Geology topics

William S. Beatty

Publications and source records attributed to William S. Beatty.

At least 19 recordsLinked to original sources

USGS2026

Pacific walrus population research

Introduction The Pacific walrus ( Odobenus rosmarus divergens ) occupies shallow continental shelf waters in the Bering and Chukchi Seas. In the winter, walruses breed in the Bering Sea. Adult females, juveniles, and some adult males follow the retreating sea ice north through the Bering Strait in the spring and summer to occupy the Chukchi Sea. Most adult males remain in the Bering Sea in summer (Fay, 1982). Walruses feed on small, bottom-dwelling invertebrates such as clams and marine worms (Sheffield and Grebmeier, 2009). They rest on sea ice or land between periods of foraging. Pacific walruses are a vital subsistence resource for Alaska Native coastal communities. These communities also harvest Pacific walrus to continue important cultural traditions, such as ivory carving. Knowledge about the Pacific walrus population trend and size helps ensure that harvest remains sustainable, supports co-management decisions, and helps identify potential risks to walruses as the Arctic continues to change.

Alaska↗

USGS2026

Restoration of Gavia immer (common loon) in Minnesota—2025 annual report

In cooperation with the Minnesota Department of Natural Resources, the U.S. Geological Survey monitored 98 Gavia immer (common loon) focal territories and 43 nonfocal territories in north-central Minnesota in 2025. Focal territories are those sampling units from which study inferences can be made. Nonfocal territories were adjacent to focal territories and were observed to monitor common loon dynamics across an entire waterbody. In collaboration with lake associations and private citizens, we deployed 44 artificial nesting platforms to 44 focal territories, called treatment territories. Territorial surveys to monitor occupancy, nesting, and chick survival were completed between April 27 and August 14, 2025. We attempted to visit each focal and nonfocal territory once per week. At least 1 nest attempt was observed in 40 of 54 control territories and 37 of 44 treatment territories. In treatment territories, 14 nests were on an artificial nesting platform, and the remaining nests were on natural substrates. Chicks or other evidence of hatching were observed in 20 of 54 control territories (37 percent) and 28 of 44 treatment territories (64 percent). Twelve of those successful nests in treatment territories were on artificial nesting platforms.

Minnesota↗

USGS2026

A sea ice entrapment event in the southern Chukchi Sea: Analysis and prediction

Amplified Arctic warming is reducing sea ice cover, which is driving an increase in geopolitical interest in the region as it offers the possibility of reducing shipping times between Asia, Europe, and eastern North America, at the risk of increased ice hazards. Here, we examine the case of the Norseman II research ship that was trapped by sea ice in the southern Chukchi Sea for 14 days in June 2024. This is the first study of its sort in this region. We show that anomalously thick and extensive sea ice was present north of the region prior to the event, and that strong northerly winds in early June advected this ice southward, trapping the ship. Later in June, southerly winds advected ice northwards away from the ship, helping to free it. We further show that the event was forecastable.

Alaska↗

USGS2026

Combining individual and close-kin mark–recapture to design an effective wildlife population survey

Close-kin mark–recapture (CKMR) is a promising approach for assessing population size of species that have been difficult to survey using more traditional methods. Here, we combine individual and close-kin mark–recapture in a single modeling framework (ICKMR) and provide an example of study design using this approach for Pacific walrus ( Odobenus rosmarus divergens ). We develop the ICKMR model and test it using simulated datasets, then use properties of the pseudo-likelihood to investigate the expected precision in estimates of abundance with different proposed survey designs. Our motivating example, the Pacific walrus, is an ice-associated marine mammal found in the Bering and Chukchi seas, where it is an important resource for Indigenous peoples. Pacific walrus abundance declined in the late 20th century, and it is currently a species of conservation concern due to potential impacts of climate change, particularly the loss of sea ice. To reduce uncertainty in population size estimates, researchers undertook a genetic mark–recapture sampling campaign from 2013 to 2017 and collected tissue samples from over 8000 individuals. Another campaign of a similar scale is ongoing (2023–2028). While sample collection was designed for individual mark–recapture, advances in CKMR methods and associated molecular techniques mean that these samples could also be suitable for CKMR. The advantages of CKMR over mark–recapture include an increased effective sample size (because each individual tags itself and its parents, siblings, and offspring) and additional insights into demographic quantities of interest. To make best use of genetic samples, we combine individual mark–recapture (IMR) with CKMR (ICKMR) and investigate whether different sampling strategies can increase precision in estimates of abundance. Our modeling approach includes special considerations for walrus life history, including a multi-year inter-birth interval. We found that expected coefficients of variation (CVs) of the ICKMR estimates of abundance, adult female survival, juvenile female survival, and proportion of breeding females are lower than those expected from IMR alone, and with ICKMR, fewer years of sampling can be conducted to obtain sufficient precision in estimates of abundance. This work demonstrates the utility of ICKMR and could be applicable across a variety of taxa.

Ecology↗

USGS2026

Harvest of long-tailed ducks from an important hunting location on Lake Michigan

Annual waterfowl harvest in North America is estimated through a collaborative and strategic process, with federal harvest surveys the primary method of estimation. Sea duck hunters participating in federal harvest surveys represent a small proportion of the overall waterfowl hunting population, limiting the utility of harvest estimates for sea ducks. The long-tailed duck ( Clangula hyemalis ) is one such species. To partially address the paucity of long-tailed duck harvest survey information, we conducted in-person hunter surveys from 1 November through 4 December 2016 at a boat launch in Two Rivers, Wisconsin, USA (Lake Michigan), an important area for long-tailed duck harvest within the state. Hunters were present on 15 of 21 survey days, and we surveyed occupants of 62 individual hunting boats on 127 occasions. Long-tailed ducks were the most common (97%) of the 1,431 sea ducks reported harvested by hunters. Hunter harvest of long-tailed ducks averaged 3.8 (95% CI = 3.4, 4.1; range = 0–6) long-tailed ducks/hunter/day. We used count models to evaluate the effects of environmental variables on hunter participation and harvest of long-tailed ducks. Wave height was the most influential predictor variable for hunter participation; an information criterion-based best model (wave height + temperature) indicated that hunter participation decreased by 91.9% (95% CI = 79.3–97.1%) for each 1-m increase in wave height. Long-tailed duck harvest was positively associated with air temperature; the relationship indicated a 9.5% (95% CI = 6.2–12.9%) increase in long-tailed duck harvest with each degree increase in temperature. Our results contribute to the understanding of waterfowl hunter participation, hunter preferences, and harvest on Lake Michigan and can inform managers as they assess regulatory frameworks for sea duck hunting.

Wisconsin↗

USGS2025

Greater white-fronted goose habitat use in Louisiana provides water depth management insights

Numerous waterfowl species have altered their geographic distribution in recent decades. The greater white-fronted goose ( Anser albifrons ) has shifted its wintering distribution from coastal marshes in Texas and Louisiana, USA, to interior landscapes, creating challenges for conservation managers. Although the range shift has been primarily attributed to landscape-scale changes in rice production, effects of fine-scale habitat conditions on greater white-fronted goose habitat use are unknown. Thus, information on fine-scale environmental conditions could provide information to managers working to mitigate effects of the shift. We used global positioning system neck collars to monitor 78 greater white-fronted geese in Louisiana each winter during 2016–2019 and visited all used locations to record vegetation height, water depth, and land cover. We modeled greater white-fronted goose habitat use in 4 regions across Louisiana (central, coastal, north, southwest), and evaluated effects of vegetation height, water depth, land cover, and interactions. In our candidate model set, we included a sampling null, which accounted for differences in sampling frequencies among hunt seasons and diel periods. The top model in the central, coastal, and north regions included water depth, whereas the top model in the southwest region included water depth, vegetation height, and land cover. Parameter estimates and confidence intervals indicated that goose habitat use was higher at sites with >5.1 cm of water compared to dry sites or sites with <5.1 cm of water. In the southwest region, goose habitat use was highest in areas identified as other land cover (e.g., corn, cotton, rye, sugarcane) and lowest in open water. Although Louisiana has substantial anthropogenic food resources in the form of rice agriculture and abundant grazing opportunities afforded by mild winters, our results indicate that wet areas provide better habitat to greater white-fronted geese than dry areas. New agricultural flooding regimes in Louisiana could improve habitat quality and potentially mitigate some effects of the winter distribution shift.

Louisiana↗

USGS2025

Restoration of Gavia immer (common loon) in Minnesota—2024 annual report

In cooperation with the Minnesota Department of Natural Resources, the U.S. Geological Survey monitored 98 common loon ( Gavia immer ) focal territories and an additional 37 nonfocal territories in 2024 across 53 study lakes in Minnesota. Focal territories were those territories from which study inferences will be made, whereas nonfocal territories were observed to monitor common loon dynamics in territories adjacent to focal territories. In collaboration with lake associations and private citizens, we deployed 44 artificial nesting platforms within 44 treatment territories, and the remaining 54 focal territories were controls. We completed territorial surveys from April 29 to August 9, 2024, to evaluate occupancy, nest success, and chick survival. We attempted to visit each territory once a week. At least one nest attempt was observed in 41 of 54 control territories. Precisely one nest attempt was observed in 30 control territories, two nest attempts (first attempts failed) were observed in 9 control territories, and three nest attempts (first and second attempts failed) were observed in 2 control territories. At least one nest attempt was observed in 33 of 44 treatment territories. Precisely one nest attempt was observed in 25 treatment territories, two nest attempts (first attempts failed) were observed in 7 treatment territories, and three nest attempts (first and second attempts failed) were observed in 1 treatment territory. In treatment territories, 8 nests were on an artificial nesting platform; the remaining nest locations were natural. Chicks or other evidence of hatching were observed in 26 of 54 (48.1 percent) control territories and 21 of 44 (47.7 percent) treatment territories, with 7 of those successful treatment nests on an artificial nesting platform. This report includes no formal analysis, but we plan to analyze data after collection of all field data in subsequent years.

Minnesota↗

USGS2024

Restoration of common loon (Gavia immer) in Minnesota—2023 annual report

The Deepwater Horizon mobile drilling platform exploded on April 20, 2010. The resulting massive oil spill injured natural resources in the Gulf of Mexico, including wintering common loons ( Gavia immer ). We report on activities completed under the “Restoration of Common Loons in Minnesota” project in calendar year 2023, which was funded by the Open Ocean Trustee Implementation Group. In 2022, a subset of monitored breeding territories was identified as focal territories, which are sampling units for the study. The U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources, monitored 98 common loon focal territories and an additional 43 nonfocal territories in 2023 across 56 study lakes in Minnesota. We collaborated with lake associations and private citizens to deploy 42 artificial nesting platforms within 44 focal treatment territories. The remaining 54 focal territories were controls. Territorial surveys were completed from May 8 to August 11, 2023, to evaluate occupancy, nest success, and chick survival. At least one nest attempt was observed in 31 of 44 treatment territories and a second nest attempt was observed after a failed initial attempt in 6 treatment territories. However, only one nest was on an artificial nesting platform in a treatment territory; the remaining nest locations were natural. At least one nest attempt was observed in 37 of 54 control territories, and a second nest attempt was observed after a failed initial attempt in 5 control territories. Chicks or other evidence of hatching were observed in 17 of 54 control territories and 17 of 44 treatment territories, with 1 of those successful treatment nests occurring on an artificial nesting platform. This report includes no formal analysis, but we plan to analyze data after collection of all field data in subsequent years.

Minnesota↗

USGS2023

Informing management of recovering predators and their prey with ecological diffusion models

The reintroduction and recovery of predators can be ecologically beneficial as well as socially and economically controversial. However, the growth and expansion of predator populations, and thus their ecological, social, and economic impacts, are not static but rather they vary in space and time. We propose a spatiotemporal statistical modeling framework based on ecological diffusion to better inform the ecology and management of recovering predators and their prey. We demonstrate its utility by applying it to a recovering sea otter ( Enhydra lutris ) population in Southeast Alaska, where sea otters were reintroduced in the late 1960s and have exhibited unprecedented population growth. Estimated parameters yield inferences about movement and population ecology, and our approach provides useful derived quantities, such as local abundance and carrying capacity as well as a quantity we term the equilibrium differential. We used our model to examine how density dependence and carrying capacity of sea otters vary spatially across a region. The diffusion modeling approach we present can be generalized for use in other instances of (re)colonization across taxa to inform management and conservation efforts.

Alaska↗

USGS2023

Restoration of Gavia immer (common loon) in Minnesota—2022 annual report

The explosion of the Deepwater Horizon mobile drilling platform on April 20, 2010, caused a massive oil spill and injury to natural resources in the Gulf of Mexico. Gavia immer (common loon) were negatively affected from the spill. The Open Ocean Trustee Implementation Group funded the project “Restoration of Common Loons in Minnesota” to restore common loons lost to the spill. Here, we report on activities conducted for this project in an eight-county region in Minnesota in calendar year 2022. We identified a subset of territories that were monitored in 2021 as focal territories ( n =99) from which multiyear study inferences can ultimately be made. We monitored nonfocal territories on all study lakes as well. We conducted surveys from May 9 to August 12, 2022. At least 1 nest attempt was observed in 68 of 99 focal territories, and a second nest attempt after a failed initial attempt was observed in 17 focal territories. Chicks or other evidence of hatching was observed in 33 of 99 territories. Data collected in 2021 and 2022 for this project are presented in a U.S. Geological Survey data release ( https://doi.org/10.5066/P9LA536E ). We present no formal data analysis in this report.

Minnesota↗

USGS2023

Exploring effects of vessels on walrus behaviors using telemetry, automatic identification system data and matching

Arctic marine mammals have had little exposure to vessel traffic and potential associated disturbance, but sea ice loss has increased accessibility of Arctic waters to vessels. Vessel disturbance could influence marine mammal population dynamics by altering behavioral activity budgets that affect energy balance, which in turn can affect birth and death rates. As an initial step in studying these linkages, we conducted the first comprehensive analysis to evaluate the effects of vessel exposure on Pacific walrus ( Odobenus rosmarus divergens ) behaviors. We obtained >120,000 h of location and behavior (foraging, in-water not foraging, and hauled out) data from 218 satellite-tagged walruses and linked them to vessel locations from the marine automatic identification system (AIS). This yielded 206 vessel-exposed walrus telemetry hours for comparison to unexposed hours, which we used to assess if vessel exposure altered walrus behavior. We developed a filter to account for misclassification of vessel exposure of telemetered walruses. Then we tested for an effect of vessel exposure on walrus behaviors using a combination of exact and propensity score-based matching to account for confounding covariates, and we conducted statistical power analyses. We did not detect an effect of vessel exposure on walrus behaviors even when statistical power was high (i.e., for foraging walruses), which may have been due to the sample size-driven need to define vessel presence within a larger than desired distance (15-km measured radius) around a walrus. Although this study did not determine at what distance vessel exposure affects walrus behaviors, it provided an upper bound on the distance at which the vessels encountered may disturb foraging walruses. When more situation-specific information is lacking, this distance could be used as a conservative buffer to maintain between vessels and areas of high use by foraging walruses. Studies on behavioral consequences of closer proximities between walruses and vessels are needed, and our assessments of misclassification rates and statistical power can be used for future studies. We demonstrated that analytical approaches such as matching, which are rarely used in wildlife studies, are particularly useful for testing hypotheses with observational data.

Alaska↗

USGS2023

An agent-based model to quantify energetics, movement and habitat selection of mid-continent mallards in the Mississippi Alluvial Valley

The dynamics of wintering waterfowl populations at the landscape scale are the result of complex interactions of environmental, behavioral and energetic drivers. Agent-based models provide a method to directly link these factors in a spatially explicit framework and allow the emergence of patterns from the aggregation of individual agent actions. We adapted the Spatially-explicit Waterbird Agent-based Model Program (SWAMP), originally developed for waterfowl in central California, to simulate a basin-scale population of mallards ( A. platyrhynchos ) wintering in the Mississippi Alluvial Valley over a four-month period (November–February). Simulated agents move within the landscape, foraging on areas made available based on a probabilistic inundation status, and converting food resources to endogenous energy. The model uses a high-resolution map of eastern Arkansas waterfowl habitats and incorporates a hierarchical habitat selection system that enables mallards to relocate at increasing scales in response to changing food availability. We validated the performance of modeled mallard body condition and behavioral metrics under a range of environmental conditions against expected outcomes derived from empirical data and found that the simulation produced realistic representations of changes in flight distances, energy expenditure, lipid storage, and foraging habitat use in response to depleting food resources over time. We discuss the model's applicability as a tool to quantify waterfowl response to a range of environmental conditions and to evaluate scenarios of landscape composition and configuration in the context of waterfowl population management.

Ecological Modelling↗

USGS2022

Restoration of Gavia immer (common loon) in Minnesota—2021 annual report

The Deepwater Horizon oil spill caused extensive injury to natural resources in the Gulf of Mexico, and Gavia immer (common loon) were negatively affected from the spill. The Open Ocean Trustee Implementation Group funded the project Restoration of Common Loons in Minnesota to restore common loons lost to the spill. In 2020–21, priority lakes in an eight-county region in north-central Minnesota were identified to focus project activities. In 2021, surveys on these lakes were started to monitor common loon territory occupancy, nest success, and chick survival. We surveyed 62 lakes and identified 110 common loon territories that will be included in the project. At least 1 nest attempt was observed in 78 of 110 territories, and a second nest attempt was observed in 23 territories. A third nest attempt was observed in one territory. Successful nesting was observed in 32 of 110 territories. We present no formal data analysis and plan to analyze the data after the collection of all field data in subsequent years.

Minnesota↗

USGS2022

Environmental drivers of autumn migration departure decisions in midcontinental mallards

Background The timing of autumn migration in ducks is influenced by a range of environmental conditions that may elicit individual experiences and responses from individual birds, yet most studies have investigated relationships at the population level. We used data from individual satellite-tracked mallards ( Anas platyrhynchos ) to model the timing and environmental drivers of autumn migration movements at a continental scale. Methods We combined two sets of location records (2004–2007 and 2010–2011) from satellite-tracked mallards during autumn migration in the Mississippi Flyway, and identified records that indicated the start of long-range (≥ 30 km) southward movements during the migration period. We modeled selection of departure date by individual mallards using a discrete choice model accounting for heterogeneity in individual preferences. We developed candidate models to predict the departure date, conditional on daily mean environmental covariates (i.e. temperature, snow and ice cover, wind conditions, precipitation, cloud cover, and pressure) at a 32 × 32 km resolution. We ranked model performance with the Bayesian Information Criterion. Results Departure was best predicted (60% accuracy) by a “winter conditions” model containing temperature, and depth and duration of snow cover. Models conditional on wind speed, precipitation, pressure variation, and cloud cover received lower support. Number of days of snow cover, recently experienced snow cover (snow days) and current snow cover had the strongest positive effect on departure likelihood, followed by number of experienced days of freezing temperature (frost days) and current low temperature. Distributions of dominant drivers and of correct vs incorrect prediction along the movement tracks indicate that these responses applied throughout the latitudinal range of migration. Among recorded departures, most were driven by snow days (65%) followed by current temperature (30%). Conclusions Our results indicate that among the tested environmental parameters, the dominant environmental driver of departure decision in autumn-migrating mallards was the onset of snow conditions, and secondarily the onset of temperatures close to, or below, the freezing point. Mallards are likely to relocate southwards quickly when faced with snowy conditions, and could use declining temperatures as a more graduated early cue for departure. Our findings provide further insights into the functional response of mallards to weather factors during the migration period that ultimately determine seasonal distributions.

Movement Ecology↗

USGS2022

Estimating Pacific walrus abundance and survival with multievent mark-recapture models

Arctic marine ecosystems are undergoing rapid physical and biological change associated with climate warming and loss of sea ice. Sea ice loss will impact many species through altered spatial and temporal availability of resources. In the Bering and Chukchi Seas, the Pacific walrus Odobenus rosmarus divergens is one species that could be impacted by rapid environmental change, and thus, population assessments are needed to monitor changes in the status of this ecologically and culturally important marine mammal. We conducted a 5 yr genetic mark-recapture study to estimate demographic parameters for the Pacific walrus. We developed a Bayesian multievent mark-recapture model to estimate walrus survival and abundance while accounting for age misclassification. We estimated the probability of juvenile annual survival as 0.63 (95% credible interval [CrI]: 0.39-0.87) and adult female annual survival as 0.90 (95% CrI: 0.74-1.00). We estimated total abundance as 257 193 (95% CrI: 171 138-366 366). We provide the first estimate of total Pacific walrus abundance since an aerial survey in 2006, which generated a substantially less precise total population size estimate (129 000; 95% CI: 55 000-507 000). The emerging ecosystem state in the northern Bering and Chukchi Seas will likely result in a decline in Pacific walrus abundance, but there is substantial uncertainty regarding the magnitude of the anticipated decline. Our demographic estimates provide critical information to evaluate future population trends of this subsistence resource vital to communities that border the Bering and Chukchi Seas in the USA and Russia.

Alaska↗

USGS2022

Agent-based modeling of movements and habitat selection by mid-continent mallards

We found that the absence of existing conservation measures would reduce wintering mallard population size by ~70-80%, underlining the importance of current wetland easements for waterfowl foraging. Under standard conditions, the partial active flooding of easements later in the season and the upgrading of unmanaged wetlands to managed status resulted in greatest mallard populations, indicating that active flooding (stored water release) was able to considerably increase carrying capacity under strong drought conditions.

Cooperator Science Series↗

USGS2021

Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska Distinct Population Segment

For the sea otter ( Enhydra lutris ), genetic population structure is an area of research that has not received significant attention, especially in Southwest Alaska where that distinct population segment has been listed as threatened since 2005 pursuant to the U.S. Endangered Species Act. In this study, 501 samples from 14 locations from Prince William Sound, Alaska to the Commander Islands in Russia were analyzed for variation at 13 microsatellite loci. Our results indicate a high degree of genetic divergence among the 14 locations ( F ST = 0.120) with gene flow conforming to the isolation by distance (IBD) model ( r 2 = 0.491, p < .05). The 14 sampling locations formed six geographic associations in clustering and ordination analyses that likely correspond to remnant population lineages: (1) Southcentral Alaska, (2) Kodiak and North Alaska Peninsula, (3) South Alaska Peninsula and Bristol Bay, (4) Eastern Aleutian, (5) Western Aleutian, and (6) the Commander Islands. Except for South Alaska Peninsula and Bristol Bay, these clusters closely agree with previously defined stock and management unit boundaries. Our results reveal significant genetic population structure and are generally congruent with current management strategies for the threatened Southwest Alaska distinct population segment.

Alaska↗

USGS2021

Diffusion modeling reveals effects of multiple release sites and human activity on a recolonizing apex predator

Background Reintroducing predators is a promising conservation tool to help remedy human-caused ecosystem changes. However, the growth and spread of a reintroduced population is a spatiotemporal process that is driven by a suite of factors, such as habitat change, human activity, and prey availability. Sea otters ( Enhydra lutris ) are apex predators of nearshore marine ecosystems that had declined nearly to extinction across much of their range by the early 20th century. In Southeast Alaska, which is comprised of a diverse matrix of nearshore habitat and managed areas, reintroduction of 413 individuals in the late 1960s initiated the growth and spread of a population that now exceeds 25,000. Methods Periodic aerial surveys in the region provide a time series of spatially-explicit data to investigate factors influencing this successful and ongoing recovery. We integrated an ecological diffusion model that accounted for spatially-variable motility and density-dependent population growth, as well as multiple population epicenters, into a Bayesian hierarchical framework to help understand the factors influencing the success of this recovery. Results Our results indicated that sea otters exhibited higher residence time as well as greater equilibrium abundance in Glacier Bay, a protected area, and in areas where there is limited or no commercial fishing. Asymptotic spread rates suggested sea otters colonized Southeast Alaska at rates of 1–8 km/yr with lower rates occurring in areas correlated with higher residence time, which primarily included areas near shore and closed to commercial fishing. Further, we found that the intrinsic growth rate of sea otters may be higher than previous estimates suggested. Conclusions This study shows how predator recolonization can occur from multiple population epicenters. Additionally, our results suggest spatial heterogeneity in the physical environment as well as human activity and management can influence recolonization processes, both in terms of movement (or motility) and density dependence.

Alaska↗