Behavior of juvenile green turtles in a coastal neritic habitat: Validating time–depth–temperature records using visual observations

•Subjective decisions to infer green turtle using time–depth recorder (TDR) data•Simultaneous comparison of TDR data with visual observation videos•TDR data describes only four of six primary behaviors, and not completely.•TDR data describes behavior weaker with added habitat variable.•TDR data insufficient on its own to describe a turtle's full behavioral repertoire.

There are inherent limitations to inferring green turtle (Chelonia mydas L.) diving behavior from time–depth recorders (TDRs). Validating TDR data with independent observations of turtle behaviors is imperative to derive behavioral inferences from these archival data. Logistic regressions of video observational data and corresponding TDR data from six juvenile green turtles at the Kawai‘nui Marsh Estuary (KME) in Kailua Bay, O‘ahu, Hawai‘i, were used to determine the extent to which TDR records capture six specific behaviors recorded using a submersible video camera. While foraging, food searching, hovering, and breathing could be explained using a combination of TDR-derived metrics, the records could not describe swimming and resting. The habitat associations of turtle activity patterns (activities) were also evaluated, with some behaviors being more commonly encountered in specific habitat types, including resting and breathing. Comparison of video-recorded in situ observations of juvenile green turtles to concurrent TDR records indicated that TDR data alone can accurately describe certain turtle behaviors at KME, but are insufficient to describe a turtle's full range of behavior. Therefore, we contend that direct behavioral observations augment TDR deployments by ensuring the full behavioral repertoire of juvenile green turtles is captured. The integration of these disparate datasets can enhance the understanding of juvenile green turtle behaviors, especially within shallow heterogeneous habitats like the Kawai‘nui Marsh Estuary.