Microhabitat Selection and Movement Patterns of Black Rat Snakes (Pantherophis obsoletus obsoletus) in the Western Piedmont of North Carolina

Lisa C. Marks, Pierson Hill, Diana C. Chemotti and Michael E. Dorcas

Black rat snakes (Elaphe obsoleta) have a large geographic range, extending from southeastern Ontario west to Kansas and south to the Gulf Coast of Texas. Because of its broad range, populations of these snakes can differ greatly in habitat, activity, and home range size. To investigate black rat snake ecology in Davidson, North Carolina, we surgically implanted radio transmitters into 10 adult snakes captured on the Davidson College Ecological Preserve. Over the past year, we tracked each snake twice a week via radiotelemetry. When a snake was located, we recorded its location, general habitat, microhabitat, behavior, position, exposure to the sun, and UTMs. Using GIS, we analyzed home range size and activity patterns. By determining these factors in addition to habitat preferences of black rat snakes under natural conditions, this study will provide information necessary for the development of sound management and conservation plans.

Radio transmitter, coated in plasti-dip
The snake is intubated and placed under anesthesia
Insertion of transmitter into body cavity of snake
Radiotracking equipment: a receiver and antenna
Radiotracking in the field


Average Seasonal Variation in Movement


Microhabitat Selection


Mean Home Range Size vs. Sex



Our current conclusions are tentative as we plan to continue the study for several more years. Presented below are our preliminary conlusions representing nour interpretation of the first year's worth of data.

1. We located black rat snakes most frequently underground and least frequently on the surface. Other microhabitats frequented included up in trees, inside trees, and in tree stumps.

2. Black rat snakes were most active in the spring and early fall, with activity decreasing in the winter months during hibernation.

3. Mean black rat snake home range size in our study was smaller than that of other studies, which could be attributed to a short study duration thus far.

4. Preliminary results indicate that mean female home range size was greater than mean male home range. This differs from the results of previous studies, and may be due to our short study duration thus far.

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