Craig Stricker, PhD
Craig Stricker is a Research Biologist at the Fort Collins Science Center.
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Isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast fo
Authors
Karyn D. Rode, Craig A. Stricker, Joy Erlenbach, Charles T. Robbins, Seth Cherry, Seth D. Newsome, Amy Cutting, Shannon Jensen, Gordon Stenhouse, Matt Brooks, Amy Hash, Nicole Nicassio
Reproductive allochrony in seasonally sympatric populations maintained by differential response to photoperiod: Implications for population divergence and response to climate change
Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in response to supp
Authors
A.M. Fudickar, T.J. Grieves, Jonathan W. Atwell, Craig A. Stricker, Ellen D. Ketterson
Wood decay in desert riverine environments
Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks or cylind
Authors
Douglas Andersen, Craig A. Stricker, S. Mark Nelson
Isotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellula
Authors
Richard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David Walters, Travis S. Schmidt, Francesca Podda, G. De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, R. Cidu
Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)
Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the
Authors
Ashley K. McGrew, Todd M. O'Hara, Craig A. Stricker, Margaret Castellini, Kimberlee B. Beckmen, Mo D. Salman, Lora R. Ballweber
Comment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174."
Donders (2014) has recently proposed that the climate of Florida became progressively wetter over the past 5000 years in response to a marked strengthening of the El Niño regime. This reconstruction is largely based on a re-analysis of pollen records from regions north of Lake Okeechobee (Fig. 1) using a new set of pollen transfer functions. Donders concluded that a latitudinal gradient in precipi
Authors
Paul H. Glaser, Barbara CS Hansen, Joseph J. Donovan, Thomas J. Givnish, Craig A. Stricker, John C. Volin
Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions
Steller sea lions (SSL; Eumetopias jubatus) grow their vibrissae continually, providing a multiyear record suitable for ecological and physiological studies based on stable isotopes. An accurate age-specific vibrissae growth rate is essential for registering a chronology along the length of the record, and for interpreting the timing of ecologically important events. We utilized four methods to es
Authors
L.D. Rea, A.M. Christ, A.B. Hayden, V.K. Stegall, S.D. Farley, Craig A. Stricker, J.E. Mellish, John M. Maniscalco, J.N. Waite, V.N. Burkanov, K.W. Pitcher
Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary
We examine individual specialization in foraging habits (foraging habitat and trophic level) of female bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, Florida, USA, by analyzing time series of stable isotope (δ15N and δ13C) values in sequential growth layer groups within teeth. The isotope data provide a chronology of foraging habits over the lifetime of the individual and allow
Authors
Sam Rossman, Peggy H. Ostrom, Megan Stolen, Nélio B. Barros, Hasand Gandhi, Craig A. Stricker, Randall S. Wells
Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus
Multiple factors, including limitation in food resources, have been proposed as possible causes for the lack of recovery of the endangered western segment of the Steller sea lion population in the United States. Because maternal body condition has important consequences on fetal development and neonatal survival, the diets of pregnant females may be particularly important in regulating population
Authors
Rick D. Scherer, Andrew C. Doll, Lorrie D. Rea, Aaron M. Christ, Craig A. Stricker, Briana Witteveen, Thomas C. Kline, Carolyn M. Kurle, Michael B. Wunder
Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets
Nutritional constraints have been proposed as a contributor to population declines in the endangered Steller sea lion Eumetopias jubatus in some regions of the North Pacific. Isotopic analysis of vibrissae (whiskers) is a potentially useful approach to resolving the nutritional ecology of this species because long-term (up to 8 yr) dietary information is sequentially recorded and metabolically ine
Authors
Craig A. Stricker, Aaron M. Christ, Michael B. Wunder, Andrew C. Doll, Sean D. Farley, Lorrie D. Rea, David A. S. Rosen, R. D. Scherer, Dominic J. Tollit
Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
The use of stable isotopes in animal ecology depends on accurate descriptions of isotope dynamics within individuals. The prevailing assumption that laboratory-derived isotopic parameters apply to free-living animals is largely untested. We used stable carbon isotopes (δ13C) in whole blood from migratory Dunlin (Calidris alpina arcticola) to estimate an in situ turnover rate and individual diet-sw
Authors
Andrew C. Doll, Richard B. Lanctot, Craig A. Stricker, Stephen M. Yezerinac, Michael B. Wunder
Foraging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus)
This study examines resource use (diet, habitat use, and trophic level) within and among demographic groups (males, females, and juveniles) of bottlenose dolphins (Tursiops truncatus). We analyzed the δ13C and δ15N values of 15 prey species constituting 84% of the species found in stomach contents. We used these data to establish a trophic enrichment factor (TEF) to inform dietary analysis using a
Authors
Sam Rossman, Elizabeth Berens McCabe, Nelio B. Barros, Hasand Gandhi, Peggy H. Ostrom, Craig A. Stricker, Randall S. Wells
Non-USGS Publications**
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789
Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866
**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.
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Isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast foAuthorsKaryn D. Rode, Craig A. Stricker, Joy Erlenbach, Charles T. Robbins, Seth Cherry, Seth D. Newsome, Amy Cutting, Shannon Jensen, Gordon Stenhouse, Matt Brooks, Amy Hash, Nicole NicassioReproductive allochrony in seasonally sympatric populations maintained by differential response to photoperiod: Implications for population divergence and response to climate change
Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in response to suppAuthorsA.M. Fudickar, T.J. Grieves, Jonathan W. Atwell, Craig A. Stricker, Ellen D. KettersonWood decay in desert riverine environments
Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks or cylindAuthorsDouglas Andersen, Craig A. Stricker, S. Mark NelsonIsotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellulaAuthorsRichard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David Walters, Travis S. Schmidt, Francesca Podda, G. De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, R. CiduEcotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)
Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within theAuthorsAshley K. McGrew, Todd M. O'Hara, Craig A. Stricker, Margaret Castellini, Kimberlee B. Beckmen, Mo D. Salman, Lora R. BallweberComment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174."
Donders (2014) has recently proposed that the climate of Florida became progressively wetter over the past 5000 years in response to a marked strengthening of the El Niño regime. This reconstruction is largely based on a re-analysis of pollen records from regions north of Lake Okeechobee (Fig. 1) using a new set of pollen transfer functions. Donders concluded that a latitudinal gradient in precipiAuthorsPaul H. Glaser, Barbara CS Hansen, Joseph J. Donovan, Thomas J. Givnish, Craig A. Stricker, John C. VolinAge-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions
Steller sea lions (SSL; Eumetopias jubatus) grow their vibrissae continually, providing a multiyear record suitable for ecological and physiological studies based on stable isotopes. An accurate age-specific vibrissae growth rate is essential for registering a chronology along the length of the record, and for interpreting the timing of ecologically important events. We utilized four methods to esAuthorsL.D. Rea, A.M. Christ, A.B. Hayden, V.K. Stegall, S.D. Farley, Craig A. Stricker, J.E. Mellish, John M. Maniscalco, J.N. Waite, V.N. Burkanov, K.W. PitcherIndividual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary
We examine individual specialization in foraging habits (foraging habitat and trophic level) of female bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, Florida, USA, by analyzing time series of stable isotope (δ15N and δ13C) values in sequential growth layer groups within teeth. The isotope data provide a chronology of foraging habits over the lifetime of the individual and allowAuthorsSam Rossman, Peggy H. Ostrom, Megan Stolen, Nélio B. Barros, Hasand Gandhi, Craig A. Stricker, Randall S. WellsStable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus
Multiple factors, including limitation in food resources, have been proposed as possible causes for the lack of recovery of the endangered western segment of the Steller sea lion population in the United States. Because maternal body condition has important consequences on fetal development and neonatal survival, the diets of pregnant females may be particularly important in regulating populationAuthorsRick D. Scherer, Andrew C. Doll, Lorrie D. Rea, Aaron M. Christ, Craig A. Stricker, Briana Witteveen, Thomas C. Kline, Carolyn M. Kurle, Michael B. WunderStable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets
Nutritional constraints have been proposed as a contributor to population declines in the endangered Steller sea lion Eumetopias jubatus in some regions of the North Pacific. Isotopic analysis of vibrissae (whiskers) is a potentially useful approach to resolving the nutritional ecology of this species because long-term (up to 8 yr) dietary information is sequentially recorded and metabolically ineAuthorsCraig A. Stricker, Aaron M. Christ, Michael B. Wunder, Andrew C. Doll, Sean D. Farley, Lorrie D. Rea, David A. S. Rosen, R. D. Scherer, Dominic J. TollitImproved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
The use of stable isotopes in animal ecology depends on accurate descriptions of isotope dynamics within individuals. The prevailing assumption that laboratory-derived isotopic parameters apply to free-living animals is largely untested. We used stable carbon isotopes (δ13C) in whole blood from migratory Dunlin (Calidris alpina arcticola) to estimate an in situ turnover rate and individual diet-swAuthorsAndrew C. Doll, Richard B. Lanctot, Craig A. Stricker, Stephen M. Yezerinac, Michael B. WunderForaging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus)
This study examines resource use (diet, habitat use, and trophic level) within and among demographic groups (males, females, and juveniles) of bottlenose dolphins (Tursiops truncatus). We analyzed the δ13C and δ15N values of 15 prey species constituting 84% of the species found in stomach contents. We used these data to establish a trophic enrichment factor (TEF) to inform dietary analysis using aAuthorsSam Rossman, Elizabeth Berens McCabe, Nelio B. Barros, Hasand Gandhi, Peggy H. Ostrom, Craig A. Stricker, Randall S. WellsNon-USGS Publications**
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866**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.