Osprey provision young as cottonwoods release seed

The cottonwoods along the South Boulder Creek corridor near Lafayette release their seeds now, white tufts drifting on the late spring air like snow that refuses to settle. Above the canopy, an osprey circles with measured wingbeats, scanning the water below where runoff keeps the creek running high and clear. The bird's broad wings catch thermals rising from the warming earth, each turn revealing the dark patches at the wrist that mark it unmistakably as a fish hawk.

This osprey pair has claimed a tall cottonwood for their platform nest, a mass of sticks and debris built in the crown where the trunk splits into major branches. The female tends eggs or recently hatched young while the male hunts, his fishing runs timed to the creek's rhythms. He hovers thirty feet above the water, yellow eyes fixed on movement below, then folds his wings and drops talons-first into the current. The splash sends rings across the surface, and he emerges with a fish gripped headfirst in his specialized feet, the outer toe reversible to give him a two-front, two-back grip that no other raptor can match.

The timing connects everything. Late spring runoff fills the creek with fish moving upstream to spawn, exactly when osprey young need the most protein. A single male may catch six fish daily during peak provisioning, each one carried back to the nest in that distinctive pose, the fish's head pointing forward to reduce drag. The cottonwoods fruit at the same time, their seeds requiring the moist soil that spring floods provide. Both species depend on water's seasonal abundance, the osprey for prey concentration, the cottonwoods for seed dispersal and germination sites in newly deposited sediments.

The relationship runs deeper than shared timing. Mature cottonwoods provide the height and structure ospreys need for their massive nests, platforms that may weigh half a ton after years of additions. The trees tolerate this burden because their wood is light and flexible, evolved to bend rather than break in the prairie winds that also carry cottonwood seeds to new ground. Meanwhile, the osprey's presence brings nutrients from the water to the tree, fish remains and droppings enriching the soil around the nest tree's base. The partnership anchors this riparian corridor, predator and tree both riding the pulse of snowmelt that defines late spring along the Front Range.

Look up now at any tall cottonwood, its leaves still that fresh yellow-green of new growth, and you might catch the flash of broad wings overhead. The osprey's call carries across the water, a series of sharp whistles that pierce the softer sounds of flowing current and rustling leaves heavy with approaching summer.