Julie Yee
Dr. Julie Yee is a research scientist with the U.S. Geological Survey's Western Ecological Research Center.
Science and Products
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.
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...
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...
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...
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:
Annual California sea otter stranding data
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. Since 1985, stranded otters from throughout their California coastal range have been collected and analyzed to inform resource management on recovery and conservation of the species.
Annual sea otter survey data
WERC scientists conduct annual population surveys of the southern sea otter, a federally listed threatened species. Download annual survey data from 1985 to present.
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...
Yee, Julie L.; Tomoleoni, Joseph A.; Kenner, Michael C.; Fujii, Jessica; Bentall, Gena B.; Tinker, M. Tim; Hatfield, Brian B.
The distribution of woody species in relation to climate and fire in Yosemite National Park, California, USA
BackgroundThe effects of climate on plant species ranges are well appreciated, but the effects of other processes, such as fire, on plant species distribution are less well understood. We used a dataset of 561 plots 0.1 ha in size located throughout Yosemite National Park, in the Sierra Nevada of California, USA, to determine the joint effects of...
van Wagtendonk, Jan W.; Moore, Peggy E; Yee, Julie L.; Lutz, James A. Good prospects: High-resolution telemetry data suggests novel brood-site selection behavior in waterfowl
Breeding success should increase with prior knowledge of the surrounding environment, which is dependent upon an animal’s ability to evaluate habitat. Prospecting for nesting locations and migratory stop-over sites are well-established behaviors among bird species. We assessed whether ducks in Suisun Marsh, California, USA, a brackish marsh,...
Casazza, Michael L.; McDuie, Fiona; Lorenz, Austen; Keiter, David A.; Yee, Julie L.; Overton, Cory T.; Peterson, Sarah H.; Feldheim, Cliff L.; Ackerman, Joshua T. Assessing population-level consequences of anthropogenic stressors for terrestrial wildlife
Human activity influences wildlife. However, the ecological and conservation significances of these influences are difficult to predict and depend on their population‐level consequences. This difficulty arises partly because of information gaps, and partly because the data on stressors are usually collected in a count‐based manner (e.g., number of...
Katzner, Todd E.; Braham, Melissa A.; Conkling, Tara; Diffendorfer, James E.; Duerr, Adam E.; Loss, Scott R.; Nelson, David M.; Vander Zanden, Hannah B.; Yee, Julie L. An uncertain future for a population of desert tortoises experiencing human impacts
We evaluated the status of a population of Mojave Desert Tortoises (Gopherus agassizii), a threatened species, in the El Paso Mountains of the northwestern Mojave Desert in California, USA. The study area lies north of and adjacent to a designated critical habitat unit for the species, is adjacent to a state park, and is a short distance from the...
Berry, Kristin H.; Yee, Julie L.; Lyren, Lisa L.; Mack, Jeremy S Detection probabilities of bird carcasses along sandy beaches and marsh edges in the northern Gulf of Mexico
We estimated detection probabilities of bird carcasses along sandy beaches and in marsh edge habitats in the northern Gulf of Mexico to help inform models of bird mortality associated with the Deepwater Horizon oil spill. We also explored factors that may influence detection probability, such as carcass size, amount of scavenging,...
Zimmerman, Guthrie S.; Varela, Veronica; Yee, Julie L.
Trends in mammalian predator control trapping events intended to protect ground-nesting, endangered birds at Haleakalā National Park, Hawaiʻi: 2000–14
Predation and habitat degradation by non-native species are principal terrestrial threats to the federally endangered Hawaiian Petrel (ʻuaʻu, Pterodroma sandwichensis) and Hawaiian Goose (nēnē, Branta sandvicensis) within Haleakalā National Park (HALE), Maui, Hawaiʻi. Since 1981, HALE has maintained a network of live traps to control invasive...
Kelsey, Emily C.; Adams, Josh; Czapanskiy, Max F.; Felis, Jonathan J.; Yee, Julie L.; Kaholoaa, Raina L.; Bailey, Cathleen Natividad
California sea otter (Enhydra lutris nereis) census results, spring 2019
The 2019 census of southern sea otters (Enhydra lutris nereis), also known as California sea otters, was conducted from early May to early July along the mainland coast of central California and in April at San Nicolas Island in southern California. The range-wide index, defined as the 3-year average of combined counts from the mainland range and...
Hatfield, Brian B.; Yee, Julie L.; Kenner, Michael C.; Tomoleoni, Joseph A. Which trees die during drought? The key role of insect host-tree selection
1. During drought, the tree subpopulations (such as size or vigor classes) that suffer disproportionate mortality can be conceptually arrayed along a continuum defined by the actions of biotic agents, particularly insects. At one extreme, stress dominates: insects are absent or simply kill the most physiologically stressed trees. At the...
Stephenson, Nathan L.; Das, Adrian J.; Ampersee, Nicholas J.; Bulaon, Beverly M; Yee, Julie L. Changes in breeding population sizes of double-crested Cormorants Phalacrocorax auritus in the Humboldt Bay area, California, 1924–2017
To better understand recent population growth of the Double-crested Cormorant Phalacrocorax auritus along the Pacific coast of North America, we assessed long-term breeding population trends in the Humboldt Bay area, California, using aerial photographic survey data collected since 1989 as well as available prior data. The earliest...
Capitolo, Phillip J.; Carter, Harry R; Yee, Julie L.; McChesney, Gerard J.; Parker, Michael W; Young, Richard J; Golightly, Richard T.; Tyler, W Breck
California sea otter (Enhydra lutris nereis) census results, spring 2018
The 2018 census of southern sea otters (Enhydra lutris nereis) was conducted from late April to mid-May along the mainland coast of central California and in April at San Nicolas Island in southern California. The 3-year average of combined counts from the mainland range and San Nicolas Island was 3,128, a decrease of 58 sea otters from the...
Hatfield, Brian B.; Yee, Julie L.; Kenner, Michael C.; Tomoleoni, Joseph A.; Tinker, M. Tim Body mass, wing length, and condition of wintering ducks relative to hematozoa infection
Waterfowl managers lack information regarding factors that may be reducing the positive response of waterfowl body condition to habitat improvements. Protozoan blood parasites (i.e., hematozoa) are commonly found in birds and have been related to reduced body mass, wing length, and body condition. We studied relationships between 12 measures of...
Fleskes, Joseph; Ramey, Andrew M.; Reeves, Andrew B.; Yee, Julie L.
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. Fish and Wildlife Service have decided to cancel this year's annual rangewide southern sea otter census.
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 researchers was asked to gain a better understanding of the actual environmental impacts of renewable energy generation on sensitive species and habitats in California.
Demographic Consequences of Human Stressors on Wildlife Populations
Predicting the ecological and conservation significances of human influences on wildlife populations is difficult. However, methodological developments can help make the transition from count-based field data on individuals to rate-based demographic estimates.