Craig A Stricker, PhD
Craig Stricker is an ecologist at the Fort Collins Science Center that specializes in the application of chemical and isotopic tracers for addressing societally relevant questions related to ecosystem ecology. His research interests are focused on biogeochemistry, food webs, and animal resource allocation and movement.
Geology, Geophysics, and Geochemistry Stable Isotope Laboratory (GSIL)
Geology, Geophysics, and Geochemistry Stable Isotope Laboratory (GSIL)
The GSIL is a state-of-the-art facility located on the Denver Federal Center that specializes in the measurement of light stable isotope — Hydrogen (H), Carbon (C), Nitrogen (N), Oxygen (O), and Sulfur (S) — compositions and other chemical and biomarker analytes in matrices relevant to the Earth sciences.
Research Highlights
Research Highlights
- Continental-scale nutrient and contaminant delivery by Pacific salmon
- Diet and macronutrient assimilation in an Arctic predator
- Animal tracing with sulfur isotopes
- Effects of protein overconsumption limit dietary adaptation in an apex predator
- Carbon chemistry of peatlands in the southeastern USA
- Design, development, and implementation of IsoBank
- Diet energy density associated with survival, habitat, and population dynamics
As an ecologist at the Fort Collins Science Center, Craig Stricker’s research program focuses on an improved understanding of the roles of hydrology, biogeochemistry, and food web interactions on ecosystem structure and function with the goal of assisting land managers. His expertise in chemical and isotopic tracers offers novel insights in ecosystem ecology and has benefitted multidisciplinary collaborations across a variety of state, federal, and academic institutions. Tracer-based approaches to studying wildlife and ecosystems is a capability unique to Stricker’s research and the Fort Collins Science Center with examples ranging from wildlife nutrition, trophic dynamics, impacts of invasive species, animal movements and phenology, biogeochemistry, and environmental stressors such as fire and drought. The spatial domain of his work ranges from discrete habitats, regional assessments, to continental and oceanic basins, with studies from the sub-tropics to the high Arctic. Results of these projects inform on species life history and fitness to ecosystem health and function, but also offer frameworks for monitoring programs, model development, restoration, and risk assessment.
Professional Experience
2009 - Present, Research Biologist, US Geological Survey, Fort Collins Science Center
2005 - 2008, Research Biologist, US Geological Survey, Geologic Division - Crustal, Geology, and Geochemistry
2002 - 2004, Mendenhall Postdoctoral Fellow, US Geological Survey, Geologic Division - Crustal, Geology, and Geochemistry
Education and Certifications
PhD in Limnology, Michigan State University, 2003
MS in Aquatic Ecology, Central Michigan University, 1997
BS in Biology, Central Michigan University, 1994
Science and Products
Filter Total Items: 22
Chemistry of water, stream sediment, wildfire ash, soil, dust, and mine waste for Fourmile Creek Watershed, Colorado, 2010-2019 Chemistry of water, stream sediment, wildfire ash, soil, dust, and mine waste for Fourmile Creek Watershed, Colorado, 2010-2019
In response to the 2010 Fourmile Canyon fire near Boulder, Colorado, the U.S. Geological Survey collected data to support investigations into the magnitude and critical drivers of water-quality impairment after wildfire. We analyzed chemistry of stream water, sediment, wildfire ash, soil, dust, and mine waste for metals and other parameters in order to evaluate the effects of legacy...
Radiogenic strontium isotope data for non-native walleye otoliths collected from select areas of the Upper Colorado River Basin Radiogenic strontium isotope data for non-native walleye otoliths collected from select areas of the Upper Colorado River Basin
This dataset includes radiogenic strontium isotope compositions of non-native walleye otoliths collected from select areas of the Upper Colorado River Basin (UCRB). Strontium isotope data have been widely used to assess natal areas for a variety of fish species. Following on previous work, this project sought to fill data gaps for walleye collected from the Colorado River (river miles 11...
Stable carbon isotope and wood component concentration data for riparian cottonwood tree rings, Little Missouri River, North Dakota Stable carbon isotope and wood component concentration data for riparian cottonwood tree rings, Little Missouri River, North Dakota
This dataset includes stable carbon isotope values, lignin, cellulose, and hemicellulose concentrations (expressed as percent of ash-free dry mass) for riparian cottonwood (Populus deltoides) tree rings growing on the Little Missouri River floodplain, Theodore Roosevelt National Park, North Dakota. Drought stress induces stomatal closure and the carbon isotope ratio of annual tree rings...
Stable carbon and nitrogen isotope data for Siberian barn swallow subspecies collected during the breeding season Stable carbon and nitrogen isotope data for Siberian barn swallow subspecies collected during the breeding season
This dataset includes stable carbon and nitrogen isotope values for the inner tail retrices of three subspecies of barn swallow (Hirundo rustica rustica, H. r. tytleri, and H. r. gutturalis). Sampling was conducted in Russia (summer 2013), China (summer 2014), Mongolia (summer 2014), Japan (summer 2014), and western China (summer 2015) using mist nets. Stable carbon and nitrogen isotope...
Ovary mass and stable hydrogen isotope data for resident and migratory female dark-eyed juncos Ovary mass and stable hydrogen isotope data for resident and migratory female dark-eyed juncos
This dataset includes ovary mass and stable hydrogen isotope compositions of feathers and claws from resident and migratory female dark-eyed juncos (Junco hyemalis) collected during early spring at Mountain Lake Biological Station, Pembroke, Virginia. A total of 18 migrant and 15 resident female dark-eyed juncos, a songbird that exhibits seasonal sympatry, were caught during March-April...
Lignin phenol data for solid phase peat cores collected from the Alligator River and Great Dismal Swamp National Wildlife Refuges Lignin phenol data for solid phase peat cores collected from the Alligator River and Great Dismal Swamp National Wildlife Refuges
This dataset includes lignin phenol monomer concentrations normalized to 100 mg of organic carbon. These analyses were conducted on select intervals from peat cores collected at the Alligator River (AR) and Great Dismal Swamp (GDS) National Wildlife Refuges in North Carolina and Virginia/North Carolina, USA, respectively. The eight lignin phenol monomers provide unique proxy information...
Stable carbon and nitrogen isotope data for: 'Ecotoxicoparasitology of the gastrointestinal tracts of pinnipeds: effect of parasites on bioavailability of total mercury (THg)' Stable carbon and nitrogen isotope data for: 'Ecotoxicoparasitology of the gastrointestinal tracts of pinnipeds: effect of parasites on bioavailability of total mercury (THg)'
Parasites, such as acanthocephalans, cestodes, and some species of nematodes acquire nutrients from the lumen contents within the host gastrointestinal (GI) tract. For ubiquitous toxicants like mercury, both the host species and parasites are potentially exposed. The focus of this study was to determine if there is an effect of parasites on the dietary availability and therefore exposure...
Data for Biogeochemical and Physical Processes Controlling Mercury and Selenium Bioaccumulation in Bighorn Lake, Bighorn Canyon National Recreation Area, Montana and Wyoming, 2015-2016 Data for Biogeochemical and Physical Processes Controlling Mercury and Selenium Bioaccumulation in Bighorn Lake, Bighorn Canyon National Recreation Area, Montana and Wyoming, 2015-2016
This dataset includes the field measurements and laboratory analyses of surface water, seston, fish tissue, and sediment samples collected from Bighorn Lake, within Bighorn Canyon National Recreation area (BICA), during high flow (July 2015) and low flow (August 2016) conditions. The study area includes 7-9 sampling sites that follow a transect spanning the entire length of the reservoir...
Hydrogen stable isotope data for: 'Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird'. Hydrogen stable isotope data for: 'Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird'.
This dataset includes stable hydrogen isotope values of the nonexchangeable hydrogen contained in the outer most secondary feathers of dark-eyed juncos (Junco hyemalis thurberi) collected from the University of California San Diego campus in La Jolla, California in 2014. Hydrogen isotope values in feathers have become a powerful tool for inferring the breeding grounds of a wide variety...
Zinc concentrations and isotopic signatures of an aquatic insect (mayfly, Baetis tricaudatus) Zinc concentrations and isotopic signatures of an aquatic insect (mayfly, Baetis tricaudatus)
Insect metamorphosis often results in substantial chemical changes that can fractionate isotopes and alter contaminant concentrations. We exposed larval mayflies (Baetis tricaudatus) to an aqueous zinc gradient (3-340 g Zn/l) and measured the change in zinc tissue concentrations at different stages of metamorphosis. We also measured changes in stable isotopes (δ15N and δ13C) in unexposed...
Filter Total Items: 86
The reuse of avian samples: Opportunities, pitfalls and a solution The reuse of avian samples: Opportunities, pitfalls and a solution
Tissue samples are frequently collected to study various aspects of avian biology, but in many cases these samples are not used in their entirety and are stored by the collector. The already collected samples provide a largely overlooked opportunity because they can be used by different researchers in different biological fields. Broad reuse of samples could result in multispecies or...
Authors
Vojtech Brlik, Pavel Pipek, Kate Brandis, Nikita Chernetsov, Fabio Costa, L. Herrera M., Yosef Kiat, Richard B. Lanctot, Peter Marra, D. Norris, Chima Nwaogu, Petra Quillfeldt, Sarah Saalfeld, Craig Stricker, Robert Thomson, Tianhao Zhao, Petr Procházka
Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator
Studies of predator feeding ecology commonly focus on energy intake. However, captive predators have been documented to selectively feed to optimize macronutrient intake. As many apex predators experience environmental changes that affect prey availability, limitations on selective feeding can affect energetics and health. We estimated the protein:fat ratio of diets consumed by wild...
Authors
Karyn Rode, Charles Robbins, Craig Stricker, Brian Taras, Troy Tollefson
Temporal influences on selenium partitioning, trophic transfer, and exposure in a major U.S. river Temporal influences on selenium partitioning, trophic transfer, and exposure in a major U.S. river
Hydrologic and irrigation regimes mediate the timing of selenium (Se) mobilization to rivers, but the extent to which patterns in Se uptake and trophic transfer through recipient food webs reflect the temporal variation in Se delivery is unknown. We investigated Se mobilization, partitioning, and trophic transfer along approximately 60 river miles of the selenium-impaired segment of the...
Authors
Jessica E Brandt, James Roberts, Craig Stricker, Holly Rogers, Patricia Nease, Travis S. Schmidt
Breeding at higher latitude is associated with higher photoperiodic threshold and delayed reproductive development in a songbird Breeding at higher latitude is associated with higher photoperiodic threshold and delayed reproductive development in a songbird
Many seasonally breeding animals exhibit a threshold day length (critical photoperiod; CPP) for gonadal growth, and populations breeding at higher latitudes typically have a higher CPP. Much less is known about latitudinal variation in CPP in migratory population that winter away from their breeding range and must time their reproduction to match favorable conditions at their destination...
Authors
Devraj Singh, S. Reed, A. A. Kimmitt, K. Alford, Craig Stricker, P. D. Polly, Ellen Ketterson
Evidence of post-breeding prospecting in a long-distance migrant. Evidence of post-breeding prospecting in a long-distance migrant.
Organisms assess biotic and abiotic cues at multiple sites when deciding where to settle. However, due to temporal constraints on this prospecting, the suitability of available habitat may be difficult for an individual to assess when cues are most reliable, or at the time they are making settlement decisions. For migratory birds, the postbreeding season may be the optimal time to...
Authors
Max Ciaglo, Ross Calhoun, Scott Yanco, Michael B. Wunder, Craig Stricker, Brian Linkhart
Short- and long-term responses of riparian cottonwoods (Populus spp.) to flow diversion: Analysis of tree-ring radial growth and stable carbon isotopes Short- and long-term responses of riparian cottonwoods (Populus spp.) to flow diversion: Analysis of tree-ring radial growth and stable carbon isotopes
Long duration tree-ring records with annual precision allow for the reconstruction of past growing conditions. Investigations limited to the most common tree-ring proxy of ring width can be difficult to interpret, however, because radial growth is affected by multiple environmental processes. Furthermore, studies of living trees may miss important effects of drought on tree survival and...
Authors
Derek Schook, Jonathan Friedman, Craig Stricker, Adam Csank, David Cooper
Juvenile Coho and Chinook salmon growth, size, and condition linked to watershed-scale salmon spawner abundance Juvenile Coho and Chinook salmon growth, size, and condition linked to watershed-scale salmon spawner abundance
Anadromous Pacific salmon Oncorhynchus spp. are semelparous, and resource subsidies from spawning adult salmon (marine-derived nutrients [MDN]) benefit juvenile salmonids while they rear in freshwater. However, it is unclear if juvenile salmon populations respond predictably to the abundance of spawning salmon at the watershed scale. To address whether hypothesized benefits to rearing...
Authors
Philip Joy, Craig Stricker, Renae Ivanoff, Shiao Wang, Mark Wipfli, Andrew C. Seitz, Jiaqi Huang, Mathew Tyers
Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau
Migratory divides are proposed to be catalysts for speciation across a diversity of taxa. However, it is difficult to test the relative contributions of migratory behaviour vs. other divergent traits to reproductive isolation. Comparing hybrid zones with and without migratory divides offers a rare opportunity to directly examine the contribution of divergent migratory behaviour to...
Authors
Elizabeth Scordato, Christian Smith, Georgy Semenov, Liu Yu, Matthew Wilkins, Wei Liang, Alexander Rubtsov, Gombobaataar Sundev, Kazuo Koyama, Sheela Turbek, Michael B. Wunder, Craig Stricker, Rebecca Safran
Benthic algal (Periphyton) growth rates in response to nitrogen and phosphorus: Parameter estimation for water quality models Benthic algal (Periphyton) growth rates in response to nitrogen and phosphorus: Parameter estimation for water quality models
Nitrogen (N) and phosphorus (P) are important pollutants that can stimulate nuisance blooms of algae. Water-quality models (e.g., WASP, CE-QUAL-R1, CE-QUAL-ICM, QUAL2k) are valuable and widely used management tools for algal accrual because of excess nutrients in the presence of other limiting factors. These models utilize the Monod and Droop equations to associate algal growth rate with...
Authors
Travis S. Schmidt, Christopher Konrad, Janet Miller, Stephen Whitlock, Craig Stricker
Carbon chemistry of intact versus chronically drained peatlands in the southeastern USA Carbon chemistry of intact versus chronically drained peatlands in the southeastern USA
The Great Dismal Swamp (GDS) is a large temperate swamp in Virginia/North Carolina with peat soils historically resistant to microbial decomposition. However, this peatland has been subject to ~200 years of disturbance during which extensive drainage, fire suppression, and wide-spread logging have increased decomposition and dramatically decreased the distribution of Atlantic white cedar...
Authors
Craig Stricker, Judith Drexler, Kevin A. Thorn, Jamie A. Duberstein, Sam Rossman
Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbirds. Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbirds.
1. Divergent migratory strategies among populations can result in population-level differences in timing of reproduction (allochrony) and local adaptation. However, the mechanisms underlying among-population variation in timing are insufficiently understood, particularly in females. 2. We studied differences in reproductive development and its related mechanisms along the hypothalamic...
Authors
Abigail Kimmitt, Jack Hardman, Craig Stricker, Ellen Ketterson
Bridging the gap between salmon spawner abundance and marine nutrient assimilation by juvenile salmon: Seasonal cycles and landscape effects at the watershed scale Bridging the gap between salmon spawner abundance and marine nutrient assimilation by juvenile salmon: Seasonal cycles and landscape effects at the watershed scale
Anadromous Pacific salmon are semelparous, and resource subsidies from spawning adults (marine-derived nutrients, or MDN) benefit juvenile salmonids rearing in freshwater. However, it remains unclear how MDN assimilation relates to spawner abundance within a watershed. To address this, we examined seasonal, watershed-scale patterns of MDN assimilation in rearing coho (Oncorhynchus...
Authors
Philip J. Joy, Craig Stricker, Renae Ivanoff, Mark Wipfli, Andrew C. Seitz, Matthew Tyers
Non-USGS Publications**
Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 22
Chemistry of water, stream sediment, wildfire ash, soil, dust, and mine waste for Fourmile Creek Watershed, Colorado, 2010-2019 Chemistry of water, stream sediment, wildfire ash, soil, dust, and mine waste for Fourmile Creek Watershed, Colorado, 2010-2019
In response to the 2010 Fourmile Canyon fire near Boulder, Colorado, the U.S. Geological Survey collected data to support investigations into the magnitude and critical drivers of water-quality impairment after wildfire. We analyzed chemistry of stream water, sediment, wildfire ash, soil, dust, and mine waste for metals and other parameters in order to evaluate the effects of legacy...
Radiogenic strontium isotope data for non-native walleye otoliths collected from select areas of the Upper Colorado River Basin Radiogenic strontium isotope data for non-native walleye otoliths collected from select areas of the Upper Colorado River Basin
This dataset includes radiogenic strontium isotope compositions of non-native walleye otoliths collected from select areas of the Upper Colorado River Basin (UCRB). Strontium isotope data have been widely used to assess natal areas for a variety of fish species. Following on previous work, this project sought to fill data gaps for walleye collected from the Colorado River (river miles 11...
Stable carbon isotope and wood component concentration data for riparian cottonwood tree rings, Little Missouri River, North Dakota Stable carbon isotope and wood component concentration data for riparian cottonwood tree rings, Little Missouri River, North Dakota
This dataset includes stable carbon isotope values, lignin, cellulose, and hemicellulose concentrations (expressed as percent of ash-free dry mass) for riparian cottonwood (Populus deltoides) tree rings growing on the Little Missouri River floodplain, Theodore Roosevelt National Park, North Dakota. Drought stress induces stomatal closure and the carbon isotope ratio of annual tree rings...
Stable carbon and nitrogen isotope data for Siberian barn swallow subspecies collected during the breeding season Stable carbon and nitrogen isotope data for Siberian barn swallow subspecies collected during the breeding season
This dataset includes stable carbon and nitrogen isotope values for the inner tail retrices of three subspecies of barn swallow (Hirundo rustica rustica, H. r. tytleri, and H. r. gutturalis). Sampling was conducted in Russia (summer 2013), China (summer 2014), Mongolia (summer 2014), Japan (summer 2014), and western China (summer 2015) using mist nets. Stable carbon and nitrogen isotope...
Ovary mass and stable hydrogen isotope data for resident and migratory female dark-eyed juncos Ovary mass and stable hydrogen isotope data for resident and migratory female dark-eyed juncos
This dataset includes ovary mass and stable hydrogen isotope compositions of feathers and claws from resident and migratory female dark-eyed juncos (Junco hyemalis) collected during early spring at Mountain Lake Biological Station, Pembroke, Virginia. A total of 18 migrant and 15 resident female dark-eyed juncos, a songbird that exhibits seasonal sympatry, were caught during March-April...
Lignin phenol data for solid phase peat cores collected from the Alligator River and Great Dismal Swamp National Wildlife Refuges Lignin phenol data for solid phase peat cores collected from the Alligator River and Great Dismal Swamp National Wildlife Refuges
This dataset includes lignin phenol monomer concentrations normalized to 100 mg of organic carbon. These analyses were conducted on select intervals from peat cores collected at the Alligator River (AR) and Great Dismal Swamp (GDS) National Wildlife Refuges in North Carolina and Virginia/North Carolina, USA, respectively. The eight lignin phenol monomers provide unique proxy information...
Stable carbon and nitrogen isotope data for: 'Ecotoxicoparasitology of the gastrointestinal tracts of pinnipeds: effect of parasites on bioavailability of total mercury (THg)' Stable carbon and nitrogen isotope data for: 'Ecotoxicoparasitology of the gastrointestinal tracts of pinnipeds: effect of parasites on bioavailability of total mercury (THg)'
Parasites, such as acanthocephalans, cestodes, and some species of nematodes acquire nutrients from the lumen contents within the host gastrointestinal (GI) tract. For ubiquitous toxicants like mercury, both the host species and parasites are potentially exposed. The focus of this study was to determine if there is an effect of parasites on the dietary availability and therefore exposure...
Data for Biogeochemical and Physical Processes Controlling Mercury and Selenium Bioaccumulation in Bighorn Lake, Bighorn Canyon National Recreation Area, Montana and Wyoming, 2015-2016 Data for Biogeochemical and Physical Processes Controlling Mercury and Selenium Bioaccumulation in Bighorn Lake, Bighorn Canyon National Recreation Area, Montana and Wyoming, 2015-2016
This dataset includes the field measurements and laboratory analyses of surface water, seston, fish tissue, and sediment samples collected from Bighorn Lake, within Bighorn Canyon National Recreation area (BICA), during high flow (July 2015) and low flow (August 2016) conditions. The study area includes 7-9 sampling sites that follow a transect spanning the entire length of the reservoir...
Hydrogen stable isotope data for: 'Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird'. Hydrogen stable isotope data for: 'Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird'.
This dataset includes stable hydrogen isotope values of the nonexchangeable hydrogen contained in the outer most secondary feathers of dark-eyed juncos (Junco hyemalis thurberi) collected from the University of California San Diego campus in La Jolla, California in 2014. Hydrogen isotope values in feathers have become a powerful tool for inferring the breeding grounds of a wide variety...
Zinc concentrations and isotopic signatures of an aquatic insect (mayfly, Baetis tricaudatus) Zinc concentrations and isotopic signatures of an aquatic insect (mayfly, Baetis tricaudatus)
Insect metamorphosis often results in substantial chemical changes that can fractionate isotopes and alter contaminant concentrations. We exposed larval mayflies (Baetis tricaudatus) to an aqueous zinc gradient (3-340 g Zn/l) and measured the change in zinc tissue concentrations at different stages of metamorphosis. We also measured changes in stable isotopes (δ15N and δ13C) in unexposed...
Filter Total Items: 86
The reuse of avian samples: Opportunities, pitfalls and a solution The reuse of avian samples: Opportunities, pitfalls and a solution
Tissue samples are frequently collected to study various aspects of avian biology, but in many cases these samples are not used in their entirety and are stored by the collector. The already collected samples provide a largely overlooked opportunity because they can be used by different researchers in different biological fields. Broad reuse of samples could result in multispecies or...
Authors
Vojtech Brlik, Pavel Pipek, Kate Brandis, Nikita Chernetsov, Fabio Costa, L. Herrera M., Yosef Kiat, Richard B. Lanctot, Peter Marra, D. Norris, Chima Nwaogu, Petra Quillfeldt, Sarah Saalfeld, Craig Stricker, Robert Thomson, Tianhao Zhao, Petr Procházka
Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator
Studies of predator feeding ecology commonly focus on energy intake. However, captive predators have been documented to selectively feed to optimize macronutrient intake. As many apex predators experience environmental changes that affect prey availability, limitations on selective feeding can affect energetics and health. We estimated the protein:fat ratio of diets consumed by wild...
Authors
Karyn Rode, Charles Robbins, Craig Stricker, Brian Taras, Troy Tollefson
Temporal influences on selenium partitioning, trophic transfer, and exposure in a major U.S. river Temporal influences on selenium partitioning, trophic transfer, and exposure in a major U.S. river
Hydrologic and irrigation regimes mediate the timing of selenium (Se) mobilization to rivers, but the extent to which patterns in Se uptake and trophic transfer through recipient food webs reflect the temporal variation in Se delivery is unknown. We investigated Se mobilization, partitioning, and trophic transfer along approximately 60 river miles of the selenium-impaired segment of the...
Authors
Jessica E Brandt, James Roberts, Craig Stricker, Holly Rogers, Patricia Nease, Travis S. Schmidt
Breeding at higher latitude is associated with higher photoperiodic threshold and delayed reproductive development in a songbird Breeding at higher latitude is associated with higher photoperiodic threshold and delayed reproductive development in a songbird
Many seasonally breeding animals exhibit a threshold day length (critical photoperiod; CPP) for gonadal growth, and populations breeding at higher latitudes typically have a higher CPP. Much less is known about latitudinal variation in CPP in migratory population that winter away from their breeding range and must time their reproduction to match favorable conditions at their destination...
Authors
Devraj Singh, S. Reed, A. A. Kimmitt, K. Alford, Craig Stricker, P. D. Polly, Ellen Ketterson
Evidence of post-breeding prospecting in a long-distance migrant. Evidence of post-breeding prospecting in a long-distance migrant.
Organisms assess biotic and abiotic cues at multiple sites when deciding where to settle. However, due to temporal constraints on this prospecting, the suitability of available habitat may be difficult for an individual to assess when cues are most reliable, or at the time they are making settlement decisions. For migratory birds, the postbreeding season may be the optimal time to...
Authors
Max Ciaglo, Ross Calhoun, Scott Yanco, Michael B. Wunder, Craig Stricker, Brian Linkhart
Short- and long-term responses of riparian cottonwoods (Populus spp.) to flow diversion: Analysis of tree-ring radial growth and stable carbon isotopes Short- and long-term responses of riparian cottonwoods (Populus spp.) to flow diversion: Analysis of tree-ring radial growth and stable carbon isotopes
Long duration tree-ring records with annual precision allow for the reconstruction of past growing conditions. Investigations limited to the most common tree-ring proxy of ring width can be difficult to interpret, however, because radial growth is affected by multiple environmental processes. Furthermore, studies of living trees may miss important effects of drought on tree survival and...
Authors
Derek Schook, Jonathan Friedman, Craig Stricker, Adam Csank, David Cooper
Juvenile Coho and Chinook salmon growth, size, and condition linked to watershed-scale salmon spawner abundance Juvenile Coho and Chinook salmon growth, size, and condition linked to watershed-scale salmon spawner abundance
Anadromous Pacific salmon Oncorhynchus spp. are semelparous, and resource subsidies from spawning adult salmon (marine-derived nutrients [MDN]) benefit juvenile salmonids while they rear in freshwater. However, it is unclear if juvenile salmon populations respond predictably to the abundance of spawning salmon at the watershed scale. To address whether hypothesized benefits to rearing...
Authors
Philip Joy, Craig Stricker, Renae Ivanoff, Shiao Wang, Mark Wipfli, Andrew C. Seitz, Jiaqi Huang, Mathew Tyers
Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau
Migratory divides are proposed to be catalysts for speciation across a diversity of taxa. However, it is difficult to test the relative contributions of migratory behaviour vs. other divergent traits to reproductive isolation. Comparing hybrid zones with and without migratory divides offers a rare opportunity to directly examine the contribution of divergent migratory behaviour to...
Authors
Elizabeth Scordato, Christian Smith, Georgy Semenov, Liu Yu, Matthew Wilkins, Wei Liang, Alexander Rubtsov, Gombobaataar Sundev, Kazuo Koyama, Sheela Turbek, Michael B. Wunder, Craig Stricker, Rebecca Safran
Benthic algal (Periphyton) growth rates in response to nitrogen and phosphorus: Parameter estimation for water quality models Benthic algal (Periphyton) growth rates in response to nitrogen and phosphorus: Parameter estimation for water quality models
Nitrogen (N) and phosphorus (P) are important pollutants that can stimulate nuisance blooms of algae. Water-quality models (e.g., WASP, CE-QUAL-R1, CE-QUAL-ICM, QUAL2k) are valuable and widely used management tools for algal accrual because of excess nutrients in the presence of other limiting factors. These models utilize the Monod and Droop equations to associate algal growth rate with...
Authors
Travis S. Schmidt, Christopher Konrad, Janet Miller, Stephen Whitlock, Craig Stricker
Carbon chemistry of intact versus chronically drained peatlands in the southeastern USA Carbon chemistry of intact versus chronically drained peatlands in the southeastern USA
The Great Dismal Swamp (GDS) is a large temperate swamp in Virginia/North Carolina with peat soils historically resistant to microbial decomposition. However, this peatland has been subject to ~200 years of disturbance during which extensive drainage, fire suppression, and wide-spread logging have increased decomposition and dramatically decreased the distribution of Atlantic white cedar...
Authors
Craig Stricker, Judith Drexler, Kevin A. Thorn, Jamie A. Duberstein, Sam Rossman
Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbirds. Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbirds.
1. Divergent migratory strategies among populations can result in population-level differences in timing of reproduction (allochrony) and local adaptation. However, the mechanisms underlying among-population variation in timing are insufficiently understood, particularly in females. 2. We studied differences in reproductive development and its related mechanisms along the hypothalamic...
Authors
Abigail Kimmitt, Jack Hardman, Craig Stricker, Ellen Ketterson
Bridging the gap between salmon spawner abundance and marine nutrient assimilation by juvenile salmon: Seasonal cycles and landscape effects at the watershed scale Bridging the gap between salmon spawner abundance and marine nutrient assimilation by juvenile salmon: Seasonal cycles and landscape effects at the watershed scale
Anadromous Pacific salmon are semelparous, and resource subsidies from spawning adults (marine-derived nutrients, or MDN) benefit juvenile salmonids rearing in freshwater. However, it remains unclear how MDN assimilation relates to spawner abundance within a watershed. To address this, we examined seasonal, watershed-scale patterns of MDN assimilation in rearing coho (Oncorhynchus...
Authors
Philip J. Joy, Craig Stricker, Renae Ivanoff, Mark Wipfli, Andrew C. Seitz, Matthew Tyers
Non-USGS Publications**
Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.