Hikers in Papua New Guinea heard an “eep-eep-eep” sound and followed it to a yellow-spotted animal. Take a look.

The team collected over 130 of these Ecuadorian tree frogs by combing museum archives, searching the rainforest and raising some eggs in captivity, the study said. A pattern began to emerge.

The team collected over 130 of these Ecuadorian tree frogs by combing museum archives, searching the rainforest and raising some eggs in captivity, the study said. A pattern began to emerge. The frogs ...