Cliff swallows nest where insects rise

The cliff swallows are back over Liberty Park's water, their voices sharp and quick in the early morning air. They dart and wheel above the pond surface, where something invisible to us draws them down again and again. The longest days of the year have arrived, and with them the peak of the swallows' nesting season. If you listen closely, you can hear the constant chatter from their mud colonies, built now into the eaves of park structures and tucked under bridge spans throughout the Salt Lake Valley.

Each swallow carries a beak full of wet earth back to its gourd-shaped nest, but the real work happens in the air above the water. Aquatic insects are emerging now in steady pulses from the pond and nearby streams. Midges, caddisflies, and mayflies spend months underwater as larvae, then rise to the surface in synchronized emergences that can last for hours. The swallows know this rhythm. They time their nesting to coincide with these daily hatches, when protein-rich insects lift off the water in concentrated clouds. A single emergence can feed an entire colony.

The swallows hunt with precision that comes from generations of practice. They read the water's surface for the subtle disturbances that signal insects breaking through. A slight dimple, a momentary sparkle, and the bird adjusts its flight path mid-air. Unlike their barn swallow cousins who hunt higher in the air column, cliff swallows work the interface between water and sky. They snatch insects just as they complete their transformation from aquatic nymph to flying adult. This timing matters. The insects are soft-bodied and vulnerable in these first moments of flight, before their wings harden and their escape patterns develop. For the swallows, it is a harvest that requires split-second coordination between dozens of birds working the same patch of water.

The colony's success depends on this abundance. Each pair of cliff swallows feeds four or five nestlings, and each nestling requires hundreds of insects daily during the three weeks before fledging. The parents make continuous trips between the emergence sites and their mud nests, carrying insects back in their throat pouches. The timing of peak emergence matches precisely with the swallows' highest energy demands. When you watch them hunt, you are seeing both an individual bird feeding and an entire ecosystem synchronized to the rhythm of insect metamorphosis.

The water holds its own light this morning, reflecting the swallows' quick shadows as they pass. Each dive sends small ripples across the surface, and somewhere below, the next generation of aquatic insects continues its slow development toward another emergence.