Movements of high-level predators between habitats highlight the importance of disparate, yet critical habitats. Resulting habitat linkages have important ecological implications. Establishing linkages and their consequences requires thorough understanding of spatio-temporal patterns of habitat use and their drivers. This is often lacking in marine predators which can occur at low density and are difficult to track.
To address this, we applied a multi-method approach to the critically endangered great hammerhead. Tracking of hammerheads and bull sharks within a large-scale acoustic-array in Queensland was combined with stable-isotope-analysis of predator and prey and video/drone surveys. Movement/stable isotope analyses link small-scale movements in hammerheads to year-round available batoid prey. Supporting this, drone surveys reveal no seasonality in batoid abundance in inshore habitats, frequented by hammerheads. Videos documented numerous predation events on batoids along the coast. In contrast, the wider trophic niche of bull sharks corresponds to seasonal large-scale movements.
Repeated movements between inshore and coral reef environments by hammerheads provide important linkages. The specialized trophic ecology of this predator likely affects batoid bioturbation rates and space-use. Inshore habitats are disproportionately affected by anthropogenic stressors and trophic specialization culminating in dependence on such habitats with limited demographic connectivity make the great hammerhead particularly vulnerable.