Relocating nuisance American crocodiles (Crocodylus acutus) has become a common practice aimed at reducing human–wildlife conflict. However, recent research led by Dr. Christopher Murray at Southeastern Louisiana University and a team of collaborators from Costa Rica and the United States reveals that these efforts might be less effective than previously thought. The study, published in Animals, explores the movement patterns of relocated crocodiles using advanced satellite tracking technology, uncovering significant insights into the challenges of managing these apex predators.
The research team, which includes Dr. Mahmood Sasa, MsC. Davinia Garrigos, Dr. Tyler Steven Coleman, Wray Gabel, Michael Easter, and Maggie McGreal, set out to evaluate the efficacy of crocodile relocation by tracking five individuals, three of which were captured and relocated from aquaculture ponds, while two were wild residents of Palo Verde National Park. The relocated crocodiles, all males, were transported to the park, a distance believed to keep them away from human activity.
Advanced satellite tracking devices, specifically Telonics Iridium SeaTrkr-4370-4 transmitters, were affixed to the crocodiles, allowing the researchers to monitor their movements with unprecedented precision. The study revealed that two of the relocated crocodiles, named George and Jerry, traveled significantly greater distances compared to their wild counterparts, with George covering nearly 89 kilometers and Jerry approximately 70 kilometers. This extensive movement contrasted sharply with the wild crocodiles, who stayed within much smaller home ranges.
Intriguingly, the study found that the relocated crocodiles demonstrated a strong tendency to return to their original capture sites, effectively undermining the purpose of their relocation. “These results highlight the need for alternative management strategies,” said author Christopher M. Murray. The research suggests that the current practice of relocating nuisance crocodiles may be futile, as these animals are highly adept at navigating back to familiar territories, even over considerable distances.
The implications of these findings are significant. The frequent return of relocated crocodiles to areas of human activity allows the likelihood of dangerous encounters to persist, thereby maintaining the very conflict the relocations are meant to mitigate. The study underscores the importance of re-evaluating current management practices globally. “If relocation is to become an effective practice, nuisance animals require much more distant relocation or relocation to a place that presents an impenetrable barrier between the release and capture site,” Dr. Coleman adds.
This research also raises questions about the potential use of other mitigation strategies, such as relocating crocodiles to controlled environments like educational facilities or limiting human access to crocodile habitat, which could serve as more permanent solutions to the problem. Additionally, the study calls for further investigation into the sensory cues that enable crocodiles to navigate so effectively over long distances, which could lead to new insights into improving relocation strategies.
As human populations continue to expand into wildlife habitats, the frequency and severity of human–wildlife conflicts are likely to increase. This study provides valuable data that could inform future efforts to manage these conflicts, not just in Costa Rica, but in similar ecosystems worldwide. The researchers recommend that future studies expand on this work by exploring variations in crocodile movement patterns across different environmental conditions, including seasonality and ecotoxin exposure.
In conclusion, while the relocation of nuisance crocodiles remains a widely used management tool, this study demonstrates that without significant changes, these efforts may not be sufficient to reduce human–wildlife conflict effectively. The findings suggest a need for more innovative approaches, such as Coupled Human and Natural Systems, that consider the complex behaviors and ecological needs of these apex predators during the Anthropocene.
Journal Reference
Coleman, T.S., Gabel, W., Easter, M., McGreal, M., Sasa Marin, M., Beneyto Garrigos, D., & Murray, C.M. (2024). “The Spatial Ecology of Nuisance Crocodiles: Movement Patterns of Relocated American Crocodiles (Crocodylus acutus) in Guanacaste, Costa Rica.” Animals. DOI: https://doi.org/10.3390/ani14020339
About the Authors
Chris Murray PhD: received his Bachelors of Science from Juniata College in 2008, a Master’s of Science from Southeastern Louisiana University in 2011, and a doctorate from Auburn University in 2015. Chris is primarily focused on the evolution and physiological ecology of vertebrates in temperate, Neotropical and subtropical coastal wetlands. He is interested in diagnostic and functional morphology utilizing geometric morphometrics to identify diagnostic characters of undescribed species and assess phenotypic plasticity in an ecological context. Many of his questions address how the physiology of individuals alters relevant population or community ecology. Lastly, Chris strives to contribute to biogeographic and evolutionary ontology and operation and novel metaphysical thinking regarding the existence and appropriate use of biological units.
Tyler Steven Coleman PhD: received his Bachelors of Science from Tennessee Tech University in 2016, a Master’s of Science from Auburn University in 2019, and a doctorate from the University of Florida in 2023. Tyler’s research lies at the interface between ecology (e.g., population, community, behavioral), biology (e.g., physiology, morphology, ontogeny), and natural resource management. He is particularly interested in integrating these theoretical and applied fields using innovative quantitative techniques. He is passionate about the multi-disciplinary aspect of ecological studies, as this is essential to integrate knowledge across disciplines to develop, test, and apply theory to advance human understanding and inform management decision-making.
Mahmood Sasa PhD: is a Costa Rican biologist that holds a Masters of Science and a Ph.D. in Quantitative Biology from the University of Texas at Arlington. He is a full professor at the Department of Microbiology and the School of Biology at the University of Costa Rica. His research at the Instituto Clodomiro Picado and the Center for Research in Biodiversity and Tropical Ecology of the same university, spanning almost three decades, focuses on the biology of reptiles, especially snakes, and their interactions with human communities. His main areas of interest include herpetology, tropical ecology, biogeography, evolution of envenoming mechanisms, biodiversity analysis, and biostatistics. Additionally, he participates in conservation biology projects, conflict wildlife management, and the management of protected wildlife areas.
Davinia Beneyto Garrigos: received her Bachelors of Biology in 2011 and a Master’s of Biodiversity: Conservation and Evolution in 2012 from University of Valencia. Davinia’s research is focused mainly in Conservation, Ecology and Biodiversity of Tropical and European Reptiles and Amphibians. She currently works as a professor at the University of Costa Rica, researching birth patterns resulting from mass nesting in sea turtles in the North Pacific of Costa Rica, where climate change could have important implications for the survival of these species.
Wray Gabel: received her B.A. in 2016 from Skidmore College and her Masters degree in 2019 from the University of Florida in Wildlife Ecology and Conservation. Her main area of expertise is in avian monitoring and research, but she also has a research interest in crocodilians, specifically in their apparent mutualism with colonial nesting wading birds. She has extensive experience conducting remote field research all over the world with a variety of species. Wray has worked on monitoring, management, and research projects all over the world, and is passionate about the implementation of research-based conservation and management practices in wildlife ecology.
Michael Easter: earned his B.A. in 2008 from Florida International University. Since then he has promoted wildlife conservation and education through various media and has performed herpetological outreach at local, regional, national and international scales. Mike has also served as a field technician for the Murray Lab since 2012 and a collaborator on the Costa Rica Crocodile Management Project.
Maggie McGreal: is a graduate researcher in the Department of Biological Sciences at Southeastern Louisiana University where her current research investigates the movement ecology of crocodiles. Her interests involve the use of innovative technology and quantitative techniques to address complex issues related to human-wildlife conflict and environmental change, with a focus on alternative approaches that utilize movement and behavioral ecology principles.
