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.
","abstract_html":"<p>Semiaquatic snakes are disproportionately impacted by habitat alteration adjacent to wetlands because of their reliance on both terrestrial and aquatic habitats. Brazos River Watersnakes, <em>Nerodia harteri</em>, are endemic natricines with one of the most restricted geographic ranges in North America. I quantified detection and site occupancy probabilities of <em>N. harteri</em> and its sympatric congeners (<em>N. erythrogaster</em> and <em>N. rhombifer</em>), as well as microhabitat selection within the <em>Nerodia</em> community. Within occupied transects, search effort was positively correlated with detecting <em>N. harteri</em>, whereas environmental and/or habitat variables were better predictors for detecting the sympatric congeners. Microhabitat selection between the three <em>Nerodia</em> species varied, with <em>N. harteri</em> 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 (<em>Tamarix</em> spp.). The results indicate the sympatric <em>Nerodia</em> spp. are partitioning their habitat to some degree, likely related to foraging activities. To better understand demographic trends of <em>Nerodia harteri</em>, 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.</p>","abstract_has_math":false,"creators":["Yates, Jessica"],"institution":null,"degree_name":"Master of Science - Biology","degree_level":"Thesis","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":["Matthew Kwiatkowski","Stephen J. Mullin","Daniel Saenz"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-05-07T07:00:00Z","date_published":"2022-05-07T07:00:00Z","updated_at":"2026-07-24T04:30:37Z","subjects":["Brazos River Watersnakes","aquatic habitat","niche overlap","search effort","Biology","Ecology and Evolutionary Biology","Terrestrial and Aquatic Ecology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.sfasu.edu/etds/447","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Matthew Kwiatkowski","Stephen J. Mullin","Daniel Saenz"]},{"key":"dc:creator","label":"Author","values":["Yates, Jessica"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2022-04-21T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science - Biology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Brazos River Watersnakes","aquatic habitat","niche overlap","search effort","Biology","Ecology and Evolutionary Biology","Terrestrial and Aquatic Ecology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.sfasu.edu/etds/447"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["DETECTION AND OCCURRENCE OF NERODIA HARTERI (SERPENTES: COLUBRIDAE) IN AN UPPER PORTION OF THE BRAZOS RIVER WATERSHED"]}]}],"canonical_facts":{"dc:contributor":["Matthew Kwiatkowski","Stephen J. Mullin","Daniel Saenz"],"dc:creator":["Yates, Jessica"],"dc:date.available":["2022-04-21T07:00:00Z"],"dc:description.abstract":["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.
"],"dc:identifier":["https://scholarworks.sfasu.edu/etds/447"],"dc:subject":["Brazos River Watersnakes","aquatic habitat","niche overlap","search effort","Biology","Ecology and Evolutionary Biology","Terrestrial and Aquatic Ecology"],"dc:title":["DETECTION AND OCCURRENCE OF NERODIA HARTERI (SERPENTES: COLUBRIDAE) IN AN UPPER PORTION OF THE BRAZOS RIVER WATERSHED"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science - Biology"]},"updated_at":"2026-07-24T04:30:37Z"}