Population fluctuations and distribution of staging Eared Grebes (<i>Podiceps</i> <i>nigricollis</i>) in North America

Roberts, Anthony J.; Conover, Michael R.; Luft, John; Neill, John D.

doi:10.1139/cjz-2013-0181

Cited by 14 publications

(5 citation statements)

References 31 publications

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“…The likely origin of the nonlocal grebes corresponded to much of the breeding area from approximately the latitude of the Great Salt Lake and northward, whereas the likely region of origin of the local individuals included nonbreeding areas to the south of the Great Salt Lake, which includes Mono Lake and the sites where the carcasses were found (Figure 6c). Our results showed that a higher proportion of eared grebes had likely molted at the Great Salt Lake than at Mono Lake, which is consistent with historic population patterns at the two lakes (Roberts et al., 2013). This correspondence indicates there may be instances in which stable isotope data can be used to better understand species‐level distributions for species less well known than these grebes.…”

Section: Discussionsupporting

confidence: 90%

The geographic extent of bird populations affected by renewable‐energy development

Vander Zanden,

Nelson,

Conkling

et al. 2024

Conservation Biology

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Bird populations are declining globally. Wind and solar energy can reduce emissions of fossil fuels that drive anthropogenic climate change, yet renewable‐energy production represents a potential threat to bird species. Surveys to assess potential effects at renewable‐energy facilities are exclusively local, and the geographic extent encompassed by birds killed at these facilities is largely unknown, which creates challenges for minimizing and mitigating the population‐level and cumulative effects of these fatalities. We performed geospatial analyses of stable hydrogen isotope data obtained from feathers of 871 individuals of 24 bird species found dead at solar‐ and wind‐energy facilities in California (USA). Most species had individuals with a mix of origins, ranging from 23% to 98% nonlocal. Mean minimum distances to areas of likely origin for nonlocal individuals were as close as 97 to >1250 km, and these minimum distances were larger for species found at solar‐energy facilities in deserts than at wind‐energy facilities in grasslands (Cohen's d = 6.5). Fatalities were drawn from an estimated 30–100% of species’ desingated ranges, and this percentage was significantly smaller for species with large ranges found at wind facilities (Pearson's r = −0.67). Temporal patterns in the geographic origin of fatalities suggested that migratory movements and nonmigratory movements, such as dispersal and nomadism, influence exposure to fatality risk for these birds. Our results illustrate the power of using stable isotope data to assess the geographic extent of renewable‐energy fatalities on birds. As the buildout of renewable‐energy facilities continues, accurate assessment of the geographic footprint of wildlife fatalities can be used to inform compensatory mitigation for their population‐level and cumulative effects.

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Section: Discussionsupporting

confidence: 90%

The geographic extent of bird populations affected by renewable‐energy development

Vander Zanden,

Nelson,

Conkling

et al. 2024

Conservation Biology

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“…In contrast to cyst removal by waterfowl, eared grebes occupying the GSL from October through December consumed 11% of combined harvest and eared grebe consumption (Roberts and Conover ), an order of magnitude more than ducks. Though eared grebe diets contain fewer brine shrimp cysts than shovelers or teal (Roberts and Conover ), their populations on the GSL are substantially greater, with yearly populations regularly reaching greater than 1.5 million birds (Roberts et al ). No other avian species occurs on pelagic areas of the GSL during winter months so the combined duck and eared grebe cyst removal likely accounts for all avian cyst depletion sources.…”

Section: Discussionmentioning

confidence: 99%

Diet and body mass of ducks in the presence of commercial harvest of brine shrimp cysts in the Great Salt Lake, Utah

Roberts

Conover

2014

Jour. Wild. Mgmt.

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Commercial fisheries and waterbirds are often in competition for available resources and may affect each other through limiting available forage for birds or reducing harvest for commercial fisheries. Relatively little is known regarding the wintering population of waterfowl on the hypersaline Great Salt Lake (GSL), Utah, but mid‐winter counts indicate waterfowl use the GSL during winter coinciding with a commercial harvest of brine shrimp (Artemia franciscana) cysts (i.e., eggs). We surveyed previously unmonitored pelagic regions of GSL to estimate total wintering populations of waterfowl and collected northern shoveler (Anas clypeata) and green‐winged teal (Anas crecca) during 3 nonbreeding seasons, 2009–2012, to examine patterns in diet and body mass of birds using the GSL and estimate the amount of cyst removal by ducks. Our results indicated >200,000 northern shovelers and >150,000 green‐winged teal wintered in the GSL and their diets, based on esophageal contents, changed seasonally, likely because of food availability. Esophagi contained predominately wetland plant seeds in fall and spring, whereas GSL invertebrates (i.e., brine shrimp adults and cysts, brine fly [Ephydra spp.] larvae) made up 75–100% aggregate wet weight during winter. Body mass of both species of ducks was greatest in fall and decreased through winter until a partial to full recovery of mass by spring. Though decreases in body mass were positively associated with decreases in GSL cyst abundance, cyst mass in duck diets peaked when cyst abundance was lowest in the GSL. Our results suggest current management of commercial cyst harvest leaves adequate cysts for waterfowl consumption during late winter. Furthermore, estimates of cyst removal from the GSL by ducks suggests they consume <1% of the yearly raw mass removed by ducks and commercial harvest combined, which implies ducks do not have an adverse impact on the commercial cyst harvest. We suggest managers begin incorporating pelagic areas in mid‐winter waterfowl surveys to better monitor the relationship between cyst harvest and waterfowl abundance and distributions. © 2014 The Wildlife Society.

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“…Although all bird detections tend to increase at the beginning of the fall period in September, detections of water associates and water obligates continued to increase until the end of October, whereas detections of other birds declined steadily throughout the fall. Waterfowl, loons, and grebes are all known to move in comparatively large numbers in fall when weather conditions are favorable for migration [31,32,33]. Eared grebes stage at the Great Salt Lake in Utah, and synchronize migration with upwards of 100,000 to 200,000 birds departing simultaneously en route to the Gulf of California [34].…”

Section: Phenologymentioning

confidence: 99%

A summary of bird mortality at photovoltaic utility scale solar facilities in the Southwestern U.S.

et al. 2020

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Recent trends in renewable energy development in the United States (U.S.) show that new installed capacity of utility-scale solar energy has exceeded 30% of total installed capacity of all sources per year since 2013. Photovoltaic solar energy provides benefits in that no emissions are produced; however, there are potential impacts from photovoltaic solar development on birds that include habitat loss and potential for collision mortality. Only 2 papers in the peer-reviewed literature present fatality information from fatality monitoring studies at a photovoltaic utility-scale solar energy facility; however, more data exists in unpublished reports. To provide a more comprehensive overview of bird mortality patterns, we synthesized results from fatality monitoring studies at 10 photovoltaic solar facilities across 13 siteyears in California and Nevada. We found variability in the distribution of avian orders and species among and within Bird Conservation Regions, and found that water-obligate birds, which rely on water for takeoff and landing, occurred at 90% (9/10) of site-years in the Sonoran and Mojave Deserts Bird Conservation Region. We found that a cause of mortality could not be determined for approximately 61% of intact carcasses, and that approximately 54% of all carcasses were feather spots, introducing uncertainty into the interpretation of the fatality estimates. The average annual fatality estimate we calculated for photovoltaic solar (high-end estimate of 2.49 birds per megawatt per year) is lower than that reported by another study (9.9 birds per megawatt per year) that included one photovoltaic facility. Our results provide a summary of fatalities in bird conservation regions where the facilities are located, but expanding our conclusions to new regions is limited by the location of facilities with fatality monitoring data.

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Population fluctuations and distribution of staging Eared Grebes (Podiceps nigricollis) in North America

Cited by 14 publications

References 31 publications

The geographic extent of bird populations affected by renewable‐energy development

The geographic extent of bird populations affected by renewable‐energy development

Diet and body mass of ducks in the presence of commercial harvest of brine shrimp cysts in the Great Salt Lake, Utah

A summary of bird mortality at photovoltaic utility scale solar facilities in the Southwestern U.S.

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