There is no birdsong at Ritidian Point. The limestone forest behind this beach, at the northern tip of Guam, holds insects and the sound of the sea and little else. A brown tree snake that arrived on cargo after the Second World War worked through the island's native forest birds, and the path from the sand into the trees is the fastest way to understand what happened here. If you stand still for a minute, the quiet is what you take away. In front of the trees is the last undeveloped coastline on Guam. Inside the reef line the water lies waist-deep and glass-clear over pale sand and coral heads, calm as a pool, and no boats are allowed in there, so nothing crosses it but you. Green turtles nest on this beach through the year, and their tracks often last until mid-morning: two lines of flipper prints running up the sand and back to the water.
Behind the beach the cliff is itself an old reef, coral that grew underwater and was lifted clear. Northern Guam is one slab of that raised limestone, so porous that no river runs across it; the rain sinks straight through and dissolves the caves in the cliff face. CHamoru hands painted inside them, in red, white and black. In the one the refuge calls the Star Cave, sixteen painted dots are read as a calendar: a year of sixteen months, none the same length, tracked by the constellations rather than by counting days. You see those caves only on a guided walk. Out on the flat, a few days after the last-quarter moon, clouds of juvenile rabbitfish sweep in off the ocean. CHamoru families come down to the waterline with a talåya, the circular net thrown open with a flick of the shoulders. The birds did more than sing. Most of these trees needed them to carry their seeds away, and one study put the loss of seedlings at between 61 and 92 per cent, so the silence is also the forest failing to replace itself.