It’s an installation: Wrens pinned like brooches to the trees, singing, their eyes glass beads. Shake a branch, be wary of what falls. In the unofficial spring, sunshine plays xylophone on the lawn. The trebly notes are mouths singing oh, oh, oh. A paper boat leads the children downstream, through countless shades of green—spring, grass, moss, forest. Light plus one green makes another. The exhibit rotates seasonally. Soon enough the children will instead be foxes, the greens will rust. Someone will strike the wren set. But for now their songs saturate the air. If the message is urgent, they’ll tell again tomorrow.