Date of Award

Spring 5-7-2022

Degree Type


Degree Name

Master of Science - Biology



First Advisor

Matthew Kwiatkowski

Second Advisor

Stephen J. Mullin

Third Advisor

Daniel Saenz

Fourth Advisor

Josephine Taylor


Semiaquatic snakes are disproportionately impacted by habitat alteration adjacent to wetlands because of their reliance on both terrestrial and aquatic habitats. Brazos River Watersnakes, Nerodia harteri, are endemic natricines with one of the most restricted geographic ranges in North America. I quantified detection and site occupancy probabilities of N. harteri and its sympatric congeners (N. erythrogaster and N. rhombifer), as well as microhabitat selection within the Nerodia community. Within occupied transects, search effort was positively correlated with detecting N. harteri, whereas environmental and/or habitat variables were better predictors for detecting the sympatric congeners. Microhabitat selection between the three Nerodia species varied, with N. harteri selecting for riffle presence and increased canopy cover. The focal species was 97% less likely to be found in habitat characterized by bank vegetation containing saltcedar (Tamarix spp.). The results indicate the sympatric Nerodia spp. are partitioning their habitat to some degree, likely related to foraging activities. To better understand demographic trends of Nerodia harteri, long-term monitoring is needed, and habitat management — such as the preservation of riffle habitat — might be necessary to minimize the risk of continued population declines.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



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