp ( Artemia franciscana ) in Great Salt Lake, both phalarope species rarely consumed them. Our results documented that phalaropes of Great Salt Lake are dependent for food in the less‐saline Farmington Bay and on brine flies produced in the hypersaline bays. Such information is critical for wildlife managers who are tasked with ensuring that Great Salt Lake will continue to support the large phalarope populations that depend on the lake's resources. © 2021 The Wildlife Society.

ABSTRACTEared grebes (Podiceps nigricollis) are colonial‐nesting waterbirds that breed in Canada and northern United States. Great Salt Lake (GSL), Utah, is vital to the survival of this species because all eared grebes in North America stage in the fall either on the GSL or Mono Lake, California. The importance of GSL and its surrounding wetlands for breeding eared grebes is unknown. We studied eared grebe nesting status and chronology in the freshwater wetlands around GSL and found over 4,280 nests distributed among 35 colonies during 2018 and 5,794 nests among 23 colonies during 2019. We also located the 2 largest colonies of this species ever recorded (902 and 1,492 nests). Mean clutch size differed between years and was 2.4 eggs during 2018 and 2.0 during 2019; clutch sizes were lower at GSL than in colonies located in more northern latitudes, perhaps due to a local paucity of invertebrate prey during the egg‐laying period. Grebe nests around the GSL were constructed with, and anchored to, growing Stuckenia pectinate. Eared grebes near GSL started laying eggs in the first week of June during 2018 and a week later during 2019. The number of incubated nests per colony peaked on 27 June during 2018 and 9 July during 2019. Nests continued to be incubated into August in both years. These dates are later than those reported in more‐northern colonies. The later nesting in GSL colonies could be due to the birds' need to wait for Stuckenia pectinata to form mats at the water surface. This plant species needs a water depth of 38 to 45 cm to thrive, and increasing amounts of freshwater from the GSL watershed are diverted for agriculture and human development. If this trend continues, there may not be enough water to maintain the required water depth for dense stands of Stuckenia; the loss of which may prevent the grebes from nesting. © 2021 The Wildlife Society.

Great Salt Lake (GSL) is a critical staging area for 2 species of phalaropes: Wilson's (Phalaropus tricolor) and Red-necked (P lobatus). Both rely on the abundant invertebrate prey at GSL to fuel their fall migrations to Central and South America, but little is known about where phalaropes forage on GSL, what foraging methods are used, or what variables influence their foraging decisions. During 2014 and 2015, the frequency of specific foraging behaviors by phalaropes differed by GSI, bays; surface picking was the most common foraging behavior (>= 50%) on Carrington and Gilbert bays while spinning was the most common on Farmington Bay. Most (60%) Red-necked Phalaropes used surface picking for foraging compared to 32% of Wilson's Phalaropes. Spinning behavior to upwell prey was more common in Wilson's Phalaropes (used by 19% of foraging birds) than Red-necked Phalaropes (3%). The proportion of phalaropes in a flock that were foraging was positively associated with biomass of invertebrate prey at the flock's location. Most (64%) of the phalarope flocks were on Farmington Bay, and 75% of phalaropes in this bay were foraging, compared to 41% of birds on Gilbert Bay. Thus, Farmington Bay is particularly important for hundreds of thousands of Red-necked and Wilson's phalaropes that stage on GSL for 4 months during each summer. Farmington Ray is brackish, shallow, and depends on the Jordan River for its freshwater. The future of this water source, and therefore Farmington Bay itself. is uncertain because of future diversions by humans and longer droughts predicted from climate change.