Habitat loss, pollution, poaching, climate change, and disease are some of the factors that endanger turtles
Sometimes, they also suffer from injuries caused by human activities, such as boat strikes, fishing gear entanglement, or ingestion of plastic debris.
When these turtles are found by wildlife rescuers, they are often brought to rehabilitation centers where they receive medical care and nursing until they are ready to be released back into the wild. But what happens to these turtles after they are set free?
How do they adapt to their natural environment? How long do they survive? And how can we monitor their health and behavior?
These are some of the questions that researchers and conservationists are trying to answer by tracking rehabbed turtles using various methods and technologies.
Tracking rehabbed freshwater turtles in North Carolina
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In North Carolina, a group of veterinary students from North Carolina State University (NC State) runs a volunteer organization called the Turtle Rescue Team (TRT), which treats over 600 wild turtles, reptiles, and amphibians each year.
About half of these animals are successfully rehabilitated and released back into their home environment.
However, the TRT does not have the resources or means to track all of these animals and discover what their health outcomes might be in the long term.
To address this gap, a former TRT member and graduate of NC State's veterinary school, Sarah Zurbuchen, conducted a pilot study to try and figure out what the survival odds really are for these animals and what the challenges of trying to track them would be.
Zurbuchen and her fellow TRT volunteers selected 16 turtles for the pilot study based on several logistical parameters, such as their fitness for release, their location of origin, their weight, and their consent from landowners.
There were no selection criteria based on presenting injury, diagnosis, or time spent in treatment/rehabilitation.
The team attached a radio transmitter to the back of each turtle's shell with a nontoxic waterproof epoxy, which had a distance of approximately 700 meters and a battery life of about 280 days.
Then, the turtles were released within an approximately one-mile radius of where they were found.
The team attempted to check in on the turtles monthly and record their health information.
The results were not very encouraging.
Of the 16 tagged turtles, three were found deceased within 86 days of release; five were never located after release; three were found once after release but not thereafter; four were successfully tracked until brumation (overwintering in which turtles enter a period of torpor) but were subsequently unable to be located; and only one turtle was successfully tracked for the entire study period.
The study revealed some of the challenges and limitations of tracking rehabbed turtles using radio telemetry. The distance on the radio transmitters turned out to be variable depending on the terrain and vegetation.
GPS trackers would be more exact, but they cost more and have a shorter battery life.
The study also highlighted the need for more collaboration and communication between wildlife rehabilitators, researchers, landowners, and government agencies to facilitate turtle conservation efforts.
Sea turtles are among the most endangered animals in the world. Six of the seven species of sea turtles are classified as vulnerable, endangered, or critically endangered by the International Union for Conservation of Nature (IUCN).
Sea turtles face many threats from human activities, such as fishing, poaching, coastal development, pollution, climate change, and disease.
When sea turtles are injured or sick, they are often rescued by wildlife organizations and brought to rehabilitation facilities where they receive medical care and nursing until they are ready to be released back into the ocean.
The center treats about 100 sea turtles each year, mostly green sea turtles and loggerhead sea turtles.
The center also collaborates with researchers from Florida Atlantic University (FAU) to track some of the rehabbed sea turtles using satellite tags.
In 2019, a team of researchers from FAU published a study that examined the post-release movements and survival of 11 rehabbed juvenile green sea turtles that were tagged with satellite transmitters before being released into the Atlantic Ocean between 2010 and 2013.
The study aimed to evaluate the effectiveness of rehabilitation and release protocols for sea turtles and to provide insights into their ecology and behavior.
The results were more positive than the previous study. All 11 turtles survived for at least one year after release, and nine of them were still transmitting after two years.
The turtles showed a high degree of fidelity to their release sites, staying within 50 kilometers of the coast and within 100 kilometers of their release locations.
The turtles also exhibited seasonal movements, migrating northward during the summer and southward during the winter.
The study suggested that the rehabbed turtles were able to reintegrate into their natural environment and resume normal activities.
The study also demonstrated the benefits and challenges of tracking rehabbed sea turtles using satellite tags.
Satellite tags provide more accurate and frequent location data than radio tags, but they are also more expensive and prone to damage or detachment.
The study also emphasized the importance of selecting appropriate release sites and times for sea turtles to maximize their survival and minimize human interactions.
