Photo-identification of juvenile hawksbills using facial scales

Abstract

The ability to identify individuals within a population is a key issue for most behavioral, ecological and conservation studies. Most sea turtle mark-recapture studies use external flipper tags (metal or plastic) previously attached to identify individual. However, considerable tag loss can occur due to: time after tag attachment, incorrect attachment, being knocked/bite off, tagger, study area, target species, size, piercing site, tag material, color and design. Considering the long duration of sea turtle life cycles, flipper tag loss can be a major issue for conducting long term studies. Studies using photo-ID techniques in sea turtles include: head coloration patterns of leatherback turtles and facial profiles of green turtles, hawksbills, and loggerheads. Assessments of hawksbill facial profiles for photo-ID have been attempted before, but have been limited by small sample sizes. Here, the authors assessed the potential of using natural facial markings to reliably identify individuals in a juvenile aggregation of hawksbill sea turtles.