Diverse migratory strategies for a hawksbill sea turtle population

Abstract

Outside of short, infrequent visits to reproductive habitats, sea turtle lifespans are largely spent in foraging areas. Supporting imperilled populations in an era of biodiversity declines and environmental change requires improvements in the understanding of foraging distributions, plus the migratory corridors that connect foraging and reproductive habitats. This study evaluates the migratory strategies and foraging geography of hawksbill sea turtles (Eretmochelys imbricata) in the Western Atlantic. The post‐nesting migrations of 22 females were tracked via satellite telemetry from Long Island, Antigua, during 2016–2019, and a state‐space model was utilized to estimate true turtle locations from Argos satellite fixes. Model output was used to characterize migratory routes and home ranges occupied during non‐migratory inter‐nesting and foraging periods. Hawksbill migrations (N = 19) resulted in displacements to foraging areas ranging 7–2300 km. Foraging geography varied considerably—whereas eight turtles remained in the immediate vicinity of Antigua and Barbuda (<30 km), there were also longer‐distance migrations (>470 km) to locations such as The Bahamas and Nicaragua. Inter‐nesting core home ranges (50% utilization distributions) ranged from 7 to 72 km2, while foraging core areas ranged from 7 to 46 km2. These results add to evidence suggesting that, broadly, post‐nesting hawksbills forage in neritic habitats throughout the Wider Caribbean, including several high‐use areas. Short displacements to foraging habitats relatively nearby to nesting beaches appear to be the most common migratory behaviour, but individuals in a single population may exhibit various migratory strategies, resulting in basin‐wide connectivity between nesting and foraging sites. Given that a single individual or nesting population may inhabit several management jurisdictions, an idealized scenario for regional hawksbill conservation would entail data sharing between managers at linked nesting areas, foraging habitats and migratory corridors such that policies to protect key habitats and mitigate human impacts are designed and evaluated based on best‐available science.