A unique study on hawksbill sea turtles (Eretmochelys imbricata) — co-authored by CI’s Bryan Wallace — was published today in the journal Biology Letters. Here, lead author and guest blogger Alexander Gaos writes about the discovery that changed what he thought he knew about hawksbill behavior.
After 10 years of working with sea turtles in countries throughout Latin America, I thought I knew all the habitats where these animals could be found. Amazingly, the one place I hadn’t considered is now where I spend most of my time.
In 2008, when my wife Ingrid and I, accompanied by our one-year-old son Joaquinn, hopped in our beat-up truck and began scouring the Pacific coast of the Americas from Mexico to Panama in search of rarely reported hawksbill turtles, we expected to write a report summarizing how they were virtually impossible to find and that their chances of survival were nil. It made perfect sense at the time, as most experts indicated the species had been extirpated in the region.
However, our three-year study — published recently in the Royal Society journal Biology Letters — has completely changed what we thought we knew about these turtles.
For this study, we tracked hawksbill movements in four countries (El Salvador, Honduras, Nicaragua and Ecuador) using specialized transmitters that relay the turtles’ whereabouts via satellite. The principal findings of the research showed that adult hawksbill turtles in the eastern Pacific inhabit in-shore mangrove estuaries. This is a unique behavior that represents a new life history paradigm for this species and contrasts starkly with the open-coast, coral reef dwelling behavior typically associated with hawksbills in other parts of the world.
Why are turtles seeking shelter in mangroves? They may have developed this unique behavior due to a lack of their typical habitat (coral reefs) in the region. It’s unclear if this is a recent adaptation or a more established behavior.
Now that I spend the majority of my time working in mangrove estuaries, I can see why the species went undetected in the eastern Pacific for so long. Many researchers and recreational divers in other parts of the world study and observe hawksbills swimming near coral reefs in clear blue waters, but spying an adult hawksbill in a mangrove estuary is extremely difficult. Even the most avid diver is unlikely to enter a mangrove estuary, where visibility often does not extend beyond one’s hand. Furthermore, when hawksbills surface to breathe they do it ever so quickly, barely breaking the water’s surface before heading back down to the ocean floor.
These new findings provide important insights about where to look for key nesting and foraging habitats for hawksbills in the eastern Pacific. In doing so, we also increase optimism that this — one of the most endangered populations of sea turtle on the planet — has a real chance at recovery.
Alexander R. Gaos is a conservation scientist with San Diego State University and UC Davis, and executive director of the Eastern Pacific Hawksbill Initiative.