Let us imagine a young child who has grown bored of his pet turtles. The parents decide that the right thing to do is to release the turtles into the wild. In the child’s mind, the turtles go on to become crime fighting ninjas like in the popular cartoon series “Teenage Mutant Ninja Turtles”. The child is correct in the sense that his red-eared sliders will thrive, but research shows the sinister reality of these stars: their success threatens other turtle species across the United States.
Red-eared sliders have become a popular pet, but their popularity has a dark side. Their native range is in the Southern United States, but they have since spread to distant corners of the country. According to the United States Geological Survey’s website, they have spread as far as Oregon, New York, and even Hawaii. In fact, the IUCN’s Invasive Species Specialist Group has listed them among the top one hundred most invasive species. So what kind of damage are these turtles causing to their new habitats?
A new study published in Biological Conservation by Dr. Steven Pearson and others at Drexel University sheds some light on the issue. Their research found that the invasive red-eared slider (Trachemys scripta elegans) outcompeted the red-bellied turtle (Pseudemys rubriventris) in a series of experiments.
The results showed that red-eared sliders could outcompete the red bellied turtles through a food based mechanism. Under some conditions, they could simply consume more of the food and thus limit the resources of the red-bellied turtles. When food was abundant, the red-bellied turtles actually ate more food. This suggests that even when red-eared sliders receive less resources, they have higher efficiency and can still outcompete the red-bellied turtles.
In any environment where the red-eared slider can survive, it can outcompete and thrive. Indeed, we are already seeing these effects across the United States as the red-eared slider expands its territory. The problem is not just restricted to the United States either. The slider’s worldwide popularity as a pet contributes to its invasiveness and now the slider threatens to outcompete turtles around the world.
For example, experts became alarmed when there were reported sightings of red-eared sliders in Australia. Professor Burgin from the University of Western Sydney stated that “once they get a toe-hold in the wild, they become established quite quickly. Feral turtles … present a real threat to the indigenous turtle population because of their aggressiveness and their ability to cope with more extreme conditions”. Their fear seems rightfully placed considering the world’s ongoing biodiversity crisis. The invasion of red-eared sliders may make our current ecological problems worse.
So what can be done about this threat? Regulations have already been put in place to prevent the sale of red-eared sliders smaller than 4 inches in the United States. Although the ban was put in place to prevent the spread of salmonella, there are likely to be ecological benefits as well. By forcing consumers to only be able to consider older turtles as pets, the regulations should prevent people from underestimating the amount of care a pet turtle requires and thus result in less abandonments. Less abandoned turtles will mean less invasiveness.
That being said, there are those in the turtle breeding industry who have been working to minimize salmonella in their baby turtles. In a news piece with NPR, industry scientist Mark Mitchel claims to have been able to reduce their salmonella rates from 30% to a mere 1%. Given their great results, the industry seeks to repeal the ban. To be sure, they make a good point if we only consider the ban as a public health issue. However, we should keep in mind the positive ecological impacts of the regulations before considering repealing it.
Regulations cannot replace responsibility. Despite all of its troublemaking invasiveness, the red-eared slider is simply too charismatic. It will be a popular pet for years to come regardless of regulations. We must make a commitment to care for our red-eared sliders and in doing so, care for our wildlife as well. With our help, all turtles can thrive.
“Global Invasive Species Database.” Global Invasive Species Database. Invasive Species Specialist Group, n.d. Web. 23 Oct. 2015.
“News Archives.” Western Sydney University. University of Western Sydney, n.d. Web. 23 Oct. 2015. <http://apps.westernsydney.edu.au/news_archive/index.php?act=view&story_id=1171>.
Pearson, Steven H., Harold W. Avery, and James R. Spotila. “Juvenile Invasive Red-eared Slider Turtles Negatively Impact the Growth of Native Turtles: Implications for Global Freshwater Turtle Populations.” Biological Conservation 186 (2015): 115-21. Web.
“Red-eared Slider – FactSheet.” Red-eared Slider – FactSheet. United States Geological Survey, n.d. Web. 23 Oct. 2015.
Rovner, Julie. “Bill Seeks to Lift Ban on Baby Pet Turtles.” NPR. NPR, n.d. Web. 23 Oct. 2015.