The Hula painted frog was discovered in March 1940, when Heinrich Mendelssohn and Heinz Steinitz spotted two beautiful individuals in the wetlands of Israel’s Hula Lake. They had distinctive dark bellies with white spots, and streaks of olive, black and rust on their backs. A third adult was found in 1955, and that was the last anyone saw of it for decades. Many searched; none succeeded. In the meantime, the wetlands of the Hula Valley had been drained to make way for encroaching farmlands.

With its habitat degraded and its presence undetected, things didn’t look good for the frog. In 1996, after four decades of failed searches, it became the first amphibian to be classified as extinct by the International Union for Conservation of Nature (IUCN). That, unfortunately, was an omen of things to come. We now know that frogs and other amphibians are among the most threatened of all animal groups. Around a third of them are classified as “threatened” and up to 165 species might already have gone extinct. Their habitats are disappearing. Pollution is killing them. A deadly fungus is wiping them out.

The picture is certainly bleak, but that might partly be because many amphibians live in inaccessible places and are hard to find. They were seen once, maybe twice, and then never again. Have they actually died out, or are there small populations clinging onto life? If it’s the latter, we could double our efforts to protect the survivors, or enrol them in breeding programmes. But first, we’d have to find them.

To that end, Conservation International launched the “Search for Lost Frogs” in 2010—a huge search for 100 species that hadn’t been seen for at least a decade. They only found four of their wishlist, such as the Rio Pascado stubfoot toad, re-discovered after a 15-year absence. These were small consolations for a project that otherwise failed. The world still needed hopeful stories.