The potential for competition between the red-bellied turtle (Pseudemys rubriventris) and the red-eared slider turtle (Trachemys scripta elegans)

Invasive species are a significant cause of biodiversity declines on a global scale and novel species interactions often cause ecological damage through predation or competition. The red-eared slider turtle (Trachemys scripta elegans) has been introduced to wetlands globally and negatively impacts other native turtle species. In Pennsylvania, USA, the red-eared slider turtle is ecologically similar to the PA, state threatened red-bellied turtle (Pseudemys rubriventris). The objective of this dissertation is to examine the potential for competition between red-eared slider turtles and red-bellied turtles using field studies of adult free ranging turtles and manipulative studies of juvenile turtles in mesocosms. Field studies utilized intensive trapping, radio telemetry, stomach flushing, fecal sample collection and stable isotopes to determine populations sizes, spatial resource use and dietary resource use of both species. Intensive trapping and radio telemetry revealed that both species used wetland habitats ubiquitously. Dietary studies revealed that at a smaller, more highly fragmented and vegetative species depauperate wetland complex, red-eared slider turtles and red-bellied turtles overlapped extensively for dietary resources while at a larger, intact, more vegetative species rich wetland the diets of both species were partitioned. In manipulative experiments in which red-eared slider turtles and red-bellied turtles were housed in low resource availability groups and high resource availability groups with conspecifics or in mixed species groups red-eared slider turtles were competitively superior to red-bellied turtles. Field study results suggest that the potential for competition between red-eared slider turtles and red-bellied turtles varies depending on local habitat characteristics, while manipulative experiment results suggest that red-eared slider turtles are competitively superior in resource limited environments. These results combined suggest that in degraded wetland habitats, when resources become limited, red-eared slider turtles will have a competitive advantage over red-bellied turtles potentially leading to population declines. Red-eared slider turtles should not be sold outside of their native range as pets and when possible they should be removed from wetland habitats outside of their native range. Furthermore, wetland habitats should be managed and preserved to provide intact, species rich and species diverse habitats.