Meeting Abstract
Glucocorticoids are hormones that free up energy which allows organisms to deal with challenging events. Challenging events, or “stressors” can include predictive daily, seasonal, or lifetime changes with regard to the life history of the organism. For example, organisms may maintain elevated glucocorticoid levels during more active times of the year such as foraging or the mating season. The objective of our study was to determine if individual timber rattlesnakes (Crotalus horridus) that maintain greater movement rates also maintain elevated baseline corticosterone (CORT) levels. We radio-tracked timber rattlesnakes (n = 12) every 2-3 days for two years (2016 and 2017) and collected blood samples from individuals during mid-summer (reproductive season) of each year. We determined CORT levels for each blood sample using a competitive enzyme immunoassay. We determined movement rates and home range sizes using ArcGIS. We compared individual movement rates with baseline corticosterone levels using a mixed-model linear regression. Individuals with greater movement rates also had higher baseline CORT levels (F1,3= 23.76, P = 0.017). Although males tended to have higher baseline CORT levels compared to females (F1,3 = 7.95, P = 0.067), it is important to note that not all male snakes had high movement rates (and thus did not maintain elevated baseline CORT levels). Snakes that moved more often maintained larger home ranges (t = 4.48, df = 18,P <0.001). Results from this study can assist biologists in interpreting the effect of behaviors on an animal’s physiology and further assist in the definition of a “stressor”.
