No more toe-clipping: a frog's golden eyes are its fingerprint

To follow a wild frog, scientists used to clip its toes — a marking method that can harm an animal that climbs for a living. In French Guiana's Nouragues Nature Reserve, a University of Bern team led by Dr Mélissa Peignier found a kinder way: the golden irises of the Amazonian treefrog Osteocephalus oophagus are crossed by fine black lines unique to each frog, like a fingerprint. Across 392 captures over three rainy seasons, they identified 103 individual frogs from photographs alone, re-identifying 56% to 80% of them within a season without touching them. The study, in the journal Herpetozoa, suggests other amphibians with complex eyes could be tracked the same gentle way. 'If we can reliably identify individuals using naturally occurring features, we may be able to reduce the need for more invasive marking,' Peignier says.

SDG 15 · Life on land — Mechanism: tech innovation