An international team of researchers have discovered seven new species of tree frogs that make otherworldly calls in the rainforests of Madagascar. Their strange, high-pitched whistling calls sound more like sound effects from the sci-fi series "Star Trek.

In the rainforests of Madagascar, it can feel like you’ve stepped into another world. The air hums with life, dense with the sounds of birds, insects, and rushing streams. But if you listen closely, you might hear something even stranger — a faint,