Male treefrogs call to attract mates. When multiple males call simultaneously, the chorus self-organizes: nearby frogs alternate calls (taking turns), while distant frogs show no coordination. The transition from independent calling to structured alternation has been demonstrated in laboratory pairs. What happens in a real chorus of dozens of animals in a natural habitat?

Three years of field recordings — 11 choruses, 66 males — reveal the answer (arXiv:2603.16051). Synchronized behavior emerges gradually as a function of distance between callers. Close neighbors alternate with high precision. Frogs slightly farther apart show weaker but detectable coordination. Beyond a critical distance, coordination vanishes into noise. The transition is smooth, not a sharp boundary.

The through-claim: the chorus structure is locally determined but globally emergent. No frog coordinates the group. Each animal adjusts its timing based only on what it hears from its nearest neighbors. The distance-dependent gradient of coordination emerges from this purely local rule because acoustic signal strength decays with distance. Closer frogs hear each other more loudly, respond more precisely, and produce tighter alternation. The spatial structure of the chorus encodes the spatial structure of the sound field.

What makes this result significant is that it holds despite moderate variation in call frequency and chorus density. The temporal organization is robust to the very factors that vary most across nights and populations. The frogs don’t need identical conditions to coordinate — they just need to be close enough to hear each other clearly.