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Colleen A Caldwell

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Effects of Non-native Brown Trout and Temperature on the Production of Rio Grande Cutthroat Trout Populations
Native Cutthroat Trout Oncorhynchus clarkii spp. populations in the western U.S. have declined in part due to displacement by nonnative trout, but mechanisms to explain displacement vary by species and geography. Using a production framework, we demonstrated allopatric populations of Rio Grande Cutthroat Trout O. c. virginalis (RGCT) exhibited consistently higher biomass and secondary production rates (0.19–0.92 g DM·m-2·yr-1) than sympatric populations with Brown Trout Salmo trutta (0.01–0.05 g DM·m-2·yr-1) and that an interactive temperature effect on RGCT biomass and production was overshadowed by the presence of Brown Trout across cold and warm streams. Interestingly, over half of trout production was fueled...
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
We studied the impacts of drought and invasive trout on survival and productivity on Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis, RGCT) populations. Rio Grande cutthroat trout is the southernmost subspecies of cutthroat trout and endemic to the Rio Grande, Canadian, and Pecos River basins of Colorado and New Mexico. The subspecies is reduced to less than 11% of its historic range with most populations occupying isolated high elevation headwater streams. One of the greatest threats to its survival is the effect that low stream flow due to drought will have on this coldwater trout living at the edge of its range. Our work will provide insight into the current and future threats of RGCT populations...
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The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
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