L Michael Romero

..Overall, our data suggest that molt is not only energetically expensive but that it also alters multiple stress response pathways. Furthermore, most acute stressors do not appear to require a significant increase in energy expenditure...

..Reactive scope thus provides a foundation for interpreting and predicting physiological stress responses...

..Consequently, seasonal modulation of corticosterone release in house sparrows appear to result from a complicated mix of adrenal, pituitary, and hypothalamic changes that also vary seasonally...

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..The results suggest a tradeoff; a complete set of new feathers may be more important to the survival of a bird than the ability of CORT to respond maximally to a stressor...

..However, the failure of negative feedback at night suggests that the response is not equivalent to the controlled downregulation seen in mammals...

..The Reactive Scope Model, as an extension of allostasis, should be useful to both biomedical researchers studying laboratory animals and humans, as well as ecologists studying stress in free-living animals...

..Stress-induced free CORT, however, was higher in Massachusetts males and females during the Fall and Winter, suggesting a potential differential response to stress associated with commensalism...

..These data suggest that a greater ability to terminate a stress response conferred a survival advantage during starvation...

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..Taken together, these data provide further evidence that there are complex regulatory mechanisms controlling diel and seasonal changes in corticosterone titers in birds...

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..The duration of these alterations likely varies due to differences in capture techniques, transport distance, and species studied...

..Overall, our results suggest that more research is need before FGM analysis can be used as a reliable measure of stress in animals, especially those kept in captivity...

..These data are the first to show that successive acute stressors and introduction to a captive setting significantly alter the physiology and responsiveness of the cardiovascular stress response system...

..These data support the hypothesis that AVT's attenuation of general behavior and crowding induced aggression are modulated by a cardiovascular mechanism...

..Finally, openness measures may have applications for predicting effects of habitat management or development, such as adding wind turbines, in open habitat...

..This seasonal shift in response suggests that a higher tolerance for intrusion (i.e., considering a nearby starling as less stressful) may facilitate flocking behavior, while a lower tolerance may aid in territoriality...

..However, both central and peripheral AVT attenuated heart rate independent of increased plasma corticosterone. These data suggest that AVT's behavioral effects may be modulated by a corticosterone-independent cardiovascular mechanism...

..Together, these data suggest that the baseline B rhythm in marine iguanas is influenced by the tidal cycle/food intake as well as the light:dark cycle...

..Overall, chronic stress in wild-caught starlings elicited profound changes in cardiac function that were primarily regulated by changes in the PNS...

..We extend that paradigm by demonstrating that nest style may influence how adults perceive the correlation between offspring-directed and self-directed threats...

..In conclusion, starlings appear resistant to developing symptoms of chronic stress from repeated food restriction...

..These data indicate that it is not always a good assumption that birds can be categorized as individuals with higher and lower titers, which will complicate analyses of the causes of interindividual variation...

..Additionally, the purpose for downregulating CORT concentrations during molt appears to be more complicated than simply protecting feather production from CORT's catabolic effects...

..Altogether these findings suggest that tree swallows chronically exposed to high PCB and TCDD levels exhibit altered baseline and stress-induced corticosterone responses, but the patterns of alteration might not be predictable...

..Overall, the data suggest that molt requires a degree of physiological stability that must be protected, so that if a bird is exposed to chronic stress during this life-history stage, molt takes priority...

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..The ability to sample blood from spotted salamanders using a non-lethal technique offers an opportunity to better understand both amphibian physiology and ecology...

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..These tests will help identify hormonal habituation in free-living animals and prevent potential problems of falsely describing an individual or population of individuals as habituated...

..This conclusion emphasizes the need for understanding and alleviating translocation-induced chronic stress in order to use most effectively this important conservation tool...

..We conclude that minor changes in temperature can elicit a stress response in European starlings, which suggests that this may be an important mechanism by which animals cope with minor rapid environmental changes...

..Further, mercury contamination may not alter stress-induced corticosterone concentrations in tree swallows but appears to have a significant impact on baseline circulating corticosterone...

..The data indicate that starlings modulate HR, CORT, and behavioral responses depending upon the stressor, but that these three pathways are regulated independently...

..Brood size was not correlated with age of nest departure or individual corticosterone concentrations. These data indicate that it is unlikely that corticosterone plays a role in triggering nest departure in snowy owl chicks...

..Consequently, understanding seasonal modulation of GC release has far-reaching importance for both the physiology of the stress response and the short-term survival of individual animals...

..017). No associations were found between cortisol and age or parity. The implications of these findings for maternity health service policy and practice in Eritrea are considered...

..Z. l. gambelii retain sensitivity to corticosterone levels that may occur naturally in response to environmental perturbations resulting in suppression of territorial behavior...

..In general, we predict that island endemics show flexible physiological stress responses but are restricted by narrow behavioural plasticity...

..Our results suggest that GC-induced changes in respiration may be important for understanding the overall energetic implications of stress...

..The data suggest that even under polar day conditions diel rhythms can persist. The maintenance of hormone rhythms could provide a physiological basis to reports of rhythmic behavior in many birds during the Arctic summer...

..This study presents evidence for adrenocortical involvement in avian pair bonding, and for hypothalamic-pituitary-adrenal activation in response to an ecologically relevant social stressor...

..Our data show that cort can induce immunosuppression, but they do not support the immunocompetence handicap hypothesis in its narrow sense because T concentrations were not related to immunosuppression...

..However, the adjustments in FID are not sufficient to cope with the novel predators. We suggest that low behavioral plasticity in the face of introduced predators may drive many island species to extinction...