Social media mining and photo-identification detects the shift of long-term seasonal foraging habitat for a juvenile loggerhead sea turtle

Abstract

Animal imagery uploaded on social media has been identified as an important tool in wildlife research and conservation and has been used in a variety of recent studies. Here a case study is presented, where a detailed analysis of social media content revealed a shift of a long-term foraging habitat for a juvenile loggerhead sea turtle (Caretta caretta) in Greece. In particular, this individual was a long term resident of Zakynthos island, Greece, from 2016 until 2020 (5 consecutive summer seasons), regularly foraging on a nearshore reef, with no observations of it being made during the 2021 season. However regular social media image mining combined with photo-identification, detected this individual foraging in the Gulf of Corinth in August 2021, more that 200km away from his previous foraging habitat. This case study (i) shows the possibility for juvenile loggerheads to shift their foraging site even after long term use, with implications in capture-mark-recapture studies and (ii) once more highlights the useful- ness of social media mining and citizen science in diverse aspects of sea turtle studies.

Underreported in-water behaviours of the loggerhead sea turtle:Foraging on sea cucumbers

“…All four observations took place in Agios Sostis area, around Agios Sostis Islet at the northwest part of Laganas Bay, Zakynthos, see Figure 1 for the approximate locations. The reef around Agios Sostis Islet is a well-known foraging ground in which resident male and juvenile turtles of Zakynthos prey on the sponge Chondrilla nucula which is abundant on this reef, (Papafitsoros and Schofield, 2016;Schofield et al, 2022). All the three turtles in the observations below have been such long-term residents and they have been logged in a existing photo-identification database consisting of more than 1500 individuals from this site, (Schofield et al, 2020;Papafitsoros et al, 2021).…”

“…At the same time a second loggerhead approached it (ID name "t323"). The second turtle was also a long-term occupant of the reef, foraging consistently on sponges, from 2016 until 2020, see also (Papafitsoros, 2022a). The male turtle "G18-04" began making circular avoiding movements, eventually releasing the sea cucumber.…”

“…In-water observations, citizen science and photo-identification have also revealed the existence of a small year-round resident population (approximately 40 individuals) consisting mainly by adult males and juveniles (Papafitsoros et al, 2021;Papafitsoros et al, 2023). These individuals can be regularly seen foraging on sponges (Chondrilla nucula), molluscs (Papafitsoros and Schofield, 2016;Schofield et al, 2022), as well as discarded fishermen bycatch at a small port in Laganas Bay, (Agios Sostis port; author's personal observations).…”