Christopher A Pearl
I am a Wildlife Biologist at the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, OR.
I work on research and monitoring studies for a variety of aquatic and terrestrial species in the Pacific Northwest. I am particularly interested in restoration of wetland and riparian systems, herpetology, and interactions between native and invasive species.
Professional Experience
2001-Present: Wildlife Biologist, USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR
The Nature Conservancy
Faculty Research Associate, Oregon State University, Corvallis, OR
Education and Certifications
M.S., Environmental Studies, University of Oregon (1999)
B.S., Community Forestry and Horticulture, University of Vermont, Burlington, VT (1988)
Science and Products
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 18
Long-term amphibian monitoring data from the Willamette Valley, Oregon (2004-2015)
This dataset contains information from surveys conducted 2004-2015 by USGS as part of a long-term amphibian monitoring effort in the Willamette Valley, Oregon. Data consist of site, survey, habitat, and species detection covariates.
Oregon Spotted Frog (Rana pretiosa) Monitoring at Jack Creek 2015-2018 (final)
This dataset contains information from mark-recapture and egg mass surveys conducted 2015-2018 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort at Jack Creek, Klamath County, Oregon. Data consist of spotted frog counts (handled by surveyors) aggregated by date, location, life stage, and sex, as well as data on environmental conditions at the time each survey. Not
Telemetry and habitat data for Oregon spotted frogs (Rana pretiosa) in Oregon, USA
We used radio-telemetry to study late-season movement and habitat use by the Oregon spotted frog (Rana pretiosa) at 9 sites from 4 populations along the Cascade Mountains in Oregon. This dataset includes individual frog morphometrics, location data, and habitat use during each tracking event that occurred roughly weekly between September and January of 2011, 2012, and 2016.
Vegetation data from Columbia spotted frog (Rana luteiventris) exclosure study in eastern Oregon
We studied the short-term effects of full and partial livestock grazing exclosures on Columbia Spotted Frog (CSF; Rana luteiventris) populations using a controlled manipulative field experiment with pre- and post-treatment data. This dataset includes vegetation data collected 2002-2010 and 2013 at 94 lakes and ponds in and around the Blue Mountains in eastern Oregon. Data collection followed stand
Oregon Spotted Frog Monitoring in the Oregon Cascades 2012-2016
This dataset contains information from visual encounter surveys conducted between 2012 and 2016 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort in the Oregon Cascade Mountain Range. We surveyed 91 sites using a rotating frame design in the Klamath and Deschutes Basins, Oregon, which encompass most of the species' core extant range. Data consist of spotted frog c
Oregon Spotted Frog Monitoring at Jack Creek 2015-2016
This dataset contains information from mark-recapture and egg mass surveys conducted 2015-2016 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort at Jack Creek, Klamath County, Oregon. Data consist of spotted frog counts aggregated by date, location, life stage, and sex, as well as data on environmental conditions at the time each survey.
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 64
Quantifying climate sensitivity and climate-driven change in North American amphibian communities
Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 8
Authors
David A.W. Miller, Evan H. Campbell Grant, Erin L. Muths, Staci M. Amburgey, M. J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T.J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A.G. Rittenhouse, Susan C. Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price, Andrew M. Ray, Walter Sadinski, Daniel Saenz, William J. Barichivich, Adrianne B. Brand, Cheryl S. Brehme, Rosi Dagit, Katy S. Delaney, Brad M. Glorioso, Lee B. Kats, Patrick M. Kleeman, Christopher Pearl, Carlton J. Rochester, Seth P. D. Riley, Mark F. Roth, Brent Sigafus
By
Ecosystems Mission Area, Water Resources Mission Area, Species Management Research Program, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, John Wesley Powell Center for Analysis and Synthesis, Northern Rocky Mountain Science Center, South Atlantic Water Science Center (SAWSC), Southwest Biological Science Center, Upper Midwest Environmental Sciences Center, Western Ecological Research Center (WERC), Wetland and Aquatic Research Center
Late-season movement and habitat use by Oregon spotted frogs (Rana pretiosa) in Oregon, USA
Many amphibians use multiple habitats across seasons. Information on seasonal habitat use, movement between seasonal habitat types, and habitats that may be particularly valuable is important to conservation and management. We used radio-telemetry to study late-season movement and habitat use by Oregon Spotted Frog (Rana pretiosa) at nine sites from four populations along the Cascade Mountains in
Authors
Christopher Pearl, Brome McCreary, Jennifer Rowe, M. J. Adams
Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest
Comparative landscape genetics has uncovered high levels of variability in which landscape factors affect connectivity among species and regions. However, the relative importance of species traits versus environmental variation for predicting landscape patterns of connectivity is unresolved. We provide evidence from a landscape genetics study of two sister taxa of frogs, the Oregon spotted frog (R
Authors
Jeanne M. Robertson, Melanie A. Murphy, Christopher Pearl, M. J. Adams, Monica I. Paez-Vacas, Susan M. Haig, David S. Pilliod, Andrew Storfer, W. Chris Funk
Effect of cattle exclosures on Columbia Spotted Frog abundance
Livestock grazing is an important land use in the western USA and can have positive or negative effects on amphibians. Columbia Spotted Frog (Rana luteiventris) often use ponds that provide water for cattle. We conducted a long-term manipulative study on US Forest Service land in northeastern Oregon to determine the effects of full and partial exclosures that limited cattle access to ponds used by
Authors
M. J. Adams, Christopher Pearl, Thierry Chambert, Brome McCreary, Stephanie Galvan, Jennifer Rowe
A new parameterization for integrated population models to document amphibian reintroductions
Managers are increasingly implementing reintroduction programs as part of a global effort to alleviate amphibian declines. Given uncertainty in factors affecting populations and a need to make recurring decisions to achieve objectives, adaptive management is a useful component of these efforts. A major impediment to the estimation of demographic rates often used to parameterize and refine decision
Authors
Adam Duarte, Christopher Pearl, M. J. Adams, James Peterson
Using occupancy models to accommodate uncertainty in the interpretation of aerial photograph data: status of beaver in Central Oregon, USA
Beavers (Castor canadensis) influence habitat for many species and pose challenges in developed landscapes. They are increasingly viewed as a cost-efficient means of riparian habitat restoration and water storage. Still, information on their status is rare, particularly in western North America. We used aerial photography to evaluate changes in beaver occupancy between 1942–1968 and 2009 in upper
Authors
Christopher A. Pearl, M. J. Adams, Patricia K. Haggerty, Leslie Urban
Short-term occupancy and abundance dynamics of the Oregon spotted frog (Rana pretiosa) across its core range
The Oregon spotted frog (Rana pretiosa) occupies only a fraction of its original range and is listed as Threatened under the Endangered Species Act. We surveyed 93 sites in a rotating frame design (2010–13) in the Klamath and Deschutes Basins, Oregon, which encompass most of the species’ core extant range. Oregon spotted frogs are declining in abundance and probability of site occupancy. We did no
Authors
M. J. Adams, Christopher A. Pearl, Brome McCreary, Stephanie Galvan
Invasive crayfish as vectors of mercury in freshwater food webs of the Pacific Northwest
Invasive species are important drivers of environmental change in aquatic ecosystems and can alter habitat characteristics, community composition, and ecosystem energetics. Such changes have important implications for many ecosystem processes, including the bioaccumulation and biomagnification of contaminants through food webs. Mercury concentrations were measured in 2 nonnative and 1 native crayf
Authors
Branden L. Johnson, James J. Willacker, Collin A. Eagles-Smith, Christopher A. Pearl, M. J. Adams
New host and distribution records of the leech Placobdella sophieae Oceguera-Figueroa et al., 2010 (Hirudinida: Glossiphoniidae)
Placobdella sophieae Oceguera-Figueroa et al., 2010 (Hirudinida: Glossiphoniidae) is reported from Oregon, California, and British Columbia for the first time. New hosts reported for P. sophieae include Taricha granulosa (rough-skinned newt), Rana pretiosa (Oregon spotted frog), and Anaxyrus boreas (western toad). Placobdella sophieae exhibits relatively low host specificity and all amphibians occ
Authors
William E. Moser, Jay Bowerman, Peter Hovingh, Christopher A. Pearl, Alajandro Oceguera-Figueroa
Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian
Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades
Authors
Blake R. Hossack, M. J. Adams, Christopher A. Pearl, Kristine W. Wilson, Evelyn L. Bull, Kristin Lohr, Debra Patla, David S. Pilliod, Jason Jones, Kevin Wheeler, Samuel McKay, P. Stephen Corn
Habitat and co-occurrence of native and invasive crayfish in the Pacific Northwest, USA
Biological invasions can have dramatic effects on freshwater ecosystems and introduced crayfish can be particularly impacting. We document crayfish distribution in three large hydrographic basins (Rogue, Umpqua, Willamette/Columbia) in the Pacific Northwest USA. We used occupancy analyses to investigate habitat relationships and evidence for displacement of native Pacifastacus leniusculus (Dana, 1
Authors
Christopher A. Pearl, M. J. Adams, Brome McCreary
Northwestern salamanders Ambystoma gracile in mountain lakes: record oviposition depths among salamanders
Oviposition timing, behaviors, and microhabitats of ambystomatid salamanders vary considerably (Egan and Paton 2004; Figiel and Semlitsch 1995; Howard and Wallace 1985; Mac-Cracken 2007). Regardless of species, however, females typically oviposit using sites conducive to embryo development and survival. For example, the results of an experiment by Figiel and Semlitsch (1995) on Ambystoma opacum (M
Authors
R. Hoffman, C.A. Pearl, G.L. Larson, B. Samora
Science and Products
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 18
Long-term amphibian monitoring data from the Willamette Valley, Oregon (2004-2015)
This dataset contains information from surveys conducted 2004-2015 by USGS as part of a long-term amphibian monitoring effort in the Willamette Valley, Oregon. Data consist of site, survey, habitat, and species detection covariates.
Oregon Spotted Frog (Rana pretiosa) Monitoring at Jack Creek 2015-2018 (final)
This dataset contains information from mark-recapture and egg mass surveys conducted 2015-2018 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort at Jack Creek, Klamath County, Oregon. Data consist of spotted frog counts (handled by surveyors) aggregated by date, location, life stage, and sex, as well as data on environmental conditions at the time each survey. Not
Telemetry and habitat data for Oregon spotted frogs (Rana pretiosa) in Oregon, USA
We used radio-telemetry to study late-season movement and habitat use by the Oregon spotted frog (Rana pretiosa) at 9 sites from 4 populations along the Cascade Mountains in Oregon. This dataset includes individual frog morphometrics, location data, and habitat use during each tracking event that occurred roughly weekly between September and January of 2011, 2012, and 2016.
Vegetation data from Columbia spotted frog (Rana luteiventris) exclosure study in eastern Oregon
We studied the short-term effects of full and partial livestock grazing exclosures on Columbia Spotted Frog (CSF; Rana luteiventris) populations using a controlled manipulative field experiment with pre- and post-treatment data. This dataset includes vegetation data collected 2002-2010 and 2013 at 94 lakes and ponds in and around the Blue Mountains in eastern Oregon. Data collection followed stand
Oregon Spotted Frog Monitoring in the Oregon Cascades 2012-2016
This dataset contains information from visual encounter surveys conducted between 2012 and 2016 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort in the Oregon Cascade Mountain Range. We surveyed 91 sites using a rotating frame design in the Klamath and Deschutes Basins, Oregon, which encompass most of the species' core extant range. Data consist of spotted frog c
Oregon Spotted Frog Monitoring at Jack Creek 2015-2016
This dataset contains information from mark-recapture and egg mass surveys conducted 2015-2016 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort at Jack Creek, Klamath County, Oregon. Data consist of spotted frog counts aggregated by date, location, life stage, and sex, as well as data on environmental conditions at the time each survey.
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 64
Quantifying climate sensitivity and climate-driven change in North American amphibian communities
Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 8
Authors
David A.W. Miller, Evan H. Campbell Grant, Erin L. Muths, Staci M. Amburgey, M. J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T.J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A.G. Rittenhouse, Susan C. Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price, Andrew M. Ray, Walter Sadinski, Daniel Saenz, William J. Barichivich, Adrianne B. Brand, Cheryl S. Brehme, Rosi Dagit, Katy S. Delaney, Brad M. Glorioso, Lee B. Kats, Patrick M. Kleeman, Christopher Pearl, Carlton J. Rochester, Seth P. D. Riley, Mark F. Roth, Brent Sigafus
By
Ecosystems Mission Area, Water Resources Mission Area, Species Management Research Program, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, John Wesley Powell Center for Analysis and Synthesis, Northern Rocky Mountain Science Center, South Atlantic Water Science Center (SAWSC), Southwest Biological Science Center, Upper Midwest Environmental Sciences Center, Western Ecological Research Center (WERC), Wetland and Aquatic Research Center
Late-season movement and habitat use by Oregon spotted frogs (Rana pretiosa) in Oregon, USA
Many amphibians use multiple habitats across seasons. Information on seasonal habitat use, movement between seasonal habitat types, and habitats that may be particularly valuable is important to conservation and management. We used radio-telemetry to study late-season movement and habitat use by Oregon Spotted Frog (Rana pretiosa) at nine sites from four populations along the Cascade Mountains in
Authors
Christopher Pearl, Brome McCreary, Jennifer Rowe, M. J. Adams
Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest
Comparative landscape genetics has uncovered high levels of variability in which landscape factors affect connectivity among species and regions. However, the relative importance of species traits versus environmental variation for predicting landscape patterns of connectivity is unresolved. We provide evidence from a landscape genetics study of two sister taxa of frogs, the Oregon spotted frog (R
Authors
Jeanne M. Robertson, Melanie A. Murphy, Christopher Pearl, M. J. Adams, Monica I. Paez-Vacas, Susan M. Haig, David S. Pilliod, Andrew Storfer, W. Chris Funk
Effect of cattle exclosures on Columbia Spotted Frog abundance
Livestock grazing is an important land use in the western USA and can have positive or negative effects on amphibians. Columbia Spotted Frog (Rana luteiventris) often use ponds that provide water for cattle. We conducted a long-term manipulative study on US Forest Service land in northeastern Oregon to determine the effects of full and partial exclosures that limited cattle access to ponds used by
Authors
M. J. Adams, Christopher Pearl, Thierry Chambert, Brome McCreary, Stephanie Galvan, Jennifer Rowe
A new parameterization for integrated population models to document amphibian reintroductions
Managers are increasingly implementing reintroduction programs as part of a global effort to alleviate amphibian declines. Given uncertainty in factors affecting populations and a need to make recurring decisions to achieve objectives, adaptive management is a useful component of these efforts. A major impediment to the estimation of demographic rates often used to parameterize and refine decision
Authors
Adam Duarte, Christopher Pearl, M. J. Adams, James Peterson
Using occupancy models to accommodate uncertainty in the interpretation of aerial photograph data: status of beaver in Central Oregon, USA
Beavers (Castor canadensis) influence habitat for many species and pose challenges in developed landscapes. They are increasingly viewed as a cost-efficient means of riparian habitat restoration and water storage. Still, information on their status is rare, particularly in western North America. We used aerial photography to evaluate changes in beaver occupancy between 1942–1968 and 2009 in upper
Authors
Christopher A. Pearl, M. J. Adams, Patricia K. Haggerty, Leslie Urban
Short-term occupancy and abundance dynamics of the Oregon spotted frog (Rana pretiosa) across its core range
The Oregon spotted frog (Rana pretiosa) occupies only a fraction of its original range and is listed as Threatened under the Endangered Species Act. We surveyed 93 sites in a rotating frame design (2010–13) in the Klamath and Deschutes Basins, Oregon, which encompass most of the species’ core extant range. Oregon spotted frogs are declining in abundance and probability of site occupancy. We did no
Authors
M. J. Adams, Christopher A. Pearl, Brome McCreary, Stephanie Galvan
Invasive crayfish as vectors of mercury in freshwater food webs of the Pacific Northwest
Invasive species are important drivers of environmental change in aquatic ecosystems and can alter habitat characteristics, community composition, and ecosystem energetics. Such changes have important implications for many ecosystem processes, including the bioaccumulation and biomagnification of contaminants through food webs. Mercury concentrations were measured in 2 nonnative and 1 native crayf
Authors
Branden L. Johnson, James J. Willacker, Collin A. Eagles-Smith, Christopher A. Pearl, M. J. Adams
New host and distribution records of the leech Placobdella sophieae Oceguera-Figueroa et al., 2010 (Hirudinida: Glossiphoniidae)
Placobdella sophieae Oceguera-Figueroa et al., 2010 (Hirudinida: Glossiphoniidae) is reported from Oregon, California, and British Columbia for the first time. New hosts reported for P. sophieae include Taricha granulosa (rough-skinned newt), Rana pretiosa (Oregon spotted frog), and Anaxyrus boreas (western toad). Placobdella sophieae exhibits relatively low host specificity and all amphibians occ
Authors
William E. Moser, Jay Bowerman, Peter Hovingh, Christopher A. Pearl, Alajandro Oceguera-Figueroa
Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian
Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades
Authors
Blake R. Hossack, M. J. Adams, Christopher A. Pearl, Kristine W. Wilson, Evelyn L. Bull, Kristin Lohr, Debra Patla, David S. Pilliod, Jason Jones, Kevin Wheeler, Samuel McKay, P. Stephen Corn
Habitat and co-occurrence of native and invasive crayfish in the Pacific Northwest, USA
Biological invasions can have dramatic effects on freshwater ecosystems and introduced crayfish can be particularly impacting. We document crayfish distribution in three large hydrographic basins (Rogue, Umpqua, Willamette/Columbia) in the Pacific Northwest USA. We used occupancy analyses to investigate habitat relationships and evidence for displacement of native Pacifastacus leniusculus (Dana, 1
Authors
Christopher A. Pearl, M. J. Adams, Brome McCreary
Northwestern salamanders Ambystoma gracile in mountain lakes: record oviposition depths among salamanders
Oviposition timing, behaviors, and microhabitats of ambystomatid salamanders vary considerably (Egan and Paton 2004; Figiel and Semlitsch 1995; Howard and Wallace 1985; Mac-Cracken 2007). Regardless of species, however, females typically oviposit using sites conducive to embryo development and survival. For example, the results of an experiment by Figiel and Semlitsch (1995) on Ambystoma opacum (M
Authors
R. Hoffman, C.A. Pearl, G.L. Larson, B. Samora