The common spotted eagle (Aetobatus narinari), found in estuaries and lagoons throughout Florida, is listed as endangered on the IUCN’s Red List of Threatened Species. Keeping records of this highly mobile species for conservation efforts can be extremely difficult, especially over long periods of time. Researchers at the Oceanographic Institute at Atlantic University of the University of Florida have used uniquely coded transmitters and acoustic telemetry to track the movement and behavior of the endangered species. Biotelemetry has provided researchers with unique insights into the occupation of this species. The research results are published in the journal Endangered Species Research.
Although the species has been a protected state in Florida for over two decades, this study is the first to characterize the ecology and small-scale use of the spotted eagle’s habitat in Florida. And also identify areas of potential interactions between this species and numerous environmental threats.
Scientists tracked seven mature individuals of this species (six males and one female) and tracked them individually for a total of 119.6 hours. They used the tracking vessel to continuously and manually track the eagles between June 2017 and August 2018.
The results of the study indicate that spotted eagles use the deeper parts of the Indian River Lagoon (a long brackish lagoon in Florida) during the day and shallower parts at night. In addition, they move faster in the ocean and lagoon and slower in channels and entrances.
This information suggests that spotted eagles may spend more time foraging for food at night in the shallow lagoon than during the day. The observations revealed similarities between the habitat of the endangered species and places of great recreational and commercial importance.
Understanding channel use is critical for assessing risks and potentially developing strategies to mitigate negative impacts on spotted eagles. Their habitats are subject to intense human activity – boating and fishing, and dredging operations for commercial purposes. In addition, noise and chemical pollution are increasing in these areas.
As spotted eagles are already more likely to appear in human-modified habitats, increased interaction with humans and additional pollution and/or disturbances can lead to changes in movement patterns and species health. Ultimately, such human-induced changes in habitat can reduce the exacerbating pressures already being felt by populations of spotted eagles.