Kilauea is one of six active volcanoes in Hawaii. This spring and summer, it erupted, and ribbons of molten orange lava flowed down to the sea, destroying homes and burning through the forest. It’s a spectacular, cataclysmic sight, and the sounds that it makes are strange and surprising....

Indris, the largest living lemurs, are known for their high-pitched cries, which paired males and females make in tandem. They mate for life, and as they grow closer over time, their songs become more and more coordinated. Photograph by Piotr Naskrecki. Field recordings by the Ethology Lab at the...