Hawksbills help maintain the structural complexity of the habitat, playing an important role in the function of marine ecosystems. In coral reef systems, for instance, they feed on certain species of sponges, which would otherwise out-compete coral, invertebrates and other sponges for space and nutrients and limit the biodiversity of these environments. Hawksbills free up the reefs for a mix of species to thrive.
Additionally, by depositing their nutrient-rich eggs along the shoreline, hawksbills serve as a critical link between the marine and terrestrial environments. Many eggs do not hatch, and the nutrients are reincorporated into the typically nutrient-poor beaches and dunes. Sea turtle eggs also provide a food source for many natural predators, which in turn redistribute nutrients among dunes through their feces.
When you meet a hawksbill turtle, you’ll notice their tapered heads – ending in a sharp point resembling a bird’s beak – which are perfect for finding their food sources, often located in hard-to-reach areas. Hawksbills are the only species of sea turtle with a brilliantly colored, keratinous shell consisting of overlapping (imbricated) scutes, colloquially referred to as a tortoise shell. Scutes are bony external plates, like scales, overlaid with a tough outer layer. Keratine is also the chief structural component of fingernails, horns and hooves, which makes the shells of hawksbills strong, yet pliable. Hawksbills are the only sea turtle species with a combination of two pairs of prefrontal scales on the head and four pairs of costal scutes on the carapace.
Hawksbill can be found in tropical and sub-tropical waters throughout the world’s oceans. Post-hatching hawksbills are thought to undertake ‘swim frenzy’ until reaching oceanic waters where they spend their first years developing. After several years in the open ocean they recruit to coastal zones, where they spend the majority of their juvenile and adult lives. Juvenile hawksbills are typically more sedentary than adults and while adults can undertake migrations of thousand of kilometers, some individuals have been found to be completely non-migratory. In general, the species is typically considered less migratory than other sea turtles.
Hawksbills have traditionally been known to inhabit areas with hard substrates, such as rock and coral reefs. However, while they also use these habitats in the eastern Pacific, a large proportion of adult and juvenile hawksbills have been discovered living in mangrove estuaries. In fact, this is how researchers believed the species evaded detection for so long in the eastern Pacific, no one was looking for them in the estuaries! The use of estuaries may be the result of the fact that coral reefs are much less common in this ocean region (compared to the Caribbean and Indo-Pacific for example). Juvenile hawksbills are typically omnivorous, feeding on an amalgam of fauna and flora, while adults feeding predominately on sponges and algae. In the eastern Pacific however, where adult hawksbills are living in mangrove estuaries, their diets are still not clear, but research has identified mangrove shoots, algae, invertebrates and sponges as important dietary items. Investigations are currently underway to understand this aspect of their life history in the region.