The Spatial Ecology of the Timber Rattlesnake (Crotalus horridus) in southeastern Louisiana

The Timber Rattlesnake (Crotalus horridus) has a large distribution spanning much of the eastern United States. Because temperature, habitat type, prey composition and abundance, and a variety of other factors may dictate reptile behavior, populations of conspecific species may exhibit behavioral differences across latitudinal and elevational gradients. Using radio telemetry, we tracked 10 adult Timber Rattlesnakes (7 males, 3 females) from May 2016 to June 2017 in southeastern Louisiana to examine the spatial ecology of male and non-gravid female snakes. Mean annual and seasonal home ranges of non-gravid female Timber Rattlesnakes were not statistically different from that of males. Mean seasonal home range sizes and average distances travelled of both sexes was smallest in winter, and had a general increasing trend beginning in spring with a peak in fall. These increases seemed to coincide with the breeding season, taking place from early July until the end of November. Comparison of this study with other studies throughout its distribution could have implications towards future management of conservation for other southern populations of Timber Rattlesnakes.

Abstract 15837: Particulate Matter 2.5 Exposure Increases Risk of Subsequent Myocardial Infarction

Introduction: Particulate matter 2.5 (PM 2.5 ) are airborne particles small enough to be inhaled into the pulmonary alveoli, and are associated with increased hospitalization rates, morbidity, and mortality. The purpose of this study was to evaluate the levels of PM 2.5 in southeastern Louisiana and describe associated cardiovascular outcomes in patients with a history of myocardial infarction (MI). Methods: Air quality monitoring stations were placed around southeastern Louisiana and were analyzed from March 1 st , 2019 to March 1 st , 2020. Samples were collected every 80 seconds, and values were aggregated at the hourly and daily level. We used conditional logistic regression models to determine the risk of MI. Control observations per patient were created using PM 2.5 exposure on the same day of the week for the two weeks before and after the event. Temperature, pressure, humidity, and their interactions with PM 2.5 were included in the model. Results: The average PM 2.5 exposure for the year was 10.41 ug/m 3 +/- 5.57 ug/m 3 , with a daily low of 1.93 ug/m 3 and a daily high of 31.32 ug/m 3 . Peaks from individual sensors reached PM 2.5 concentrations greater than 100 ug/m 3 . PM 2.5 concentration showed a significant, weakly positive correlation with daily average temperature and a significant, weakly negative correlation with daily average barometric pressure. Among patients (n=263) with history of MI, risk of subsequent MI increased by 24.3% per 10 ug/m 3 increase in PM 2.5 exposure with a lag of three days after exposure. (Figure) No significant risk associated with PM 2.5 exposure was observed at shorter lag times. Conclusion: Although the average PM 2.5 levels in southeastern Louisiana were within the WHO guidelines of air quality, PM 2.5 exposure remained a significant risk factor for MI among a those with previous MI.