Western Ecological Research Center
Distinguishing recent dispersal from historical genetic connectivity in the coastal California gnatcatcher
Habitat loss and fragmentation are primary threats to biodiversity worldwide. We studied the impacts of habitat loss and fragmentation on genetic connectivity and diversity among local aggregations of the California gnatcatcher (Polioptila californica californica) across its U.S. range. With a dataset of 268 individuals genotyped at 19...Vandergast, Amy G.; Kus, Barbara E.; Preston, Kristine L.; Barr, Kelly R.
Freshwater tidal forests and estuarine wetlands may confer early life growth advantages for delta-reared Chinook Salmon
Large river deltas are complex ecosystems that are believed to play a pivotal role in promoting the early marine growth and survival of threatened Chinook Salmon Oncorhynchus tshawytscha. We used a fish bioenergetics model to assess the functional role of multiple delta habitats across a gradient of salinities and vegetation types, where...Davis, Melanie J.; Woo, Isa; Ellings, Christopher S.; Hodgson, Sayre; Beauchamp, David A.; Nakai, Glynnis; De La Cruz, Susan E. W.
Mercury contamination in resident and migrant songbirds and potential effects on body condition
Methlymercury is a significant risk to environmental health globally. We examined the ecological drivers of methylmercury bioaccumulation in songbirds and its effect on body condition while experimentally removing the potentially confounding and predominant effects of site and habitat. We measured blood and...Ackerman, Joshua T.; Hartman, Christopher; Herzog, Mark P.
Early-warning signals of individual tree mortality based on annual radial growth
Tree mortality is a key driver of forest dynamics and its occurrence is projected to increase in the future due to climate change. Despite recent advances in our understanding of the physiological mechanisms leading to death, we still lack robust indicators of mortality risk that could be applied at the individual tree scale. Here, we build on a...Cailleret, Maxime; Dakos, Vasilis; Jansen, Steven; Robert, Elisabeth M. R.; Aakala, Tuomas; Amoroso, Mariano M.; Antos, Joe A.; Bigler, Christof; Bugmann, Harald; Caccianaga, Marco; Camarero, Jesus-Julio; Cherubini, Paolo; Coyea, Marie R.; Cufar, Katarina; Das, Adrian J.; Davi, Hendrik; Gea-Izquierdo, Guillermo; Gillner, Sten; Haavik, Laurel J.; Hartmann, Henrik; Heres, Ana-Maria; Hultine, Kevin R.; Janda, Pavel; Kane, Jeffrey M.; Kharuk, Viachelsav I.; Kitzberger, Thomas; Klein, Tamir; Levanic, Tom; Linares, Juan-Carlos; Lombardi, Fabio; Makinen, Harri; Mészáros, Ilona; Metsaranta, Juha M.; Oberhuber, Walter; Papadopoulos, Andreas; Petritan, Any Mary; Rohner, Brigitte; Sanguesa-Barreda, Gabriel; Smith, Jeremy M.; Stan, Amanda B.; Stojanovic, Dejan B.; Suarez, Maria-Laura; Svoboda, Miroslav; Trotsiuk, Volodymyr; Villalba, Ricardo; Westwood, Alana R.; Wyckoff, Peter H.; Martinez-Vilalta, Jordi
Effects of prescribed fire on San Francisco gartersnake survival and movement
The application of fire is prescribed for management of habitats for many plant and animal communities, but its effects on herpetofauna are diverse and remain poorly understood. To date no studies have examined the effects of prescribed fire on endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia) populations, despite a call for...Halstead, Brian J.; Thompson, Michelle E.; Amarello, Melissa; Smith, Jeffrey J.; Wylie, Glenn D.; Routman, Eric J.; Casazza, Michael L.
Movements of female Sage Grouse Centrocercus urophasianus during incubation recess
We combined GPS data‐loggers, VHF transmitters, and DVR video‐monitoring to measure fine‐scale movement patterns during daily incubation recesses by female Sage Grouse Centrocercus urophasianus, a species with uniparental incubation that has experienced widespread population decline and distributional contraction. Most (69.6%) Sage Grouse...Dudko, Jonathan E.; Coates, Peter S.; Delehanty, David J.
Assessing effects of nonnative crayfish on mosquito survival
Introductions of nonnative predators often reduce biodiversity and affect natural predator–prey relationships and may increase the abundance of potential disease vectors (e.g., mosquitoes) indirectly through competition or predation cascades. The Santa Monica Mountains (California, U.S.A.), situated in a global biodiversity hotspot, is an area of...Bucciarelli, Gary M.; Suh, Daniel; Davis Lamb, Avery; Roberts, Dave; Sharpton, Debra; Shaffer, H. Bradley; Fisher, Robert N.; Kats, Lee B.
Drivers of chaparral type conversion to herbaceous vegetation in coastal Southern California
AimIn Southern California, native woody shrublands known as chaparral support exceptional biodiversity. However, large‐scale conversion of chaparral into largely exotic herbaceous cover is a major ecological threat and serious conservation concern. Due to substantial uncertainty regarding the causes and extent of this vegetation change, we aimed...Syphard, Alexandra D.; Brennan, Teresa J.; Keeley, Jon E.
Vertical zonation and niche breadth of tidal marsh plants along the Northeast Pacific coast
The distribution patterns of sessile organisms in coastal intertidal habitats typically exhibit vertical zonation, but little is known about variability in zonation among sites or species at larger spatial scales. Data on such heterogeneity could inform mechanistic understanding of factors affecting species distributions as well as efforts to...Janousek, Christopher N.; Thorne, Karen M.; Takekawa, John Y.
Changes in aquatic prey resources in response to estuary restoration in Willapa Bay, southwestern Washington
Executive SummaryThe ongoing restoration of more than 200 hectares of estuarine habitat at Willapa National Wildlife Refuge, southwestern Washington, is expected to benefit a variety of species, including salmonids that use estuarine and tidal marshes as rearing and feeding areas as well as migratory waterbirds. During March–June 2014 and 2015, U....Woo, Isa; Davis, Melanie J.; De La Cruz, Susan E. W.
Time-to-detection occupancy modeling: An efficient method for analyzing the occurrence of amphibians and reptiles
Occupancy models provide a reliable method of estimating species distributions while accounting for imperfect detectability. The cost of accounting for false absences is that detection and nondetection surveys typically require repeated visits to a site or multiple-observer techniques. More efficient methods of collecting data to estimate...Halstead, Brian J.; Kleeman, Patrick M.; Rose, Jonathan
Wildlife underpass use and environmental impact assessment: A southern California case study
Environmental planners often rely on transportation structures (i.e., underpasses, bridges) to provide connectivity for animals across developed landscapes. Environmental assessments of predicted environmental impacts from proposed developments often rely on literature reviews or other indirect measures to establish the importance of wildlife...Longcore, Travis; Almaleh, Lindsay; Chetty, Brittany; Francis, Kathryn; Freidin, Robert; Huang, Ching-Sheng; Pickett, Brooke; Schreck, Diane; Scruggs, Brooke; Shulman, Elise; Swauger, Alissa; Tashnek, Alison; Wright, Michael; Boydston, Erin E.