Physiology of Stress in Wild Animals

Tufts University, Medford MA

Investigators

Abstract

L. Michael Romero Physiology of Stress in Wild Animals Proposal Number 0235044 All organisms are faced with noxious stimuli from the environment (such as predators or storms). Vertebrates activate a suite of physiological mechanisms to protect themselves from these stimuli, collectively called the stress response. A vital part of the stress response is the release of the glucocorticoid steroid hormones, but even after more than 60 years of studying stress we still have only a rudimentary idea of how glucocorticoids help wild animals survive. Earlier work indicated that several free-living bird species seasonally regulate glucocorticoid release by varying concentrations of the hormone throughout the year. This proposal builds upon these results to ask the following questions: why do animals seasonally regulate glucocorticoid levels; is there a physiological consequence; and does it affect their susceptibility to chronic stress? Answering these questions will require an integrated approach of both laboratory and field studies, such as the one proposed here. We will capture wild free-living house sparrows (Passer domesticus) and test how glucocorticoids help regulate blood glucose and triglyceride levels at different times of the year. We anticipate that glucose and triglyceride regulation will depend upon seasonal changes in glucocorticoid levels. We will also bring house sparrows into the laboratory to test whether physiological responses to chronic stress vary seasonally. We anticipate that the magnitude of the negative consequences of chronic stress will depend upon the time of year. These results will help define the physiological consequences of seasonal glucocorticoid release during stress in wild animals, thus having a far-reaching impact on our basic knowledge of the ecological validity of stress responses. This research will also provide important training for students. Both graduate and undergraduate students will be exposed to, and learn, many important research skills in both the laboratory and field. These findings will be valuable to researchers in diverse fields including Conservation Biology, Endocrinology, and Population Biology, just to mention a few.