Western Ecological Research Center (WERC)

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The Western Ecological Research Center (WERC) is a USGS Ecosystems Mission Area operation serving primarily California and Nevada. WERC scientists work closely with Federal, State, academic, and other collaborators to address a diverse array of high-profile topics. Topics include research on effects of wildfire, sea level rise, drought, energy development and more on federal Trust species.

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Date published: August 18, 2021

Research Spotlight: New Study Explores Nocturnal Nest Breaks and Predation Events for Dabbling Ducks

A new study by USGS scientists, in collaboration with the California Department of Water Resources and California Department of Fish and Wildlife, examined whether female ducks (hens) in Suisun Marsh, California leave their nest at night voluntarily or in response to a predator. They find that most nest breaks at night are initiated by the hen, but a quarter of nest departures are the result...

Date published: August 2, 2021

When Unchecked, Free-Roaming Horse Populations Threaten Greater Sage-Grouse

Greater sage-grouse populations may decline by more than 70% within free-roaming horse-occupied areas by 2034 if horse populations increase unchecked at current rates. Reducing horse numbers could neutralize their negative impacts.

Publications

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Year Published: 2021

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...

Berry, Kristin H.; Yee, Julie L.
Berry, K.H., and Yee, J.L., 2021, Development of demographic models to analyze populations with multi-year data—Using Agassiz’s Desert Tortoise (Gopherus agassizii) as a case study: U.S. Geological Survey Open-File Report 2018–1094, 55 p., https://doi.org/10.3133/ofr20181094.

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Year Published: 2021

Distribution and abundance of Southwestern Willow Flycatchers (Empidonax traillii extimus) on the upper San Luis Rey River, San Diego County, California—2020 data summary

We surveyed for Southwestern Willow Flycatchers (Empidonax traillii extimus; flycatcher) along the upper San Luis Rey River, near Lake Henshaw, in Santa Ysabel, California, in 2020. Surveys were completed at four locations: three downstream from Lake Henshaw, where nest monitoring occurred from 2015 to 2019 (Rey River Ranch [RRR], Cleveland...

Howell, Scarlett L.; Kus, Barbara E.
Howell, S.L., and Kus, B.E., 2021, Distribution and abundance of Southwestern Willow Flycatchers (Empidonax traillii extimus) on the upper San Luis Rey River, San Diego County, California—2020 data summary: U.S. Geological Survey Data Series 1140, 11 p., https://doi.org/10.3133/ds1140.

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Year Published: 2021

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...

Tinker, M. Tim; Carswell, Lilian P.; Tomoleoni, Joseph A.; Hatfield, Brian B.; Harris, Michael D.; Miller, Melissa A.; Moriarty, Megan E.; Johnson, Christine K.; Young, Colleen; Henkel, Laird A.; Staedler, Michelle M.; Miles, A. Keith; Yee, Julie L.
Tinker, M.T., Carswell, L.P., Tomoleoni, J.A., Hatfield, B.B., Harris, M.D., Miller, M.A., Moriarty, M.E., Johnson, C.K., Young, C., Henkel, L.A., Staedler, M.M., Miles, A.K., and Yee, J.L., 2021, An integrated population model for southern sea otters: U.S. Geological Survey Open-File Report 2021–1076, 50 p., https://doi.org/10.3133/ofr20211076.