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Julie Yee

Dr. Julie Yee is a Research Statistician with the Western Ecological Research Center (WERC). 

Since 1997, she has used statistics and biometry for WERC to quantitatively analyze and interpret a variety of aspects of wildlife and plant population dynamics, such as recruitment, growth, survival, and wildlife movement.  Her research has been applied to study the effects of renewable energy, contaminants, fire, and other influences on wildlife populations and ecosystems.  She is currently a PI at the Santa Cruz field station where she supervises continued work on sea otter and nearshore research. 

 

RESEARCH INTERESTS

  • Frequentist and Bayesian statistical analysis
  • Survival analysis
  • Population dynamics
  • Mark-recapture
  • State-space modeling
  • Integrated population modeling
  • High performance computing

 

EDUCATION

  • Ph.D., 1997, Statistics with Emphasis in Biostatistics, University of California, Davis.
    • Dissertation Title:  Asymptotic Approximations to Bayesian Posterior Distributions in Survival Problems with Incomplete Data
  • M.S., 1993, Statistics, University of California, Davis
  • B.S., 1991, Mathematics, California Institute of Technology

Science and Products

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WERC Sea otter research in Big Sur, California

California Sea Otter Stranding Network

The California Sea Otter Stranding Network is part of the USGS effort to monitor southern sea otters (Enhydra lutris nereis) and provide data to the U.S. Fish and Wildlife Service. WERC's sea otter team works with multiple institutions and partners to report, recover, and examine stranded sea otters. In addition, instructions on how to report a stranded sea otter are included in this webpage.
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Ecosystems, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Ecological Research Center (WERC)
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California Sea Otter Stranding Network

The California Sea Otter Stranding Network is part of the USGS effort to monitor southern sea otters (Enhydra lutris nereis) and provide data to the U.S. Fish and Wildlife Service. WERC's sea otter team works with multiple institutions and partners to report, recover, and examine stranded sea otters. In addition, instructions on how to report a stranded sea otter are included in this webpage.
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Sea otter Elkhorn Slough National Estuarine Research Reserve (WERC)

Population Biology and Behavior of Sea Otters

WERC's sea otter researchers are developing and utilizing a variety of methodological and analytical tools to understand the causes of biological and ecological trends in sea otter populations, and to predict the ecological consequences of management practices on these populations and their ecosystems.
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Ecosystems, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Ecological Research Center (WERC)
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Population Biology and Behavior of Sea Otters

WERC's sea otter researchers are developing and utilizing a variety of methodological and analytical tools to understand the causes of biological and ecological trends in sea otter populations, and to predict the ecological consequences of management practices on these populations and their ecosystems.
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WERC sea otter

California Sea Otter Surveys and Research

WERC collaborates with other research scientists to conduct annual population surveys of the southern sea otter -- a federally listed threatened species. In coordination with the California Department of Fish and Game and other institutions, ongoing surveys and research continues to inform the southern sea otter recovery plan for the U.S. Fish and Wildlife Service, and contributes to our...
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Ecosystems, Species Management Research Program, Western Ecological Research Center (WERC)
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California Sea Otter Surveys and Research

WERC collaborates with other research scientists to conduct annual population surveys of the southern sea otter -- a federally listed threatened species. In coordination with the California Department of Fish and Game and other institutions, ongoing surveys and research continues to inform the southern sea otter recovery plan for the U.S. Fish and Wildlife Service, and contributes to our...
Learn More
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Image: Sea Otter Ready for a Nap

Pacific Nearshore Project

Sea otters are crucial indicators of the health of our nearshore waters and coastal resources, from kelp forests to fisheries. What clues does the sea otter's decline hold for our knowledge of ecosystem and global change? WERC's sea otter team and U.S. and Canadian researchers have teamed together to investigate. Relevance to USGS Missions: This research project has direct relevance for the...
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Ecosystems, Species Management Research Program, Western Ecological Research Center (WERC)
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Pacific Nearshore Project

Sea otters are crucial indicators of the health of our nearshore waters and coastal resources, from kelp forests to fisheries. What clues does the sea otter's decline hold for our knowledge of ecosystem and global change? WERC's sea otter team and U.S. and Canadian researchers have teamed together to investigate. Relevance to USGS Missions: This research project has direct relevance for the...
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Photo of scientist climbing an island off the coast of Big Sur

Santa Cruz Field Station

Scientists at the Santa Cruz Field Station study sea otters and seabirds in their environment. The USGS Western Ecological Research Center has two research missions based in the Santa Cruz region:
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Western Ecological Research Center (WERC)
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Santa Cruz Field Station

Scientists at the Santa Cruz Field Station study sea otters and seabirds in their environment. The USGS Western Ecological Research Center has two research missions based in the Santa Cruz region:
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Demographic model inputs and code, catchment area population estimates, and counterfactual (CIU) estimates for population growth for 23 focal bird species.

Renewable energy production can kill birds, but little is known about how it affects avian populations. We assessed vulnerability of populations for 23 priority bird species killed at wind and solar facilities in California, USA.
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Forest and Rangeland Ecosystem Science Center

Annual California Sea Otter Census-2018 Spring Census Summary

The spring 2018 mainland sea otter count began on April 26, and was completed by May 24, 2018. Overall viewing conditions this year were good and rounded off to the same conditions experienced during the 2017 spring census (View Score 2.4, where 0=poor, 1=fair, 2=good, 3=very good, and 4=excellent). The surface canopies of kelp (Macrocystis sp.) were considered by most participants to be above nor
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Western Ecological Research Center (WERC)

At-Sea Distribution and Abundance of Seabirds and Marine Mammals off Southern California GIS Resource Database: Aerial seabird and marine mammal surveys off southern California, 1999-2002

Background - Interest in developing alternative sources of renewable energy to reduce dependence on oil has increased in recent years. Some sources of renewable energy being considered will include power generation infrastructure and support activities located within continental shelf waters, and potentially within deeper waters off the U.S. Pacific coast and beyond state waters (i.e., outside thr
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Western Ecological Research Center (WERC)
sea otters floating among kelp
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Black Abalone surveys at Naval Base Ventura County, San Nicolas Island, California—2021, annual report

The U.S. Geological Survey monitors a suite of intertidal black abalone sites at San Nicolas Island, California, in cooperation with the U.S. Navy, which owns the island. The nine rocky intertidal sites were established in 1980 to study the potential effect of translocated sea otters on the intertidal black abalone population at the island. The sites were monitored from 1981 to 1997, usually annua
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Ecosystems, Western Ecological Research Center (WERC)

Spatial effects in relation to reproductive performance of Common Murres (Uria aalge) at a re-established colony

A main goal of seabird colony restoration is for the colony to become self-sustaining. To do so, elevated rates must be attained in (1) reproductive success and (2) recruitment by immigrants and birds produced at the colony. Thus, an understanding of the factors affecting reproductive success and recruitment at restoration sites is vital. We examined how spatial features at the colony level affect
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Ecosystems, Western Ecological Research Center (WERC)

Vulnerability of avian populations to renewable energy production

Renewable energy production can kill individual birds, but little is known about how it affects avian populations. We assessed the vulnerability of populations for 23 priority bird species killed at wind and solar facilities in California, USA. Bayesian hierarchical models suggested that 48% of these species were vulnerable to population-level effects from added fatalities caused by renewables and
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Ecosystems, Forest and Rangeland Ecosystem Science Center, Western Ecological Research Center (WERC)

Kelp-forest dynamics controlled by substrate complexity

The factors that determine why ecosystems exhibit abrupt shifts in state are of paramount importance for management, conservation, and restoration efforts. Kelp forests are emblematic of such abruptly shifting ecosystems, transitioning from kelp-dominated to urchin-dominated states around the world with increasing frequency, yet the underlying processes and mechanisms that control their dynamics r
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Ecosystems, Western Ecological Research Center (WERC)

Development of demographic models to analyze populations with multi-year data—Using Agassiz’s Desert Tortoise (Gopherus agassizii) as a case study

We developed a model for analyzing multi-year demographic data for long-lived animals and used data from a population of Agassiz’s desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area in the western Mojave Desert of California as a case study. The study area was 7.77 square kilometers and included two locations: inside and outside the fenced boundary. The wildlife-perm
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Ecosystems, Western Ecological Research Center (WERC)

An integrated population model for southern sea otters

Southern sea otters (Enhydra lutris nereis) have recovered slowly from their near extinction a century ago, and their continued recovery has been challenged by multiple natural and anthropogenic factors. Development of an integrated population model (IPM) for southern sea otters has been identified as a management priority, to help in evaluating the relative impacts of known threats and guide best
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Ecosystems, Western Ecological Research Center (WERC)

Changes in the abundance and distribution of waterfowl wintering in the Central Valley of California, 1973–2000

The Central Valley of California is one of the most important areas for wintering waterfowl in the world and the focus of extensive conservation efforts to mitigate for historical losses and counter continuing stressors to habitats. To guide conservation, we analyzed trends in the abundance and distribution (spatiotemporal abundance patterns) of waterfowl and their habitats in the Central Valley a
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Ecosystems, Western Ecological Research Center (WERC)

Waterfowl use of wetland habitats informs wetland restoration designs for multi‐species benefits

Extensive global estuarine wetland losses have prompted intensive focus on restoration of these habitats. In California, substantial tracts of freshwater, brackish and tidal wetlands have been lost. Given the anthropogenic footprint of development and urbanization in this region, wetland restoration must rely on conversion of existing habitat types rather than adding new wetlands. These restoratio
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Ecosystems, Western Ecological Research Center (WERC)

Body condition of wintering Pacific greater white-fronted geese

Extreme changes to key waterfowl habitats in the Klamath Basin (KB) on the Oregon–California border and the Sacramento Valley (SV) in California, USA, have occurred since 1980. The spatial distribution of Pacific greater white‐fronted geese (Anser albifrons sponsa; geese) has likewise changed among these areas and population size has grown from 79,000 to >600,000 geese during the same period. To a
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Ecosystems, Western Ecological Research Center (WERC)

Habitat features predict carrying capacity of a recovering marine carnivore

The recovery of large carnivore species from over‐exploitation can have socioecological effects; thus, reliable estimates of potential abundance and distribution represent a valuable tool for developing management objectives and recovery criteria. For sea otters (Enhydra lutris), as with many apex predators, equilibrium abundance is not constant across space but rather varies as a function of loca
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Ecosystems, Western Ecological Research Center (WERC)

Feral burros and other influences on desert tortoise presence in the western Sonoran Desert

Across the globe, conflicting priorities exist in how land and resources are managed. In the American West, conflicts are common on public lands with historical mandates for multiple uses. We explored the impacts of multiple uses of land in a case study of Agassiz's Desert Tortoises (Gopherus agassizii), a federally threatened species, in the western Sonoran Desert. The tortoise has declined for m
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Ecosystems, Western Ecological Research Center (WERC)

Southern (California) sea otter population status and trends at San Nicolas Island, 2017–2020

The southern sea otter (Enhydra lutris nereis) population at San Nicolas Island, California, has been monitored annually since the translocation of 140 sea otters to the island was completed in 1990. Monitoring efforts have varied in frequency and type across years. In 2017, the U.S. Navy and the U.S. Fish and Wildlife Service initiated a sea otter monitoring and research plan to determine the eff
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Ecosystems, Western Ecological Research Center (WERC)
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Sea Otter Surveys Get a High-Tech, COVID-Safe Update for 2021

After a 2020 cancellation of the annual sea otter census, the count was back on for 2021.

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Annual Southern Sea Otter Census Cancelled Due to Health and Safety Concerns

In light of the ongoing COVID-19 pandemic, the USGS and partners at the California Department of Fish and Wildlife, Monterey Bay Aquarium, and the U.S...

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Learning From Real-World Experience to Understand Renewable Energy Impacts to Wildlife

A comprehensive analysis of how renewable energy facilities affect wildlife could inform efforts to predict and reduce these impacts. A team of...

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Demographic Consequences of Human Stressors on Wildlife Populations

Predicting the ecological and conservation significances of human influences on wildlife populations is difficult. However, methodological...

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