Photo‐identification confirms polyandry in loggerhead sea turtles

Abstract

While polyandry in sea turtles is indicated through multiple‐paternity analyses of offspring, confirmed observations of the same female mating with multiple males are extremely challenging to obtain. To contribute to this discussion, we analysed a long‐term photo‐identification database (>20 years) of adult male and female loggerhead sea turtles frequenting the breeding area of Zakynthos, Greece, Mediterranean. A total of 38 records of mating individuals within and across seasons were assimilated via field surveys and citizen science records between 2003 and 2020. For one female, we recorded it mating with two different males within a 5.5‐h interval on the same day in 2015. This observation constitutes the first direct evidence of polyandry in sea turtles, in addition to highlighting the potential for photo‐identification to contribute information on less well‐known aspects of sea turtle biology, such as validating outputs of genetic studies.

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

“…Photo-identification relies on stable sea turtle external characteristics and thus can overcome the flipper tag-loss problem, a permanent point of concern for traditional CMR projects in both nesting and foraging grounds, (Pfaller et al ., 2019). Photo-identification has already been employed in Zakynthos island for a variety of sea turtle studies, like survival analysis (Schofield et al ., 2020), interspecific interactions in cleaning stations and foraging sites (Papafitsoros and Schofield, 2016; Schofield et al ., 2017; Dujon et al ., 2018), quantifying tourism pressure (Papafitsoros et al ., 2021), as well as documenting polyandry (Papafitsoros et al ., 2022). This study also took advantage of social media mining which together with dedicated citizen science platforms can help towards the collection of imaging data in large spatial and temporal scales and also retrospectively (Papafitsoros et al ., 2021; Papafitsoros et al ., 2022).…”

“…Photo-identification has already been employed in Zakynthos island for a variety of sea turtle studies, like survival analysis (Schofield et al, 2020), interspecific interactions in cleaning stations and foraging sites (Papafitsoros and Schofield, 2016;Schofield et al, 2017;Dujon et al, 2018), quantifying tourism pressure (Papafitsoros et al, 2021), as well as documenting polyandry (Papafitsoros et al, 2022). This study also took advantage of social media mining which together with dedicated citizen science platforms can help towards the collection of imaging data in large spatial and temporal scales and also retrospectively (Papafitsoros et al, 2021;Papafitsoros et al, 2022). Recent and continuous developments in automatic animal re-identification algorithms (Dunbar et al, 2021;Stewart et al, 2021) in combination with automatic mining for animal imagery in social media, open-data citizen science platforms (Berger-Wolf et al, 2017;Giovos et al, 2019), as well as advances in machine learning already facilitate these type of studies (Di Minin et al, 2018;Dujon and Schofield, 2019) and are expected to do so even more in the future.…”

“…In particular, with respect to sea turtles, citizen science has been exploited in many different ways during the last years, in a variety of studies. These range from determining foraging and nesting habitat distributions (Hudgins et al ., 2017; Montagna et al ., 2017; Baumbach et al ., 2019; Casale et al ., 2020; Hanna et al ., 2021; Read and Jean, 2021), and evaluating tourism pressure (Papafitsoros et al ., 2021) to documenting polyandry in loggerhead sea turtles (Papafitsoros et al ., 2022). Typically in these type of studies photo-identification is also employed, exploiting the unique facial scale pattern of sea turtles, which is stable throughout their lifetime (Schofield et al ., 2008; Carpentier et al ., 2016), allowing for monitoring of specific individuals.…”

“…For instance, a recent study that took place during the 2018-2019 seasons, and was based on the number of photographs of sea turtles of Zakynthos uploaded by tourists to social media (Instagram), revealed that the resident individuals are subject to high tourism pressure linked to high risk of propeller injuries and boat strikes (Papafitsoros et al ., 2021). Another study also based on browsing online images of loggerhead sea turtles of Zakynthos led to the first direct documentation of polyandry in that species (Papafitsoros et al ., 2022).…”