Flycatchers time their arrival with insect emergence

The air above the wetlands near Geneva Township carries a different energy in early summer. Close your eyes and listen for the sharp snap of beaks closing on invisible prey. Eastern kingbirds perch on the tallest dead snags, launching themselves into the air with sudden purpose before returning to the same branch. Their white-tipped tails flash against the green backdrop of breaking oak and maple leaves.

These aerial hunters have timed their arrival precisely. Beneath the water's surface, mayfly and caddisfly larvae that have spent months or even years developing are now climbing toward the light. The water temperature has reached the threshold that triggers their final transformation. They emerge in waves, their delicate wings still soft as they struggle free from their larval cases. For a brief window, the air fills with insects that have never flown before, their flight patterns erratic and vulnerable.

Eastern wood-pewees hunt from lower perches in the mid-canopy, their plaintive calls carrying through the humid air. Unlike the aggressive kingbirds above, pewees make shorter flights, picking off smaller midges and gnats with surgical precision. They return to the same perch repeatedly, their bills clicking shut on each capture. The two species divide the airspace between them, kingbirds claiming the open sky above the treeline while pewees work the shadowed spaces beneath. Both are feeding young now, their breeding cycles synchronized with this abundance. A single wood-pewee may catch three hundred insects in a day during peak emergence, carrying beakfuls of protein back to nestlings that demand food every twenty minutes from dawn to dusk.

The emergence itself happens in pulses tied to water temperature and daylight hours. Caddisflies emerge at dusk, their tent-shaped wings catching the last light as they rise from the water in clouds. Mayflies often emerge at dawn, their brief adult lives measured in hours rather than days. Midges emerge throughout the day in smaller numbers, providing a steady food source between the larger hatches. The flycatchers read these patterns, positioning themselves where the insects will be thickest, their hunting territories overlapping with the emergence zones of different species. Listen for that sharp snap again, somewhere in the canopy above you, as another insect completes its ancient journey from water to air to waiting beak.